Current Status of Radionuclide Renal Cortical Imaging in Pyelonephritis

Pyelonephritis is an infection of the kidneys that is seen more commonly in children than the adults. ^99mTc-dimercaptosuccinic acid (^99mTc-DMSA) scanning is a radionuclide imaging study to detect renal scarring after acute pyelonephritis (a late ^99mTc-DMSA scan) and also helps to diagnose acute pyelonephritis in febrile urinary tract infections (an acute ^99mTc-DMSA scan). Planar imaging in multiple views (posterior and bilateral posterior oblique) is generally used. Pinhole imaging with a high-resolution-collimator magnification of each kidney allows detection of smaller cortical defects. SPECT is optional. SPECT/CT is not recommended in children because it has a higher radiation exposure than routine ^99mTc-DMSA scans. The main limitations of ^99mTc-DMSA scanning include a relatively long waiting time after radiotracer injection, a long acquisition time, and a high radiation dose, which is particularly important in repeated studies on children and with the limited spatial resolution of γ-cameras. ^99mTc-glucoheptonate is an alternative radiotracer when ^99mTc-DMSA is not available. Radiotracers for dynamic renal functional imaging can grossly assess the renal cortex in the first few minutes of imaging. ⁶⁸Ga-prostate-specific membrane antigen ligand (⁶⁸Ga-PSMA ligand) PET has the ability to provide images of normal renal cortex and demonstrate renal cortical defects from cysts. In this article, we assess the current status of renal cortical imaging and present ⁶⁸Ga-PSMA ligand PET images. ⁶⁸Ga-PSMA ligand provides excellent renal cortical images, and studies should be done to compare ⁶⁸Ga-PSMA ligand PET with ^99mTc-DMSA scanning in renal diseases, particularly in pyelonephritis.