Method analysis for optimal continuous imaging using intravascular optical coherence tomography

OBJECTIVES: Optical coherence tomography(OCT)is a high-resolution imaging method that can clearly visualize vessels through the displacement of blood with flushing agents. Continuous imaging methods have not been established. This study investigated optimal methods for continuous OCT imaging. METHODS: Thirty-four arteries with stent implantation (24 peripheral and 10 coronary arteries)in 14 pigs were examined using OCT with a motorized pullback device. Two imaging methods (flush alone by liquid substance and flush with occlusion) were compared. Adequate image acquisition was defined as the entire circumferential intimal layer being detectable within continuous segments. To investigate factors that could influence image quality, stented regions were divided into 4-5 mm segments. RESULTS: The flush with occlusion method provided better OCT images compared to flush alone (flush with occlusion: 60.9%, flush alone: 8.7%, p = 0.0002). Using the flush with occlusion method, the rate of adequate image acquisition was 64.4% and visualization of > 75% intimal circumference was 83.5%. Intravascular ultrasound could detect all stented regions. Segmental analyses found more adequate images were detected in smaller vessels (adequate segment: 3.8 +/- 0.4 mm, inadequate segment: 4.2 +/- 0.8 mm, p < 0.0001) or with centered image wire position (adequate segment: center 35%, inadequate segment: center 14%, p = 0.003). In addition, side branches did not affect image quality. CONCLUSIONS: To acquire continuous OCT images, the flush with occlusion method was more effective compared to flush alone. Moreover, image quality is affected by vessel size and imaging wire position. These results suggest that optimized OCT imaging can provide continuous vessel detection.     

Optical coherence tomography-guided stenting of a large coronary aneurysm: images at implantation and at 6 months

Intravascular imaging with optical coherence tomography (OCT) can produce high-resolution images (10-20 μm) of the coronary vessel wall and is being increasingly used to provide insight into coronary pathology and neointima formation following coronary stenting. Fourier domain OCT (FD-OCT) permits a greater scan diameter than time domain OCT and enables larger-caliber coronary structures to be effectively imaged. We present a case of a large, symptomatic and expanding right coronary artery aneurysm treated with FD-OCT-guided pericardial covered stenting and describe the OCT findings immediately after stent deployment and at 6 months.     

Peripheral arterial involvement in Behcet’s disease: an analysis of the results from a Korean referral center

The purposes of this study are to review the results of endovascular and surgical interventions and to evaluate clinical appearances of recurrent arterial involvement in patients with peripheral arterial Behçet disease (BD). A total of 28 patients with peripheral arterial BD were identified. There were 24 males (85.7 %), with mean age of 40.0 ± 9.0 years (range 21–59). Arterial involvements were confirmed with computed tomography angiography, magnetic resonance image angiography, or ultrasound. Immunosuppressive agents were administrated to all patients. Indications of intervention were acute symptoms due to arterial occlusion and aneurysmal changes with or without rupture. Among 28 patients with peripheral arterial BD, 10 endovascular and 24 surgical interventions were performed in 21 patients. All 21 patients who underwent endovascular and surgical intervention were followed up for a mean duration of 78.7 ± 52.5 months (range 0–182 months). There was one mortality due to the rupture of pseudoaneurysm in patient who underwent stent-graft insertion for abdominal aortic aneurysm. New arterial involvements of BD occurred in 10 patients. All patients were male, and median age was 33.5 years (range 29–59 years). Mean time of onset of the new arterial lesion was 32.7 ± 32.1 months. In conclusion, the result of endovascular and surgical interventions is satisfactory in patients with acute peripheral arterial BD. Accurate diagnosis with immunosuppressive therapy is mandatory to prevent recurrence and activation of peripheral arterial BD.     

