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Metaphorical signs in computed tomography of chest and abdomen 2014

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Metaphorical signs in computed tomography of chest and abdomen 2014

  1. 1. Metaphorical Signs in ComputedTomography of Chest and Abdomen 123 AndreyYudin
  2. 2. Metaphorical Signs in Computed Tomography of Chest and Abdomen
  3. 3. Andrey Yudin Metaphorical Signs in Computed Tomography of Chest and Abdomen
  4. 4. Andrey Yudin Department of Radiology Russian National Research Medical University Moscow Russia The Work was first published in 2012 by Prof. Dr. Andrey Yudin. ISBN 978-3-319-04012-7 ISBN 978-3-319-04013-4 (eBook) DOI 10.1007/978-3-319-04013-4 Springer Cham Heidelberg New York Dordrecht London Library of Congress Control Number: 2014933396 © Springer International Publishing Switzerland 2014 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. Exempted from this legal reservation are brief excerpts in connection with reviews or scholarly analysis or material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. Duplication of this publication or parts thereof is permitted only under the provisions of the Copyright Law of the Publisher's location, in its current version, and permission for use must always be obtained from Springer. Permissions for use may be obtained through RightsLink at the Copyright Clearance Center. Violations are liable to prosecution under the respective Copyright Law. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com)
  5. 5. v Andrey Yudin was born in 1957. Much in common: the same age, the exclusive models, all options, in good working condi- tions, with no rot and rust, sit down and drive, some problems on the body, etc. … Long ago in some of the radiology papers, I found a discussion concerning the peculiari- ties of the names of symptoms: if they are given the names of the authors, then we do not understand their meaning (after all, our specialty is largely metaphorical), and if we have a picturesque description of the image, then it is sometimes excessively emotional. As an From the Author Cadillac Eldorado 1957 model.
  6. 6. vi example of a failed metaphorical formation, they cited the “1957 Cadillac Lights” sign. Not everyone in the world does know about this car; who knows? However, the well-known saying insists: “If you did one million bucks – buy the pink Cadillac to success unless that luck turns away!” I hope this publication will help you get lucky in our profession. Enjoy imaginative percep- tion of radiology! I want to tell the truth which I do not know, but I’m looking for it. Professor A. Yudin From the Author
  7. 7. vii Contents Saber-Sheath Trachea..................................................................................................... 1 Eggshell Calcification and Rim Enhancement ............................................................. 3 Split Pleura Sign.............................................................................................................. 5 Consolidation................................................................................................................... 7 Ground-Glass Opacity and Black Bronchus Sign........................................................ 9 Bat Wing, Butterfly, or Angel Wing Sign...................................................................... 11 Crazy-Paving Sign........................................................................................................... 13 Honeycombing................................................................................................................. 15 Vanishing Lung ............................................................................................................... 17 Mosaic Perfusion or Mosaic Lung Sign ........................................................................ 19 Air Trapping.................................................................................................................... 21 Swiss Cheese Appearance............................................................................................... 23 Feeding Vessel Sign or Fruits on the Branch Sign ....................................................... 25 Snowstorm Sign and Cannonball Metastases............................................................... 27 Air Bronchograms and Pseudocavitations ................................................................... 29 Halo Sign.......................................................................................................................... 31 Corona Radiata or Corona Maligna and Pleural Tail Sign ........................................ 33 Positive Bronchus Sign ................................................................................................... 35 Umbilical Retraction Sign or Rigler Incisura .............................................................. 37 Popcorn Sign and Bull’s Eye Calcifications.................................................................. 39 Target Calcification Sign ................................................................................................ 41 Satellite Foci and Galaxy Sign ....................................................................................... 43 Rounded Atelectasis, Comet-Tail Sign, and Crow’s Foot Sign ................................... 45 Tree-in-Bud Sign ............................................................................................................. 47 Air Crescent Sign ............................................................................................................ 49 Signet Ring Sign, Tram-Tracking Sign, String of Pearls, and Cluster of Grapes........... 51 Finger-in-Glove or Hand-in-Glove Sign........................................................................ 53 Atoll or Reversed Halo Sign........................................................................................... 55
  8. 8. viii Parachute Sign ................................................................................................................ 57 Atelectasis Discoidea, Atelectasis Lamellosa, or Platelike Atelectasis ....................... 59 Mesa, Tafelberg, or Table Mountain Sign..................................................................... 61 Pleural Mouse, Fibrin Body, Fibrin Ball, and Thoracolith......................................... 63 Draped Aorta Sign.......................................................................................................... 65 Sentinel Clot Sign............................................................................................................ 67 Intimal Flap and Beak Sign ........................................................................................... 69 Cobweb Sign and Mercedes-Benz Sign......................................................................... 71 Hyperdense Crescent Sign and Beret Sign ................................................................... 73 Web Sign and White (Calcified) Pulmonary Arteries ................................................. 75 Marble Liver Sign or Fatty Liver (Foie Gras).............................................................. 77 Geographic Liver ............................................................................................................ 79 Boxing Glove Sign........................................................................................................... 81 Confluent Fibrosis........................................................................................................... 83 Bull’s Eye Sign................................................................................................................. 85 Lacelike Fibrosis and Salt and Pepper Sign ................................................................. 87 White Liver Sign ............................................................................................................. 89 Periportal Halo................................................................................................................ 91 Ripples in the Water Sign or Target Sign ..................................................................... 93 Cluster of Grapes Sign.................................................................................................... 95 Water Lily Sign or Snake Sign....................................................................................... 97 Bright Dot Sign and Iris or Eye Diaphragm Sign........................................................ 99 Stellate Scar Sign or Spoke-Wheel Pattern .................................................................. 101 Funeral Frame Sign, Rim Enhancement, and Target-Like Appearance................... 103 Double Duct Sign............................................................................................................. 105 Central Dot Sign.............................................................................................................. 107 Mercedes-Benz Sign........................................................................................................ 109 Porcelain or Incrusted Gallbladder Sign...................................................................... 111 Annular Pancreas............................................................................................................ 113 Lake Chain Sign or String of Beads Sign and Pancreas with Sausage-Like Form and Hypodense Halo............................................................ 115 Honeycomb or Spongelike Mass and Spoke-Wheel Sign ............................................ 117 Fetal Lobulation or Lobation and Column of Bertin Hypertrophy........................... 119 Horseshoe Kidney ........................................................................................................... 121 White Pyramids Sign...................................................................................................... 123 Claw Sign or Beak Sign.................................................................................................. 125 Contents
  9. 9. ix Faceless Kidney Sign....................................................................................................... 127 Swiss Cheese Sign............................................................................................................ 129 Stellate Scar Sign or Starlike Scar Sign and Spoke-Wheel Pattern........................... 131 Fan Sign, Wedge-Shaped or Striated Enhancement, and Patchy Nephrogram........ 133 Medullary Sponge Kidney and Paintbrush Appearance............................................. 135 Putty Kidney Sign ........................................................................................................... 137 Cortical Rim Sign and Reversed Rim Sign................................................................... 139 String of Beads Sign or String of Pearls Sign............................................................... 141 Soft Tissue Rim Sign and Comet Sign........................................................................... 143 Whirlpool, Whirl, Swirl, and Whirling Sign................................................................ 145 Comb Sign........................................................................................................................ 147 Stratified Attenuation, Double Halo Sign, and Target Sign........................................ 149 Target Sign, Sausage-Shaped Mass, and Reniform or Kidney-Shaped Bowel.......... 151 Fat Halo Sign................................................................................................................... 153 Accordion Sign ................................................................................................................ 155 Rim Enhancement or Target Sign ................................................................................. 157 Soap Bubble Appearance and Small Bowel Feces Sign............................................... 159 Ring Sign.......................................................................................................................... 161 Omental Cake Sign ......................................................................................................... 163 Sandwich Sign ................................................................................................................. 165 Misty Mesentery Sign and Fat Halo Sign ..................................................................... 167 Dirty Fat Sign .................................................................................................................. 169 Hematocrit Sign .............................................................................................................. 171 Recommended Literature .............................................................................................. 173 Index................................................................................................................................. 175 Contents
  10. 10. 1A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_1, © Springer International Publishing Switzerland 2014 Saber-Sheath Trachea Saber-sheath trachea (↑) refers to diffuse coronal narrowing of the intrathoracic portion of the trachea with concomitant widening of the sagittal diameter. Inward bowing or dis- placement of the lateral tracheal walls as a result of cartilage weakness is a type of tracheal collapse seen in chronic obstructive pulmonary disease. The sagittal-to-coronal diameter is over 2:1, and the extrathoracic portion of the trachea is not narrowed. Mild intrathoracic tracheal wall thickening and ossifications of tracheal rings can also be seen. There may be further inward bowing of lateral tra- cheal walls during forceful expiration.
