Cerebrovascular diseases manifest as abnormalities of and disruption to the intracranial vasculature and its capacity to carry blood to the brain. However, the pathogenesis of many cerebrovascular diseases begins in the vessel wall. Traditional luminal and perfusion imaging techniques do not provide adequate information regarding the differentiation, onset, or progression of disease. Intracranial high-resolution MR vessel wall imaging (VWI) has emerged as an invaluable technique for understanding and evaluating cerebrovascular diseases. The location and pattern of contrast enhancement in intracranial VWI provides new insight into the inflammatory etiology of cerebrovascular diseases and has potential to permit earlier diagnosis and treatment. In this report, technical considerations of VWI are discussed and current applications of VWI in vascular malformations, blunt cerebrovascular injury/dissection, and steno-occlusive cerebrovascular vasculopathies are reviewed.
Christopher C. Young, Robert H. Bonow, Guilherme Barros, Mahmud Mossa-Basha, Louis J. Kim, and Michael R. Levitt
Vance T. Lehman, Waleed Brinjikji, Mahmud Mossa-Basha, Giuseppe Lanzino, Alejandro A. Rabinstein, David F. Kallmes, and John Huston III
Intracranial aneurysms are heterogeneous in histopathology and imaging appearance. The biological behavior of different types of aneurysms is now known to depend on the structure and physiology of the aneurysm wall itself in addition to intraluminal flow and other luminal features. Aneurysm wall structure and imaging markers of physiology such as aneurysm wall enhancement have been assessed in many prior investigations using conventional-resolution MRI. Recently, high-resolution vessel wall imaging (HR-VWI) techniques with MRI have been introduced. Reports of findings on high-resolution imaging have already emerged for many types of aneurysms demonstrating detailed characterization of wall enhancement, thickness, and components, but many questions remain unexplored. This review discusses the key HR-VWI literature to date. Aneurysm wall findings on conventional-resolution MRI are also discussed as these may help one understand the potential utility and findings on HR-VWI for various aneurysm types. The authors have illustrated these points with several examples demonstrating both features already described in the literature and novel cases demonstrating the potential for future clinical and research applications.
Mahmud Mossa-Basha, Thien J. Huynh, Daniel S. Hippe, Peter Fata, Ryan P. Morton, and Michael R. Levitt
The aim of this paper was to evaluate the association between intracranial vessel wall MRI enhancement characteristics and the development of angiographic vasospasm in endovascularly treated aneurysm patients.
Consecutive cases of both ruptured and unruptured intracranial aneurysms that were treated endovascularly, followed by intracranial vessel wall MRI in the immediate postoperative period, were included. Two raters blinded to clinical data and follow-up imaging independently evaluated for the presence, pattern, and intensity of wall enhancement. Development of angiographic vasospasm was independently evaluated. Delayed cerebral ischemia; cerebral infarct; procedural details; and presence and grade of subarachnoid, parenchymal, and intraventricular hemorrhage were evaluated. Statistical associations were determined on a per–vessel segment and per-patient basis.
Twenty-nine patients with 30 treated aneurysms (8 unruptured and 22 ruptured) were included in this study. Interobserver agreement was substantial for the presence of enhancement (κ = 0.67) and nearly perfect for distribution (κ = 0.87) and intensity (κ = 0.84) of wall enhancement. Patients with ruptured aneurysms had a significantly greater number of enhancing segments than those with unruptured aneurysms (29.9% vs 7.2%; OR 5.5, 95% CI 2.2–13.7). For ruptured cases, wall enhancement was significantly associated with subsequent angiographic vasospasm while controlling for grade of hemorrhage (adjusted OR 3.9, 95% CI 1.7–9.4). Vessel segments affected by balloon, stent, or flow-diverter use demonstrated greater enhancement than those not affected (OR 22.7, 95% CI 5.3–97.2 for ruptured; and OR 12.9, 95% CI 3.3–49.8 for unruptured).
Vessel wall enhancement after endovascular treatment of ruptured aneurysms is associated with subsequent angiographic vasospasm.
Robert H. Bonow, Cordelie E. Witt, Mahmud Mossa-Basha, Joseph Cuschieri, Saman Arbabi, Monica S. Vavilala, Frederick P. Rivara, and Randall M. Chesnut
The goal of this study was to compare the odds of stroke 24 hours or more after hospital arrival among patients with blunt cerebrovascular injury (BCVI) who were treated with therapeutic anticoagulation versus aspirin.
The authors conducted a retrospective cohort study at a regional level I trauma center including all patients with BCVI who were treated over a span of 10 years. Individuals with stroke on arrival or within the first 24 hours were excluded, as were those receiving alternative antithrombotic drugs or procedural treatment. Exact logistic regression was used to examine the association between treatment and stroke, adjusting for injury grade. To account for the possibility of residual confounding, propensity scores for the likelihood of receiving anticoagulation were determined and used to match patients from each treatment group; the difference in the probability of stroke between the two groups was then calculated.
A total of 677 patients with BCVI receiving aspirin or anticoagulation were identified. A total of 3.8% (n = 23) of 600 patients treated with aspirin sustained a stroke, compared to 11.7% (n = 9) of 77 receiving anticoagulation. After adjusting for injury grade with exact regression, anticoagulation was associated with higher likelihood of stroke (OR 3.01, 95% CI 1.00–8.21). In the propensity-matched analysis, patients who received anticoagulation had a 15.0% (95% CI 3.7%–26.3%) higher probability of sustaining a stroke compared to those receiving aspirin.
Therapeutic anticoagulation may be inferior to aspirin for stroke prevention in BCVI. Prospective research is warranted to definitively compare these treatment strategies.