5. US of acute pyelonephritis
US abnormalities (20 %)
Renal enlargement (> 15 cm – affected kidney > 1.5 cm longer )
Hypoechoic renal parenchyma
Loss of corticomedullary differentiation
Loss of renal sinus fat
Dilatation of collecting system without obstructive cause
Abscess formation
Rumack CM et al. Diagnostic Ultrasound. Elsevier-Mosby, St. Louis, USA, 3rd edition, 2005.
Majority of cases (80 %)
Normal-appearing kidney – Routine Imaging not required
6. Acute pyelonephritis
Diffuse renal enlargement
Decreased echogenicity
Loss of corticomedullary differentiation
Longitudinal US of left kidney Longitudinal US of right kidney
Normal right kidney
Kao HW et al. J Med Ultrasound 2008 ; 16 : 113 – 122.
7. Severe acute bacterial pyelonephritis
Craig WD et al. RadioGraphics 2008 ; 28 : 255 – 276.
Slightly enlarged right kidney
that is otherwise unremarkable
despite advanced disease
US image of right kidney Abdominal CT scan
Enlarged kidney
Small low-attenuation foci (abscess)
Findings prompted nephrectomy
US is limited in visualization of small micro-abscesses
8. Fungal ball
Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
Longitudinal US of right kidney
Immunocompromised patient
Echogenic mass within dilated calyx
Confirmed to be a fungus ball
9. CT (before, immediately after, & at delayed
intervals from contrast material injection)
is the preferred modality for evaluating
acute bacterial pyelonephritis
11. Acute focal & multifocal pyelonephritis
• Focal PN Infection confined to single lobe
Multifocal PN Infection confined to multiple lobes
• Risk factors DM – immunosuppression
• Clinical features More severe symptoms than APL
Commonly progresses to sepsis
• Treatment Similar to other cases of APL
7 days of parenteral antibiotics
Then 7day of oral antibiotics
Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
12. US of acute multifocal pyelonephritis
Identical to focal disease but seen in more than one lobe
US of acute focal pyelonephritis
Sonolucent mass Poorly marginated
Extending from medulla to capsule
Absence of distinct wall (abscess)
Occasional low amplitude echoes
Echogenic mass Commonly seen
CT scan more sensitive than US to detect focal disease
13. Acute focal pyelonephritis
Infection confined to single lobe
Rubens DJ et al. Ultrasound Clin 2007 ; 2 : 391 – 413.
Decreased attenuation area
Typical of focal pyelonephritis
3-cm echogenic mass
in lower pole of right kidney
CT scan more sensitive than US to detect focal pyelonephritis
14. Acute multifocal pyelonephritis
Infection confined to multiple lobes
Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
Absence of color flow
Color Doppler
2 wedge-shaped areas of decreased
echogenicity in renal cortex
Transverse US of right kidney
15. Acute bacterial pyelonephritis
Wedge-shaped hyperechoic focus
in upper pole of right kidney
US scan of right kidney Color flow US image
Diminished flow through
involved area
Craig WD et al. RadioGraphics 2008 ; 28 : 255 – 276.
17. Renal abscess
• Symptoms Fever, chills, & pain in back & abdomen
Symptoms of urinary tract infection
• Hig risk DM, hemodialysis, IV drug abusers
• Causes Renal carbuncles before antibiotics: SA
Ascending infection: EC, Klebsiella, Proteus
• Management < 3 cm Parenteral antibiotics
3 – 5 cm Percutaneous drainage
> 5 cm Surgical drainage
Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
18. US of renal abscess
• Hypoechoic mass with thick irregular walls or capsule
• Indistinct margins acutely & distinct wall thereafter
• Increased through-transmission
• Occasional development of fluid debris level
• Gas in hypoechoic/cystic mass strongly suggests abscess
Serial US examinations are essential in following
the evolution of an abscess
Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
19. Early and mature abscess cavities
Craig WD et al. RadioGraphics 2008 ; 28 : 255 – 276.
