Optical Coherence Tomography in Cerebrovascular Disease: Open up New Horizons

Quantitative Evaluation of Incomplete Stent Apposition in Intracranial Aneurysms Using Optical Coherence Tomography: a Porcine Model Study

Incomplete stent apposition (ISA) of intracranial stents is recognized as a significant issue in aneurysm treatment leading to in-stent thrombosis and aneurysm recurrence. Traditional imaging techniques like DSA have limitations in accurately assessing stent apposition. This study aimed to explore the efficacy of optical coherence tomography (OCT) in the detection of ISA after stent-assisted coiling (SAC) and its impact on stent endothelialization and aneurysm healing in a porcine model. Twelve healthy minipigs with surgically established common carotid artery sidewall aneurysm were utilized and treated with SAC. DSA and OCT were used immediately post-procedure and during follow-ups at 4 and 12 weeks to assess aneurysm occlusion and stent apposition. Histopathology ultimately assessed stent endothelialization and aneurysm healing. ISA distance, measured by OCT, was analyzed using logistic regression to predict the association between ISA severity and stent endothelialization outcome. OCT detected ISA sites (n = 30) in all subjects at the aneurysm neck, stent ends, and locally in the stent, with a mean ISA distance of 639.65 ± 146.82 µm immediately after the procedure. One experimental pig developed in-stent occlusion after 4 weeks, resulting in death. OCT detected residual ISAs in 54.2% (13/24) at 4 weeks, decreasing to 16.7% (4/24) at 12 weeks in the remaining 11 subjects. DSA showed complete aneurysm occlusion in the remaining subjects at 12 weeks. An ISA distance of > 600 µm was found to be associated with significantly higher rates of poor stent endothelialization at the 12-week follow-up. OCT demonstrated higher sensitivity in detecting ISA after SAC. ISA distance > 600 µm can be a critical prognostic factor, associated with poor outcomes.

A systematic review of application of frequency-domain optical coherence tomography in cerebral large artery atherosclerosis

AIMS

Frequency-domain optical coherence tomography (FD-OCT) is an emerging intravascular imaging modality that offers exceptional spatial resolution in interventional neuroradiology. We aimed to systematically review clinical studies on the applications of FD-OCT in cerebral large artery atherosclerosis (LAA).

METHODS

A systematic literature review of PubMed, Embase, and Cochrane Library was conducted to identify eligible studies published before 1 March, 2025. Eligible studies included all clinical articles written in English that reported the applications of FD-OCT in patients diagnosed with LAA.

RESULTS

A total of 50 studies with 1134 patients were included. FD-OCT was considered to be a feasible intravascular imaging modality as successful imaging could be achieved in 87.0% of patients with a 1.2% periprocedural complication rate. Unsuccessful FD-OCT imaging was attributed primarily to its current limitations, particularly inadequate blood clearance and failure to navigate the tortuous cerebrovascular anatomy or stenosis. The majority of the included studies (35/50) employed FD-OCT to evaluate extracranial atherosclerotic stenosis. FD-OCT could better stratify subsequent stroke risk by adequately identifying features of plaque vulnerability such as thin-cap fibroatheroma, neovascularization, and cholesterol crystal. Through accurately assessing stent-vessel interaction, FD-OCT has the potential to guide the selection of tailored interventions during carotid artery stenting. Recent research (10/50) has shown its potential utility for intracranial atherosclerotic stenosis, including culprit lesion differentiation, peri-intervention evaluation, and mechanistic insight into pathophysiology of stenosis and in-stent restenosis. As for acute ischemic stroke, FD-OCT following thrombectomy can potentially guide the selection of tailored adjunctive treatments to optimize clinical outcomes by assessing the intrinsic properties of the culprit lesion.

CONCLUSIONS

FD-OCT has emerged as a valuable intravascular imaging tool for evaluating the intrinsic properties of culprit lesions and stent-vessel interactions, showing substantial potential in the diagnosis, evaluation, and treatment of cerebral LAA.

Advancements in imaging of intracranial atherosclerotic disease: beyond the arterial lumen to the vessel wall

Intracranial atherosclerotic disease (ICAD) significantly increases the risk of ischemic stroke. It involves the accumulation of plaque within arterial walls and narrowing or blockage of blood vessel lumens. Accurate imaging is crucial for the diagnosis and management of ICAD at both acute and chronic stages. However, imaging the small, tortuous intracranial arterial walls amidst complex structures is challenging. Clinicians have employed diverse approaches to improve imaging quality, with a particular emphasis on optimizing the acquisition of images using new techniques, enhancing spatial and temporal resolution of images, and refining post-processing techniques. ICAD imaging has evolved from depicting lumen stenosis to assessing blood flow reserve and identifying plaque components. Advanced techniques such as fractional flow reserve (FFR), high-resolution vessel wall magnetic resonance (VW-MR), optical coherence tomography (OCT), and radial wall strain (RWS) now allow direct visualization of flow impairment, vulnerable plaques, and blood flow strain to plaque, aiding in the selection of high-risk stroke patients for intervention. This article reviews the progression of imaging modalities from lumen stenosis to vessel wall pathology and compares their diagnostic value for risk stratification in ICAD patients.

