Multiple Arterial Stenoses

Contrast-Enhanced-MRA-A-TimCT-Run-Off.0001.jpg

A

Contrast-Enhanced-MRA-B-TWIST-lower-leg.0001.jpg

B

C

Contrast-Enhanced-MRA-D-Native-Lower-Legs.0001-wc.jpg

D

Clinical History: 
This 63-year-old man presented with a longstanding history of peripheral arterial occlusive disease, hypertension, diabetes, coronary artery disease, prior myocardial infarction, crossover bypass, and renal artery stenosis with increasing leg pain.

Diagnosis:
Multifocal stenoses of the lower extremity vessels, superficial femoral artery stenoses, renal artery stenosis, occlusion of the pelvic axis.

MR Technique: 
Scans were acquired at 3 T on a Tim Trio system, using one body matrix and a dedicated 32-element PA-matrix coil. Bolus timing was used, employing 1 ml of contrast. For the exam itself, 14 ml of gadolinium chelate was administered at a rate of 1.5 ml/sec. This was followed by a 25 ml saline flush, administered at the same rate. The scan parameters (for the 3D volume gradient echo acquisition) were TR/TE 2.43 msec/1.02 msec, with an almost isotropic voxel size of 1.2 x 1.2 x 1.3 mm3 and a scan time of 1:02 min:sec (acquired during breath-holding). Parallel imaging was utilized (GRAPPA), with an acceleration factor of 2. The MRA was acquired during continuous table movement (TimCT) over a large FOV of 140 cm (A). Five minutes after the MRA acquisition an additional time-resolved MRA (TWIST, TR/TE 2.75/1.12 ms, voxel size 1.1x1.1x1.1 mm3, temporal resolution 5.5 sec) was acquired. For the time-resolved MRA, 4 ml of contrast agent was injected at 1.5 ml/sec followed by a saline chaser of 25 ml injected at the same flow rate. The delay between the injection of contrast agent and the start of the time-resolved MRA was set to 7 sec (B, C). Before contrast administration, an investigational non-enhanced native SPACE sequence (D) (TR/TE 1193/34 ms, voxel size 1.4x1.4x1.3mm3) was acquired. This EKG-triggered sequence acquires images during systole and diastole, subtracts the diastolic from the systolic data set, with the resulting image only demonstrating the arterial system.

Imaging Findings:
Patency of the femoro-femoral bypass is demonstrated on the TimCT MRA (A). The proximal part of the right superficial femoral artery is occluded and re-filled via a collateral vessel that originates from the profundus (deep) femoral artery. Inspection of the distal part of the left superficial femoral artery reveals a high-grade stenosis, followed by multiple intermediate-grade stenoses involving the P1 segment of the popliteal artery, but with good enhancement of the run-off vessels in the calf. The right popliteal artery is also occluded over a short section, but sufficiently collateralized, with good enhancement demonstrated of the calf arteries. In the non-enhanced native SPACE MRA (D), the vessels of the lower extremity are depicted almost equivalently to the contrast-enhanced TWIST-MRA (B, D), however with an artifactual stenosis in the proximal left anterior tibial artery and non-depiction of the distal left peroneal artery.