Cavity better defined
Well defined border
Through transmission
Mature abscess
Hypoechoic focus from abscess
in upper pole of right kidney
Early abscess
20. Renal abscess
Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
Well-defined hypoechoic lesion
Posterior through transmission
Increased peripheral vascularity
21. Gas-forming renal abscesses
Kao HW et al. J Med Ultrasound 2008 ; 16 : 113 – 122.
Large hypoechoic mass
Gas causing reverberation artifact
Longitudinal US of right kidney
Gas-forming renal abscess
Axial CECT
22. It will be difficult to distinguish abscess from renal tumor
Radiologic-guided drainage can be helpful
24. Pyohydronephrosis
Infection of obstructed collecting system
• Obstruction Stone, tumor, sloughed papilla, stricture
• Complications Decline in renal function, septic shock
• Symptoms UT obstruction with flank pain & fever
Subtle symptoms: weight loss, dull pain
No symptoms at all (15% of cases)
• Ultrasound Echogenic debris in collecting system
Fluid-fluid levels within collecting system
Gas in collecting system (dirty shadows)
Early diagnosis & treatment is crucial
Craig WD et al. RadioGraphics 2008 ; 28 : 255 – 276.
25. Pyohydronephrosis
Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
Longitudinal US of right kidney
Enlarged hydronephrotic kidney
Fluid–fluid level in dilated calyces secondary to pus
26. Pyohydronephrosis
Craig WD et al. RadioGraphics 2008 ; 28 : 255 – 276.
Dilated collecting system
that is nearly completely filled with echogenic debris
28. Classification & management of EPN
Retrospective review of 48 cases based on CT only
Clinical risk factors: thrombocytopenia, ARF, mental status changes, shock
Huang JJ et al. Arch Intern Med 2000 ; 160 : 797 – 805.
Radiologic class Finding on CT Management
Class 1 Gas in collecting system only IV antibiotics
PCD
Decompression of UT obstruction
Class 2 Gas in renal parenchyma
No extension to perirenal space
IV antibiotics
PCD
Decompression of UT obstruction
Class 3A Extension of gas or abscess
to perirenal space
IV antibiotics
Immediate nephrectomy if risk factors
Class 3B Extension of gas or abscess
to pararenal space
IV antibiotics
Immediate nephrectomy if risk factors
Class 4 Bilateral EPN or solitary
functioning kidney with EPN
IV antibiotics & PCD
Nephrectomy if failed
29. US in emphysematous pyelonephritis
• Enlarged kidney
• High amplitude echoes within renal parenchyma
• Low-level posterior dirty acoustic shadowing
• Depth of parenchymal involvement underestimated by US
Isolated presence of gas within collecting system seen after
many interventional procedures
CT always warranted & considered ideal study to
visualize extent & amount of gas
Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
30. Emphysematous pyelonephritis
Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
Longitudinal gray-scale sonogram of left kidney
Air within renal parenchyma with reverberation artifact
32. Emphysematous pyelonephritis
Tajima K et al. N Engl J Med 2007 ; 356 ; 526 – 527.
Gas throughout right kidney
Abdominal radiograph CT scan of abdomen
Extensive destruction of renal
parenchyma with associated gas
Gas in retroperitoneal tissues
33. Gas in renal parenchyma
Differential diagnosis
• Emphysematous pyelonephritis (EPN)
• Focal renal abscess
• Enterorenal fistula
• Trauma to kidney or bladder Surgery
Biopsy
Bladder catheterization
Nephrostomy placement
Akhtar AL et al. AJR 2010 ; 194 : WS31 – WS33.
36. Xanthogranulomatous Pyelonephritis (XGPN)
Rare inflammatory condition
• Long-term & recurrent obstruction from stone with infection
• Replacement of parenchyma by lipid-laden macrophages
• Most common organism: Proteus mirabilis or E. Coli
• Adults in fifth to seventh decade – Women in 70%
• Nonspecific symptoms: malaise, flank pain, low-grade fever
• Nephrectomy is the standard approach for diagnostic & tt
• Excellent prognosis
Kao HW et al. J Med Ultrasound 2008 ; 16 : 113 – 122.
