HRCT TECHNIQUE AND INTERPRETATION

HRCT Technique and
Interpretation in ILD

•  TECHNIQUE
•  ANATOMICAL RECAP
•  PATTERNED APPROACH TO
INTERPRETATION

HRCT
S  HRCT is the use of thin section CT images (0.625 to 2 mm slice
thickness) often with a high-spatial-frequency reconstruction algorithm.
S  GOAL: to detect, characterize, and determine the extent of diseases that
involve the lung parenchyma and airways.

4
HRCT -- MEANING
o  It is often used for anything and everything to do with “high resolution”.
o  Resolution : Means ability to resolve small object that are close
together ,as separate form.
Actual meaning
o  A scan performed using high- spatial frequency algorithm to accentuate
the contrast between tissue of widely differing densities, eg.,
- air & vessels (lung)
- air & bone (temporal & paranasal sinus)

INDICATIONS
S  Diffuse pulmonary disease discovered on CXR or CT of
the chest, including selection of the appropriate site for
biopsy of diffuse lung disease.
S  Clinically suspected pulmonary disorders with normal or
equivocal CXR.
S  Suspected small and/or large airway disease.
S  Quantification of the extent of diffuse lung disease for
evaluating effectiveness of treatment.
ACR PRACTICE GUIDELINE FOR THE PERFORMANCE OF HRCT OF THE LUNGS IN
ADULTS (REVISED 2010)

HRCT TECHNIQUE
Parameters:
S  Slice thickness
S  kV
S  mAs
S  Scan time
S  FoV
S  Interslice gap
S  Filming

SLICE THICKNESS
•  Thin sections 0.5 – 1.5 mm is essential for optimal spatial
resolution
•  Thicker slices are prone for volume averaging and reduces
ability to resolve smaller structure
•  Better for delineation of bronchi, wall thickness and
diameter
7

HRCT TECHNIQUE - kV
S  Standard (110-133) depending on the scanner – as low as
possible.
S  In obese patients, a higher possible kV is used.

HRCT TECHNIQUE - mAs
S  150-350. Even doses as low as 40 have been used to give
reasonable images.

HRCT TECHNIQUE – Scan
time
S As low as possible, 1-2 seconds to
minimise respiration.

HRCT TECHNIQUE - FoV
S Field of view is minimized, so as to
minimize the size of each pixel.

13
LOW DOSE HRCT
•  Low dose HRCT uses Kvp of 120- 140 and mA of 30-20 at 2
sec scan time.
•  Equivalent to conventional HRCT in 97 % of cases
•  Disadvantage : Fails to identify GGO in few cases and have
more prominent streak artifact.
•  Not recommended for initial evaluation of patients with lung
disease.
•  Indicated in following up patients with a known lung
abnormality or in screening large populations at risk for lung
ds.

HRCT TECHNIQUE - Filming
S  Should be at wide window levels.
S  Standard widths of 1600 and levels of -600.
S  Wider windows reduce contrast and narrower windows
obsure details.

HRCT TECHNIQUE –
Radiation Dose
S  Scanning at 10 and 20mm intervals produces 12% and 6%
of the dose associated with conventional CT.
S  Combining HRCT scan at 20mm intervals with a low mAs
(40 mAs) would result in a skin dose comparable to the dose
administered with routine CXR.

18
•  INTERSLICE GAP – varies from examination to
examination, but is usually 10- 20 mm
•  INSPIRATORY LEVEL : Routine HRCT is obtained in
suspended full inspiration, which
q  optimizes contrast between normal structures,
various abnormalities and normal aerated lung
parenchyma; and
q reduces transient atelectasis, a finding that may
mimic or obscure significant abnormalities.
•  EXPIRATORY SCAN : valuable in obstructive lung disease
or airway abnormality

S  Coverage of entire lung possible with 1mm collimation at a
pitch of 6 or 16 to give an effective slice thickness of
1.25mm or less with contrast.

Pa#ent
Posi#on
and
the
Use
of

Prone
Scanning
•  Supine adequate in most instances.
•  Prone for diagnosing subtle lung abnormalities.
e.g., asbestosis, suspected early lung fibrosis
•  Prone scan is useful in differentiating dependent lung
atelectasis from early lung fibrosis
21

Dynamic expiratory HRCT
S  Imaging the patient during a forced vital capacity maneuver.
•  Images are acquired at user-selected levels with imaging performed in cine
mode (without table increment), usually for six to eight images per level.
•  Dynamic expiratory HRCT provides a greater overall increase in lung
attenuation compared with static expiratory methods and may be more
sensitive for the detection of subtle or transient air trapping than static
expiratory methods.
•  Dynamic expiratory HRCT may be performed using low-dose techniques
with no compromise in diagnostic quality.

27
TECHNIQUE OF SCAN ACQUISITION:
1.  Spaced axial scans :
S  Obtained at 1cm intervals from lung apices to bases. In this manner,
HRCT is intended to “sample” lung anatomy
S  It is assumed that the findings seen at the levels scanned will be
representative of what is present throughout the lungs
S  Results in low radiation dose as the individual scans are widely
placed

2. Volumetric HRCT -
S  MDCT scanner are capable of rapid scanning and thin slice acquisition.
Advantages :
1. Viewing of contagious slice for better delineation of lung abnormality
2. Complete imaging of lung and thorax
3. Reconstruction of scan data in any plane using MIPs or MinIPs.
4. diagnosis of other lung abnormalities
Disadvantage : greater radiation dose. It delivers 3-5 times greater radiation.
28

Multidetector Helical
HRCT
S  Multiple images are acquired due to presence of multiple detectors
array
S  Advantages : - shorter acquisition times and retrospective creation
of both thinner and thicker sections from the same raw data
S  Acquisition time is so short that whole-lung HRCT can be
performed in one breath-hold.
29

30
Which is better HRCT or MD- HRCT
S  Various study shows the image quality of axial HRCT with multi-
detector CT is equal to that with conventional single-detector CT.
S  HRCT performed with spaced axial images results in low radiation
dose as compared with MD-HRCT.
S  Increased table speed may increase the volume-averaging artifact and
may result in indistinctness of subtle pulmonary abnormalities.
S  MDCT provides for better reconstruction in Z axis

31
Radiation dose
S  Annual background radiation ----- --- 2.5 mSv
S  PA CHEST Radiograph ----- ----- ----- 0.05 mSv
S  Spaced axial HRCT (10mm space) ----- 0.7 mSv ( 14 X ray)
S  Spaced axial HRCT (20 mm space) ------ 0.35 mSv ( 7 X ray)
S  Low Dose Spaced axial HRCT -------- 0.02 mSV
S  MD-HRCT ---- ------- 4 - 7 msv ( 60-80 x ray)
Combining HRCT scan at 20 mm interval with low mAs scan (40 mAs) would result in radiation
comparable to conventional X ray.

