Preliminary experience with optical coherence tomography imaging to evaluate carotid artery stents: safety, feasibility and techniques

Flow diverter surface modifications for aneurysm treatment: A review of the mechanisms and data behind existing technologies

Flow diversion (FD) has become a mainstay treatment for large wide-necked aneurysms. Despite excellent safety and efficacy, the risk of thromboembolic complications necessitates the use of dual antiplatelet therapy (DAPT). The use of DAPT makes hemorrhagic complications of stenting carry high morbidity and mortality. Additionally, DAPT usage carries a risk of "nuisance" complications that do not directly impact intracranial circulation but need to be managed nonetheless. To circumvent this issue, the most recent generation of flow diverters have undergone surface modification with various compounds to confer blood compatibility to limit clotting and thrombosis. While these newer generation flow diverters are marketed to enhance ease of deployment, the goal is to eventually facilitate single antiplatelet use with flow diverter treatment. This generation of FDs have potential to expand indications beyond unruptured wide-necked aneurysms to include ruptured intracranial aneurysms without the necessity of DAPT. Currently, no comprehensive review details the molecular mechanisms and pre-clinical and clinical data on these modifications. We seek to fill this gap in the literature by consolidating information on the coating technology for four major FDs currently in clinical use-PipelineTM Flex and Vantage Shield TechnologyTM, FREDTMX, p48/64 hydrophilic coating, and Acandis Dervio® 2heal-to serve as a reference guide in neurointerventional aneurysm treatment. Although the Balt silkTM was one of the first FDs, it is uncoated, thus we will not cover this device in our review. A literature review was performed to obtain information on each coating technology for the major flow diverters currently on the market using international databases (PUBMED, Embase, Medline, Google Scholar). The search criteria used the keywords for each coating technology of interest "phosphorylcholine," "poly 2-methoxyethyl acrylate," "hydrophilic polymer coating," and "fibrin-heparin" Keywords related to the device names "Pipeline Shield," "Pipeline Shield with Flex Technology," "FRED," "FREDX," "p64," "p64-HPC," "Derivo 2heal" were also used. Studies that detailed the mechanism of action of the coating, any pre-clinical studies with surface-modified intravascular devices, and any clinical retrospective series, prospective series, or randomized clinical trials with surface-modified devices for aneurysm treatment were included.

Overview of Imaging Modalities in Stroke

PURPOSE OF THE REVIEW

This article reviews common imaging modalities used in diagnosis and management of acute stroke. Each modality is discussed individually and clinical scenarios are presented to demonstrate how to apply these modalities in decision-making.

RECENT FINDINGS

Advances in neuroimaging provide unprecedented accuracy in determining tissue viability as well as tissue fate in acute stroke. In addition, advances in machine learning have led to the creation of decision support tools to improve the interpretability of these studies.

SUMMARY

Noncontrast head computed tomography (CT) remains the most commonly used initial imaging tool to evaluate stroke. Its exquisite sensitivity for hemorrhage, rapid acquisition, and widespread availability make it the ideal first study. CT angiography (CTA), the most common follow-up study after noncontrast head CT, is used primarily to identify intracranial large vessel occlusions and cervical carotid or vertebral artery disease. CTA is highly sensitive and can improve accuracy of patient selection for endovascular therapy through delineations of ischemic core. CT perfusion is widely used in endovascular therapy trials and benefits from multiple commercially available machine-learning packages that perform automated postprocessing and interpretation. Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) can provide valuable insights for outcomes prognostication as well as stroke etiology. Optical coherence tomography (OCT), positron emission tomography (PET), single-photon emission computerized tomography (SPECT) offer similar insights. In the clinical scenarios presented, we demonstrate how multimodal imaging approaches can be tailored to gain mechanistic insights for a range of cerebrovascular pathologies.

