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

Abstract

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.

Comprehensive imaging analysis of intracranial atherosclerosis

“…Additionally, transcranial Doppler may also provide estimations of arterial stenosis. 6 While DSA, CTA, and MRA directly measure the lumen to determine stenosis, transcranial Doppler indirectly estimates stenosis by assessing blood flow velocity. 2 7 DSA provides detailed information about the anatomy, severity of the stenosis, and collateral circulation of the intracranial arteries.…”

“…Bash et al studied 115 diseased arterial segments where CTA demonstrated higher sensitivity (98% vs 70%) and a positive predictive value (93% vs 65%) than TOF MRA for detecting intracranial stenosis. 23 It is important to note that, like DSA, MRA is a luminal modality and by itself cannot provide information about the arterial wall and may be susceptible to motion artifacts due to longer acquisition times, 6 potentially affecting image quality and diagnostic accuracy. However, MRA has the advantage that a HR-MRI protocol including T2, T1 and T1 post Gd sequences can be performed during the same session and increase the detection and characterization of plaques.…”