Etiology of Intracranial Arterial Stenosis: Are Transcranial Color-Coded Duplex Ultrasound and 3T Black Blood MR Imaging Complementary?

Multimodal imaging approach for the diagnosis of intracranial atherosclerotic disease (ICAD): Basic principles, current and future perspectives

PURPOSE

To review the different imaging modalities utilized in the diagnosis of Intracranial Atherosclerotic Disease (ICAD) including their latest development and relevance in management of ICAD.

METHODS

A review of the literature was conducted through a search in google scholar, PubMed/Medline, EMBASE, Scopus, clinical trials.gov and the Cochrane Library. Search terms included, "imaging modalities in ICAD," "ICAD diagnostic," "Neuroimaging of ICAD," "Evaluation of ICAD". A summary and comparison of each modality's basic principles, advantages and disadvantages were included.

RESULTS

A total of 144 articles were identified and reviewed. The most common imaging used in ICAD diagnoses were DSA, CTA, MRA and TCD. They all had proven accuracy, their own benefits, and limitations. Newer modalities such as VWI, IVUS, OCT, PWI and CFD provide more detailed information regarding the vessel walls, plaque characteristics, and flow dynamics, which play a tremendous role in treatment guidance. In certain clinical scenarios, using more than one modality has been shown to be helpful in ICAD identification. The rapidly evolving software related to imaging studies, such as virtual histology, are very promising for the diagnostic and management of ICAD.

CONCLUSIONS

ICAD is a common cause of recurrent ischemic stroke. Its management can be both medical and/or procedural. Many different imaging modalities are used in its diagnosis. In certain clinical scenario, a combination of two more modalities can be critical in the management of ICAD. We expect that continuous development of imaging technique will lead to individualized and less invasive management with adequate outcome.

Value of transcranial color-code Doppler in evaluating intracranial atherosclerotic stenosis in patients with diabetes mellitus type 2: a comparison of transcranial Doppler and computed tomography angiography

BACKGROUND

There are several imaging assessment methods for intracranial atherosclerotic stenosis (ICAS). This study investigated the most efficient method by which to diagnose ICAS in patients with diabetes mellitus.

METHODS

One hundred seven patients with type 2 diabetes mellitus were enrolled as the experimental group and 68 healthy subjects were designated as the control group. The experimental group was examined with transcranial color-code Doppler (TCCD) and transcranial Doppler (TCD). Sixty-five patients in the experimental group were diagnosed by computed tomography angiography (CTA) on a voluntary basis. The 68 subjects in the control group were examined by TCCD alone.

RESULTS

Based on TCCD examinations, the ICAS positivity rate was 71.0% (76/107) in the experimental group, which was greater than the 42.6% (29/68) in the control group (χ2 = 13.954, P＜0.001). The middle cerebral artery was most frequently affected by ICAS (χ2 = 4.684，P=0.030), with a higher incidence of moderate and severe stenosis (χ2 =4.510，P=0.034). The ICAS positivity rate was 64.6% (42/65) by TCCD, 75.4% (49/65) by CTA, and 53.8% (35/30) by TCD. There was a statistically significant difference between the TCCD and CTA (χ2=1.795, P=0.180) and between the TCD and CTA (χ2=6.594, P=0.010) positivity rates.

CONCLUSIONS

ICAS is expected to occur in patients with diabetes mellitus more often than healthy subjects, and to involve the middle cerebral artery with moderate-to-severe stenosis. The ICAS positivity rate evaluated by TCCD was lower than CTA and higher than TCD.

A Review on the Value of Imaging in Differentiating between Large Vessel Vasculitis and Atherosclerosis

Imaging is becoming increasingly important for the diagnosis of large vessel vasculitis (LVV). Atherosclerosis may be difficult to distinguish from LVV on imaging as both are inflammatory conditions of the arterial wall. Differentiating atherosclerosis from LVV is important to enable optimal diagnosis, risk assessment, and tailored treatment at a patient level. This paper reviews the current evidence of ultrasound (US), 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography (FDG-PET), computed tomography (CT), and magnetic resonance imaging (MRI) to distinguish LVV from atherosclerosis. In this review, we identified a total of eight studies comparing LVV patients to atherosclerosis patients using imaging—four US studies, two FDG-PET studies, and two CT studies. The included studies mostly applied different methodologies and outcome parameters to investigate vessel wall inflammation. This review reports the currently available evidence and provides recommendations on further methodological standardization methods and future directions for research.