Slices 1mm ,5mm
FoV 315 mm
Imaging Order Craniocaudal
Increment 5mm
Kernel B80f Ultra sharp
Window Lung
mAs 120,140
Kv 120
Rotation Time .5 sec
DLP 392.6 mGy*cm
Scan Time 7.79 secs
3d technique Vrt and Mip
Recon interval 10mm

HRCT TECHNIQUE -
Artifacts
S  Streak artifacts:
•  Radiate from the edges of sharply marginated, high contrast
structures such as bronchial walls, ribs or vertebral bodies.
q  Motion artifacts:
•  Respiratory motion - these can mask disease and simulate
bronchiectasis.
•  Cardiac motion - especially in relation to the lingula, both mask and/
or simulate disease.

HRCT TECHNIQUE -
Summary
S  In all cases:
•  Breath hold
•  Full inspiration
•  Expiratory images
q  In selected cases:
•  Prone images

S
Review of anatomy
PART 2
36

LUNG ANATOMY
S  Right lung is divided by major
and minor fissure into 3 lobes
and 10 broncho-pulmonary
segments
S  Left lung is divided by major
fissure into 2 lobes with a
lingular lobe and 8
bronchopulmonary segments
1.1 kg
37

There are approximately 23 generation
of dichotomous branching
From trachea to the alveolar sac
HRCT can identify upto 8th order
central bronchioles
39

BRONCHIAL ANATOMY
S  Approximately 23 generations of branches from the trachea
to the alveoli.
S  Bronchi with a wall thickness of less than 300 um is not
visible on CT or HRCT.
S  As a consequence, normal bronchi less than 2 mm in
diameter or closer than 2 cm from pleural surfaces equivalent
to seventh to ninth order airways are generally below the
resolution even of high-resolution CT
40

BRONCHUS
BLOOD SUPPLYà Bronchial Arteries—
2 on left side i.e. superior and inferior
1 on right side
Left arises from thoracic aorta
Right from either thoracic aorta, sup. left bronchial or right 3rd
intercostal artery
VENOUS DRAINAGEà
on right- azygous vein
on left- left superior intercostal or accessory
hemiazygous vein
41

BRONCHOARTERIAL
RATIO (B/A)
S  Internal diameter of both bronchus and accompanying arterial diameter
calculated and ratio measured.
S  Normal ratio is 0.65-0.70
S  B/A ratio >1 indicates bronchiectasis.
NB:: B/A ratio increases with age and may exceed 1 in normal patients > 40
years. 42

SECONDARY LOBULE
•  The secondary lobule is the basic anatomic unit of pulmonary
structure and function.
•  Interpretation of interstitial lung diseases is based on the type of
involvement of the secondary lobule.
•  Smallest lung unit that is surrounded by connective tissue septa.
•  It measures about 1-2 cm and is made up of 5-15 pulmonary acini,
that contain the alveoli for gas exchange.

•  Supplied by a terminal bronchiole
in the center, parallelled by the
centrilobular artery.
•  Pulmonary veins and lymphatics
run in the periphery of the lobule
within the interlobular septa.
•  2 lymphatic systems: a central
network, that runs along the
bronchovascular bundle towards
the centre of the lobule and a
peripheral network, that is located
within the interlobular septa and
along the pleural linings.

S  Centrilobular area
•  Site of diseases, that enter the
lung through the airways ( i.e.
hypersensitivity pneumonitis,
respiratory bronchiolitis,
centrilobular emphysema).
q  Perilymphatic area
•  Site of diseases, that are located
in the lymphatics of in the
interlobular septa ( i.e. sarcoid,
lymphangitic carcinomatosis,
pulmonary edema).

Anatomy of the Secondary Lobule
and Its Components
1.  Interlobular septa and
contiguous subpleural
interstitium,
2. Centrilobular structures,
and
3. Lobular parenchyma
and acini.
46

PULMONARY ACINUS
v  Portion of lung parenchyma supplied
by a single respiratory Bronchiole.
v  Size is 7 to 8 mm in adults
v  3 to 24 acini = Sec Pul. Lobule
Primary Lobule: Lung parenchyma
associated with a single Alveolar
duct.
v 4-5 Primary Lobules à Acinus
47

A group of terminal bronchioles
49

Accompanying
pulmonary arterioles
50

Surrounded by lymph
vessels
51

LUNG INTERSTITUM
Lung
interstitium
Axial fiber system
Peribronchovascular
interstitium
Centrilobular
interstitium
Peripheral fiber
sysem
Subpleural
interstitium
Interlobular septa
55

NORMAL LUNG
ATTENUATION
S  Normal lung attenuation : –700 to – 900 HU
S  Attenuation gradient : densest at dependent region of lung as a
result of regional difference in blood and gas density due to
gravity
Difference in attenuation of anterior and posterior lung ranges
from 50 – 100 HU
S  In children, lung attenuation is greater than adults.
56

58
Q.1. What is the dominant HR-pattern ?
Q.2. Where is it located within the secondary lobule
(centrilobular, Perilymphatic or random) ?
Q.3. Is there an upper versus lower zone or a central versus
peripheral predominance ?
Q.4. Are there additional findings (pleural fluid,
lymphadenopathy, traction bronchiectasis) ?
STRUCTURED APPROACH

HRCT
PATTERN
INCREASED
LUNG
ATTENUATION
LINEAR AND
RETICULAR
OPACITIES
NODULES AND
NODULAR
OPACITIES
PARENCHYMAL
OPACIFICATION
consolidation
Ground glass
DECREASED
LUNG
ATTENUATION
CYSTIC LESIONS,
EMPHYSEMA, AND
BRONCHIEACTASIS
MOSAIC
ATTENUATION
AND PERFUSION
AIR TRAPPING ON
EXPIRATORY
SCANS
59

•  These
morphologic
ﬁndings
have
to
be
combined
with

the
history
and
important
clinical
ﬁndings.

•  Common
diseases
like
pneumonias,
pulmonary
emboli,

cardiogenic
edema
and
lung
carcinoma
are
already

ruled
out.

•  So
uncommon
diseases
like
Sarcoidosis,

Hypersensi?vity
pneumoni?s,
Langerhans
cell

his?ocytosis,
Lymphangi?c
carcinomatosis,
Usual

Inters??al
Pneumoni?s
(UIP)
and
many
others
become

regular
HRCT
diagnoses.

