Contrast enhanced MR angiography with parallel imaging in the early period after renal transplantation

Abstract

To evaluate renal allograft vessels in the early period after kidney transplantation with three-dimensional (3D) contrast-enhanced MR angiography (3D CE MRA) using a parallel imaging technique. Sixty-three consecutive patients were examined with 3D CE MRA and integrated SENSE technique (Sensitivity Encoding) 2 to 21 days after renal transplantation. MR angiography studies were analyzed for the presence of arterial stenosis. The degree of renal transplant artery stenosis was graded qualitatively as <50% = mild, 50-70% = moderate, 70-99% = severe, and occlusion. Four patients (6.3%) with moderate (n = 1) or severe (n = 3) arterial stenoses on CE MRA underwent selective intra-arterial digital subtraction angiography. In two patients, selective intravenous digital subtraction angiography (DSA) was performed. Twenty-seven (42.9%) of the 63 patients had normal CE MR angiograms, 29 (46%) showed mild, 3 patients (4.8%) moderate, and 4 patients (6.3%) severe stenoses of the donor artery. In three patients, the severe stenosis of the graft artery was confirmed by surgery or intra-arterial DSA. One patient with suspicion of severe arterial stenosis on MRA had moderate vessel narrowing on DSA. Twelve months after kidney transplantation, serum creatinine levels were not significantly different in patients with mild and moderate stenoses from those without (P > 0.19) but significantly different from those with severe stenoses (P < 0.05). The incidence of mild and moderate vessel narrowing at the arterial anastomosis is unexpectedly high in the early period after kidney transplantation and is most likely due to surgery-related tissue edema.