SCAI expert consensus statement for aorto‐iliac arterial intervention appropriate use

Aorto‐iliac arterial occlusive disease is common and may cause a spectrum of chronic symptoms from intermittent claudication to critical limb ischemia. Treatment is indicated for symptoms that have failed lifestyle and medical therapies or occasionally to facilitate other interventional procedures such as TAVR and/or placement of hemodynamic assist devices. It is widely accepted that TASC A, B, and C lesions are best managed with endovascular intervention. In experienced hands, most TASC D lesions may be treated by endovascular methods, and with the development of chronic total occlusion devices, many aorto‐iliac occlusions may be recanalized safely by endovascular means. Interventional cardiologists should be well versed in the anatomy, as well as the treatment of aorto‐iliac disease, given their need to traverse these vessels during transfemoral procedures. Overall, aorto‐iliac occlusive disease is more commonly being treated with an endovascular‐first approach, using open surgery as a secondary option. This document was developed to guide physicians in the clinical decision‐making related to the contemporary application of endovascular intervention among patients with aorto‐iliac arterial disease. © 2014 Wiley Periodicals, Inc.     

Current evidence for endovascular therapy in stroke and remaining uncertainties

Class 1 level A evidence now supports endovascular thrombectomy as best practice in the management of large vessel occlusion acute ischaemic stroke. However, significant questions pertaining to initial imaging, radiological assessment, patient selection and therapeutic limits remain unanswered. A specific cohort of patients who benefit from endovascular thrombectomy has been established, although current uncertainties regarding selection of those not meeting top‐tier evidence criteria may potentially deny certain patients the benefit of intervention. This is of particular relevance in patients presenting in a delayed manner. Whilst superior outcomes are achieved with reduced time to endovascular reperfusion, denying patients intervention based on symptom duration alone may not be appropriate. Advanced understanding of ischaemic stroke pathophysiology supports an individualized approach to patient evaluation, given variance in the rate of ischaemic core progression and the extent of salvageable penumbra. Physiological imaging techniques may therefore be utilized to better inform patient selection for endovascular thrombectomy and evidence suggests that a transition from time‐based to tissue‐based therapeutic thresholds may be of greater value. Multiple ongoing randomized controlled trials aim to further define the benefit of endovascular thrombectomy and it is hoped that these results will advance, and possibly broaden, patient selection criteria to ensure that maximum benefit from the intervention may be achieved.     

Ocelot catheter for the recanalization of lower extremity arterial chronic total occlusion

Peripheral arterial disease (PAD) is a growing clinical condition affecting more than 10 million patients in the United States and it is responsible for more than 120,000 amputations annually. The presence of chronic total occlusions (CTO) increases the complexity of endovascular procedures and open surgery may often be the preferred approach. Despite the optimization of the CTO devices and technique, percutaneous CTO revascularization remains a challenging procedure even for experienced operators with important complication rates. The Ocelot^TM system is a novel CTO device to use real-time optical coherence tomography (OCT) imaging guidance for the recanalization of peripheral CTOs. We review the mechanism of the Ocelot system, the initial results from the multi-center Connect-II trial and two cases of Ocelot-assisted CTO recanalization.     

Recurrent popliteal endoprosthesis thrombosis secondary to extrinsic compression

Endovascular intervention to exclude popliteal artery aneurysms (PAA) achieves results comparable to surgical intervention with less associated morbidity and mortality. However, the biomechanical forces inherent to this region pose unique impediments that can limit successful endovascular exclusion. Herein, we present a case of recurrent thrombotic occlusion of a PAA endoprosthesis secondary to dynamic extrinsic compression from the excluded PAA in the absence of an endoleak. Multimodality imaging proved vital in elucidating this novel etiology and enabled an appropriate definitive intervention. © 2010 Wiley‐Liss, Inc.     

Efficacy and safety of argatroban in patients with heparin induced thrombocytopenia undergoing endovascular intervention for peripheral arterial disease