Frequency-Domain Optical Coherence Tomography for Intracranial Atherosclerotic Stenosis: Feasibility, Safety, and Preliminary Experience

Background: Despite advances in non-invasive imaging, the characterization of atherosclerotic plaque remains superior with frequency-domain optical coherence tomography (FD-OCT) in the clinical coronary and experimental cerebrovascular literature. An assessment of the feasibility and safety of FD-OCT for intracranial atherosclerotic stenosis (ICAS) is desirable. Methods: We analyzed a cohort of all consecutive FD-OCT evaluations for ICAS performed at our institution from April 2017 to August 2018 (16 months) in patients who suffered from transient ischemic attack (TIA) or non-disabling stroke despite optimal medical management within 90 days of admission attributable to angiographically verified 70-99% stenosis of an intracranial artery. Results: Thirty-three patients harboring 36 lesions with an average age of (57.6 ± 7.1) years (male sex 27 cases) comprising nine cases of lesions located within the anterior circulation and 24 cases within the posterior circulation were identified. Of the 33 patients with 36 lesions, the FD-OCT imaging catheter detected 35/36 (97%) lesions except in one case in which the FD-OCT catheter failed to navigate excessively tortuous vessels, and FD-OCT images in 27 patients (81.8%) were finally obtained successful, where the target lesion was fully visible, and image quality under at least one pullback was graded 2 or 3. There were no symptomatic complications. Blood flow was the most common artifact encountered (51.9%). Conclusion: FD-OCT is safe and feasible for the assessment of ICAS in the anterior and posterior circulation. The use of diagnostic interferometry will have to be weighed against its cost, and these preliminary findings should be verified by prospective large-scale studies.

Is it possible to prevent cerebral embolization by improving the design and technology of carotid stent implantation?

INTRODUCTION

The prevention of atherosclerotic plaque fragmentation during carotid artery stenting is a fundamental problem in decreasing the risk of disability of patients. The goal of this review is to clarify whether the stent design can have a decisive impact on the rate of intraoperative and postoperative complications.

AREAS COVERED

Different designs of the carotid stents are briefed and the advantages and disadvantages of different stent designs are discussed as well as the results of their clinical use. Various solutions are presented to reduce cerebral embolism during carotid artery stenting.

EXPERT OPINION

There is no conclusive evidence for the benefits of closed cell and hybrid stents. The stent design cannot completely resolve the problem of cerebral embolism. Most of the events of cerebral microembolism occur at the stages of stent delivery rather than protrusion of an atherosclerotic plaque in the long-term follow-up. Most likely, minimization of the risks for periprocedural and postprocedural strokes requires not only the new solutions in stent design as well as the corresponding delivery systems and brain embolic protection systems, but also the new strategies of preprocedural drug stabilization of the atherosclerotic plaque in the carotid artery. Abbreviations: CAS, carotid artery stenting; CE, carotid endarterectomy; DW-MRI, diffusion-weighted magnetic resonance imaging; ECA, external carotid artery; ICA, internal carotid artery; IVUS, intravascular ultrasound examination; OCT, optical coherence tomography.

Endovascular optical coherence tomography imaging in cerebrovascular disease

Endovascular optical coherence tomography (OCT) is the highest resolution imaging modality currently available with spatial resolution of 10 µm. Although originally developed for interventional cardiology, the ability to visualize the luminal environment and anatomy, along with the stent-vessel interaction could be of great utility for various cerebrovascular diseases, and the adoption of endovascular OCT imaging in the evolving field of interventional neuroradiology seems instinctive. The purpose of this study is to conduct a systematic review of the literature regarding applications of endovascular OCT in the diagnosis and treatment of cerebrovascular diseases. In addition, the authors report their institutional experience with the use of OCT in carotid atherosclerotic disease, cerebral aneurysms, and acute ischemic stroke. A systematic review of the literature was undertaken. Peer-reviewed articles were collected through MEDLINE, Embase, Scopus, and Cochrane Central Register of Controlled Trials (CENTRAL) searches through March 2020. A total of 34 studies with 598 patients were included in the qualitative synthesis. These include 23 studies of carotid atherosclerotic disease, 7 studies of cerebral aneurysms, and 4 studies of non-aneurysmal posterior circulation pathology. OCT imaging was feasible in 94% of patients with 0.6% complication rate. Endovascular OCT appears to be safe and feasible, allowing clinicians to visualize stent-vessel interactions, aneurysmal healing, and vulnerable atherosclerotic plaque features. OCT carries great promise, however additional investigations are needed before any imposing statement can be made about the role of OCT in cerebrovascular imaging.