LINEAR AND RETICULAR
OPACITIES
S  Represents thickening of
interstitial fibers of lung
by
- fluid or
- fibrous tissue or
- infiltration by cells
61

Interface sign
q Irregular interfaces
between the aerated
lung parenchyma and
bronchi, vessels, or
visceral pleural
surfaces.
q Represent thickened
interlobular septa,
intralobular lines, or
irregular scars.
q Nonspecific.
q Common in patients
with an interstitial
abnormality, fibrotic
lung disease.
62

Peribronchovascular Interstitial Thickening
PBIT
Smooth
Pulmonary
edema/
hemorrhage
Lymphoma /
leukemia
Lymphangitic
spread of
carcinoma
Nodular
Sarcoidosis
Lymphangitic
spread of
carcinoma
Irregular
Due to
adjacent lung
fibrosis
Sarcoidosis,
silicosis, TB
and talcosis
Venous,
lymphatic or
infiltrative
disease
lymphatic or
infiltrative
diseases
63

INTERLOBULAR SEPTAL
THICKENING
S  Normally, only a few septa seen
S  On HRCT, if numerous interlobular septas are
seen, it almost always indicate abnormality.
S  Septal thickening d/t -interstitial fluid, cellular
infiltration or fibrosis.
S  The thickened interstitium outline the secondary
pulmonary lobules and are perpendicular to the
pleura.
S  D/D are similar to that of PBIT.
64

Smooth Septal thickening
Septal thickening and ground-glass opacity with a
gravitational distribution in a patient with cardiogenic
pulmonary edema.
65

Cardiogenic
pulmonary
edema

S  Generally
results
in
a
combina?on
of
septal
thickening
and
ground-‐glass
opacity.

S  There
is
a
tendency
for
hydrosta?c
edema
to
show
a
perihilar
and
gravita?onal
distribu?on.

S  Peribronchial
cuffing

and
fissural
thickening
are
also
common.

S  Common
addi?onal
findings
are
an
enlarged
heart
and
pleural
fluid.

S  Usually
these
pa?ent
are
not
imaged
with
HRCT
as
the
diagnosis
is
readily
made
based
on

clinical
and
radiographic
findings,
but
some?mes
unsuspected
hydrosta?c
pulmonary
edema

is
found.

Nodular Septal thickening
Focal septal thickening in
lymphangitic carcinomatosis
Sarcoidosis :
right lung base shows interlobular
septal thickening associated with
several septal nodules giving
beaded appearance
67

Pulmonary
lymphangi#c
carcinomatosis

(PLC)
S  In
50%
of
pa?ents
the
septal
thickening
is
focal
or
unilateral.

S  This
finding
is
helpful
in
dis?nguishing
PLC
from
other
causes
of
interlobular
septal

thickening
like
Sarcoidosis
or
cardiogenic
pulmonary
edema.

S  Hilar
lymphadenopathy
in
50%
and
usually
there
is
a
history
of
(adeno)carcinoma.

S  Iden?cal
findings
seen
in
pa?ents
with
Lymphoma
and
in
children
with
HIV

infec?on,
who
develop
Lymphocy?c
inters??al
pneumoni?s
(LIP),
a
rare
benign

infiltra?ve
lymphocy?c
disease.

Intralobular interstitial thickening
(Intralobular lines)
S  Results in a fine reticular pattern
on HRCT, with the visible lines
separated by a few millimeters
S  Fine lace- or netlike appearance
S  Causes : Pulmonary fibrosis
Asbestosis
Chronic Eosinophilic
pneumonitis.
69

PARENCHYMAL
BANDS
S  Non tapering , reticular opacity
usually 1 to 3 mm in thickness and
from 2 to 5 cm in length.
S  Is often peripheral and generally
contracts the pleural surface
S  D/D : 1. Asbestosis
2. Sarcoidosis
3. Silicosis/ coal worker
pneumoconiosis
4. Tuberculosis with associated
scarring. 70

Subpleural Interstitial Thickening
S  Mimic thickening
of fissure.
S  DD similar to
that of
interlobular
septal thickening.
S  more common
than septal
thickening in IPF
or UIP of any
cause.
71

HONEYCOMBING
S  Defined as - small cystic spaces with irregularly thickened walls composed
of fibrous tissue.
S  Predominate in the peripheral and subpleural lung regions
S  Subpleural honeycomb cysts typically occur in several contiguous layers.
D/D- paraseptal emphysema in which subpleural cysts usually occur in a
single layer.
S  Indicates the presence of “END stage” disease regardless of the cause.
72

Causes
Lower lobe predominance :
1. UIP or interstitial fibrosis
2. Connective tissue disorders
3. Hypersensitivity pneumonitis
4. Asbestosis
5. NSIP (rare)
Upper lobe predominance :
1. End stage sarcodosis
2. Radiation
3. Hypersensitivity Pneumonitis
4. End stage ARDS
73

Usual interstitial pneumonia/idiopathic
pulmonary fibrosis
Usual interstitial pneumonia (UIP) refers to a morphological pattern of
interstitial lung disease..
Other causes include chronic hypersensitivity pneumonitis, asbestosis, connective tissue
disease and rarely drugs.
S  Pathognomonic appearance of IPF on HRCT is of a predominantly subpleural bibasal
reticular pattern within which there are areas of honeycomb destruction.
S  Disease progression involves the anterior aspects of the upper lobes; the finding of upper
lobe irregularities (reticulation) is an important discriminator between UIP and other
conditions with similar clinical presentations.
S  The presence of ground-glass opacification is not a dominant feature and when present,
there is usually obvious traction bronchiectasis and bronchiolectasis.
S  Mediastinal lymphadenopathy (up to 2 cm) unrelated to infection or malignancy is a
frequent accompaniment.

Size, Distribution, Appearance
Nodules and Nodular Opacities
Size
Small Nodules: <10 mm Miliary - <3 mm
Large Nodules: >10 mm Masses - >3 cms
Appearance
Interstitial opacity:
ü Well-defined, homogenous,
ü Soft-tissue density
ü Obscures the edges of vessels or adjacent structure
Air space:
ü Ill-defined, inhomogeneous.
ü Less dense than adjacent vessel – GGO
ü small nodule is difficult to identify
78

Interstitial nodules Air space opacity
79
Miliary tuberculosis
sarcoidosis
in a lung transplant patient with
bronchopneumonia

Nodular
pa*ern

The
distribu?on
of
nodules

shown
on
HRCT
is
the
most

important
factor
in
making
an

accurate
diagnosis
in
the
nodular

paPern.

In
most
cases
small
nodules
can

be
placed
into
one
of
three

categories:
perilympha?c,

centrilobular
or
random

distribu?on.

