Screening a living kidney donor for polycystic kidney disease using heavily T2-weighted MRI

Autosomal dominant polycystic kidney disease (ADPKD) accounts for approxima tely 8% of those awaiting renal transplantation. Living related kidney dono rs for these patients require screening for ADPKD, most commonly by ultraso nography. Ultrasound has a negative predictive value (NPV) of 100% in patie nts aged older than 30 years, but only 96% for donors aged 20 to 30 years, This case shows that heavily T2-weighted magnetic resonance Imaging (HT2MRI ) may be a more sensitive screening method for ADPKD in younger kidney dono rs, Despite a normal screening ultrasound result, a kidney donor with a fam ily history of ADPKD was found to have renal cysts intraoperatively, and th e transplantation was canceled. Afterward, the donor was imaged with HT2MRI . In addition, the mathematical relationship between sensitivity, specifici ty, and NPV for ADPKD screening tests was derived, After the canceled trans plantation, a second ultrasound still could not identify renal cysts, Howev er, HT2MRI showed multiple small (similar to3-mm) cysts in both kidneys and a 2.5-cm cyst on the right kidney. Mathematical analysis showed that the N PV of a screening test for ADPKD was most closely related to sensitivity an d that only tests with 100% sensitivity would have a 100% NPV, We conclude that ultrasound is not a sufficiently sensitive screening test for ADPKD in younger living related renal donors. HT2MRI has improved sensitivity and m ay be the best screening test for ADPKD in this population. (C) 2001 by the National Kidney Foundation, Inc.