Stenting of the carotid artery with CGuard and Acculink stents: interim results of a randomized trial

AIM

The study was undertaken to evaluate safety and efficacy of carotid stents Acculink (open-cell carotid stent) and CGuard (closed-cell type stent) in treatment of patients presenting with atherosclerotic lesions of carotid arteries.

PATIENTS AND METHODS

The study enrolled a total of 50 patients diagnosed with haemodynamically significant stenosis of the carotid artery and divided into two groups of 25 patients each. Group One patients received Acculink stents and Group Two patients underwent implantation of CGuard stents. Ultrasonographic examination was performed in all patients before and after surgery, as well as at 6 and 12 months thereafter; magnetic resonance imaging of the brain was carried out before and after surgery (at 24-48 postoperative hours and on POD 30). The entire period of follow up included 5 examinations of each patient by a neurologist. The obtained findings were statistically analysed using the Statistica 12 software (StatSoft, USA). The level of deviation of the null hypothesis of the absence of differences between the groups was regarded as significant at p<0.05.

RESULTS

The technical success of the operation amounted to 100% in both groups. There were no complications (such as haematoma, arterial dissection, etc.) in the area of the approach in either group. The findings of ultrasonographic examination of the extracranial portion of the carotid arteries demonstrated a significant difference in the form of a decrease in the degree of narrowing of the operated vessel (p<0.05) as compared with its initial parameters. The number of the detected foci of acute cerebral ischaemia in the postoperative period (24-48 h) amounted to: in the Acculink group - 14 (56%), in the CGuard group - 12 (48%), p>0.77. Of these, multiple foci in Group One were encountered significantly more often than in Group Two (p=0.02). The patients with the Acculink stent implanted were found to develop 2 (4%) episodes of acute cerebral circulation impairment: the first one occurring after 24 hours and the second one at 28 days after stenting, with no such complications observed in Group Two patients.

CONCLUSION

Comparing the two stents (Acculink and CGuard) demonstrated no advantages with respect to safety and efficacy of either stent in endovascular treatment of patients with atherosclerotic lesions of brachiocephalic arteries.

Effect of stenting on the near-infrared spectroscopy-derived lipid core burden index of carotid artery plaque

AIMS

Catheter-based intravascular near-infrared spectroscopy (NIRS) detects a lipid signal from atherosclerotic plaque. The aim of this study was to describe the effect of carotid artery stenting (CAS) on the lipid signal in a carotid stenosis.

METHODS AND RESULTS

We performed NIRS combined with intravascular ultrasound (IVUS) during 120 CAS procedures. Minimal luminal area (MLA) and plaque burden (PB) at the site of MLA were measured with IVUS and lipid core burden index (LCBI), maximal LCBI in a 4 mm segment of the artery (LCBImax) and LCBI in a 4 mm segment at the site of MLA (LCBImla) with NIRS-derived chemograms. NIRS-IVUS imaging was performed at baseline, after stent implantation and after balloon post-dilatation. The most common lesion type was the fibrocalcific plaque (76%). Lipid-rich plaque (LCBImax ≥400) was present in 33% of carotid stenoses and in 20% at the site of MLA. Median MLA increased significantly from baseline to stent implantation (3.63 mm2 to 5.56 mm2, p<0.001) and to post-dilatation (5.56 mm2 to 12.03 mm2, p<0.001). Median LCBI, LCBImax and LCBImla significantly decreased from baseline to stent implantation: LCBI (60 to 8, p<0.001), LCBImax (294 to 60, p<0.001) and LCBImla (124 to 0, p<0.001). Post-dilatation of the stent had no further significant effect on median LCBI (8 to 5, p=0.890), LCBImax (60 to 50, p=0.690) and LCBImla (0 to 0, p=0.438).

CONCLUSIONS

Carotid artery stenting significantly reduced the NIRS-derived lipid core burden index at the stented segment.

Carotid stenting with double layered stents: Double trouble or double benefit?

