Diagnostic accuracy of Tc-99m DMSA scintigraphy and renal ultrasonography for detecting renal scarring and relative function in patients with spinal dysraphism

AIMS: To study additional benefits of performing Tc-99m dimercaptosuccinic acid (Tc-99m-DMSA) scintigraphy as part of the follow-up of adults with spinal dysraphism (SD), compared with ultrasonography, with regard to finding renal scarring and difference in split renal function. METHODS: Between January 2011 and April 2013 every patient visiting our specialized outpatient clinic for adults with SD was invited to undergo both renal ultrasonography and Tc-99m-DMSA scintigraphy. Outcomes of both modalities were compared, with focus on renal scarring. The relation between renal scarring and hypertension was also assessed. RESULTS: In total, 122 patients (with 242 renal units) underwent both renal scintigraphy and ultrasonography. More scars were seen on DMSA scintigraphy than on ultrasonography: 45.9% vs. 10.3% of renal units; P < 0.001. Renal scarring seen on DMSA was associated with the presence of hypertension (P = 0.049) whereas scarring seen on ultrasonography was not (P = 0.10). If ultrasonography was difficult to interpret, many more scars were missed on ultrasonography (78.9%) compared with easily interpretable ultrasonographic images (30.6%; P < 0.001). CONCLUSIONS: In adults with SD, ultrasonography is of value to diagnose dilatation and stones of the upper urinary tract; however, compared with DMSA renography, renal scars are often missed, especially when the ultrasound is difficult to interpret.