Random
refers
to
no
preference

for
a
speciﬁc
loca?on
in
the

secondary
lobule.

Centrilobular
distribu#on

Unlike
perilympha?c
and
random
nodules,

centrilobular
nodules
spare
the
pleural
surfaces.

The
most
peripheral
nodules
are
centered

5-‐10mm
from
fissures
or
the
pleural
surface.

Random
distribu#on

Nodules
are
randomly
distributed
rela?ve
to

structures
of
the
lung
and
secondary
lobule.

Nodules
can
usually
be
seen
to
involve
the

pleural
surfaces
and
fissures,
but
lack
the

subpleural
predominance
oSen
seen
in
pa?ents

with
a
perilympha?c
distribu?on.

Perilympha#c
distribu#on

Nodules
are
seen
in
rela?on
to
pleural
surfaces,

interlobular
septa
and
the
peribronchovascular

inters??um.

Subpleural
loca?on,
par?cularly
in
rela?on
to
the

fissures.

Perilympha2c
distribu2on

Due
to
overlap
in
diﬀeren?al
diagnosis
of
perilympha?c

nodules
and
the
nodular
septal
thickening
in
the
re?cular

paPern.

Some?mes
the
term
re?culonodular
is
used.

q Perilympha?c
distribu?on
of
nodules
in
a
pa?ent
with
sarcoidosis.

q The
nodules
are
seen
along
the
fissures
indica?ng
a
perilympha?c
distribu?on.

q These
nodules
are
also
situated
in
the
subpleural
region
and
along
the
fissures,
because
this
finding
is
very

specific
for
sarcoidosis.

q Typically
in
sarcoidosis
is
an
upper
lobe
and
perihilar
predominance
and
in
this
case
we
see
the
majority
of

nodules
located
along
the
bronchovascular
bundle.

q Sarcoidosis.

q In
addi?on
to
the
perilympha?c
nodules,
there
are
mul?ple
enlarged
lymph
nodes,

which
is
also
typical
for
sarcoidosis.

q In
end
stage
sarcoidosis
we
will
see
ﬁbrosis,
which
is
also
predominantly
located
in

the
upper
lobes
and
perihilar.

S  Centrilobular
distribu2on

•  Hypersensi?vity
pneumoni?s

•  Respiratory
bronchioli?s
in
smokers

•  infec?ous
airways
diseases
(endobronchial
spread
of
tuberculosis
or
nontuberculous
mycobacteria,

bronchopneumonia)

•  In
many
cases
centrilobular
nodules
are
of
ground
glass
density
and
ill
deﬁned
seen
in
a
case
of

hypersensi?vity
pneumoni?s

They
are
called
acinar
nodules.

S  Tree-‐in-‐budIn
centrilobular

nodules,

Tree-‐in-‐bud
describes
the

appearance
of
an
irregular

and
oSen
nodular
branching

structure,
most
easily

iden?ﬁed
in
the
lung

periphery.

It
represents
dilated
and

impacted
(mucus
or
pus-‐
ﬁlled)
centrilobular

bronchioles.

S  Tree-‐in-‐bud
almost
always
indicates
the
presence
of:

S  Endobronchial
spread
of
infec?on
(TB,
any
bacterial
bronchopneumonia)

Airway
disease
associated
with
infec?on
(cys?c
ﬁbrosis,
bronchiectasis)

S  less
oSen,
an
airway
disease
associated
primarily
with
mucus
reten?on

(allergic
bronchopulmonary
aspergillosis,
asthma).

S  In
the
proper
clinical
seZng
suspect
ac?ve
endobronchial
spread
of
TB.

S  In
most
pa?ents
with
ac?ve
tuberculosis,
the
HRCT
shows
evidence
of

bronchogenic
spread
of
disease
even
before
bacteriologic
results
are

available.

90
Centrilobular nodules with or without tree-in-bud opacity: D/D :
With tree-in-
bud opacity
ü  Bacterial pneumonia
ü  Typical and atypical
mycobacteria infections
ü  Bronchiolitis
ü  Diffuse panbronchiolitis
ü  Aspiration
ü  Allergic bronchopulmonary
aspergillosis
ü  Cystic fibrosis
ü  Endobronchial-neoplasms
(particularly
ü  Bronchioloalveolar
carcinoma)
Without tree-in-bud
opacity
ü  All causes of centrilobular
nodules with tree-in-bud opacity
ü  Hypersensitivity pneumonitis
ü  Respiratory bronchiolitis
ü  Cryptogenic organizing
pneumonia
ü  Pneumoconioses
ü  Langerhans’ cell histiocytosis
ü  Pulmonary edema
ü  Vasculitis
ü  Pulmonary hypertension

91
Random nodules
v  Random nodules – No definable distribution.Are usually
distributed uniformly throughout the lung parenchyma in a
bilaterally symmetric distribution.
Random
nodules: Miliary
tuberculosis.
Axial HRCT
image shows
multiple nodules
scattered
uniformly
throughout the
lung
parenchyma.

92
Random nodules: D/D
1.  Haematogenous metastases
2.  Miliary tuberculosis
3.  Miliary fungal infection
4.  Disseminated viral infection
5.  Silicosis or coal-worker’s pneumoconiosis
6.  Langerhans’ cell histiocytosis

S  Langerhans cell histiocytosis (LCH), (pulmonary histiocytosis X or eosinophilic
granuloma of the lung) is a granulomatous disorder characterized histologically
by the presence of large histiocytes containing rod- or racket-shaped organelles
(Langerhans cells).
S  M:F :: 4:1, adult patients, cigarette smokers.
S  Dyspnoea, cough, constitutional symptoms or a spontaneous pneumothorax.
S  Pulmonary involvement is widespread, bilateral and usually symmetrical.
S  Typical appearances are of reticulonodular shadowing in the mid and upper
zones of the lungs that are of normal or increased volume.
S  The nodules vary in size from micronodular to approximately 1 cm in diameter.
LANGERHANS CELL HISTIOCYTOSIS

HRCT - LANGERHANS CELL HISTIOCYTOSIS
S  The classical appearances of
LCH on HRCT are nodules
(ranging in size from a few
millimetres to 2 cm), several
of which show cavitation
(this feature often clinches
the diagnosis) and have
bizarre shapes.
S  typical sparing of the
extreme lung bases and
anterior tips of the right
middle lobe and lingula is
preserved even in end-stage
disease.
S  The typical nodules of LCH
tend to show a predictable
progression: cavitation of
the nodules, thin-walled
cystic lesions, and finally
emphysematous and
fibrobullous destruction

