Using gadolinium-enhanced three-dimensional MR angiography to assess arterial inflow stenosis after kidney transplantation

OBJECTIVE. Our objective was to evaluate use of gadolinium-enhanced three-d imensional (3D) MR angiography in the assessment of suspected arterial infl ow stenosis after kidney transplantation. SUBJECTS AND METHODS, Twenty-eight consecutive patients receiving kidney tr ansplants (26 single-kidney transplants and two en block transplants) with suspected arterial inflow stenosis were examined with two MR angiography se quences: gadolinium-enhanced 3D fast spoiled gradient-recalled (SPGR) imagi ng and 3D phase-contrast imaging. Twenty-four of these patients then were e xamined using the gold standards: either digital subtraction angiography (D SA) (n = 23) or surgery (n = 1), MR angiography and DSA studies were indepe ndently and prospectively analyzed for the presence of arterial stenoses (m ild [<50%], severe [50-90%], or critical [>90%]) in the iliac, anastomotic, and renal artery segments. Two independent observers retrospectively evalu ated the MR angiography sequences for ability to detect or exclude signific ant (greater than or equal to 50%) arterial stenoses. RESULTS. In 22 single-kidney transplants, DSA showed eight significant sten oses in 66 arterial segments. MR angiograms adequately showed 66 of 66 segm ents (prospective observers) and 64 of 66 segments teach retrospective obse rver), which were subsequently evaluated, The sensitivity and specificity o f MR angiography in revealing significant stenoses were 100% and 98% (prosp ective analysis), 88% and 98% (retrospective observer 1), and 86% and 100% (retrospective observer 2), Concordance between observers showed kappa valu es exceeding .85 for all comparisons except the analysis of phase-contrast series (kappa = .62), In one en block transplant, DSA showed that stenosis was greater than 90%, although it had been graded at less than 50% with MR angiography. CONCLUSION. Gadolinium-enhanced 3D MR angiography accurately evaluated arte rial inflow in single-kidney transplants.