Noncontrast MRA of the neck may overestimate the degree of stenosis when severe and/or near occlusive. Contrast administration can reduce the degree of overestimation of the degree of stenosis in some cases. However, contrast-enhanced and TOF MRA of the neck have a similar sensitivity for the detection of >70% stenosis of the carotid when 2-D and 3-D techniques of TOF are combined [27,117]. MRA of the neck may also be useful for treatment planning. However, the anatomic definition of the surrounding structures may be inadequate for treatment planning in some cases depending on the sequences used [114]. Additionally, anatomical features of carotid plaque including intraplaque high-intensity signal on 3-D TOF source images can be useful predictors of future stroke risk, beyond assessing the degree of luminal narrowing [85,118,119]. MRI Head Perfusion With IV Contrast Contrast-enhanced MRI head perfusion imaging (or, if available, noncontrast ASL perfusion) may help delineate the hemodynamic significance of a known asymptomatic carotid lesion and the collateral support in each distribution. More specifically, perfusion imaging may be helpful in cases of moderate stenosis, approaching 70% or severe stenosis [124]. MRI Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRI of the head in the surveillance imaging of asymptomatic carotid stenosis. MRI Head Without IV Contrast MRI of the head is useful in evaluating for the sequela of carotid stenosis such as clinically silent strokes or microvascular ischemic changes in the setting of an established diagnosis of carotid stenosis, which is particularly important in cases of hemodynamically significant stenosis. There may be a role for noncontrast MRI of the head Cerebrovascular Diseases-Stroke when monitoring patients with risk factors for stroke or known carotid stenosis.
Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Noncontrast MRA of the neck may overestimate the degree of stenosis when severe and/or near occlusive. Contrast administration can reduce the degree of overestimation of the degree of stenosis in some cases. However, contrast-enhanced and TOF MRA of the neck have a similar sensitivity for the detection of >70% stenosis of the carotid when 2-D and 3-D techniques of TOF are combined [27,117]. MRA of the neck may also be useful for treatment planning. However, the anatomic definition of the surrounding structures may be inadequate for treatment planning in some cases depending on the sequences used [114]. Additionally, anatomical features of carotid plaque including intraplaque high-intensity signal on 3-D TOF source images can be useful predictors of future stroke risk, beyond assessing the degree of luminal narrowing [85,118,119]. MRI Head Perfusion With IV Contrast Contrast-enhanced MRI head perfusion imaging (or, if available, noncontrast ASL perfusion) may help delineate the hemodynamic significance of a known asymptomatic carotid lesion and the collateral support in each distribution. More specifically, perfusion imaging may be helpful in cases of moderate stenosis, approaching 70% or severe stenosis [124]. MRI Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRI of the head in the surveillance imaging of asymptomatic carotid stenosis. MRI Head Without IV Contrast MRI of the head is useful in evaluating for the sequela of carotid stenosis such as clinically silent strokes or microvascular ischemic changes in the setting of an established diagnosis of carotid stenosis, which is particularly important in cases of hemodynamically significant stenosis. There may be a role for noncontrast MRI of the head Cerebrovascular Diseases-Stroke when monitoring patients with risk factors for stroke or known carotid stenosis.