Rare-MR-urography--a new diagnostic method in autosomal recessive polycystic kidney disease.

Objective: To describe the appearance of autosomal recessive polycystic kidney disease (ARPKD) by using a new diagnostic method: RARE-MR-urography.

Methods: Eight children were evaluated using MR images from 0.23 T and 1.5 T MR units, using T1-weighted spin-echo and T2-weighted turbo spin-echo sequences and RARE-MR-urography. Signal intensities, morphological appearance of the affected kidneys and, specifically, the picture of the urinary tract in RARE-MR-urography, were evaluated.

Results: All children showed enlargement, reniform but humpy kidney shape, homogeneous-grainy renal parenchyma, normal renal pelvis and calyces. Although ARPKD is always associated with some degree of congenital hepatic fibrosis, there was no bile duct dilatation or liver fibrosis at the time of examination. Signal intensity was hyperintense in T2-weighted images in all cases. In 5 cases, T1-weighted images were hypointense. In RARE-MR-urography, hyperintense, linear, radial patterns in cortex and medulla were seen, which represent microcystic dilatation of collecting ducts and are therefore characteristic of ARPKD. Four patients presented with a few circumscribed small subcapsular cysts.

Conclusions: RARE-MR-urography is a noninvasive method which demonstrates the pathognomonic water-filled cystic structures throughout the kindeys in ARPKD.