Parenchymal Opacification
§ Ground-glass opacity
§ Consolidation
§ Lung calcification &
high attenuation
opacities.
95

GROUND GLASS OPACITIES
S  Hazy increased attenuation of lung, with
preservation of bronchial and vascular margins
S  Pathology : it is caused by
# partial filling of air spaces,
# interstitial thickening,
# partial collapse of alveoli,
# normal expiration, or
# increased capillary blood volume
S  D/t volume averaging of morphological
abnormality too small to be resolved by HRCT
96

97
IMPORTANCE OF GGO
S  Can represent - microscopic interstitial disease
(alveolar interstitium)
- microscopic alveolar space disease
- combination of both
§  In the absence of fibrosis, mostly indicates the presence of an ongoing,
active, potentially treatable process
§  NB :: Ground Glass opacity should be diagnosed only on scans obtained
with thin sections : with thicker sections volume averaging is more -
leading to spurious GGO, regardless of the nature of abnormality

DIFFERNTIAL DIAGNOSIS :
GGO
99

The location of the abnormalities in ground glass pattern can be helpful:
S  Upper zone predominance:
Respiratory bronchiolitis
PCP.
S  Lower zone predominance: UIP, NSIP
S  Centrilobular distribution:
Hypersensitivity pneumonitis,
Respiratory bronchiolitis
100

GGO with few cystic and reticular lesion
in HIV + ve patient -- PCP
Combination of GGO with
fibrosis and tractional
bronchiectasis-- NSIP
101

Crazy
Paving

S  Crazy
Paving
is
a
combina?on
of
ground

glass
opacity
with
superimposed
septal

thickening.

It
was
ﬁrst
thought
to
be
speciﬁc
for

alveolar
proteinosis,
but
later
was
also

seen
in
other
diseases.

S  Crazy
Paving
can
also
be
seen
in:

S  Sarcoid

S  NSIP

S  Organizing
pneumonia
(COP/BOOP)

S  Infec?on
(PCP,
viral,
Mycoplasma,

bacterial)

S  Neoplasm
(Bronchoalveolar
cell
Ca)
(BAC)

S  Pulmonary
hemorrhage

S  Edema
(heart
failure,
ARDS,)

.

Alveolar
proteinosis
S  Rare
diﬀuse
lung
disease
of
unknown
e?ology

characterized
by
alveolar
and
inters??al

accumula?on
of
a
periodic
acid-‐Schiﬀ
(PAS)

stain-‐posi?ve
phospholipoprotein
derived

from
surfactant.

Combination of ground glass
opacity and septal thickening :
Alveolar proteinosis.
104

Non-specific interstitial
pneumonia
S  NSIP is characterized by varying degrees of
interstitial inflammation and fibrosis without the
specific features that allow a diagnosis of UIP or
desquamative interstitial pneumonia (DIP).
S  While NSIP may have significant fibrosis, it is
usually of uniform temporality (in comparison to
UIP), and fibroblastic foci and honeycombing, if
present, are scanty.
S  Although the clinical features of NSIP resemble
those of UIP, prognosis is considerably better.
S  On HRCT, ground-glass opacification in a
predominantly basal and subpleural distribution
with or without associated distortion of airways.
S  In general, NSIP may be distinguished from UIP
on CT by a more prominent component of
ground-glass attenuation and a finer reticular
pattern in the absence of honeycombing

Consolida2on

Consolida?on
is
synonymous
with
airspace
disease.

Even
ﬁbrosis
as
in
UIP,
NSIP
and
long
standing
sarcoidosis
can
replace
the
air
in
the
alveoli
and

cause
consolida?on.

Acute
consolida2on
is
seen
in:

Pneumonias
(bacterial,
mycoplasma,
PCP)

Pulmonary
edema
due
to
heart
failure
or
ARDS

Hemorrhage

Acute
eosinophilic
pneumonia

Chronic
consolida2on
is
seen
in:

Organizing
Pneumonia

Chronic
eosinophilic
pneumonia

Fibrosis
in
UIP
and
NSIP

Bronchoalveolar
carcinoma
or
lymphoma

Most
pa#ents
who
are
evaluated
with
HRCT,
will
have
chronic

consolida#on,
which
limits
the
diﬀeren#al
diagnosis.

There
are
patchy
non-‐segmental

consolida?ons
in
a
subpleural
and

peripheral
distribu?on.

The
ﬁnal
diagnosis
was
cryptogenic

organizing
pneumonia
(COP).

In
chronic
eosinophilic
pneumonia

the
HRCT
ﬁndings
will
be
the
same,

but
there
will
be
eosinophilia.

Bronchoalveolar
carcinoma
can
also

look
like
this.

Cryptogenic organizing pneumonia
S  Clinicopathological entity of isolated organizing pneumonia in patients
without an identifiable associated disease.
S  On a chest radiograph the most frequent feature of COP is patchy, often
subpleural and basal, areas of consolidation with preservation of lung
volumes.
S  On HRCT, consolidation corresponding to areas of organizing
pneumonia is the cardinal feature found more frequently in the lower
zones, with either a subpleural or a peribronchial distribution; the
peribronchial distribution is typically seen in patients with polymyositis
or dermatomyositis.
S  Ground-glass opacification, subpleural linear opacities and a
distinctive perilobular pattern are also commonly encountered.
S  The lung architecture is generally well preserved

111
Patchy ground-glass opacity,
consolidation, and nodule mainly with
peribronchovascular distribution with
reversed halo signs (central ground-glass
opacity and surrounding air-space
consolidation)
Peripheral consolidations with
upper lobe predominance (photo
negative of pulmonary edema)

S  A
case
of
chronic
eosinophilic

pneumonia.

It
was
a
pa?ent
with
low-‐grade
fever,

progressive
shortness
of
breath
and
an

abnormal
chest
radiograph.

There
was
a
marked
eosinophilia
in
the

peripheral
blood.

Like
in
COP
we
see
patchy
non-‐
segmental
consolida?ons
in
a
subpleural

distribu?on.

S  Chronic
eosinophilic
pneumonia
is
an

idiopathic
condi?on
characterized
by

extensive
ﬁlling
of
alveoli
by
an
inﬁltrate

consis?ng
primarily
of
eosinophils.

Chronic
eosinophilic
pneumonia
is

usually
associated
with
an
increased

number
of
eosinophils
in
the
peripheral

blood
and
pa?ents
respond
promptly
to

treatment
with
steroids.