37. US of Xanthogranulomatous Pyelonephritis
Definitive preoperative diagnosis extremely difficult
• Focal form
Mass-like lesion – Mistaken for renal cell carcinoma
• Diffuse form (more common)
Diffuse renal enlargement
Hypoechoic masses: Abscesses (↑ sound transmission)
Granulomatous (↓ sound transmission)
Echogenic foci (stones) – Acoustic shadow not always present
Common extension to perirenal spaces with abscess & fistula
CT evaluation more informative than US in XGPN
38. Xanthogranulomatous pyelonephritis (XGPN)
Craig WD et al. RadioGraphics 2008 ; 28 : 255 – 276.
Bilateral staghorn calculi
Dilated right collecting system
CECT scanUS image of right kidney
Staghorn calculus with AS
Dilated collecting system
39. US of Xanthogranulomatous pyelonephritis
Diffuse renal enlargement
with echogenic foci
Kao HW et al. J Med Ultrasound 2008 ; 16 : 113 – 122.
Right kidney hydronephrosis
with stones in lower pole
Coronal CECTLongitudinal US of right kidney
41. Renal malakoplakia
Rare inflammatory disorder
• Chronic gram-negative urinary tract infection (E. coli)
• Deposition of soft, yellow plaques in bladder & urinary tract
• Abnormal macrophage function causing incomplete
intracellular bacterial lysis.
• Deposition of histiocytes (von Hansemann cells) filled with
these bacteria & bacterial fragments
• Bacteria form nidus for calcium phosphate crystals forming
small basophilic bodies called Michaelis-Gutmann bodies
Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
42. Renal malakoplakia
• Usually occurs in women
• Most patients older than 50 years
• Underlying condition compromising immune system:
Diabetes, immunosuppression, chronic debilitating disease
• Symptoms of urinary tract infection
Fever, irritative voiding symptoms, flank pain
• Symptoms of bladder irritability & hematuria may be seen
Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
43. • Nonspecific
• Often mimic other pathology such as renal tumors
• Most common US features:
Diffuse enlargement of affected kidney
Increased echogenicity of renal parenchyma
Hypoechoic lesions &distortion of parenchymal echoes
US of Renal malakoplakia
Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
44. Renal malakoplakia
Dharmadhikari R & Crisp A. J Ultrasound Med 2006 ; 25 : 1219 – 1222.
Enlarged right kidney
Well-defined hypoechoic mass occupying lower two thirds
Decreased corticomedullary differentiation at upper pole
46. WHO classification of cystic echinococcosis (CE)
International consensus classification
5 types on the basis of US appearances
CE I Unilocular simple cysts
CE 3
CE 2
CE 4
CE 5
WHO Informal Working Group. Acta Trop 2003 ; 85 : 253 – 261.
Floating membrane (water lily sign)
Multivesicular multiseptated cyst
Heterogeneous degenerative contents
Thick calcified wall
Active
Transitional
Active
Inactive
Inactive
47. Hydatid disease of kidney (very rare)
Imaging findings depend on stage of cyst growth
Volders WK et al. RadioGraphics 2001 ; 21 : S255 – S260.
Multicystic hypoechoic mass
with septations
Thick-walled cystic mass in left kidney
Fluid in central part hyperattenuating
Posterior coarse peripheral calcifications
48. Hydatid disease of the kidney
Imaging findings depend on stage of cyst growth
Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
Well-defined cystic lesion
Multiple internal septae
suggestive of daughter cysts
Floating membranes of hydatid cyst
following rupture of cyst
Water lily sign
CE 2 CE 3
50. Renal tuberculosis
• Considered in patients with history of tuberculosis
• Often asymptomatically even in advanced disease
• ¼ of patients present with unilateral poorly functioning kidney
• Other suspicious findings
Chronic cystitis or epididymitis recalcitrant to treatment
Firm seminal vesicles on digital rectal examination
Chronic fistula tract that forms at surgical sites
• Dg: urine culture demonstrating growth of M tuberculosis.
Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
51. US of renal tuberculosis
Traditionally described as limited
• Mass lesions in renal parenchyma of mixed echogenicity
with or without necrotic areas & calcifications
• Mucosal thickening & stenosis of calyces
• Mucosal thickening of renal pelvis & ureter
• Ureteral stricture & hydronephrosis
• Bladder changes: mucosal thickening & reduced capacity
Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
Role of high-resolution ultrasonography
52. US of renal tuberculosis
Known case of tuberculosis
Hypoechoic areas in renal cortex suggestive of lobar caseation
Longitudinal US of right kidney
Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
53. Renal tuberculosis
Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
Hypoechoic areas of caseous necrosis
Dense peripheral calcification with posterior acoustic shadowing
54. Renal tuberculosis
Kao HW et al. J Med Ultrasound 2008 ; 16 : 113 – 122.
Multiple chunky calcifications
in left upper abdomen
Abdominal radiography Longitudinal US of left kidney
Extensive AS caused by calcifications
Morphologic detail of kidney obscured
56. HIV-associated nephropathy (HIVAN)
Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
Major sonographic findings
Enlarged kidney
Increased cortical echogenicity
Loss of corticomedullary differentiation
Obliteration of sinus fat
In increased cortical echogenicity in a young patient without
history of medical renal disease, HIVAN must be considered
57. HIV-associated nephropathy (HIVAN)
Vourganti S et al. Ultrasound Clin 2006 ; 1 : 1 – 13.
Transverse US of right kidneyLongitudinal US of right kidney
Enlarged, markedly echogenic kidney
Loss of corticomedullary differentiation
Obliteration of sinus fat
ultrasound has been found to be less sensitive and specific in the diagnosis of acute pyelonephritis than other modalities: scintigraphy, spiral CT, & MRI. The proposed mechanism of this dilatation is that bacterial endotoxins may inhibit normal ureteric peristaltic motion, resulting in hydroureter and hydronephrosis.
Focal bacterial pyelonephritis can appear masslike and mimic a renal tumor.
This compartmentalization of the retroperitoneum is important clinically as it serves to localize various pathological processes. It also creates a barrier to the progression of various pathologic processes such as hemorrhage and infection. Collections of fluid in the anterior pararenal compartment, for example, are commonly related to pancreatitis or trauma, whereas collections of fluid in the posterior pararenal compartment are uncommon, usually representing spontaneous hemorrhage in patients with coagulopathy or related to trauma.
There are more than 15 classification schemes for liver hydatid cysts.The liver is the most common site of hydatid disease involvement, and most cysts are located in the right lobe.a CL (cystic lesion) type has been added in the WHO classification that was not included in Gharbi’s classification, for those cysts whose parasitic nature cannot be determined based on solely on the results of the US examination.There are 3 types of cyst rupture: contained, communicating, or direct.
Kidney involvement in echinococcosis is extremely rare (2%–3% of cases), even in areas where hydatid disease is endemic. Renal hydatid cysts usually remain asymptomatic for many years. There are no pathognomonic clinical signs except cystic rupture into collecting system, which leads to acute renal colic & hydatiduria.Renal hydatid disease may mimic other diseases.Detection of a cystic lesion with internal septations and sand, wall calcifications, or the rosette sign in the proper clinical setting allowsthe correct diagnosis in a majority of cases.Surgery is the treatment of choice in renal hydatid cyst. Kidney-sparing surgery (cystectomy with pericystectomy) is possible in mostcases (75%). Nephrectomy (25% of cases) must be reserved for destroyed kidneys.Studies have shown good long-term results with percutaneoushydatid cyst treatment under US guidance.
Bilateral, enlarged, markedly echogenic kidney: attributable to prominent interstitial expansion by cellular infiltrate and markedly dilated tubules containing voluminous casts.Loss of corticomedullary differentiationObliteration of sinus fatSuggestive of HIV nephropathy subsequently confirmed by histopathology.
Enlarged, markedly echogenic kidney (bilateral; left not shown)Loss of corticomedullary differentiationObliteration of sinus fatSuggestive of HIV nephropathy subsequently confirmed by histopathology.
