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.