Prevalence of intracerebral thrombus detected by optical coherence tomography in patients with posterior circulation stroke or transient ischemic attack

BACKGROUND

The incidence of thrombosis in patients with intracranial atherosclerotic stenosis (ICAS) remains unclear. Optical coherence tomography (OCT) has the potential to explore the vessel wall structure of posterior-circulation ICAS because of its relatively straight anatomical structure compared with that of the anterior cerebral arteries. This study aimed to determine the prevalence and characteristics of thrombosis in the posterior-circulation ICAS using OCT.

METHODS

This prospective study was conducted on 135 patients with posterior-circulation arterial stenosis who underwent OCT. All patients were symptomatic and had a severely stenotic lesion (70-99%) in the vetebrobasilar artery. The enrolled patients were classified according to the presence of in situ thrombus as defined by OCT. Clinical data and OCT characteristics were compared.

RESULTS

Eighty-two patients diagnosed with posterior-circulation ICAS were enrolled. In situ thrombi were identified in 34 patients. Clinically, patients with in situ thrombus were more prone to cerebral infarctions than transient ischemic attacks. The percentage area of stenosis in the non-thrombus group was significantly lower than that in the thrombus group. The thrombus burden, mean flow area, mean thrombus area, maximum lipid arc, and mean lumen area were significantly different among white, red, and mixed thrombi.

CONCLUSIONS

We achieved in vivo vessel wall structural analysis of posterior-circulation ICAS with the largest sample size. We also revealed the true incidence of in situ thrombosis and potential corresponding clinical events of posterior-circulation ICAS for the first time.

Identification of symptomatic carotid artery plaque: a predictive model combining angiography with optical coherence tomography

Objective

Symptomatic carotid artery disease is indicative of an elevated likelihood of experiencing a subsequent stroke, with the morphology of plaque and its specific features being closely linked to the risk of stroke occurrence. Our study based on the characteristics of carotid plaque assessed by optical coherence tomography (OCT), the plaque morphology evaluated by digital subtraction angiography (DSA) and clinical laboratory indicators were combined, develop a combined predictive model to identify symptomatic carotid plaque.

Methods

Patients diagnosed with carotid atherosclerotic stenosis who underwent whole-brain DSA and OCT examination at the Affiliated Hospital of Jining Medical University from January 2021 to November 2023 were evaluated. Clinical features, as well as DSA and OCT plaque characteristics, were analyzed for differences between symptomatic and asymptomatic cohorts. An analysis of logistic regression was carried out to identify factors associated with the presence of symptomatic carotid plaque. A multivariate binary logistic regression equation was established with the odds ratio (OR) serving as the risk assessment parameter. The receiver operating characteristic curve was utilized to assess the combined predictive model and independent influencing factors.

Results

A total of 52 patients were included in the study (symptomatic: 44.2%, asymptomatic: 55.8%). Symptomatic carotid stenosis was significantly linked to four main factors: low-density lipoprotein-cholesterol >3.36 mmol/L [OR, 6.400; 95% confidence interval (CI), 1.067-38.402; p = 0.042], irregular plaque (OR, 6.054; 95% CI, 1.016-36.083; p = 0.048), ruptured plaque (OR, 6.077; 95% CI, 1.046-35.298; p = 0.048), and thrombus (OR, 6.773; 95% CI, 1.194-38.433; p = 0.044). The combined predictive model generated using four indicators showed good discrimination (Area Under Curve, 0.924; 95% CI, 0.815-0. 979). The p value was <0.05 with 78.26% sensitivity and 93.10% specificity.

Conclusion

OCT is valuable in evaluating the plaque characteristics of carotid atherosclerotic stenosis. The combined predictive model comprising low-density lipoprotein-cholesterol >3.36 mmol/L, irregular plaque, ruptured plaque, and thrombus could help in the detection of symptomatic carotid plaque. Further research conducted on additional independent cohorts is necessary to confirm the clinical significance of the predictive model for symptomatic carotid plaque.