The use of double layer (covered) stents during carotid artery stenting (CAS) appears to be safe; attenuation of plaque prolapse and distal embolization is reasonable but unproven. Double layer stents are commercially available in Europe but not in the United States; similar benefits might be obtained by implanting two self-expanding stents, to decrease the effective free cell area. Embolic protection devices (EPDs) are recommended in all CAS patients; the use of double layer stents does not eliminate the need for EPDs.

Optical coherence tomography guided carotid artery stent procedure: technique and potential applications

OBJECTIVES

To (1) present a guide on how to perform optical coherence tomography (OCT) in carotid artery stenting (CAS), to (2) highlight several instructive cases illustrating OCT-guidance as an interventional strategy, and to (3) present the largest case-series of OCT-guided CAS performed in North America, demonstrating its feasibility as an imaging modality in this setting.

BACKGROUND

OCT is an intravascular imaging method that captures images with an axial resolution 10 times higher than intravascular ultrasound. OCT has proven to be a useful modality in coronary angiography and may have similar applications in evaluating carotid atherosclerotic disease.

METHODS

We compared our experience in CAS utilizing OCT (40 patients) versus that of CAS without OCT guidance (52 patients).

RESULTS

No strokes or deaths occurred in either group postprocedurally or at 12 months. Fluoroscopy time was reduced in the OCT arm (14 ± 1 vs. 16 ± 1 min). Postprocedural creatinine levels were identical (1 ± 0 mg/dl, P = 0.96). Procedure time (96 ± 8 vs. 80 ± 3 min, P = 0.06) and contrast use (94 ± 4 vs. 83 ± 4 ml, P = 0.05) was slightly elevated in the OCT arm.

CONCLUSIONS

We established a standardized protocol to consistently obtain OCT images that helped guide interventional decision-making during CAS. OCT imaging in the carotids requires a higher contrast load and prolongs procedure time. However, it can be performed without significant increases in fluoroscopy time or negatively affecting renal function. There were no negative safety signals in this pilot study.

One swallow does not a summer make but many swallows do: accumulating clinical evidence for nearly-eliminated peri-procedural and 30-day complications with mesh-covered stents transforms the carotid revascularisation field

Atherosclerotic carotid artery stenosis (CS) continues to be a common cause of acute ischaemic stroke. Optimised medical therapy (OMT), the first-line treatment modality in CS, may reduce or delay - but it does not abolish - CS-related strokes. As per current AHA/ASA and ESC/ESVS/ESO guidelines, carotid artery stenting (CAS) is a less-invasive alternative to carotid endarterectomy (CEA) for CS revascularisation in primary and secondary stroke prevention. Ten-year follow-up from the CREST trial in patients with symptomatic and asymptomatic CS confirmed equipoise of CAS and CEA in the primary endpoint. Nevertheless CAS - using a widely open-cell, first-generation stent and first-generation (distal/filter) neuroprotection - has been criticised for its relative excess of (mostly minor) strokes by 30 days, a significant proportion of which were post-procedural. Atherosclerotic plaque protrusion through conventional carotid stent struts, confirmed on intravascular imaging, has been implicated as a leading mechanism of the relative excess of strokes with CAS vs. CEA, including delayed strokes with CAS. Different designs of mesh-covered carotid stents have been developed to prevent plaque prolapse. Several multi-centre/multi-specialty clinical studies with CGurad MicroNet-Covered Embolic Prevention Stent System (EPS) and RoadSaver/Casper were recently published and included routine DW-MRI cerebral imaging peri-procedurally and at 30 days (CGuard EPS). Data from more than 550 patients in mesh-covered carotid stent clinical studies to-date show an overall 30-day complication rate of ~1% with near-elimination of post-procedural events. While more (and long-term) evidence is still anticipated, these results - taken together with optimised intra-procedural neuroprotection in CAS (increased use of proximal systems including trans-carotid dynamic flow reversal) and the positive 12-month mesh-covered stent data reports in 2017 - are transforming the carotid revascularisation field today. Establishing effective algorithms to identify the asymptomatic subjects at stroke risk despite OMT, and large-scale studies with mesh-covered stents including long-term clinical and duplex ultrasound outcomes, are the next major goals.

