Comparison between Tc-99m DMSA and Renal Ultrasonography for the Evaluation of Renal Scarring and Function Loss in Children with Spina Bifida

Abstract

Objective: We aimed to compare the sensitivity of ultrasonography (US) and Dimercaptosuccinic acid (DMSA) scintigraphy in evaluating renal scarring and kidney function in children with spina bifida (SB). Methods: The study group comprised 100 patients (51 boys and 49 girls) with SB who underwent renal US and DMSA scintigraphy. The median age was 2 years (range: 6 months - 23 years). Renal US scans were performed by applying standard protocols. Subsequently, DMSA scintigraphy was performed to evaluate suspected renal damage and function loss. Sonographic criteria for renal scarring included renal contour lobulation, renal parenchymal thinning, increased renal parenchymal echo, and decreased the age of renal size. For DMSA scintigraphy, <= 44% differential function was considered abnormal, and contour irregularities and defects were accepted as indicators of renal scarring. Results: Three patients had unilateral agenesis; thus, 197 kidneys were examined from 100 patients. DMSA scintigraphy was significantly superior to renal US in evaluating both renal scarring (p= 0.016) and renal function loss (p=0.001). DMSA scintigraphy was three times more sensitive in detecting both abnormalities than US. Conclusion: Renal US is the first imaging modality to evaluate upper and lower urinary tract infection; however, it alone is not reliable for monitoring scarring and function loss in patients with SB, who usually have rotoscoliosis, obesity, renal position anomalies, and intestinal gas distention that may corrupt the quality of the image. DMSA scintigraphy should be obtained to avoid underestimating renal scarring and function loss.