The biological applications of near-infrared optical nanomaterials in atherosclerosis

PURPOSE OF REVIEW

Atherosclerosis, a highly pathogenic and lethal disease, is difficult to locate accurately via conventional imaging because of its scattered and deep lesions. However, second near-infrared (NIR-II) nanomaterials show great application potential in the tracing of atherosclerotic plaques due to their excellent penetration and angiographic capabilities.

RECENT FINDINGS

With the development of nanotechnology, among many nanomaterials available for the visual diagnosis and treatment of cardiovascular diseases, optical nanomaterials provide strong support for various biomedical applications because of their advantages, such as noninvasive, nondestructive and molecular component imaging. Among optical nanomaterials of different wavelengths, NIR-II-range (900 ~ 1700 nm) nanomaterials have been gradually applied in the visual diagnosis and treatment of atherosclerosis and other vascular diseases because of their deep biological tissue penetration and limited background interference. This review explored in detail the prospects and challenges of the biological imaging and clinical application of NIR-II nanomaterials in treating atherosclerosis.

Retreatment with a pipeline embolization device for recanalized aneurysms following stent-assisted coiling embolization

Background and purpose

Flow diverters have emerged as viable alternatives for the retreatment of recanalized aneurysms following stent-assisted coiling embolization. In this study, we aim to present our experience of retreatment for such aneurysms using the pipeline embolization device (PED).

Materials and methods

This case series presents a retrospective single-center analysis of patients with recanalized aneurysms who underwent retreatment using the PED between July 2019 and April 2023, subsequent to stent-assisted coiling embolization.

Results

The study includes five female patients, whose relevant clinical data were recorded. All patients had aneurysms located in the internal carotid artery, comprising two blood blister-like aneurysms and two giant aneurysms. Prior to the retreatment, two LVIS stents, two enterprise stents, and one solitaire stent were implanted. Among the five patients, one experienced a fatal post-operative subarachnoid hemorrhage, while two patients achieved complete embolization, and another patient achieved near-complete embolization during the last follow-up. Furthermore, one patient faced challenges during the placement of the PED and was unable to achieve successful deployment. We propose four overlapping relationships between a newly implanted PED and a previously deployed stent: (1) PED covering only the proximal end of the previous stent, (2) PED covering only the distal end of the previous stent, (3) PED covering both the proximal and distal ends of the previous stent, and (4) PED deployed within the previous stent. Antiplatelet therapy at our center involved daily dual therapy with aspirin (100 mg/day) and clopidogrel (75 mg/day) for at least 5 days before PED placement. Intra-arterial bolus administration of tirofiban (5 mcg/kg) was administered during or immediately after PED deployment, followed by a maintenance dose of 0.08 mcg/kg/min IV infusion for at least 24-48 h if necessary. Postprocedural dual antiplatelet therapy included clopidogrel (75 mg/day) for 6 months and aspirin (100 mg/day) for 12 months.

Conclusion

The findings of this study support the efficacy of the PED for the retreatment of recanalized aneurysms following stent-assisted coiling embolization.

Magnetically assisted soft milli-tools for occluded lumen morphology detection

Methodologies based on intravascular imaging have revolutionized the diagnosis and treatment of endovascular diseases. However, current methods are limited in detecting, i.e., visualizing and crossing, complicated occluded vessels. Therefore, we propose a miniature soft tool comprising a magnet-assisted active deformation segment (ADS) and a fluid drag-driven segment (FDS) to visualize and cross the occlusions with various morphologies. First, via soft-bodied deformation and interaction, the ADS could visualize the structure details of partial occlusions with features as small as 0.5 millimeters. Then, by leveraging the fluidic drag from the pulsatile flow, the FDS could automatically detect an entry point selectively from severe occlusions with complicated microchannels whose diameters are down to 0.2 millimeters. The functions have been validated in both biologically relevant phantoms and organs ex vivo. This soft tool could help enhance the efficacy of minimally invasive medicine for the diagnosis and treatment of occlusions in various circulatory systems.

Detecting vulnerable carotid plaque and its component characteristics: Progress in related imaging techniques

Carotid atherosclerotic plaque rupture and thrombosis are independent risk factors for acute ischemic cerebrovascular disease. Timely identification of vulnerable plaque can help prevent stroke and provide evidence for clinical treatment. Advanced invasive and non-invasive imaging modalities such as computed tomography, magnetic resonance imaging, intravascular ultrasound, optical coherence tomography, and near-infrared spectroscopy can be employed to image and classify carotid atherosclerotic plaques to provide clinically relevant predictors used for patient risk stratification. This study compares existing clinical imaging methods, and the advantages and limitations of different imaging techniques for identifying vulnerable carotid plaque are reviewed to effectively prevent and treat cerebrovascular diseases.