  11. 11. 3A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_2, © Springer International Publishing Switzerland 2014 Eggshell Calcification and Rim Enhancement Eggshell calcification (↑) refers to the peripheral rim of cal- cium deposited in enlarged mediastinal and/or hilar and peri- bronchial lymph nodes. Shell-like calcifications up to 2 mm thick must be present in at least two lymph nodes; one of the affected lymph nodes must be larger than 1 cm in its greatest diameter. This pattern is most commonly seen in silicosis and coal worker’s pneumoconiosis. It may also be seen with sarcoidosis, after radiation therapy to lymph nodes affected by lymphoma, scleroderma, amyloidosis, blastomycosis, and histoplasmosis. Rim Enhancement (∆). Necrosis in lymph nodes causes decrease in attenuation within central portions (up to fatty density). This pattern is characteristically associated with mycobacterium infection (tuberculous and nontuberculous). Following contrast administration lymph nodes show periph- eral enhancement of capsules. With appropriate clinical data, this pattern may indicate active tuberculosis (or nontubercu- lous mycobacteria infection) in children and immunocom- promised adults.
  12. 12. 5A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_3, © Springer International Publishing Switzerland 2014 Split Pleura Sign The split pleura sign (↑) is seen with pleural empyemas and is considered the most reliable CT sign helping to distin- guish empyemas from noninfectious pleural effusions. The sign results from fibrin coating of both the parietal and vis- ceral surface of the pleura with resulting ingrowth of blood vessels. Following IV contrast injection CT shows a loculated fluid collection and thickened pleural layers with accompa- nying enhancement. Both layers of the pleura can then be visualized as linear regions of enhancement that divide around a less dense empyema or in other words come together at the margins of the collection. Do not confuse with subpleural lung consolidation (image right below).
  13. 13. 7A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_4, © Springer International Publishing Switzerland 2014 Consolidation Air-space (alveolar, parenchymal) consolidation (↑) is a radiologic sign of increased lung opacity obscuring vascular and interstitial pattern. Consolidations may be divided to diffuse and focal, perihilar and peripheral, round, linear, and patchy. These features are important in differential diagnosis which is based on the nature of the substance that is replacing alveolar air: blood (hemorrhage), pus (exudates, pneumonia), water (transudate, edema), protein (secretions, lipoprotein), and cells (malignancies, COP). Air-filled bronchi are often seen under opacified lung parenchyma (air bronchogram sign). The presence or absence of air broncho- grams cannot be considered as a proof of benign or malig- nant process existence.
  14. 14. 9A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_5, © Springer International Publishing Switzerland 2014 Ground-Glass Opacity and Black Bronchus Sign Ground-glass opacity (GGO) is a nonspecific finding which represents a hazy area of increased attenuation in the lung (↑) with preservation of bronchial and vascular margins. It may be caused by normal expiration, partial collapse of alveoli, increased capillary blood volume, partial filling of air spaces, or interstitial thickening. In patients with acute clinical symptoms, the presence of GGO reflects an active disease (e.g., pneumonia, edema, diffuse alveolar damage). In most patients with chronic symptoms, GGO also indicates active and potentially treatable stages of a long-lasting pathologic process (e.g., interstitial pneumonia, hypersensitivity pneu- monitis, and sarcoidosis). GGO may also be found in patients with bronchoalveolar carcinoma that assumes dynamic con- trol or morphological verification. The bronchi filled with air are markedly seen against GGO unlike normal pulmonary tissue – the “black bron- chus” sign (∆).
  15. 15. 11A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_6, © Springer International Publishing Switzerland 2014 Bat Wing,Butterfly,or Angel Wing Sign Air-space edema may be diffuse, multifocal, or patchy but mainly bilateral. Symmetrical perihilar ground-glass opaci- ties sparing the cortex of the lungs (known as the “bat wing,” “butterfly,” or “angel wing” sign) may be seen sometimes and attributed to rapid accumulation of edema fluid. Similar pulmonary opacities can be found in patients with pneu- monia, inhalation injuries, alveolar proteinosis, pulmonary hemorrhage, sarcoidosis, and bronchoalveolar carcinoma.
  16. 16. 13A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_7, © Springer International Publishing Switzerland 2014 Crazy-Paving Sign The combination of ground-glass opacity and fine reticu- lar pattern is known as the “crazy-paving” sign (↑). It is a nonspecific finding that can be seen in a number of condi- tions both acute and chronic. Common causes of this sign include acute lung injury, pneumonia, pulmonary edema, hemorrhage, pulmonary alveolar proteinosis, bronchoal- veolar carcinoma, interstitial pneumonia, and sarcoidosis. For proper diagnosis, biopsy or bronchoalveolar lavage may be warranted.
  17. 17. 15A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_8, © Springer International Publishing Switzerland 2014 Honeycombing The term honeycomb lung is used to describe pathologic processes that cause appearance of multiple small, thick- walled cystic spaces. Clustered cystic air spaces (0.3–1.0 cm in diameter) or scattered cysts are usually visible beneath the pleural surfaces. In most cases, honeycombing (↑) reflects extensive lung fibrosis with total alveolar destruction (end-stage fibrosis). In up to 70 % of cases, honeycombing reflects the presence of usual interstitial pneumonia.
  18. 18. 17A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_9, © Springer International Publishing Switzerland 2014 Vanishing Lung Vanishing lung (disappearing lung) also known as progressive (idiopathic) lung atrophy and idiopathic giant bullous emphysema is a rare disorder of unknown etiology used to describe lungs that seem to disappear on X-rays (↑). It is a progressive condition characterized by giant emphysematous bullae which commonly arise in the upper lobes and in the subpleural location. Bullae occupy at least one-third of hemithorax. They are usually seen in associa- tion with paraseptal and centrilobular emphysema, common in young men, mostly in smokers.
  19. 19. 19A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_10, © Springer International Publishing Switzerland 2014 Mosaic Perfusion or Mosaic Lung Sign Mosaic perfusion (mosaic attenuation, the “mosaic lung” sign) refers to areas of decreased attenuation of lung parenchyma (↑) in the regions of reduced blood perfusion. The term “mosaic” reflects patchy distribution of abnormalities. This sign is usually seen in patients with small airways diseases (cystic fibrosis, bronchiolitis obliterans, and chronic obstructive lung disease) and pulmonary vascular disease (mosaic oligemia in chronic pulmonary embolism). In cases with mosaic perfusion, regional pulmonary artery branches are always reduced in size. This pattern gives opportunity to distinguish mosaic perfusion from ground-glass opacities.
