THE USE OF COMPUTERIZED TOMOGRAPHY IN THE EVALUATION OF DUPLICATION ANOMALIES

Background: In duplication anomalies the upper pole ureter has a greater chance for ectopia and obstruction. The upper pole is often markedly hydronephrotic and dysplastic; the imaging findings in these cases may result in the mistaken impression of an upper pole cyst or cystic adrenal pathology. The radiographic evaluation of children with duplication anomalies has included excretory urography or sonography for evaluation of the upper portion of the urinary tract and voiding cystography for detection of reflux or other abnormalities of the lower portion of the urinary tract. Scintigraphic studies are used to quantitate renal function or for the visualization of the collecting system in the presence of severe obstruction. However, these conventional imaging studies often fail to delineate the anatomy and quantitate upper pole function. We investigated the role of spiral computed tomography as an adjunct in the assessment of duplication anomalies. Materials and Methods: Eight patients with duplication anomalies (6 ectopic ureters and 2 ureteroceles) were treated in the period from January 1997 to December 1998. All patients were evaluated with sonography, voiding cystourethrography and Dimercaptosuccinic acid (DMSA) scans. In addition, all patients underwent imaging of the abdomen and pelvis using a General Electric Advantage High-speed scanner after the administration of intravenous contrast. Plain films of the kidneys, ureters and bladder (KUB) were obtained 15 minutes and 30 minutes after the CT scan. All patients that have had surgery have had repeat sonography and CT scan with contrast. Results of all imaging studies, operative reports and pathologic specimens were reviewed. The CT scan findings were correlated with both the findings at surgery as well as the histologic findings. Function is assessed by 1: quantitating Hounsfield units of both the upper and lower poles of the duplicated kidney and 2: opacification of the upper pole collecting system on delayed KUB's. Results: Six patients have undergone laparascopic partial nephrectomies with complete ureterectomies. One patient is scheduled for an upper tract diversion and one patient was lost to follow-up. There were six females and two males. The mean age of patients is 4.3 months with a range of 2 weeks to 1.8 years. Six of the patients presented with antenatal hydronephrosis and two with urinary tract infections. Only two of the patients required sedation or analgesia for the CT study. Each study