Acute pyelonephritis

Q: Where is the lesion? show answer

A: There is a wedge shaped hypodense area at lower pole cortex of right kidney

Q: What could be possible etiologies of wedge shaped hypodense attenuation area in kidney? show answer

A: Possible etiologies include renal segmental infarct and acute pyelonephritis

Q: Peripheral cortex or 'outer rim' of kidney doesn't enhance on contrast administration. What would be the probable diagnosis? show answer

A: Acute pyelonephritis characteristically has absence of 'cortical rim' sign (i.e. peripheral rim of cortex does not enhance).

Q: If a diagnostic dilemma persists, what would be the next diagnostic modality, or what should we look for, in the same images? show answer

A: 'Cortical rim' sign may not be seen in many cases of renal infarct. CT angiography, or arterial phase post-contrast images can reveal renal artery thrombus in such cases.