TC-99M DIMERCAPTOSUCCINIC ACID SCINTIGRAPHY STUDIES OF RENAL CORTICALSCARRING AND RENAL LENGTH

dThe aims of this study were to validate (TC)-T-99m-dimercaptosuccinic acid (DMSA) scintigraphy appearances with histopathological features of scarring; to evaluate the sensitivity and specificity of Tc-99m-DMS A and ultrasound for the detection of renal scarring; to compare plana r, pinhole and SPECT techniques when using Tc-99m-DMSA; and to compare Tc-99m-DMSA and ultrasound renal length measurement. Methods: Reflux nephropathy was induced in large white pigs using established methods. To ensure that the abnormalities detected were scars and not inflamma tory changes, the pigs were not studied until 3 mo after the treated e pisode of acute pyelonephritis confirmed by Tc-99m-DMSA, Results: Twen ty pigs were enrolled in the study. Eleven reached the end point, but only nine pigs (18 kidneys) were available for analysis. Thirty-four s cars were identified pathologically; 24 were present macroscopically a nd a further 10 were seen only on microscopy. Technetium-99m-DMSA abno rmalities correlated with scars histopathologically with an accuracy o f 92% versus that of ultrasound, 75% (p < 0.001), Technetium-99m-DMSA more accurately identified scarring with a higher sensitivity (76% ver sus 29%) and specificity (98% versus 92%) than ultrasound. On the Tc-9 9m-DMSA study, pinhole imaging had the highest accuracy (92%) when com pared with planar (90%) and SPECT (87%) data. These differences were n ot statistically significant. Renal lengths as measured on Tc-99m-DMSA more closely correlated with length measurement at pathological exami nation than ultrasound. Technetium-99m-DMSA measurement was, on averag e, 6% higher than pathology, and ultrasound was, on average, 22% lower . Conclusion: Technetium-99m-DMSA appears to be the preferred method f or the detection of renal cortical scarring and accurate renal length measurement when compared with ultrasound examination.