  20. 20. 21A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_11, © Springer International Publishing Switzerland 2014 Air Trapping Air trapping or gas trapping (↑) refers to retention of excess gas in the secondary lobules of the lungs on expiratory scans (less than normal increase in attenuation of pulmo- nary parenchyma during expiration acquisition). The pres- ence of this sign usually suggests small airways disease (bronchiolitis obliterans, chronic obstructive lung disease). Air trapping often coexists with other patterns of bronchial and bronchiolar pathology (mosaic perfusion, tree-in-bud, tram-tracking, and signet ring signs).
  21. 21. 23A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_12, © Springer International Publishing Switzerland 2014 Swiss Cheese Appearance Pneumonia is the most frequent acute complication of chronic obstructive pulmonary disease. In patients with emphysema consolidation of the pulmonary tissue caused by pneumonia may look nonuniformly “perforated” so forming the “Swiss cheese” appearance (↑). The presence of emphysema often leads to wrong diagnosis of interstitial lung disease in such cases.
  22. 22. 25A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_13, © Springer International Publishing Switzerland 2014 Feeding Vessel Sign or Fruits on the Branch Sign The “feeding vessel” sign also known as the “fruits on the branch” sign (↑) refers to the branch of a pulmonary artery leading directly to a nodule or a mass. This sign is most often seen with pulmonary metastases and septic embolism and also frequently occurs in infarcts and arteriovenous fis- tulas. It is rarely seen in lung carcinomas and granulomas.
  23. 23. 27A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_14, © Springer International Publishing Switzerland 2014 Snowstorm Sign and Cannonball Metastases Lung metastases are characterized by casual (random) distri- bution. The form and the size of the nodules can vary within appreciable limits. If the nodules have small (miliary) sizes and their quantity is innumerable (the “snowstorm” sign), the metastases of vascular tumors (thyroid gland carcinoma, renal cell carcinoma, adenocarcinoma, sarcoma) usually take place (left images). If the nodes have a big size and are accurately outlined, then they are called cannonball metastases. Such metastases are characteristic of tumors of the gastrointestinal tract and genitourinary sphere (right images).
  24. 24. 29A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_15, © Springer International Publishing Switzerland 2014 Air Bronchograms and Pseudocavitations Air bronchograms and pseudocavitations (↑) are often visi- ble in adenocarcinomas (bronchoalveolar carcinomas) and seldom occur in benign lung lesions. Air bronchograms can be also found in pneumonias, round atelectases, inside con- glomerate masses in silicosis, and sarcoidosis. Fine lucen- cies against a neoplasm represent cystic sites filled with air (pseudocavitations).
  25. 25. 31A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_16, © Springer International Publishing Switzerland 2014 Halo Sign The rim formed by a zone of “ground-glass” density (↑), which surrounds a consolidation or a group of nodules in a lung (the “halo” sign), can be seen in patients with aspergil- losis (less common with other infections) and also around adenocarcinomas (especially bronchoalveolar carcinomas). In aspergillosis, the halo is caused by hemorrhages. The halo around adenocarcinoma is formed by the tumor growth in the interstitial tissue.
  26. 26. 33A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_17, © Springer International Publishing Switzerland 2014 Corona Radiata or Corona Maligna and Pleural Tail Sign Primary malignant neoplasms of lungs often have weakly outlined rough contours with spicules forming “corona radiata” or “corona maligna” (↑). 90 % of nodes with spic- ules and only 20 % of nodes with well-defined even con- tours prove to be malignant. “Corona radiata” usually corresponds to a desmoplastic reaction, but the tumor inva- sion can also be present. Additionally, detection of the thin strip propagating to the pleura (∆) with a local triangular protrusion is possible (the “pleural tail” sign). This sign also reflects the presence of fibrosis and can be detected equally with benign and malignant formations. Concerning malignant process “corona radiata” is more specific than the “pleural tail” sign.
  27. 27. 35A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_18, © Springer International Publishing Switzerland 2014 Positive Bronchus Sign Bronchoscopy with biopsy plays a limited role in verification of peripheral lesions of the lungs (about 30 % with nodes smaller than 3 cm in diameter). Efficiency of bronchoscopy considerably rises if the bronchus tends directly to the tumor or is visible in it forming on tomograms the “positive bron- chus” sign (↑).
  28. 28. 37A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_19, © Springer International Publishing Switzerland 2014 Umbilical Retraction Sign or Rigler Incisura In classic radiology, the “umbilical retraction” sign or Rigler incisura is described as a retraction of the tumor con- tour in the form of a notch caused by tumor overgrowth around the bronchus and pulmonary artery (↑). In contrast to the “positive bronchus” sign, the likelihood of morpho- logical verification during bronchoscopy in such a situation is questionable.
  29. 29. 39A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_20, © Springer International Publishing Switzerland 2014 Popcorn Sign and Bull’s Eye Calcifications The conglomerate of formless calcifications occupying the central part of a lung nodule forms the “popcorn” sign (↑) characteristic of hamartoma. Dot-like calcification in the center of a nodule is known as the bull’s eye calcification (∆) occurring in hamartomas and histoplasmomas, also pos- sible in any granuloma.
  30. 30. 41A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_21, © Springer International Publishing Switzerland 2014 Target Calcification Sign Concentric (laminar) calcification in a lung nodule known as the “target” sign (↑) occurs in tuberculomas and histoplasmosis.
  31. 31. 43A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_22, © Springer International Publishing Switzerland 2014 Satellite Foci and Galaxy Sign The satellite foci (↑) can be found near lung nodules, and usually they are a sign of benign process (granulomatoses, tuberculosis). In patients with sarcoidosis the satellite nodules are described as the “galaxy” sign (∆). In rare cases the satellite nodules can also be found at carcinomas.
  32. 32. 45A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_23, © Springer International Publishing Switzerland 2014 Rounded Atelectasis,Comet-Tail Sign, and Crow’s Foot Sign Rounded atelectasis (↑) represents a local collapse of a lung in the form of a ball-shaped zone of consolidation usually combined with pathologic changes of the pleura and archi- tectonical disturbance of the surrounding pulmonary tissue. In the formation of rounded atelectasis, the proximally located vessels, bronchi, and interstitial tissue fold and twist which results in a comet-tail appearance on images – the “comet-tail” sign (∆). A group of randomly located intersti- tial bundles in the lungs predominantly directed to the thick- ened pleura can precede the formation of rounded atelectasis mimicking a bird’s paw – the “crow’s foot” sign (►►). The local thickenings of the pleura, the “comet-tail” sign, and the rounded atelectasis quite often occur in asbestosis but are not specific for this disease.
  33. 33. 47A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_24, © Springer International Publishing Switzerland 2014 Tree-in-Bud Sign In intralobular distribution of nodules, the “tree-in-bud” sign can be seen (↑) which is characterized as the presence of small well-defined foci at the ends of linear intralobu- lar structures. This sign almost always indicates the pres- ence of dilated and filled with some substrate (mucus, detritus, pus, cellular elements) intralobular bronchioles. In overwhelming majority of cases, this sign testifies the existence of intrabronchiolar infection (tubercular, bacte- rial, fungal) and extremely rare intrabronchiolar spread of a tumor. Accordingly, for specified diagnostics, it is expedient to consider performance of bronchoalveolar lavage, sputum analysis, and PCR diagnostics.
  34. 34. 49A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_25, © Springer International Publishing Switzerland 2014 Air Crescent Sign In lung cavities of any origin (cysts, caverns, tumors, emphysema, and so forth), the soft tissue nodes can be visualized which are delimited at the edge by a crescent collection of air – the “air crescent” sign (↑). The most frequent reason for the occurrence of this sign is aspergil- loma (mycetoma), but there may be other reasons which are much less frequent (septic infarct, a carcinoma in a cyst, a cavitary carcinoma, a clot in a cyst or a cavity, echinococ- cosis, sputum in a cystic bronchiectasia, papillomatosis of lungs, gangrene, Rasmussen aneurysm).