Optical coherence tomography evaluation of tissue prolapse after carotid artery stenting using closed cell design stents for unstable plaque

BACKGROUND AND PURPOSE

During carotid artery stenting (CAS) with the use of closed cell design stents for unstable plaques, tissue prolapse between stent struts was evaluated by optical coherence tomography (OCT).

METHODS

14 carotid stenosis lesions diagnosed as unstable plaques by MRI were evaluated by OCT imaging during CAS using closed cell stents. Cross sectional OCT images within the stented segment were evaluated at 1 mm intervals. The slice rate for the presence of tissue prolapse between the struts was calculated.

RESULTS

No intra-procedural complications occurred. After single stent placement, plaque prolapse was observed in all cases. Slices with any and >500 µm tissue prolapse were seen in 30% and 7.8% of cases, respectively. In 5 of 7 lesions with tissue prolapse >500 µm, additional stents were overlapped. In cases with overlapping stents, slices with any tissue prolapse were significantly decreased from 26% to 16% (p=0.008); in particular, the occurrence of tissue prolapse >500 µm was significantly decreased from 15% to 2.3% (p<0.001). In one case of >500 µm tissue prolapse without an overlapping stent, delayed embolization due to an in-stent thrombus occurred 9 months after the procedure.

CONCLUSIONS

OCT during CAS using closed cell stent for unstable plaques frequently revealed tissue prolapse between struts. Placement of overlapping stents significantly reduced tissue prolapse, particularly tissue prolapse >500 µm. However, closed cell stents used for unstable plaques may not solve the problem of tissue prolapse.

Design and characterization of a combined OCT and wide field imaging falloposcope for ovarian cancer detection

Early detection of ovarian cancer is only achieved in around 20% of women due to lack of effective screening. We propose a method for surveillance of high risk women based on a microendoscope introduced transvaginally to image the fallopian tubes and ovaries. This requires extreme miniaturization of the optics and catheter sheath. We describe the design of a falloposcope that combines optical coherence tomography (OCT) and wide field imaging into a sub-1 mm diameter package. We characterize the systems and show that they provide contrast on ex-vivo samples of ovary and fallopian tube. In addition, we show the mechanical performance of the endoscope in an anatomically correct model of the female reproductive tract.

Carotid artery stenting with a new-generation double-mesh stent in three high-volume Italian centres: clinical results of a multidisciplinary approach

AIMS

Carotid artery stenting (CAS) is still associated with higher periprocedural cerebrovascular events (CEs) compared to vascular surgery. The Roadsaver carotid artery stent is a double layer micromesh stent which reduces plaque prolapse and embolisation by improving plaque coverage. Its clinical impact on neurological outcome was unknown. The aim of this study was therefore to report the clinical results of a large real-world population from three different centres receiving a Roadsaver stent to treat carotid artery disease.

METHODS AND RESULTS

One hundred and fifty (150) patients (age 74±8 yrs, 75% male, symptomatic 29%) treated with CAS using the Roadsaver carotid stent in three high-volume Italian centres were included in the study. Intraprocedural optical coherence tomography (OCT) evaluation was performed in 26 patients, with an off-line analysis by a dedicated core laboratory. All patients underwent duplex ultrasound and neurological evaluation at 24 hours and at 30 days. CAS was technically successful in all cases (stent diameter: 8.6±0.8 mm, stent length: 25.0±4.5 mm). No in-hospital or 30-day CEs were observed. OCT evaluation detected a low rate of plaque prolapse (two patients, 7.7%). Duplex ultrasound showed stent and external carotid artery patency in all cases both before discharge and at 30-day follow-up.

CONCLUSIONS

The Roadsaver stent is a safe and promising technology for CAS, with a low percentage of plaque prolapse and good short-term clinical outcome. Larger studies with longer follow-up are necessary to confirm this favourable clinical outcome.

Dynamic Assessment of the Endothelialization of Tissue-Engineered Blood Vessels Using an Optical Coherence Tomography Catheter-Based Fluorescence Imaging System

BACKGROUND

Lumen endothelialization of bioengineered vascular scaffolds is essential to maintain small-diameter graft patency and prevent thrombosis postimplantation. Unfortunately, nondestructive imaging methods to visualize this dynamic process are lacking, thus slowing development and clinical translation of these potential tissue-engineering approaches. To meet this need, a fluorescence imaging system utilizing a commercial optical coherence tomography (OCT) catheter was designed to visualize graft endothelialization.

