Identification of new renal scarring in repeated episodes of acute pyelonephritis using Tc-99m DMSA renal SPECT.

PURPOSE This prospective study compared the value of Tc-99m DMSA renal planar scintigraphy with SPECT to detect new renal involvement in patients with repeated episodes of acute pyelonephritis (APN). MATERIALS AND METHODS Children with suspected APN were transferred to our department for DMSA renal scans. Seventy-two children (ages 1 week to 15 years) had DMSA planar and SPECT imaging performed twice because of clinical or laboratory suspicion of repeated APN. In addition, radiographic voiding cystourethrography was also performed in all cases. The presence of vesicoureteral reflux (VUR) was graded on a scale of 0 to 5. RESULTS New lesions were observed with SPECT in 56 kidneys and with planar scintigraphy in 38 kidneys. No patients had a negative result of Tc-99m DMSA renal SPECT who also had a positive Tc-99m DMSA planar result. The degree of VUR as related to APN was diagnosed better with SPECT than with planar scintigraphy (46 compared with 30 and 10 compared with 8, respectively). There is a significant difference (P < 0.05) between the diagnostic ability of these two methods to identify the increased tendency of repeated APN to occur with high-grade VUR compared with low-grade or no VUR. CONCLUSIONS High-grade VUR is more commonly associated with renal injury than is low-grade or no VUR. If only Tc-99m DMSA renal planar scintigraphy is performed, renal scarring may be underestimated. Our results suggest that Tc-99m DMSA renal SPECT, rather than planar scintigraphy, should be used routinely in children with a clinical suspicion of APN, especially for those with scarred kidneys and high-grade VUR.