  35. 35. 51A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_26, © Springer International Publishing Switzerland 2014 Signet Ring Sign, Tram-Tracking Sign, String of Pearls, and Cluster of Grapes These are the signs of bronchiectasia. In true bronchiecta- sia, the diameter of a bronchial lumen which is perpendicu- lar to the tomogram plane exceeds the diameter of the adjacent pulmonary artery branch (↑) more than 1.5 times (the “signet ring” sign). Parallel walls of the bronchi in cyl- inder bronchiectasias when visualized in the plane of tomo- graphic image form the “tram-tracking” sign (∆) because there is no normal narrowing of a bronchial lumen to the periphery. Varicose bronchiectasias in the tomographic plane look like a chain or the “string of pearls” (right upper images). The group of cystic bronchiectasias can create a view of the “cluster of grapes” on CT (right lower images).
  36. 36. 53A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_27, © Springer International Publishing Switzerland 2014 Finger-in-Glove or Hand-in-Glove Sign The presence of central bronchiectasias in patients with bronchial asthma should suggest to a radiologist allergic bronchopulmonary aspergillosis. In some patients, bronchi- ectasias are filled with fungal micelle or mucous impactions which form the “fingers in a glove” sign (↑). In 25 % of patients, contents of bronchiectasias have high density as the fungus accumulates calcium oxalate. Additional criteria for proper diagnosis are antibodies to Aspergillae, high level of IgE, and the positive dermal test for fungal antigens. Less often similar changes can be observed in endobron- chial growth of a tumor in the central bronchus.
  37. 37. 55A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_28, © Springer International Publishing Switzerland 2014 Atoll or Reversed Halo Sign Roundish or crescent stripes and bands of consolidation sur- rounding zones of ground-glass attenuation in the lungs form the “atoll” or “reversed halo” sign (↑). Contours are usually rough. This appearance corresponds to the manifes- tation of a variant of organizing pneumonia.
  38. 38. 57A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_29, © Springer International Publishing Switzerland 2014 Parachute Sign The “parachute” sign (↑) is one of the variants of demon- stration of infarct pneumonia after pulmonary artery throm- boembolism (also the Hampton’s hump sign is widely known). The subpleural zone of consolidation in the form of a parachute dome has a higher density at the periphery, and the central part can contain pseudocavitations. Widened “neogenic” vessels extend from the lung hilum to the zone of consolidation forming parachute straps. At CT angiopul- monography thrombi can be detected (∆) in the pulmonary artery branches corresponding to consolidation.
  39. 39. 59A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_30, © Springer International Publishing Switzerland 2014 Atelectasis Discoidea,Atelectasis Lamellosa,or Platelike Atelectasis Atelectasis in the form of a disk or a plate (striate, lamellar) – atelectasis discoidea, atelectasis lamellosa, or platelike atelectasis (↑) – can develop under pulmonary circulation congestion and hypoventilation, including that caused by low diaphragm excursion in acute diseases of abdominal organs (pancreatitis, peritonitis, perforated stomach ulcer, diseases of the liver and bile ducts).
  40. 40. 61A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_31, © Springer International Publishing Switzerland 2014 Mesa, Tafelberg, or Table Mountain Sign Mesa is a flat-topped mountain to the southwest of Cape Town. The pleural disease caused by asbestosis can manifest itself in occurrence of pleural plaques, effusion, and diffuse pleural thickening. Pleural plaques consist of fibrous tissue, contain asbestos fibers, frequently calcify in the central part, and on images have “square shoulders” resembling a flat mountain – the “mesa,” “tafelberg,” or “table mountain” sign (↑). Diffuse pleural thickening can be found in 5 % of patients with asbestosis that usually is a consequence of benign pleural effusion (right lower image).
  41. 41. 63A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_32, © Springer International Publishing Switzerland 2014 Pleural Mouse,Fibrin Body,Fibrin Ball, and Thoracolith A fibrin clot in the pleural cavity (“fibrin body”, “fibrin ball”, or “pleural mouse”) can be formed in the resolution process of exudative effusion or hemothorax – a soft tissue globule up to 2 cm in diameter. On CT this globule contacts the pleu- ral surface and can spontaneously shift after a change of the patient’s position or at a repeat imaging. The fibrin body can exist for a long time, resolve, or calcify turning into a thoracolith (↑).
  42. 42. 65A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_33, © Springer International Publishing Switzerland 2014 Draped Aorta Sign The “draped aorta” sign (↑) can indicate a recent rupture of the aorta. This sign manifests itself as a blurred aortic back wall or its wide intimate contact with the contour of the ver- tebral body. Such signs as “hematocrit,” “sentinel clot,” and “hyperdense crescent” can also be visible.
  43. 43. 67A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_34, © Springer International Publishing Switzerland 2014 Sentinel Clot Sign A restricted area of high density near any organ or vessel found after a trauma or surgery represents a hematoma “cov- ering” the zone of rupture – the “sentinel clot” sign (↑). This sign points to a trauma (rupture) even in the absence of visible signs of damage to an organ or a vessel. Most obvi- ously the sign is visible at native study and can be missed on enhanced CT (the right lower image).
  44. 44. 69A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_35, © Springer International Publishing Switzerland 2014 Intimal Flap and Beak Sign Detection of an “intimal flap” (better intimomedial flap) must be considered as the most reliable sign of aortic dissec- tion which represents a linear filling defect after IV enhance- ment (∆). This flap separates true and false channels of the aorta. The sharp marginal angle between the aortic wall and the intimal flap so as its crescent form – “beak” sign – usu- ally indicates the channel with lower intraluminal pressure (↑). These changes in the aorta can coexist with the “cob- web” sign. On native images, the “beak” sign becomes apparent when calcified intima moves inside (►►).
  45. 45. 71A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_36, © Springer International Publishing Switzerland 2014 Cobweb Sign and Mercedes-Benz Sign After IV enhancement intimal flaps in the false channel of the dissected aorta may create a view of a network or a web, the “cobweb” sign (↑), or a symbol of the Mercedes-Benz company, the “Mercedes-Benz” sign (∆). These signs always coexist with the “beak sign.”
  46. 46. 73A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_37, © Springer International Publishing Switzerland 2014 Hyperdense Crescent Sign and Beret Sign Intramural hematoma caused by trauma or hypertension looks like a hyperdense crescent or a hyperdense ring in a thickened vessel wall on native images – the “hyperdense crescent” sign (↑). It is better seen on native images. The pen- etrating ulcer of the aorta can also be seen as the “hyperdense crescent” sign, but more often after IV enhancement, it rep- resents a local intramural leakage of contrast agent forming the “beret” sign (∆). Intramural hematoma and penetrating ulcer may lead to the formation of a pseudoaneurysm (►►) or dissection.
  47. 47. 75A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_38, © Springer International Publishing Switzerland 2014 Web Sign and White (Calcified) Pulmonary Arteries Linear or membrane-filling defects in the pulmonary arteries after IV enhancement must be considered as an additional sign of chronic thromboembolism – the “web” sign (↑). Thrombi in the pulmonary arteries eventually may calcify and look denser (whiter) than normal vessels at native study – “white or calcified pulmonary arteries” (∆). During CT angiopulmonography white sites of the pulmonary arter- ies can be missed (right lower image).
  48. 48. 77A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_39, © Springer International Publishing Switzerland 2014 Marble Liver Sign or Fatty Liver (Foie Gras) Liver steatosis (fatty liver metamorphosis) is a metabolic complication of a number of toxic, ischemic, and infectious damages to the liver. In steatosis liver density is lower than splenic density. So the vessels without contrast enhancement look hyperdense in comparison with the liver parenchyma forming the “marble liver” sign (↑). This sign is also known as “fatty liver” that matches foie gras.
