Contrast Enhanced MRA of the Carotid Arteries
author, Randal Aschenbeck, MD
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Clinical History:
This 84-year-old woman developed slurred speech, accompanied by a headache, which by the time of presentation to the emergency room had resolved. Her past medical history was significant for hypertension, tobacco abuse, and prior transient ischemic attacks. Current medications include aspirin, Plavix, and Hydrochlorothiazide. A brain MRI performed two days later revealed small, early subacute (corresponding with clinical presentation) infarctions involving the right frontal (illustrated in A, on diffusion weighted imaging), parietal, and occipital lobes, together with multiple chronic infarctions.
Diagnosis:
Mild atherosclerotic disease, with multiple focal stenoses, but not revealing a cause for the patient’s right-sided infarct.
MR Technique:
Scans were acquired at 3 T on a Siemens Tim Trio, using in an integrated fashion the head, neck, and spine coils. Bolus timing was used, employing 1.5 ml of contrast. For the exam itself, 18.5 ml of gadoteridol (ProHance) was administered at a rate of 1.5 ml/sec. This was followed by a 20 ml saline flush, administered at the same rate. The scan parameters (for the 3D volume gradient echo acquisition) were TR/TE = 3 msec/1.24 msec, with a voxel size of 0.8 x 0.8 x 0.8 mm3 and a scan time of 20 seconds (acquired during breath-holding). Parallel imaging was utilized (GRAPPA), with an acceleration factor of 3. A MIP was performed of the contrast-enhanced acquisition (B), following subtraction of a mask data set obtained pre-contrast.
Imaging Findings:
Mild atherosclerotic irregularity of the distal vertebral arteries is present bilaterally. There is a 50% stenosis (arrow) of the proximal left internal carotid artery, just subsequent to the bifurcation. There is a stenosis, moderate in degree, of the left vertebral artery at the level of C1. The origins of the brachiocephalic, left common carotid, right common and internal carotid, and left subclavian arteries are widely patent.
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