Imaging of renal cortex in nuclear medicine

Acute pyelonephritis (APN) is the main predisposing factor for renal cortical scar (RCS) performing. Hypertension is a complication of RCS and appears in 10-20 Percent of patient in their life. Diagnosis and treatment of APN are necessary for prevention of RCS. The aim of this review is assessment of 99mTc-DMSA (99mTc-dimercaptosuccinic acid) scan value in diagnosis of APN and RCS and comparison of its results with other diagnostic methods such as radiology and ultrasonography. Ultrasonography (US) showed almost 39% of APN that diagnosed with 99mTC-DMSA scan. Computed Tomography Scan (CT scan) is a sensitive and effective method in diagnosis of APN and its complication. Spiral CT scan and Magnetic Resonance Imaging (MRI) are sensitive and relatively reliable tools in diagnosis of APN; however they are not practicable in the first evaluation and fallow up of infant and children with acute urinary tract infection. Power Doppler Ultrasonography (PDUS) demonstrated a sensitivity of 70 Percent and a specificity of 85 Percent in diagnosis of APN. 99mTc-DMSA scan is the most sensitive diagnostic tool of APN and RCS with a sensitivity and specificity of 89-91 and 100 Percent، respectively. Because 99mTc MAG3 provides adequate images for assessment of renal cortex and accurate measurement of deferential renal function (DRF) as compared to 99mTc DMSA، and it provides important information about urodynamics of both kidneys، some authors considered that it is the best time to replace the 99mTc DMSA with 99mTc MAG3 (99mTc-mercapto-acetylglycyl-glycyl-glycine) in most nephrourologic disorders in pediatric patients to avoids unnecessary radiation to the children، however، it need more studies. Some researchers recommended that follow-up 99mTc-DMSA scan should be perform after 12 month of APN، since in comparison with at 6 month follow-up 99mTc-DMSA scan، study at 12month after APN can demonstrates more permanent lesion.