METHODS

C7 DragonFly™ intravascular OCT catheter was used as a channel for delivery and collection of excitation and emission spectra. Poly-dl-lactide (PDLLA) electrospun scaffolds were seeded with endothelial cells (ECs). Seeded cells were exposed to Calcein AM before imaging, causing the living cells to emit green fluorescence in response to blue laser. By positioning the catheter tip precisely over a specimen using high-fidelity electromechanical components, small regions of the specimen were excited selectively. The resulting fluorescence intensities were mapped on a two-dimensional digital grid to generate spatial distribution of fluorophores at single-cell-level resolution. Fluorescence imaging of endothelialization on glass and PDLLA scaffolds was performed using the OCT catheter-based imaging system as well as with a commercial fluorescence microscope. Cell coverage area was calculated for both image sets for quantitative comparison of imaging techniques. Tubular PDLLA scaffolds were maintained in a bioreactor on seeding with ECs, and endothelialization was monitored over 5 days using the OCT catheter-based imaging system.

RESULTS

No significant difference was observed in images obtained using our imaging system to those acquired with the fluorescence microscope. Cell area coverage calculated using the images yielded similar values. Nondestructive imaging of endothelialization on tubular scaffolds showed cell proliferation with cell coverage area increasing from 15 ± 4% to 89 ± 6% over 5 days.

CONCLUSION

In this study, we showed the capability of an OCT catheter-based imaging system to obtain single-cell resolution and to quantify endothelialization in tubular electrospun scaffolds. We also compared the resulting images with traditional microscopy, showing high fidelity in image capability. This imaging system, used in conjunction with OCT, could potentially be a powerful tool for in vitro optimization of scaffold cellularization, ensuring long-term graft patency postimplantation.

Stratifying carotid diseases for endovascular treatments

Endovascular angioplasty and stenting (CAS) has evolved as an alternative for treating occlusive carotid diseases in recent years. Carotid diseases are characterized by manifold etiologies and miscellaneous clinical manifestations. Although CAS is efficacious in treating patients with occlusive carotid diseases as a whole, the long-term risk-benefit ratio may vary in individual patients. Interventional strategies, such as angioplasty and stenting, should be individualized based on the etiology and clinical profiles to maximize the benefits and minimize the hazards of treatment. Based on recent publications, this review proposes a stratified treatment strategy for occlusive carotid diseases.

Frequency-domain optical coherence tomography assessment of human carotid atherosclerosis using saline flush for blood clearance without balloon occlusion

FD-OCT is a new imaging technique that allows unprecedented in vivo microlevel assessment of human carotid plaque morphologic patterns and stent-vessel interactions. Prior reports describing the use of this technique have used balloon occlusion of the target vessel or iodinated contrast media to facilitate imaging. We report, for the first time, in vivo FD-OCT imaging of human carotid arteries without the use of iodinated contrast material or balloon occlusion techniques.

Safety and feasibility of intravascular optical coherence tomography using a nonocclusive technique to evaluate carotid plaques before and after stent deployment

PURPOSE

To evaluate the safety and feasibility of optical coherence tomography (OCT) in patients with carotid stenosis undergoing carotid artery stenting (CAS).

METHODS

In a prospective study, 25 consecutive patients (15 men; mean age 74±4 years) undergoing protected CAS were enrolled and underwent high-definition (homoaxial resolution 10 µm) OCT image acquisition before stent deployment, immediately after stent placement, and following postdilation of the stent (3 scans/patient). Pullbacks were started during a nonocclusive flush, mechanically injecting 24 mL of 50% diluted contrast at 6 mL/s to displace blood from the artery. Two independent physicians judged the quality of images on a predefined 1-10 scale. The proportions of specific agreement and kappa values (κ) were calculated.

