Renal cortical scarring


99mTc-DMSA is a useful tracer for evaluating the renal parenchyma, and is particularly useful for the evaluation of renal cortical scarring, as in this case. Children with recurrent urinary tract infections, especially in the setting of vesico-ureteric reflux, are at risk of renal cortical scarring and reflux nephropathy. In some cases, extensive scarring can impact overall renal function - as in this case where the function of the left kidney has been reduced. 

Patients ideally should not be imaged within 2-3 months of the most recent urinary tract infection as pyelonephritis can mimic the appearance of renal cortical scarring on DMSA scan. 

Differential renal function can be calculated by geometric mean on planar imaging, which takes into account the relative depths of the kidneys to correct the amount of counts which are reaching the gamma camera.