Lung calcification & high attenuation opacities
Multifocal lung calcification
• Infectious granulomatous ds - TB, histoplasmosis, and varicella,
pneumonia;
• Sarcoidosis , silicosis, Amyloidosis
S  Fat embolism associated with ARDS
Diffuse & dense lung calcification
• Metastatic calcification,
• Disseminated pulmonary ossification, or
• Alveolar microlithiasis
113

114
High attenuation opacity
• Talcosis associated with fibrotic mass,
• inhalation of metals (tin/barium)
Small focal areas of increased attenuation
• injection and embolized radiodense materials such as mercury or
acrylic cement
Diffuse, increased lung attn in absence of calcification
• amiodarone lung toxicity or
• embolization of iodinated oil after chemoembolization

Low
AGenua#on
paGern

The
fourth
paPern
includes
abnormali?es
that
result
in
decreased
lung
aPenua?on
or
air-‐ﬁlled

lesions.

These
include:

Emphysema

Lung
cysts
(LAM,
LIP,
Langerhans
cell
his?ocytosis)

Bronchiectasis

Honeycombing

Most
diseases
with
a
low
aPenua?on
paPern
can
be
readily
dis?nguished
on
the
basis
of
HRCT

ﬁndings.

Emphysema

Emphysema
typically
presents
as
areas
of
low
aPenua?on
without
visible
walls
as
a
result
of

parenchymal
destruc?on.

Centrilobular
emphysema

Most
common
type

Irreversible
destruc?on
of
alveolar
walls
in
the
centrilobular
por?on
of
the
lobule

Upper
lobe
predominance
and
uneven
distribu?on

Strongly
associated
with
smoking.

Panlobular
emphysema

Affects
the
whole
secondary
lobule
.Lower
lobe
predominance.

In
alpha-‐1-‐an?trypsin
deficiency,
but
also
seen
in
smokers
with
advanced
emphysema

Paraseptal
emphysema

Adjacent
to
the
pleura
and
interlobar
fissures

Can
be
isolated
phenomenon
in
young
adults,
or
in
older
pa?ents
with
centrilobular

emphysema
.In
young
adults
oSen
associated
with
spontaneous
pneumothorax.

S  Centrilobular
emphysema
due
to

smoking.
The
periphery
of
the

lung
is
spared
(blue
arrows).

Centrilobular
artery
(yellow

arrows)
is
seen
in
the
center
of

the
hypodense
area.

Paraseptal
emphysema

Paraseptal
emphysema
is
localized
near
ﬁssures
and
pleura
and
is
frequently
associated
with

bullae
forma?on
(area
of
emphysema
larger
than
1
cm
in
diameter).

Apical
bullae
may
lead
to
spontaneous
pneumothorax.

Giant
bullae
occasionally
cause
severe
compression
of
adjacent
lung
?ssue.

Panlobular
emphysema

There
is
uniform
destruc?on
of
the
underlying
architecture
of
the
secondary
pulmonary
lobules,

leading
to
widespread
areas
of
abnormally
low
aPenua?on.

Pulmonary
vessels
in
the
affected
lung
appear
fewer
and
smaller
than
normal.

Panlobular
emphysema
is
diffuse
and
is
most
severe
in
the
lower
lobes.

In
severe
panlobular
emphysema,
the
characteris?c
appearance
of
extensive
lung
destruc?on

and
the
associated
paucity
of
vascular
markings
are
easily
dis?nguishable
from
normal
lung

parenchyma.

On
the
other
hand,
mild
and
even
moderately
severe
panlobular
emphysema
can
be
very
subtle

and
difficult
to
detect
on
HRCT.

Cicatricial Emphysema/ irregular air space
enlargement
S  previously known as irregular or cicatricial emphysema
• can be seen in association with fibrosis
• with silicosis and progressive massive fibrosis or
sarcoidosis
BULLOUS EMPHYSEMA :
• Does not represent a specific histological abnormality
• Emphysema characterized by large bullae
• Often associated with centrilobular and paraseptal
emphysema
121

Paraseptal Emphysema vs
Honeycombing
Paraseptal emphysema Honeycomb cysts
occur in a single layer at the
pleural surface
may occur in several layers in the
subpleural lung
predominate in the upper lobes predominate at the lung bases
unassociated with significant
fibrosis
Associated with other findings of
fibrosis.
Associated with other findings of
emphysema
Absent
122

123
Bullae
v  A sharply demarcated area of emphysema ≥ 1 cm in diameter
v  a thin epithelialized wall ≤ 1 mm.
v  uncommon as isolated findings, except in the lung apices
v  Usually associated with evidence of extensive centrilobular or
paraseptal emphysema
v  When emphysema is associated with predominant bullae, it may
be termed bullous emphysema

Pneumatocele
S  Defined as a thin-walled, gas-filled space within the lung,
S  Associated with acute pneumonia or hydrocarbon aspiration.
• Often transient.
• believed to arise from lung necrosis and bronchiolar obstruction.
• Mimics a lung cyst or bulla on HRCT and cannot be distinguished
on the basis of HRCT findings.
124

CAVITARY NODULE
S  Thicker and more irregular walls than
lung cysts
• In diffuse lung diseases - LCH, TB,
fungal infections, and sarcoidosis.
S  Also seen in rheumatoid lung disease,
septic embolism, pneumonia,
metastatic tumor, tracheobronchial
papillomatosis, and Wegener
granulomatosis
Cavitary nodules or cysts in
tracheobronchial papillomatosis.
fungal pneumonia
125

Cys2c
lung
disease

Lung
cysts
are
deﬁned
as
radiolucent
areas
with
a
wall
thickness
of
less
than

4mm.

Cavi?es
are
deﬁned
as
radiolucent
areas
with
a
wall
thickness
of
more
than

4mm
and
are
seen
in
infec?on
(TB,
Staph,
fungal,
hyda?d),
sep?c
emboli,

squamous
cell
carcinoma
and
Wegener's
disease.

LYMPHANGIOLEIOMYOMATOSIS
S  Lymphangioleiomyomatosis (LAM) is a disease characterized
histologically by two key features: cysts and proliferation of atypical
smooth muscle cells (LAM cells) of the pulmonary interstitium,
particularly in the bronchioles, pulmonary vessels and lymphatics.
S  almost exclusively in women, the vast majority of cases being diagnosed
during childbearing age.
S  Generalized, symmetrical, reticular, or reticulonodular opacities with
normal or increased lung volumes.
S  Pleural effusions occur in 10–40% of patients (these may be unilateral or
bilateral) and pneumothoraces in approximately 50% of cases.
S  The effusions are chylous and result from involvement of the thoracic
duct by the leiomyomatous tissue.

