Pyelonephritis CT scan

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Usama Talib, BSc, MD [2]

A CT scan can be used to detect diffuse or complicated pyelonephritis and its suspected complications. It is used when the suspicion of pyelonephritis is accompanied by other differentials. CT scan is very sensitive and CT urography is sometimes used for imaging of the urinary tract. The extent of damage to the parenchymal tissue can also be witnessed in detail with a CT scan.

Findings on a CT scan may vary with respect to the type of pyelonephritis. A CT scan usually demonstrates:^{[1][2][3][4][5][6]}

• Round swollen kidneys
• Hypodense appearance
• Abscesses may not be present

CT scan in case of acute pyelonephritis may demonstrate:^[1][7] Images courtesy of RadsWiki

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  CT: Acute pyelonephritis
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  CT: Acute pyelonephritis
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  CT: Acute pyelonephritis

Imaging findings are characterized by renal scarring, atrophy and cortical thinning, hypertrophy of residual normal tissue, caliceal clubbing secondary to retraction of the papilla from overlying scar, thickening and dilatation of the caliceal system, and overall renal asymmetry. Images courtesy of RadsWiki

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  CT image demonstrates chronic pyelonephritis on the right
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  CT image demonstrates chronic pyelonephritis on the right
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  CT image demonstrates chronic pyelonephritis on the right

• Additional evaluation with CT will confirm the presence and extent of parenchymal gas and will often allow identification of the source of obstruction when present.
• The use of intravenous contrast material will often reveal asymmetric renal enhancement or delayed excretion, and, during the nephrographic phase, will help identify areas of focal tissue necrosis or abscess formation.

Images courtesy of RadsWiki

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  CT: Emphysematous pyelonephritis
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  CT: Emphysematous pyelonephritis
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  CT: Emphysematous pyelonephritis
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  CT: Emphysematous pyelonephritis

The CT findings of xanthogranulomatous pyelonephritis are pathognomonic in most cases: diffuse reniform enlargement with ill-defined central low attenuation, apparent cortical thinning, and central calculi.^[8]

• Extension into the perinephric space and beyond the Gerota fascia is not uncommon.
• Central areas of low attenuation represent nonenhancing xanthomatous material that may demonstrate attenuation values less than those of water.

Images courtesy of RadsWiki

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  CT image demonstrates right xanthogranulomatous pyelonephritis
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  CT image demonstrates right xanthogranulomatous pyelonephritis
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  CT image demonstrates right xanthogranulomatous pyelonephritis
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  CT image demonstrates right xanthogranuomatous pyelonephritis with dilated calyces

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