Lobar dysmorphism of the kidney: reevaluation of junctional parenchyma using helical CT

BACKGROUND: The term "junctional parenchyma" (JP) has been used to represent many renal anomalies including lobar dysmorphism; however, it has not been evaluated with modalities other than ultrasound (US). METHODS: Twenty-two kidneys with lobar dysmorphism incidentally found on helical computed tomography (CT) were studied. In all cases, axial, multiplanar reformation, and three-dimensional images on corticomedullary phase scans were analyzed. Fifteen additional kidneys were prospectively examined with US, and we compared those sonograms with helical CT findings. RESULTS: Comparison of the US and helical CT findings showed that the JP defect and the JP line corresponded anatomically to the upper aspect of the renal sinus and to the thick mural cortex originating from that point, extending inferiorly, respectively. The lesions of lobar dysmorphism were situated deep in the medulla, adjacent to the cortex; however, findings on helical CT did not indicate JP. CONCLUSIONS: Although JP may have been seen on US in this study, it did not show fusion remnants of subkidneys but a combination of the upper aspect of the renal sinus, the mural cortex, and the lesion of lobar dysmorphism.