HRCT - LYMPHANGIOLEIOMYOMATOSIS
S  The CT manifestations of LAM are distinctive, characterized by
numerous thin-walled cysts randomly distributed throughout the lungs
with no zonal predilection.
S  Imaging features that help distinguish LAM from LCH include a more
diffuse distribution of cysts typically with no sparing of the bases,
more regularly shaped cysts and normal intervening lung parenchyma.

S  A
case
with
mul?ple
cysts
that
are
evenly
distributed
througout
the
lung

(
in
contrast
to
LCH)
with
pneumothorax.

There
was
no
history
of
smoking
and
this
was
a
40
year
old
female.

This
combina?on
of
ﬁndings
is
typical
for
Lymphangiomyomatosis
(LAM).

S  mul?ple
round
and
bizarre
shaped
cysts.

More
in
upper
lobes.The
pa?ent
had
a
long
history
of
smoking.

This
combina?on
of
ﬁndings
is
typical
for
Langerhans
cell
his?ocytosis.

BRONCHIEACTASIS
Bronchiectasis is defined as localized, irreversible dilation of
the bronchial tree.
HRCT findings of the bronchiectasis include
# Bronchial dilatation
# Lack of bronchial tapering
# Visualization of peripheral airways.
132

133
v  BRONCHIAL DILATATION
# The broncho-arterial ratio (internal diameter of the bronchus /
pulmonary artery) exceeds 1.
# In cross section it appears as “Signet Ring appearance”
v  LACK OF BRONCHIAL TAPERING
# The earliest sign of cylindrical bronchiectasis
# One indication is lack of change in the size of an airway over 2 cm after
branching.
v  VISUALIZATION OF PERIPHERAL AIRWAYS
# Visualization of an airway within 1 cm of the costal pleura is
abnormal and indicates potential bronchiectasis

Coned axial HRCT image shows bronchial
dilation with lack of tapering . Bronchial
morphology is consistent with varicose
bronchiectasis. 134

A NUMBER OF ANCILLARY FINDINGS ARE ALSO
RECOGNIZED:
# Bronchial wall thickening : normally wall of bronchus should be less than half the
width of the accompanying pulmonary artery branch.
# Mucoid impaction
# Air trapping and mosaic perfusion
Extensive, bilateral mucoid impaction
Mosaic perfusion caused by large and small
airway obstruction.
Small centrilobular nodules are visible in the
right lower lobe
135

Types
1. BRONCHIECTASIS
# mildest form of this disease,
# thick-walled bronchi that extend into the
lung periphery and fail to show normal
tapering
2. VARICOSE BRONCHIECTASIS
# beaded appearance of bronchial walls -
dilated bronchi with areas of relative
narrowing
# string of pearls.
# Traction bronchiectasis often appears
varicose.
136

3. CYSTIC
BRONCHIECTASIS :
# Group or cluster of
air-filled cysts,
# cysts can also be
fluid filled, giving the
appearance of a cluster
of grapes.
4.TRACTION
BRONCHIECTASIS :
# Defined as dilatation
of intralobular
bronchioles because of
surrounding fibrosis
# due to fibrotic lung
diseases
137

Differential diagnosis
1. Infective causes : specially childhood pneumonia,
pertusis, measles, tuberculosis
2. Non- infective causes : Bronchopulmonary aspergillosis, inhalation of toxic
fumes
3. Connective tissue disorder : Ehlers-Danlos Syndrome,
Marfan syndrome , tracheobronchomeglay
4. Ciliary diskinesia : Cystic fibrosis, Kartangener syndrome,
agammaglobulinemia .
5. Tractional bronchiectasis in interstitial fibrosis.
138

Chest
film
with
a
typical
finger-‐in-‐glove
shadow.

The
HRCT
shows
focal
bronchiectasis
with
extensive
mucoid
impac?on,
which
is
in
the

appropriate
clinical
seZng
(asthma
and
serum
eosinophilia)
typical
for
Allergic

bronchopulmonary
aspergillosis
(ABPA).

Allergic
bronchopulmonary
aspergillosis
is
a
lung
disease
occurring
in
pa?ents
with
asthma
or

cys?c
fibrosis,
triggered
by
a
hypersensi?vity
reac?on
to
the
presence
of
Aspergillus
fumigatus

in
the
airways.

It
characteris?cally
presents
with
the
findings
of
central
bronchiectasis,
mucoid
impac?on
and

atelectasis.

Mosaic
a*enua2on

• The
term
'mosaic
aPenua?on'
is
used
to
describe
density
differences
between
affected
and

non-‐affected
lung
areas.

• There
are
patchy
areas
of
black
and
white
lung.

• The
role
of
the
radiologist
is
to
determine
which
part
is
abnormal:
the
black
or
the
white
lung.

• When
ground
glass
opacity
presents
as
mosaic
aPenua?on
consider:

• Infiltra?ve
process
adjacent
to
normal
lung

• Normal
lung
appearing
rela?vely
dense
adjacent
to
lung
with
air-‐trapping

• Hyperperfused
lung
adjacent
to
oligemic
lung
due
to
chronic
thromboembolic
disease

• There
are
two
diagnos?c
hints
for
further
differen?a?on:

• Look
at
expiratory
scans
for
air
trapping

• Look
at
the
vessels

• If
the
vessels
are
difficult
to
see
in
the
'black'
lung
as
compared
to
the
'white'
lung,
than
it
is

likely
that
the
'black'
lung
is
abnormal.

DD’s
:
obstruc?ve
bronchioli?s
or
chronic
pulmonary
embolism.

Some?mes
these
can
be
differen?ated
with
an
expiratory
scan.

• If
the
vessels
are
the
same
in
the
'black'
lung
and
'white'
lung,

infiltra?ve
lung
disease,
like

pulmonary
hemorrhage.

HYPERSENSITIVITY PNEUMONITIS
S  Hypersensitivity pneumonitis, (extrinsic allergic alveolitis) is an immunologically
mediated lung disease characterized by an inflammatory reaction to specific
antigens contained in a variety of organic dusts.
S  Common causes: avian proteins (e.g. bird breeder's lung) and thermophilic bacteria
present in mouldy hay (farmer's lung), mouldy grain (grain handler's lung), or
heated water reservoirs (humidifier or air conditioner lung).
S  These antigens reach the alveoli where they provoke an immunological reaction that
includes both type III (immune complex response) and type IV (cell-mediated)
mechanisms.
S  Approximately 6 h after exposure the patient develops fever, chills, dyspnoea and
cough. There is no eosinophilia, and wheeze is not a prominent feature.

S  ground
glass
paPern
in
a
mosaic
distribu?on.

S  There
is
enlargement
of
pulmonary
arteries
in
the
areas
of
ground
glass.