RESULTS

No procedural or in-hospital neurological complications occurred (any stroke/death 0%). The technical success of OCT pullbacks was 97.3% (73/75). The total amount of contrast was 86±18 mL/patient. No significant alteration in glomerular filtration rate or any other significant adverse event occurred. The images obtained were of high quality (mean value 8.1 out of 10), with good inter- and intraobserver agreement (κ = 0.81-0.87 and κ = 0.95, respectively). OCT images revealed innovative features such as rupture of the fibrous cap, plaque prolapse, and stent malapposition in a high percentage of the patients (range 24%-100%).

CONCLUSION

Intravascular OCT during a nonocclusive flush appears to be feasible and safe in carotid arteries. Since some original and unexpected information after CAS has been made available for the first time at such a high definition, future studies with OCT should focus on the interaction between carotid plaque and stent design, which might revolutionize our understanding of the mechanisms of carotid stenting, as well as influence our clinical policies.

Intravascular frequency-domain optical coherence tomography assessment of atherosclerosis and stent-vessel interactions in human carotid arteries

BACKGROUND AND PURPOSE

Carotid artery-related stroke is largely an embolic disease that has been correlated with inflammation, plaque rupture, and thrombus formation in "vulnerable" atherosclerotic plaque. Nevertheless, current guidelines for carotid revascularization in asymptomatic patients rely on the calculation of stenosis for risk assessment, a parameter that has been viewed with increasing skepticism. Intravascular OCT is an imaging technique that offers high axial resolution (10 μm), allowing an unprecedented micron-level assessment of human carotid plaque morphology. This observational article reports the first successful use of the newest iteration of this technology, FDOCT without balloon occlusion to assess human carotid artery disease and carotid stent-vessel interaction in vivo.

MATERIALS AND METHODS

Four patients with asymptomatic carotid artery disease and ambiguous noninvasive and/or angiographic data underwent carotid FDOCT to assess risk and to formulate a treatment strategy.

RESULTS

Findings include the unexpected demonstration of TCFAs, plaque rupture, thrombus, inflammation, and marked tissue prolapse through stent struts in patients without high-risk factors by conventional criteria, as well as low-risk features in a patient with a high-risk noninvasive study. The procedures were performed without safety issues or special accommodations for vessel occlusion.

CONCLUSIONS

The present study demonstrates the technical feasibility of FDOCT in cervical carotid arteries. As such, this technology holds the promise of not only clarifying ambiguous data in individual patients but of providing data that might call for a future paradigm shift in the assessment of asymptomatic carotid artery disease.

Comprehensive data visualization for high resolution endovascular carotid arterial wall imaging

Carotid angioplasty and stenting is a minimally invasive endovascular procedure that may benefit from in vivo high resolution imaging for monitoring the physical placement of the stent and potential complications. The purpose of this pilot study was to evaluate the ability of optical coherence tomography to construct high resolution 2D and 3D images of stenting in porcine carotid artery. Four Yorkshire pigs were anaesthetized and catheterized. A state-of-the-art optical coherence tomography (OCT) system and an automated injector were used to obtain both healthy and stented porcine carotid artery images. Data obtained were then processed for visualization. The state-of-the-art OCT system was able to capture high resolution images of both healthy and stented carotid arteries. High quality 3D images of healthy and stented carotid arteries were constructed, clearly depicting vessel wall morphological features, stent apposition and thrombus formation over the inserted stent. The results demonstrate that OCT can be used to generate high quality 3D images of carotid arterial stents for accurate diagnosis of stent apposition and complications under appropriate imaging conditions.

Endovascular optical coherence tomography intensity kurtosis: visualization of vasa vasorum in porcine carotid artery

Application of speckle variance optical coherence tomography (OCT) to endovascular imaging faces difficulty of extensive motion artifacts inherently associated with arterial pulsations in addition to other physiological movements. In this study, we employed a technique involving a fourth order statistical method, kurtosis, operating on the endovascular OCT intensity images to visualize the vasa vasorum of carotid artery in vivo and identify its flow dynamic in a porcine model. The intensity kurtosis technique can distinguish vasa vasorum from the surrounding tissues in the presence of extensive time varying noises and dynamic motions of the arterial wall. Imaging of vasa vasorum and its proliferation, may compliment the growing knowledge of structural endovascular OCT in assessment and treatment of atherosclerosis in coronary and carotid arteries.