Purpose or Case Report: INTRODUCTION
Renal artery stenosis is a common complication after transplantation. In our institution, we have unfortunately found a high rate of false-positive Doppler ultrasound and non-contrast time-of-flight MRA studies that go to invasive catheterization which turn out negative for renal artery stenosis. We present one of many of our cases which show the utility of high-quality 3D MRA using another non-contrast technique, NATIVE True-FISP, which is appears better apt at achieving adequate signal even when the acquisition plane is not perpendicular to the vessel of interest.

CASE DESCRIPTION
A 13-year-old male with a history of idiopathic dilated cardiomyopathy and end-stage renal disease from presumed ischemic injury during cardiac catheterization underwent a combined cardiac transplant and deceased donor kidney transplant. Two months after the transplant, the patient was admitted for respiratory distress, pulmonary edema, and worsening cardiac function, the latter documented by routine outpatient echocardiography.

On admission, a Doppler ultrasound showed elevated peak systolic velocity of the transplant renal artery anastomosis, up to 434 cm/sec. To confirm the sonographic suspicion of renal artery stenosis, a non-contrast 3D MRA was requested which showed tight juxta-anastomic stenosis (see Figure 1).

The interventional radiology service was consulted who brought the patient to their angiography suite on the basis of the clinical and imaging findings. A diagnostic angiogram confirmed the pre-angiographic imaging findings with nearly one-to-one correlation with the MR 3D-volume-rendered images (see Figure 2). Angioplasty of this lesion was performed, and follow-up ultrasounds up to six-months post angioplasty show interval normalization of the renal artery velocities and blood pressure.
Methods & Materials:
Results:
Conclusions: NATIVE TrueFISP MRA can provide high-quality 3D images that can confirm the presence of suspected stenosis and help interventional radiology with pre-procedural planning. In our institution, this sequence has replaced our former time-of-flight MRA-based protocol, and our interventional radiology department now routinely requests NATIVE TrueFISP MRA of transplant kidneys with suspected arterial stenosis following ultrasound.