The
ground
glass
appearance
is
the
result
of
hyperperfused
lung
adjacent

to
oligemic
lung
with
reduced
vessel
caliber
due
to
chronic
thromboembolic

disease.

MOSIAC PATTERN
DEPENDENT LUNG
ONLY
PRONE
POSITION
RESOLVE
PLATE
ATELECTASIS
NOT RESOLVE
GROUND
GLASS
NONDEPENDENT
LUNG
EXPIRATION
NO AIR
TRAPPING
VESSEL SIZE
DECREASED
VASCULAR
NORMAL
GROUND
GLASS
AIR
TRAPPING
AIRWAYS
DISEASE
144

Inhomogeneous lung
opacity: mosaic
perfusion in a patient
with bronchiectasis.
central bronchiectasis with
multifocal, bilateral
inhomogeneous lung opacity.
The vessels within the areas of
abnormally low attenuation are
smaller than their counterparts
in areas of normal lung
attenuation.
145

Air trapping on expiration
S  Most patients with air trapping seen on expiratory scans have
inspiratory scan abnormalities, such as bronchiectasis, mosaic
perfusion, airway thickening, or nodules suggest the proper
differential diagnosis.
S  Occasionally, air trapping may be the sole abnormal finding on an
HRCT study.
S  The differential diagnosis include ---
bronchiolitis obliterans; asthma; chronic bronchitis; and
hypersensitivity pneumonitis
146

Air trapping on expiratory imaging in
the absence of inspiratory scan
findings in a patient with
bronchiolitis obliterans.
(A)  Axial inspiratory image through
the lower lobes shows no clear
evidence of inhomogeneous lung
opacity.
(B)  Axial expiratory image shows
abnormal low attenuation (arrows)
caused by air trapping,
representing failure of the expected
increase in lung attenuation that
should normally occur with
expiratory imaging.
147

Head cheese sign
S  It refers to mixed densities which includes presence of-
# consolidation
# ground glass opacities
# normal lung
# Mosaic perfusion
•  Signifies mixed infiltrative and obstructive disease
•  Common cause are : Hypersensitive pneumonitis
Sarcoidosis
DIP
148

Axial HRCT image in a patient with
hypersensitivity pneumonitis shows a
combination of ground-glass opacity, normal
lung, and mosaic perfusion (arrow) on the same
inspiratory image.
149

DISTRIBUTION WITHIN THE LUNG
UPPER ZONE
S  SARCOID/SILICOSIS
S  COAL WORKERS
PNEUMOCONIOSIS
S  CENTRILOBULAR
EMPHYSEMA
S  LCH
S  CHRONIC HYPERSENSITIVE
PNEUMONITIS
LOWER ZONE
S  OEDEMA
S  PANLOBULAR EMPHYSEMA
S  UIP in coal workers
pneumoconiosis, collagen
vascular disease, asbestosis

DISTRIBUTION WITHIN THE LUNG
CENTRAL ZONE
S  SARCOID
S  BRONCHITIS
PERIPHERAL ZONE
S  BOOP/COP
S  CHRONIC EOSINOPHILIC
PNEUMONIA
S  HEMATOGEMOUS METS
S  UIP in idiopathic pulmonary
fibrosis, collagen vascular
diseases, asbestosis

ADDITIONAL FINDINGS
PLEURAL EFFUSION
S  PULMONARY EDEMA
S  LYMPHANGITIC CARCINOMA –
often unilatera
S  TB
S  LYMPHANGIOMYOMATOSIS
S  ASBESTOSIS
HILAR/MEDIASTINAL
LYMPHADENOPATHY
S  CA LUNG
S  LYMPHANGITIC SPREAD OF
CARCINOMA
S  PROGRESSIVE SYSTEMIC
SCLEROSIS
S  ACTIVE TB/MYCOBACTERIUM
INFECTION
S  SARCOIDOSIS – symmetrical
S  COAL WORKERS
PNEUMOCONIOSIS (rare)
S  SILICOSIS (rare)

Bronchocoele
S  Dilated mucus filled bronchi
S  Seen as peripheral tubular
branching opacity
S  Causes: Bronchial carcinoid,
endobronchial metastases,
bronchostenosis, bronchiectasis,
congenital bronchial atresia and
ABPA.

15 year-old sprinter with hip pain

Avulsion of Ant. Inferior
Iliac Spine

Eisenmenger syndrome is a complication of an uncorrected high-flow,
high-pressure congenital heart anomaly leading to chronic pulmonary
arterial hypertension and shunt reversal.
As such the three lesions that account for most cases are:
ventricular septal defect (VSD)
most common
Eisenmenger syndrome in the setting of a VSD is refered to as
Eisenmenger complex
atrioventricular septal defect (AVSD)
patent ductus arteriosus (PDA)

Neuropathic (Charcot) Arthropathy
Disturbance in sensation leads to multiple microfractures
Pain sensation is intact from muscles and soft tissue
Distribution and causes
Shoulders – syrinx, spinal tumor
Hips – tertiary syphilis, diabetes
Knees – tertiary syphilis (more bone production), diabetes (less bone production)
Feet – diabetes
Other causes
Amyloidosis
Congenital indifference to pain
Polio
Alcoholism
X-ray findings
Sclerosis
Destruction of joint
Fragmentation
Soft tissue swelling from synovitis
Joint effusions
Osteophytosis
Disorganized and disrupted joint
No osteoporosis

Gamekeeper’s Thumb
AKA: Skier’s Thumb, Break-dancer’s Thumb
Chronic injury to ulnar collateral ligament (UCL) of thumb first seen in
gamekeepers in Scotland
Because of the method they used to kill rabbits
Acute injury now more common amongst skiers
Called "Skier's thumb”
Due to fall on fall on outstretched hand with abducted thumb caught in pole strap
May also be seen in rheumatoid arthritis
UCL is short ligament that originates from the metacarpal head and inserts into
medial aspect and base of proximal phalanx of thumb
Often associated with a fracture of the base of the proximal phalanx
Distal portion of ligament retracts and points superficially and proximally
Rupture of both the proper and accessory collateral ligaments must occur for this t
happen
Produces a lump over medial aspect of the MCP joint of thumb

HRCT TECHNIQUE AND INTERPRETATION

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Viewers also liked

Viewers also liked (20)

Similar to HRCT TECHNIQUE AND INTERPRETATION

Similar to HRCT TECHNIQUE AND INTERPRETATION (20)

More from Sahil Chaudhry

More from Sahil Chaudhry (12)

Recently uploaded

Recently uploaded (20)

HRCT TECHNIQUE AND INTERPRETATION