Vessel and Vessel Wall Imaging

Abstract

Angiography is a useful, important, common imaging method, with digital subtraction angiography (DSA) remaining the gold standard for luminal imaging. Computed tomography angiography (CTA) is minimally invasive and quite accurate in the evaluation of stenosis. Magnetic resonance angiography (MRA) is a good screening tool with the least invasiveness. Angiography mostly represents intracranial artery disease as luminal stenosis, which is often not sufficient to evaluate intracranial vascular pathology. The modalities provide indirect information about vascular pathology because luminal change, such as stenosis, results from the changes of vessel walls. Vessel wall imaging using high-resolution magnetic resonance imaging (HR-MRI) has been recently introduced for direct evaluation of vessel walls beyond just luminal information such as the severity of stenosis. HR-MRI for vessel walls can present the characteristic radiological findings for each intracranial artery disease such as atherosclerosis, dissection, moyamoya disease, and vasculitis. The radiological features are useful to differentiate among intracranial artery disease. This chapter discusses the role and radiological features of angiography and HR-MRI for vessel walls.

Kongcun Town Asymptomatic Intracranial Artery Stenosis study in Shandong, China: cohort profile

“…Furthermore, high-resolution MRI scans could help further evaluate the characteristics of arterial stenosis and avoid the contamination of ICAS cases with cases involving other non-atherosclerotic diseases. 42 In addition, high-resolution MRI can be used to detect intraplaque haemorrhage, lipid cores and artery fibrous caps, thus providing further insight into the long-term prognosis of aICAS. To the best of our knowledge, this is the first community-based study of aICAS among an Asian population that used high-resolution MRI as well as PWI images and DTI images.…”

Diagnosis of Symptomatic Intracranial Atherosclerotic Disease

“…According to Arenillas, CTA detects the degree of stenosis for each of 15 large intracranial arterial segments assessed: bilateral supraclinoid ICAs, A1-ACA, M1-ACM, M2-ACM, P1-PCA, proximal, mid, and distal BA, and intracranial VA. CTA identifies and characterizes the ICAS of different histopathological nature (including partially recanalized emboli), being unable to directly assess plaque instability. It allows the examination of ICAS progression and in-stent restenosis [3,68]. The stenotic lesions are considered to be atherosclerotic in nature, if no cases with subarachnoid hemorrhage or intracerebral hemorrhage are detected by CT head (in consequence, vasospasm is unlikely the cause of these ICAS).…”

“…CTA has several advantages compared with MRA: better anatomic visualization of the circle of Willis and of the state of the arteries [73] and quite accurate in the evaluation of stenosis, since the latter tends to overestimate high-grade stenosis attributable to turbulent flow; CTA is more accurate for identifying occlusion (sensitivity, 100%; specificity, 99.4-100%) than for measuring the degree of stenosis [68]. CTA is minimally invasive, performed quickly, modest cost, scanner availability 24/7, operator-independent, less susceptible to motion artifacts than MRA, and less dependent on hemodynamic effects compared with MRA [68,69,74,75]. Its disadvantages, besides radiation risk exposure, are patient movement, contrast risk reactions (allergy to iodine contrast agents), different contraindications (nephron-toxicity-serum creatinine levels >1.2 mg/dL, etc.…”

“…Maximum intensity projection (MIP) enhances high attenuation contrast tissues, including bone, wall calcification, or blood vessels. Since calcifications can interfere with the evaluation of the degree of stenosis, bone elimination is done during postprocessing [68,69].…”

“…Helical CTA is superior to DSA in the demonstration of arterial patency in posterior circulation arteries when very low-or balanced flow states are present due to a severe stenosis [76]. In the era of the mechanical thrombectomy with stent-retriever, when faster puncture time to endovascular therapy became very important, CTA became essential due to its shorter scan time and the evaluations of collaterals on multiphase imaging, which can contribute to faster recanalization and better evolution [68].…”