Dimercaptosuccinic acid scintigraphy vs. ultrasound for renal parenchymal defects in children

Abstract

Introduction: Dimercaptosuccinic acid (DMSA) scintigraphy is the gold standard in the evaluation of renal parenchymal defects and is widely used in the pediatric population. As more recent ultrasound equipment was purchased at our tertiary pediatric centre, our objective was to evaluate if renal ultrasound (US) results are equivalent or sufficient when compared to DMSA scintigraphy in the assessment of renal anomalies. Methods: The charts of all 463 patients who underwent DMSA scintigraphy between January 2009 and May 2014 at our pediatric tertiary centre were reviewed. The objective was to look for correlation between US and DMSA scan results for renal scars/dysplasia. A hundred and sixty pediatric patients followed with US and DMSA scan for a total of 285 renal units remained for evaluation after exclusions. Timing of the exams, urinary tract infection (UTI), and indication for imaging were reviewed. Results with older (105 patients) and newer (55 patients) US equipment were compared. Results: Among the 285 renal units evaluated, 39 (14%) had renal parenchymal defects shown by US and 87 (31%) by DMSA scintigraphy (sensitivity 36%, specificity 96%). The DMSA scan was normal for eight abnormal kidneys (3%) on US. The results were not statistically significant when compared to exams performed with newer or older US machines. Conclusions: At our institution, US data are not sensitive enough to give reliable information about renal parenchymal defects, even with newer equipment. DMSA scintigraphy still remains mandatory for the evaluation of renal anomalies, but could be optional if the US exam indicates parenchymal defects.

Comparison of DMSA Scintigraphy and USG in Detecting Renal Cortical Scars in Children with Urinary Tract Infection

“…20 Marceau-Grimard et al found no statistically significant differences in their studies comparing old and new USG equipment with the same criteria. 8 In our logistic regression analysis, we also found that only the parenchymal thinning among the most frequent pathologic findings was significant in evaluating parenchymal scars at the USG. Ozen et al showed that renal parenchymal thinning in the USG evaluation had a specificity value of 98%.…”

“…To our knowledge, no correlation was established between the grade of renal parenchymal anomaly and long-term adverse event risk. 8,11,23 In our study, relying solely on the USG report, we would have missed radiological parenchymal defects in 30 renal units; however, for 58 renal units no anomaly was seen on the DMSA scan, even though the USG was positive for renal damage.…”

“…14,18 Ultrasonography is commonly used because it is available at low cost and is radiation free. 8 Although some authors have advocated USG, 10 there is no doubt that DMSA scanning is more sensitive than USG in detecting renal perfusion defects. This has been proven in many reports with sensitivity ranging from 5 to 47%.…”

“…7 The gold standard imaging method to assess renal parenchymal defects (i.e., hypoplasia, dysplasia, scars) is considered to be 99mTc-dimercaptosuccinic acid (DMSA) scintigraphy. 8 A cross-sectional study that combined patients with UTIs and/or vesicoureteral reflux (VUR) showed that focal DMSA defects were present in 15.5% of 565 children. 9 DMSA renal imaging can provide information regarding the degree of existing renal cortical abnormalities that may affect the management plan.…”

“…Recent advances in ultrasound technology have led some physicians to believe that USG study could now be considered more appropriate to evaluate renal defects. 8,11 Despite the debate regarding the most appropriate investigation, the least invasive imaging method providing sufficient clinical information is usually preferred. 7 Therefore, from a practical perspective, we thought that clinicians would be interested in finding out whether USG can replace DMSA in detecting scars in children who have had UTIs.…”