MRA of Aortoiliac Arteries
Clinical History
This patient was a 57-year-old Caucasian male with a past medical history of right-sided ischemic pain at rest, left-sided minor tissue loss, smoking, diabetes, bronchitis, PVD, claudication, myocardial infarction, hyperlipidemia, proteinuria, spinal stenosis and obesity (114 kg bodyweight). He was taking cilostazol, atorvastatin and glipidide.
MR Imaging
MR imaging was carried out in 2002 on a Siemens 1.5 T whole body scanner. Time-of-flight MR was performed (data not shown). The standard TOF MR angiogram showed occlusion of the left internal iliac artery and suspected stenosis of the right internal iliac artery, adjacent to an image artifact. It was unclear from this image whether the left-sided occlusion is total or subtotal. In addition to TOF MRA, dynamic and steady-state MR angiography were performed after intravenous injection of gadofosveset. Invasive catheter-based angiography was also carried out.
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Fig. 1. This dynamic 3D gradient echo MR angiography (TE 1.9, TR 6.6, NEX 1, flip angle 25°, slice thickness 2.0 mm, field of view 400 x 400 mm, matrix 512 with 43.8 % phase resolution) was performed 30 seconds after i.v. bolus injection of the blood pool contrast agent. The overall scanning time was 28 seconds, allowing an actual resolution of 0.8 x 1.8 x 2.0 mm.
Comment: This early-phase, contrast-enhanced MR angiogram shows pronounced occlusion of the left common iliac artery with almost regular filling of the distal portion of the iliac axis. Slight irregularities of the walls of the distal abdominal aorta and both iliac arteries are also evident.
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Fig. 2a-d. The figure shows four images (coronal MIP, axial, coronal, and coronal oblique slices) obtained by steady-state 3D gradient echo MR angiography (TE 1.9, TR 25.0, NEX 1, flip angle 30°, slice thickness 0.9 mm, field of view 400 x 400 mm, matrix 512 with a 100% phase resolution, fat saturation), which was commenced 5 minutes 25 seconds after the start of the dynamic sequence with the blood pool agent. The overall scanning time was 7 minutes, allowing an actual resolution of 0.8 x 0.8 x 0.9 mm.
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Comment: These steady-state MR angiography images show the true extent of atherosclerosis in this patient. There is pronounced plaque formation on both the aortic wall and within the iliac axis on both sides, left > right. The axial image in the region of the left-sided subtotal occlusion clearly shows a small residual lumen in the left iliac artery (arrow). The coronal view demonstrates plaque formation on the vessel wall (arrows) and the coronal oblique view shows both the atherosclerotic plaques (white arrows) and the small residual lumen (black arrow).
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Fig. 3. Catheter-based angiography with insertion of the catheter on the left side. This contrast-enhanced angiogram obtained by advancing a catheter via the subtotal occlusion showed a small, residual lumen, thus providing evidence confirming the initial finding.
The catheter in place leads to a marked reduction in vessel opacification post-stenosis. Blood pool-enhanced MR angiography gives a more comprehensive picture of the true extent of the atherosclerotic lesion.