3D MRI sequence aids rupture-prone plaque detection
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.
“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.
In fact, the Canadian researchers routinely use the technique, co-author Alan R. Moody, MD, told Cardiovascular Business News. “Any patient being investigated for carotid related cerebral ischemia, i.e., TIA or stoke, or found to have significant carotid narrowing and being considered for surgery comes for assessment of their carotids and brain with MRI,” Moody said.
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 demonstrates 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.
Richard Bitar, MD, and colleagues 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 study (Radiology 2008;249[1]:259-267).
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 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.
If a patient not scheduled for carotid surgery is found to have intraplaque hemorrhage, the best option would be to put the patient on maximal medical therapy, such as statins, “though there is no evidence yet that this will improve outcome,” Moody said.
“The only thing we know so far is that patients with a positive scan have more events in the future; so this seems a logical approach. We are organizing a trial at present to see whether stenting the carotid vessel has a role to play in these non-surgical patients, but the results of this are still a little way off.”
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| Multiplanar reformations of MR images of intraplaque hemorrhage (IPH). A, As MR images of IPH are 3D volume reformations and are usually acquired in the sagittal plane, axial and coronal reformation is possible. B, Axial reformation at the level of the solid gray line in A. C, Coronal reformation at the level of the hatched gray line in A. On all images, IPH (arrows) and vessel lumen (*) are visible. Image and caption courtesy of the Radiological Society of North America. |
In fact, the Canadian researchers routinely use the technique, co-author Alan R. Moody, MD, told Cardiovascular Business News. “Any patient being investigated for carotid related cerebral ischemia, i.e., TIA or stoke, or found to have significant carotid narrowing and being considered for surgery comes for assessment of their carotids and brain with MRI,” Moody said.
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 demonstrates 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.
Richard Bitar, MD, and colleagues 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 study (Radiology 2008;249[1]:259-267).
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 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.
If a patient not scheduled for carotid surgery is found to have intraplaque hemorrhage, the best option would be to put the patient on maximal medical therapy, such as statins, “though there is no evidence yet that this will improve outcome,” Moody said.
“The only thing we know so far is that patients with a positive scan have more events in the future; so this seems a logical approach. We are organizing a trial at present to see whether stenting the carotid vessel has a role to play in these non-surgical patients, but the results of this are still a little way off.”