Peripheral cortex or 'outer rim' of kidney doesn't enhance on contrast administration. What would be the probable diagnosis?
Acute pyelonephritis characteristically has absence of 'cortical rim' sign (i.e. peripheral rim of cortex does not enhance).
If a diagnostic dilemma persists, what would be the next diagnostic modality, or what should we look for, in the same images?
'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.
Absent cortical rim sign