  49. 49. 79A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_40, © Springer International Publishing Switzerland 2014 Geographic Liver Liver steatosis can be diffuse but also lobar, segmental, and subsegmental. In such cases acute angles and somewhat straight lines of the borders among sites of normal and low densities are distinctly traced – the “geographic liver” sign (↑). In the zones with low density, there is no mass effect (vessels do not change normal direction and diameter, and bulging and indrawing of the external liver contour are absent). The presence of steatosis does not guarantee the absence of metastases. Native study must be followed by contrast enhancement.
  50. 50. 81A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_41, © Springer International Publishing Switzerland 2014 Boxing Glove Sign The first liver segment (caudate lobe) that increased in size may be the first and only sign of liver cirrhosis on CT. Covering three borders of the inferior vena cava, the first segment of the liver creates a view of a boxing glove in form – the “boxing glove” sign (↑). This sign can be combined with other implications of cirrhosis.
  51. 51. 83A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_42, © Springer International Publishing Switzerland 2014 Confluent Fibrosis The central liver site of low density with rough and fre- quently stellate contours is a typical sign of confluent fibrosis (↑) in liver cirrhosis. In the parenchymal phase of IV enhancement, the fibrous zone becomes isodense with surrounding parenchyma and less often looks hyperdense. It is possible to find other CT signs of cirrhosis: the “bull’s eye,” “lacelike or meshy” fibrosis, “salt and pepper,” and “white liver.”
  52. 52. 85A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_43, © Springer International Publishing Switzerland 2014 Bull’s Eye Sign In liver cirrhosis regenerative nodes are surrounded by zones of interstitial fibrosis. The veins pass through the centers of the nodes. On native images node tissue has a higher den- sity than the vessels and interstitium due to the deposition of hemosiderin – the “reversed bull’s eye” sign (↑). After IV contrast enhancement the veins and fibrous tissue can accumulate contrast agent more intensively than the tis- sue of regenerative nodes thus forming the “bull’s eye” sign (∆). Much more often the densities of the nodes and the fibrous tissue average in parenchymal phase of contrast enhancement.
  53. 53. 87A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_44, © Springer International Publishing Switzerland 2014 Lacelike Fibrosis and Salt and Pepper Sign On tomograms the sites of liver interstitial fibrosis can create visual similarity to abundance of hypodense stripes among high-density regenerative nodes forming an image of “lacelike fibrosis” (↑). Such fibrosis is also called “meshy” and “reticulated.” If regenerative nodules have a very small size, the “salt and pepper” sign (∆) can be formed – inter- mittent fine sites of high and low density. Other signs of cir- rhosis can also be detected.
  54. 54. 89A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_45, © Springer International Publishing Switzerland 2014 White Liver Sign Excess accumulation of substances with high features of X-ray attenuation can lead to a substantial increase in liver density on native images forming the “white liver” sign (↑). Most often such changes are visible in cirrhosis because of hemosiderin accumulation in regenerative nodes. High density of the liver can also be found in patients receiving amiodarone as a molecule of this substance includes an atom of iodine. Do not confuse the CT sign to the disease (white liver disease – visceral steatosis in sheep).
  55. 55. 91A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_46, © Springer International Publishing Switzerland 2014 Periportal Halo After IV enhancement thin low-density rims around the peripheral branches of the portal vein form the “periportal halo” sign (↑) which indicates interstitial edema of the liver. If a branch of the portal vein is located in the tomographic plane, then we speak about the “tram-tracking” sign. The causes of edema can be various: neoplasms and enlarged lymph nodes in the hepatic porta, hepatitis, active phase of autoimmune cirrhosis, congested liver in heart failure, liver trauma, early period after liver transplantation, and others. Do not confuse with biliary ducts dilatation.
  56. 56. 93A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_47, © Springer International Publishing Switzerland 2014 Ripples in the Water Sign or Target Sign Liver abscess can manifest itself as a hypodense nonuniform formation with a hyperdense capsule (especially after IV contrast enhancement) surrounded by a hypodense zone of edema. This forms the “ripples in the water” sign (↑) also known as the “target” sign. This sign may coexist with the “clusters of grapes” sign.
  57. 57. 95A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_48, © Springer International Publishing Switzerland 2014 Cluster of Grapes Sign Small pyogenic abscesses of the liver, merging into a large cavity, form an image similar to a bunch of grapes or berries – “cluster of grapes” sign (↑). The mature cavity has multi- ple septa. The density of the cavity contents is a little higher than that of water. The “cluster of grapes” sign can be com- bined with the “ripples in the water” sign. The presence of gas bubbles is also possible inside abscesses.
  58. 58. 97A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_49, © Springer International Publishing Switzerland 2014 Water Lily Sign or Snake Sign In the course of a hydatid cyst vital activity, the fibrous capsule calcifies and can also peel off (inner pressure in cysts decreases). Free fragments of the capsule in a cyst form the “water lily” sign or the “snake” sign (↑) which is specific for echinococcosis. Detection of daughter cysts is also a specific sign for E. granulosus.
  59. 59. 99A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_50, © Springer International Publishing Switzerland 2014 Bright Dot Sign and Iris or Eye Diaphragm Sign In 80 % of cases, hemangiomas have typical features after IV enhancement. In the arterial phase, foci (lacunas) with high density of blood with contrast agent appear at periph- ery of the mass – the “bright dot” sign (↑). In parenchymal and delayed phases, the foci enlarge in size as the enhanced blood fills lacunar spaces from the periphery to the center. In all phases of enhancement, lacunas have the density cor- responding to density of contrasted vessels (effect of a blood pool). In large hemangiomas centripetal filling of mass with contrast agent is called the “iris” sign or the “eye dia- phragm” sign (∆).
  60. 60. 101A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_51, © Springer International Publishing Switzerland 2014 Stellate Scar Sign or Spoke-Wheel Pattern Focal nodular hyperplasia is a benign mass in the liver formed by hyperplastic response to local vascular malfor- mation. Focal nodular hyperplasia is characterized by fast uptake and washout of contrast agent. A typical feature (present in 2/3 of cases) is the central scar depicting a star or the spokes of a wheel, which may enhance in the delayed phase – the “stellate scar” sign (↑) or the “spoke-wheel” pattern (∆).
  61. 61. 103A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_52, © Springer International Publishing Switzerland 2014 Funeral Frame Sign, Rim Enhancement, and Target-Like Appearance The low-density rim on the periphery of liver masses indi- cates parenchymal edema around quickly growing tumors, usually metastases, forming the “funeral frame” sign (↑) on CT images. After IV enhancement hypovascular metastases may be surrounded by a contrasted rim on the periphery in zones of edema and compression of liver parenchyma – the “rim enhancement” (∆). If the central zone of metastasis is necrotized, the “target-like appearance” (►►) may be formed. The “rim enhancement” can also be observed with liver abscesses, especially amebic.
  62. 62. 105A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_53, © Springer International Publishing Switzerland 2014 Double Duct Sign Simultaneous dilation of the common bile duct and the pan- creatic duct – the “double duct” sign (↑) – is extremely suspicious of an ampullary carcinoma (∆). The tumor is well defined after oral administration of water and IV enhancement. This sign can also occur in pancreatic head carcinoma invading the ampulla and pancreatitis.
  63. 63. 107A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_54, © Springer International Publishing Switzerland 2014 Central Dot Sign Caroli disease (communicating cavernous biliary ectasia) is the congenital disease characterized by multifocal segmen- tal saccular dilatation of intrahepatic bile ducts. On liver tomograms cystic formations (dilated bile ducts) may be detected with central enhancing dots or stripes (portal vein branches) – the “central dot” sign (↑). In some patients hyperdense concrements can be found in dilated bile ducts. The similar picture can be seen in mycotic liver affection.
