3D sequence aids rupture-prone plaque detection

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Canadian researchers have used 3D MRI to accurately detect bleeding within the walls of diseased carotid arteries, suggesting the technique may prove to be a useful screening tool for patients at high risk for stroke, according to a study published in this month’s issue of Radiology.

“The combination of a 3D high-spatial-resolution acquisition and extended coverage allows the full assessment of complicated carotid plaque,” wrote researchers from the University of Toronto and Sunnybrook Health Sciences Center, also in Toronto.

Intraplaque hemorrhage (IPH) leads to a rapid and excessive accumulation of red blood cells in the plaque, and this change in plaque constituents is thought to promote destabilization of advanced coronary atherosclerotic plaque, which demonstrate surface ulcerations, hemorrhage or thrombus.

“Therefore, methods with which carotid complicated plaques can be detected may have substantial clinical use, especially if these methods are noninvasive and easily applied in clinical practice,” the authors wrote.

MR direct thrombus imaging utilizes a 3D technique that has the potential to directly depict subacute hemorrhage in patients with carotid atherosclerotic plaques and enable detection of complicated plaque at a spatial resolution of approximately 1 mm.

The researchers performed MR direct thrombus imaging on 11 enrolled patients, ages 69 to 81, using a 1.5T TwinSpeed MR system from GE Healthcare. Patients were referred for evaluation of symptomatic carotid artery stenosis (transient ischemic attacks, amaurosis fugax, cerebral infarction) or asymptomatic carotid artery stenosis, according to the authors.

Endarterectomy specimens were obtained from diseased arteries and were examined by a vascular pathologist for correlation with imaging findings.

The research team found strong agreement between the lesions identified by the MRI as complicated plaques and the microscopic analysis of the tissue samples.

“With its high spatial resolution, MR imaging of IPH enabled in-slice detection of the location of hemorrhage in the plaque, resulting in strong agreement between MR imaging findings and histologic findings for each reader,” the authors reported.

According to the researchers, 3D MRI is a tool that is “ideally suited to screen high-risk patients for complicated carotid plaques and to monitor the effects of interventions designed to slow the progress of the atherosclerotic disease.”

They reported that the technique is easy to perform and interpret, because of the use of a single contrast weighting and the innate T1 hyperintense tissue contrast thought to be provided by methemoglobin (a form of the oxygen-carrying protein hemoglobin), and takes only a few minutes when added to an MR angiography study.