People with diabetes are more likely to have high blood pressure and high cholesterol and are much more likely to develop cholesterol blockages in their arteries. A person with diabetes is four times as likely to suffer from carotid disease and stroke than people without diabetes. Controlling blood pressure and cholesterol and glucose levels with medications is even more important for people with diabetes because of their higher risk for carotid artery disease. Carotid artery disease currently stratifies patient risk, however, even without thickening of plaque within this artery, a stroke may occur.
The carotid arteries are vessels on each side of the neck that supply oxygenated blood to the head. Narrowing of the carotid arteries is associated with risk of stroke, however, less is known about stroke risk in suspectible people with little or no narrowing of these arteries. Now, a study from researchers at the University of Toronto has shown that arterial imaging with 3-D MRI can be used to determine stroke risk among diabetics. The team state that the findings may be able to determine people with diabetes that are harboring advanced vascular disease that could increase their risk of stroke. The study was presented at the annual meeting of the Radiological Society of North America (RSNA)
Previous studies show that plaque imaging based on magnetic resonance imaging (MRI) represents a new modality for risk assessment in atherosclerosis, allowing for classification of carotid plaques in high-risk and low-risk lesion types (I-VIII). Diabetes represents a known risk factor for atherosclerosis, however, its specific influence on plaque vulnerability is not fully understood, although diabetes represents a well-established risk factor for atherosclerosis and stroke. IPH is a common feature of atherosclerotic plaques and is considered one of the identifying features of complex lesions preceding acute ischemic events. The cause of IPH is most often secondary to rupture of neovessels, which have invaded the plaque. However, inflammation and metabolic factors such as diabetes may also precipitate hemorrhage from mature microvessels by damaging the endothelium which leads to confusion when measuring biomarkers and analysing imaging. The current study shows the prevalence of IPH in an asymptomatic diabetic population without carotid artery narrowing, using 3-D MRI.
The current study used 3-D MRI to investigate the prevalence of carotid IPH in 159 asymptomatic type 2 diabetic patients, average age 63. Results show that of the 159 patients imaged, 37, or 23.3%, had IPH in at least one carotid artery; with five of the 37 patients shown to have IPH in both carotid arteries. Data findings show that IPH was found in the absence of carotid artery stenosis, or narrowing, and was associated with an increased carotid artery wall volume as measured by 3-D MRI.
Results show that 3-D MRI imaged the entire carotid artery and pinpointed the area of interest over a shorter period of time compared with multiple 2-D sequences. The lab stress that the study did not look at outcomes for the patients and did not draw any conclusions on whether people with IPH will develop carotid artery blockages more quickly than those with no IPH present. However, they go on to add that it is already known that blood is a destabilizing factor of plaque that promotes rupture, setting off a chain of events that can lead to a stroke. The group conclude that 3D MRI can identify high risk cardiovascular biomarkers, such as intraplaque hemorrhage, in diabetic patients before onset of stenosis (narrowing of arteries).
The team surmise that IPH can be found in the absence of carotid artery narrowing in asymptomatic diabetic patients and is associated with an increased carotid artery wall volume as measured by 3D-MRI. For the future, the researchers state that it represents a biomarker of advanced atherosclerotic disease and may identify individuals at higher risk of cardiovascular disease.
Source: Radiological Society of North America
Image A shows the 3-D MRI intraplaque hemorrhage (IPH) sequence as acquired in the coronal plane. The red dotted line indicates the level at which the reformatted axial plane, B, was obtained. C shows the section of the right carotid artery with a region of high signal consistent with IPH. Contours are drawn for the outer wall (green) and lumen (red) with the area of IPH in this segment shaded blue in D. Credit: Radiological Society of North America.