  64. 64. 109A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_55, © Springer International Publishing Switzerland 2014 Mercedes-Benz Sign Some gallbladder stones contain gas in the central zone and frequently have the form of a three-beam star – the “Mercedes-Benz” sign (↑). There is an assumption that during the evolution the central part of concrements reduces more significantly than the peripheral. Thus, cracks may be formed and filled with gas because of a vacuum phenomenon. Anyhow, this sign has no urgent potential.
  65. 65. 111A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_56, © Springer International Publishing Switzerland 2014 Porcelain or Incrusted Gallbladder Sign It is considered that the curvilinear calcification in the gallbladder wall – the “porcelain gallbladder” sign or the “incrusted gallbladder” sign (↑) – is a sign of chronic cholecystitis. However, during CT the majority of such patients demonstrate gallbladder carcinoma with soft tissue mass frequently involving liver parenchyma.
  66. 66. 113A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_57, © Springer International Publishing Switzerland 2014 Annular Pancreas Annular pancreas is a variant of development. The normal tissue of the pancreatic head and common bile duct envelop the descending part of the duodenum (↑). If detected in childhood, it may be combined with some developmental anomalies in 75 % of cases. In adult age such complications as pancreatitis and gastric and duodenal ulcers may occur.
  67. 67. 115A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_58, © Springer International Publishing Switzerland 2014 Lake Chain Sign or String of Beads Sign and Pancreas with Sausage-Like Form and Hypodense Halo In chronic pancreatitis duct dilatation is present in 50 % of patients because of atrophic parenchymal changes. The lumen is often dilated irregularly as a result of cicatricial deformity forming the “lake chain” sign (↑) or the “string of beads” sign. In autoimmune pancreatitis, the duct is narrowed and not defined, but the gland is enlarged, loses its natural lobulation, and acquires a sausage-like form with a hypodense halo (∆) on the periphery. Autoimmune pancre- atitis has a good response to corticosteroid treatment.
  68. 68. 117A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_59, © Springer International Publishing Switzerland 2014 Honeycomb or Spongelike Mass and Spoke-Wheel Sign Pancreatic serous cystadenoma (serous microcystic adenoma) is a benign tumor which consists of a consider- able amount of small cysts (more than 6 and less than 2 cm in diameter), more common in the pancreatic head. After IV enhancement the septa emphasize the contours of fine cysts forming honeycomb or spongelike mass (↑) but sometimes can prevail over cysts, creating a view of a solid mass. Central soft tissue scar, frequently with calcification, is seldom found. The septa spreading from it always form the “spoke-wheel” sign (∆).
  69. 69. 119A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_60, © Springer International Publishing Switzerland 2014 Fetal Lobulation or Lobation and Column of Bertin Hypertrophy Fetal and early-age children kidneys consist of separate lobes delimited by deep sulci from each other – the so- called “fetal lobulation or lobation” (↑). The kidneys have humpy surfaces. As children grow, the lobes coalesce forming a smooth surface of kidneys in adults, but in 4–5 % of patients, the fetal lobulation remains. During CT normal enhancement of the cortical zone must be observed but with deep surface clefts in projections of Bertin septa. Column of Bertin (∆) represents a hypertrophied wide and long cortical band deeply penetrating between the pyramids of medullary tissue. Both developmental variants have no clinical value, but they are often mistaken for renal tumors.
  70. 70. 121A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_61, © Springer International Publishing Switzerland 2014 Horseshoe Kidney The horseshoe kidney (↑) is a congenital anomaly, at which kidneys are united by the isthmus in the region of lower poles. There are two variants of coalescence: median or symmetrical (most common) and lateral or asymmetrical. This condition is associated with high probability of traumatic damage, development of Wilms tumors, renal cell carcinomas, vesicoureteral reflux, and urolithiasis.
  71. 71. 123A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_62, © Springer International Publishing Switzerland 2014 White Pyramids Sign Quite often on native images renal pyramids look hyper- dense in comparison with other tissues – the “white pyra- mids” sign (↑) – which most likely depicts concentrated urine. The presence of this sign only in one kidney may serve as an additional indirect indicator of obstructive uropathy in the opposite kidney (possible manifestation of tubular hydronephrosis).
  72. 72. 125A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_63, © Springer International Publishing Switzerland 2014 Claw Sign or Beak Sign In cases when some masses or cysts grow and bulge from renal parenchyma, the normal tissue covers their contours with the formation of acute angles – the “claw” sign or the “beak” sign (↑). If the formation is nonorganic but adjoins the organ and probably compresses it, the organ contour will be wrapped inside. This sign does not indicate the benign origin of the lesion but shows the expansive variant of growth.
  73. 73. 127A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_64, © Springer International Publishing Switzerland 2014 Faceless Kidney Sign Loss of differentiation of the renal pelvis because of any obliterative process leads to formation of the “faceless kidney” sign (↑). First, this sign was described in patients with incomplete kidney duplication. Most frequent causes of obliteration of pelvic fatty tissue are lymphomas and transitional cell carcinomas.
  74. 74. 129A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_65, © Springer International Publishing Switzerland 2014 Swiss Cheese Sign Considerably enlarged kidneys with innumerable cysts of different sizes, some of them demonstrate hemorrhages and wall calcifications, form the “Swiss cheese” sign (↑) which is a typical manifestation of autosomal dominant polycystic kidneys disease. Without adequate treatment by 40–50 years of age, patients develop renal failure because of the replacement of parenchyma by cysts. Multisystem manifestations may also involve the liver, pancreas, spleen, ovaries, and testes.
  75. 75. 131A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_66, © Springer International Publishing Switzerland 2014 Stellate Scar Sign or Starlike Scar Sign and Spoke-Wheel Pattern Renal oncocytoma is a benign tumor arising from the col- lecting ducts, which consists of eosinophilic epithelial cells. On tomograms oncocytomas are homogenous in density and in half of cases demonstrate a central scar with stellate form – the “stellate scar” sign or the “starlike scar” sign (↑). The scar may opacify intensely in the late phase of IV enhancement. Sometimes this scar looks like a wheel with spokes – the “spoke-wheel” pattern. Unfortunately, in prac- tice it is impossible to distinguish oncocytomas with central scars from renal cell carcinomas with central zones of necrosis.
  76. 76. 133A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_67, © Springer International Publishing Switzerland 2014 Fan Sign, Wedge-Shaped or Striated Enhancement, and Patchy Nephrogram In acute pyelonephritis in the parenchymal phase of IV enhancement, fan- or wedge-like, striated, or patchy zones of low attenuation may be found forming the “fan” sign (↑), “wedge-shaped or striated enhancement”, or “patchy nephrogram” (∆). These areas correspond to necrosis and edema. In the delayed phase of enhancement, the zones of previously low density can slightly enhance. Similar changes in the kidneys occur in embolism, vasculitis, atherosclerosis, and trauma. Thus, clinical correlation is necessary for dif- ferentiation of these pathologic conditions.
  77. 77. 135A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_68, © Springer International Publishing Switzerland 2014 Medullary Sponge Kidney and Paintbrush Appearance The “medullary sponge kidney” or renal tubular ectasia is a degenerative transformation consisting in cystic dilation of collecting ducts in the renal medulla. On tomograms in the excretory phase of enhancement, the delay of contrast agent in widened pyramid tubules is seen forming a “paintbrush appearance” (↑). This condition can be complicated by medullary nephrocalcinosis, urolithiasis, and abscesses. The changes are most clearly seen with thin collimation of X-rays and multiplanar reconstructions.
  78. 78. 137A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_69, © Springer International Publishing Switzerland 2014 Putty Kidney Sign “Putty kidney” is pronounced calcification (↑) of nonfunctioning kidney parenchyma (autonephrectomy), caused by end-stage tuberculosis.