Black-blood magnetic resonance imaging suggesting central nervous system vasculitis in moyamoya syndrome associated with systemic lupus erythematosus

Moyamoya syndrome is a cerebrovascular disorder characterized by bilateral stenosis and occlusion of the internal carotid arteries and their branches. A 45-year-old woman with a history of systemic lupus erythematosus was admitted for recurrent ischemic strokes. Magnetic resonance (MR) angiography revealed moyamoya-like vasculopathy. Black-blood gadolinium-based contrast-enhanced MR images showed strong, concentric enhancement along the occluded arteries, which suggested vasculitis as the etiology of moyamoya-like vasculopathy. Intensive immunosuppressive therapy combined with anticoagulation therapy and rehabilitation led to a favorable outcome in this case. Black-blood MR imaging can be a non-invasive and prompt imaging modality when central nervous system vasculitis is suspected.

Neurosonography After Mechanical Thrombectomy for Acute Stroke Treatment

BACKGROUND AND PURPOSE

Mechanical thrombectomy has been shown to be effective for acute stroke treatment, but lesions of cerebral vessels can develop thereafter. Such lesions of recanalized vessels and altered cerebral hemodynamics after mechanical thrombectomy are poorly investigated. In particular for neurosonography, data are sparse. We aimed to describe hemodynamic changes and incidence of de-novo stenosis after mechanical thrombectomy with neurosonography.

METHODS

Retrospective analysis of patients after successful mechanical thrombectomy for acute stroke therapy who received one neurosonography at baseline and during follow up. Peak systolic velocity (PSV) of all intracranial recanalized and reference vessels was extracted for analysis. Patients with an isolated increase or decrease of PSV (50% or 50 cm/second for anterior and 30% or 30 cm/second for posterior circulation) were identified and characterized.

RESULTS

Eighty-eight patients (mean age 64.4; 34.1% female) were included in this study. In 9 (10.2%) patients, the vessel occlusion was located in the posterior, and in 79 (89.9%) patients the vessel occlusion was located in the anterior circulation. With predominance to the recanalized vessel, mean PSV decreased at both, the recanalized and the reference vessel during follow up. In 3 (3.4%) patients, an isolated increase of PSV was observed in the recanalized vessel, and in 6 (6.8%) patients an isolated decrease of PSV was observed in the recanalized vessel.

CONCLUSION

Sonographic incidence of de-novo stenosis following mechanical thrombectomy seems to be low, in line with prior angiographic studies. However, as measured by neurosonography, cerebral hemodynamic in the recanalized vessel is dynamic after thrombectomy. This result is of interest for further prospective analysis.

A High-Resolution MRI Study of Relationship between Remodeling Patterns and Ischemic Stroke in Patients with Atherosclerotic Middle Cerebral Artery Stenosis

Purpose: Recently, high-resolution magnetic resonance imaging (HR-MRI) has been used to depict the wall characteristics of the intracranial arteries. The aim of this study was to explain the relationship between the remodeling patterns and acute ischemic stroke in patients with atherosclerotic middle cerebral artery (MCA) stenosis using HR-MRI. Materials and Methods: From August 2015 to May 2016, we prospectively screened 33 consecutive patients with unilateral MCA stenosis using time-to-flight MR angiography, including 15 patients with symptomatic MCA stenosis and 18 patients with asymptomatic MCA stenosis. Among them, 14 patients were diagnosed as positive remodeling (PR) and 19 as negative remodeling or non-remodeling. The cross-sectional images of the stenotic MCA wall on HR-MRI including T1WI, T2WI, and PDWI were compared between the symptomatic group and the asymptomatic group as well as the PR group and the non-PR group, based on the vessel area, lumen area, wall area, plaque area, degree of stenosis, remodeling index, and NIHSS score. Results: The symptomatic group had larger wall area (P = 0.040), plaque area (P<0.001), degree of stenosis (P = 0.038), remodeling index (P < 0.001), and NIHSS score (P = 0.003) as well as smaller lumen area (P = 0.001) than the asymptomatic group. In addition, more PR patients were observed in symptomatic group. The PR group had larger plaque area (P = 0.014) and NIHSS score (P = 0.037) than the non-PR group. Demographic and clinical characteristics between the symptomatic group and the asymptomatic group, the PR group and the non-PR group showed no statistical difference. Conclusion: The current study suggests that the HR-MRI has emerged as a promising tool to detect the characteristics of intracranial arteries wall and reveal the relationship between remodeling patterns and ischemic stroke. The PR is an unsafe remodeling way and is prone to cause acute ischemic stroke.