  79. 79. 139A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_70, © Springer International Publishing Switzerland 2014 Cortical Rim Sign and Reversed Rim Sign After IV enhancement, zones of renal infarction look like wedge-shaped low-density areas. Capsule and subcapsular kidney parenchyma is enhanced in many (but not all) patients due to collateral blood supply that forms the “cortical rim” sign (↑). This sign seldom occurs in pyelone- phritis. For correct diagnosis the results must definitely cor- relate to clinical features. In ischemic necrosis of the renal cortex, patients demon- strate enhancement of the medulla and capsule separated by a zone of cortical necrosis of low density forming the “reversed rim” sign (∆). Up to 50 % of such cases refer to pregnancy complications and also shock and sepsis.
  80. 80. 141A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_71, © Springer International Publishing Switzerland 2014 String of Beads Sign or String of Pearls Sign Fibromuscular dysplasia is the second in frequency disease causing renal artery stenoses. It is the most common cause of secondary arterial hypertension in young patients. After CT angiography beaded narrowings mainly of middle and distal segments of renal arteries may be found forming the “string of beads” sign or the “string of pearls” sign (↑).
  81. 81. 143A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_72, © Springer International Publishing Switzerland 2014 Soft Tissue Rim Sign and Comet Sign Concrements in the ureter cause edema and probably tissue inflammation that leads to wall thickening and periureteral stranding in ambient adipose tissue with formation of the “soft tissue rim” sign (↑). This sign is never noted around phleboliths. A curved line of a vein and phlebolith (always without the rim of soft tissue) visible in the tomographic plane can form the “comet” sign (∆). Thin collimation of X-rays and multiplanar reconstructions confidently help to determine the relationship of a ureter and a concrement as well as a vein and a phlebolith.
  82. 82. 145A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_73, © Springer International Publishing Switzerland 2014 Whirlpool, Whirl, Swirl, and Whirling Sign The “whirlpool” sign (also known as the “whirl”, “swirl,” and “whirling” sign) can be found in patients with small bowel volvulus (usually as a complication of bowel malrotation). On axial tomograms rotation of the intestine, mesentery, and superior mesenteric vein occurs around the superior mesenteric artery in a counterclockwise direction (↑). Curved mesenteric vessels form the image of a whirlpool. This sign can be seen also at the cecal and sigmoid volvulus. Most distinctly the rotation is distinguished when study- ing cine CT scans.
  83. 83. 147A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_74, © Springer International Publishing Switzerland 2014 Comb Sign The increases in mesenteric blood flow and perivascular inflammatory infiltration form the image of linear structures near the bowel on the side of the mesentery forming the “comb” sign (↑). This sign is most often seen in Crohn disease and in ulcerative colitis. In any case it is the sign of active inflammatory process.
  84. 84. 149A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_75, © Springer International Publishing Switzerland 2014 Stratified Attenuation, Double Halo Sign, and Target Sign Stratified attenuation of bowel segments may take the form of a double circlet (with internal layer of low density and external layer of high density) forming the “double halo” sign or a target (with internal and external layers of high density and middle zone of low density) forming the “target” sign (↑). These signs usually reflect acute inflammation or ischemia. The layers with high density mean hyperemia and the layers with low density mean edema.
  85. 85. 151A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_76, © Springer International Publishing Switzerland 2014 Target Sign,Sausage-Shaped Mass, and Reniform or Kidney-Shaped Bowel Invagination is the prolapse of the intestine loop together with a part of the mesentery inside the neighboring segment of the bowel. Three variants of bowel image on tomograms are described with invaginations: 1. Soft tissue formation in the bowel with eccentric location of the mesentery with fatty density – the “target” sign (↑) 2. Sausage-shaped mass (∆) with alternating sites of low and high density of the bowel wall, mesentery, fluid, gas, and contrast medium 3. Reniform or kidney-shaped bowel (►►) with thickened bowel walls and edematous mesentery The first variant refers to initial manifestations with a minimal degree of obstruction, but the second and the third ones refer to late changes with ileus and ischemia.
  86. 86. 153A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_77, © Springer International Publishing Switzerland 2014 Fat Halo Sign Fatty infiltration of the submucosal bowel layer – the “fat halo” sign (↑) – can be regarded as specific for inflamma- tory bowel diseases (Crohn disease, ulcerative colitis), but unlike the “double halo” sign and the “target” sign, it indi- cates the chronic stage of disease.
  87. 87. 155A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_78, © Springer International Publishing Switzerland 2014 Accordion Sign The increased enhancement of mucosa and submucosal edema of low density may form the “accordion” sign (↑) characteristic of pseudomembranous colitis. This sign also can be seen in other inflammatory processes, massive blood loss (“shock” bowel), mesentery thrombosis, edema, and hypoalbuminemia. It is necessary to correlate CT features to clinical data.
  88. 88. 157A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_79, © Springer International Publishing Switzerland 2014 Rim Enhancement or Target Sign An abdominal abscess represents a collection of pus limited to a fibrocapillary “capsule.” After IV enhancement, the capsule intensively accumulates the contrast agent but inter- nal contents keep low density – the “rim enhancement” or the “target” sign (↑). In 50 % of patients, gas bubbles in the abscess can be observed. In 10 % of patients in an appen- dicular abscess, an appendicolith may be found which is better seen on native images.
  89. 89. 159A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_80, © Springer International Publishing Switzerland 2014 Soap Bubble Appearance and Small Bowel Feces Sign On tomograms colonic fecal masses look like lather due to a considerable amount of gas bubbles – soap bubble appear- ance (∆). It is possible to find a colonic wall thickening and increased density of fatty tissue due to inflammation in chronic constipations around such a fecaloma. This set of features suggests the presence of a fecal ulcer (stercoral ulceration) as a necrosis caused by the pressure on the bowel wall (►►). The presence of a substrate similar to colonic fecal masses in the small intestine – the “small bowel feces” sign (↑) – first of all creates suspicion of subacute or partial small bowel obstruction. Such changes can also be found out in small bowel dysfunction (metabolic or infectious diseases).
  90. 90. 161A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_81, © Springer International Publishing Switzerland 2014 Ring Sign Acute inflammation or infarct of a mesenteric appendage (epiploic appendagitis) can be detected on tomograms as a structure of oval or irregular form containing fatty tissue and surrounded by a thin hyperdense ring – the “ring” sign (↑). Signs of inflammation of surrounding fat can also be visible. A dense “point” may be seen in the center represent- ing a thrombosed vein.
  91. 91. 163A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_82, © Springer International Publishing Switzerland 2014 Omental Cake Sign The pathologically thickened and infiltrated omentum forms the “omental cake” sign on tomograms (↑). After IV injec- tion of contrast agent, the omentum enhances irregularly and shows the cellular structure imitating a layer cake. The most frequent causes for infiltration of the large omentum are metastases from carcinomas of the ovaries, stomach, and colon. Also similar images of omental infiltration can be found in tuberculous peritonitis and, extremely seldom, in primary tumors of the large omentum (mesothelioma in particular).
  92. 92. 165A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_83, © Springer International Publishing Switzerland 2014 Sandwich Sign The “sandwich” sign (↑) is formed in lymphomas of the mesentery when the enlarged lymph nodes surround the enhanced mesenteric vessels. Damage to the mesenteric lymph nodes occurs in non-Hodgkin’s lymphomas (>50 %), whereas in Hodgkin’s lymphoma, it is seen in not more than 5 % of the surveyed.
  93. 93. 167A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_84, © Springer International Publishing Switzerland 2014 Misty Mesentery Sign and Fat Halo Sign Any inflammatory and proliferative process involving mes- enteric tissues leads to increase in the density of the fatty tissue – the “misty mesentery” sign (↑). The most probable idiopathic variant is mesenteric panniculitis (sclerosing mesenteritis). In addition to the “misty mesentery,” the spe- cific feature of mesenteric panniculitis must be defined as the rim of normal fatty density around mesenteric vessels – the “fat halo” sign (∆). Unlike liposarcomas the mass effect is absent. In differential diagnostics in the presence of the “misty mesentery” sign, it is necessary to consider hypoal- buminemia, cirrhosis, lymphedema, pancreatitis, tuberculo- sis, bleeding, non-Hodgkin’s lymphoma, cholelithiasis, peptic ulcer and carcinoma of the stomach, blunt abdominal trauma, autoimmune diseases, and so forth.
  94. 94. 169A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_85, © Springer International Publishing Switzerland 2014 Dirty Fat Sign Liposarcomas of the retroperitoneal space are characterized by three variants of images on tomograms, based on the amount of fat in different parts of the tumor. 1. The mixed variant (mixed pattern) – sites of a fatty tissue alternate with soft tissue zones and vessels – the “dirty fat” sign (↑). It is the most frequent pattern. 2. The soft tissue variant (solid pattern) – mass with density higher than +20НU, nonuniform (mainly myxoid tissue). 3. Pseudocystic variant (pseudocystic pattern) – mass of homogeneous density from −20 НU to +20 НU. In liposarcomas, the “claw or beak” sign is always absent.
  95. 95. 171A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4_86, © Springer International Publishing Switzerland 2014 Hematocrit Sign Coagulopathic retroperitoneal hemorrhages become appar- ent as the zones of high density in the retroperitoneal space, muscles, and tissues. A horizontal level between blood with high density and tissues is usually found, forming the “hema- tocrit” sign (↑). Most of the so-called retroperitoneal bleedings form in the posterior abdominal wall muscles. The most common causes for bleedings include anticoagulant therapy and coagulopathy. After IV enhancement sites of various shapes with the density corresponding to the enhanced blood can be identified in active bleeding.
  96. 96. 173A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4, © Springer International Publishing Switzerland 2014 Algın O, Gökalp G, Topal U (2011) Signs in chest imaging. Diagn Interv Radiol 17:18–29 Baldwin M, Genant J, Braver J et al (2011) Classic signs in gastrointes- tinal radiology. Part 1. Appl Radiol 12:22–27 Baldwin M, Genant J, Braver J et al (2012) Classic signs in gastrointes- tinal radiology. Part 2. Appl Radiol 1:29–35 Dyer RB, Chen MY, Zagoria RJ (2004) Classic signs in uroradiology. Radiographics 24:S247–S280 Eisenberg RL (1984) Atlas of signs in radiology. Philadelphia: J.B. Lippincott, p 505 http://www.appliedradiology.com/Article.aspx?id=27386&terms=Clas sic+signs+in+gastrointestinal+radiology http://en.wikipedia.org/wiki/Category:Radiologic_signs http://findebookee.com/r/radiological-signs Marshall GB, Farnquist BA, MacGregor JH et al (2006) Signs in tho- racic imaging. J Thorac Imaging 21:76–90 Mehboob H, Al Damegh S (2007) Food signs in radiology. Int J Health Sci 1:168–178 Mulligan ME (1996) Classic radiologic signs: an atlas and history. New York, NY: Parthenon, p 208 Strang JG, Dogra VS (2006) Body CT secrets. Elsevier Science, New York, p 424 Recommended Literature
  97. 97. 175A. Yudin, Metaphorical Signs in Computed Tomography of Chest and Abdomen, DOI 10.1007/978-3-319-04013-4, © Springer International Publishing Switzerland 2014 Index A Accordion sign, 155 Air bronchograms, 29 Air-crescent sign, 49 Air trapping, 21 Angel wing sign, 11 Annular pancreas, 113 Atelectasis discoidea, 59 Atelectasis lamellosa, 59 Atoll sign, 55 B Batwing sign, 11 Beak sign, 69, 125 Beret sign, 73 Black bronchus sign, 9 Boxing glove sign, 81 Bright dot sign, 99 Bull’s eye calcifications, 39 Bull’s eye sign, 85 Butterfly sign, 11 C Cannonball metastases, 27 Central dot sign, 107 Claw sign, 125 Cluster of grapes, 51 Cluster of grapes sign, 95 Cobweb sign, 69, 71 Column of Bertin hypertrophy, 119 Comb sign, 147 Comet sign, 143 Comet-tail sign, 45 Confluent fibrosis, 83 Consolidation, 7 Corona maligna, 33 Corona radiata, 33 Cortical rim sign, 139 Crazy paving sign, 13 Crow’s foot sign, 45 D Dirty fat sign, 169 Double duct sign, 105 Double halo sign, 149 Draped aorta sign, 65 E Eggshell calcification, 3 Eye diaphragm sign, 99 F Faceless kidney sign, 127 Fan sign, 133 Fat halo sign, 153, 167 Fatty liver, 77 Feeding vessel sign, 25 Fetal lobulation, 119 Fibrin ball, 63 Fibrin body, 63 Finger in glove sign, 53 Foie gras, 77 Fruits on the branch sign, 25 Funeral frame sign, 103 G Galaxy sign, 43 Geographic liver, 79 Ground glass opacity, 9 H Halo sign, 31 Hand in glove sign, 53 Hematocrit sing, 171 Honeycombing, 15 Honeycomb mass, 117 Horseshoe kidney, 121 Hyperdense crescent sign, 73 I Incrusted gallbladder sign, 111 Intimal flap, 69 Iris sign, 99 K Kidney-shaped bowel, 151 L Lace-like fibrosis, 87 Lake chain sign, 115 Lobation, 119
  98. 98. 176 M Marble liver sign, 77 Medullary sponge kidney, 135 Mercedes-Benz sign, 71, 109 Mesa sign, 61 Misty mesentery sign, 167 Mosaic lung sign, 19 Mosaic perfusion sign, 19 O Omental cake sign, 163 P Paintbrush appearance, 135 Pancreas with sausage-like form and hypodense halo, 115 Parachute sign, 57 Patchy nephrogram, 133 Periportal halo, 91 Platelike atelectasis, 59 Pleural mouse, 63 Pleural tail sign, 33 Popcorn sign, 39 Porcelain gallbladder sign, 111 Positive bronchus sign, 35 Pseudocavitations, 29 Putty kidney sign, 137 R Reniform bowel, 151 Reversed halo sign, 55 Reversed rim sign, 139 Rigler incisura, 37 Rim enhancement, 3, 103, 157 Ring sign, 161 Ripples in the water sign, 93 Rounded atelectasis, 45 S Saber-sheath trachea, 1 Salt and pepper sign, 87 Sandwich sign, 165 Satellite foci, 43 Sausage-shaped mass, 151 Sentinel clot sign, 67 Signet-ring sign, 51 Small bowel feces sign, 159 Snake sign, 97 Snowstorm sign, 27 Soap bubble appearance, 159 Soft tissue rim sign, 143 Split pleura sign, 5 Spoke-wheel pattern, 101, 131 Spoke-wheel sign, 117 Sponge-like mass, 116 Star-like scar sign, 131 Stellate scar sign, 101, 131 Stratified attenuation, 149 Striated enhancement, 133 String of beads sign, 115, 141 String of pearls, 51 String of pearls sign, 141 Swirl sign, 145 Swiss cheese appearance, 23 Swiss cheese sign, 129 T Table mountain sign, 61 Tafelberg sign, 61 Target calcification sign, 41 Target-like appearance, 103 Target sign, 93, 149, 151, 157 Thoracolith, 63 Tram tracking, 51 Tree-in-bud sign, 47 U Umbilical retraction sign, 37 V Vanishing lung, 17 W Water lily sign, 97 Web sign, 75 Wedge-shaped enhancement, 133 Whirling sign, 145 Whirlpool sign, 145 Whirl sign, 145 White liver sign, 89 White (calcified) pulmonary arteries, 75 White pyramids sign, 123 Index
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Metaphorical signs in computed tomography of chest and abdomen 2014

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