Objectives: This study aimed to evaluate the efficacy and safety of argatroban during percutaneous interventions for peripheral arterial disease (PAD). Background: Endovascular interventions are commonly used in patients with peripheral arterial disease. Heparin is routinely administered during these procedures, but cannot be used in patients with a history of heparin‐induced thrombocytopenia (HIT). Argatroban is an approved direct thrombin inhibitor for treatment of patients with HIT. There are currently few data on the efficacy and safety of argatroban during endovascular interventions for PAD. Methods: Patients who underwent endovascular interventions for PAD on argatroban between 2002 and 2005 were identified from out database. Efficacy was evaluated using a composite of death, urgent revascularization, and amputation, while safety was assessed by TIMI major bleeding during the index hospitalization. Results: A total of 48 patients undergoing lower extremity revascularization on argatroban were identified. Thirty two of these patients (67%) had antibody‐confirmed HIT and the other 16 (33%) had suspected HIT. A mean dose of argatroban was 173.5 ± 143 μg/kg bolus, followed by a 10.7 ± 9.64 μg/kg/min infusion during the procedure. Twelve patients (25%) met the composite end point (two deaths, one urgent revascularization, nine amputations because of progressive peripheral arterial disease). TIMI major bleeding occurred in three (6%) patients. Conclusion: In patients with confirmed or suspected HIT undergoing endovascular intervention for PAD, argatroban appears to be effective and safe. A larger study is warranted to confirm these findings from a single center. © 2008 Wiley‐Liss, Inc.     

Assessment of coronary plaque with optical coherence tomography and high-frequency ultrasound

This study compares the ability of intravascular optical coherence tomography (OCT) and high-frequency intravascular ultrasound (IVUS) to image highly stenotic human coronary arteries in vitro. Current imaging modalities have insufficient resolution to perform risk stratification based on coronary plaque morphology. OCT is a new technology capable of imaging at a resolution of 5 to 20 microm, which has demonstrated the potential for coronary arterial imaging in prior experiments. Human postmortem coronary arteries with severely stenotic segments were imaged with catheter-based OCT and IVUS. The OCT system had an axial resolution of 20 microm and a transverse resolution of 30 microm. OCT was able to penetrate and image near-occlusive coronary plaques. Compared with IVUS, these OCT images demonstrated superior delineation of vessel layers and lack of ring-down artifact, leading to clearer visualization of the vessel plaque and intima. Histology confirmed the accuracy and high contrast of vessel layer boundaries seen on OCT images. Thus, catheter-based OCT systems are able to image near-occlusive coronary plaques with higher resolution than that of IVUS.     

SCAI expert consensus statement for femoral‐popliteal arterial intervention appropriate use

Successful endovascular intervention for femoral‐popliteal (FP) arterial disease provides relief of claudication and offers limb‐salvage in cases of critical limb ischemia. Technologies and operator technique have evolved to the point where we may now provide effective endovascular therapy for a spectrum of lesions, patients, and clinical scenarios. Endovascular treatment of this segment offers a significant alternative to surgical revascularization, and may confer improved safety for a wide range of patients, not solely those deemed high surgical risk. Although endovascular therapy of the FP segment has historically been hampered by high rates of restenosis, emerging technologies including drug‐eluting stents, drug‐coated balloons, and perhaps bio‐absorbable stent platforms, provide future hope for more durable patency in complex disease. By combining lessons learned from clinical trials, international trends in clinical practice, and insights regarding emerging technologies, we may appropriately tailor our application of endovascular therapy to provide optimal care to our patients. This document was developed to guide physicians in the clinical decision‐making related to the contemporary application of endovascular intervention among patients with FP arterial disease. © 2014 Wiley Periodicals, Inc.     

Diagnostic approach to peripheral arterial disease

This article discusses diagnostic imaging techniques used in the evaluation and management of patients with peripheral arterial disease (PAD). Along with a complete vascular examination, noninvasive physiologic testing is used for the initial evaluation of patients with suspected PAD. Duplex ultrasonography provides information on the degree of stenosis or occlusion within a vessel and allows assessment of the vessel wall and plaque morphology. Angiographic imaging techniques should be reserved for determining the optimal endovascular or surgical approach for patients requiring revascularization. Together, all available diagnostic modalities contribute to successful evaluation and management of patients with PAD.     

The role of optical coherence tomography in coronary intervention

Optical coherence tomography (OCT) is an optical analog of intravascular ultrasound (IVUS) that can be used to examine the coronary arteries and has 10-fold higher resolution than IVUS. Based on polarization properties, OCT can differentiate tissue characteristics (fibrous, calcified, or lipid-rich plaque) and identify thin-cap fibroatheroma. Because of the strong attenuation of light by blood, OCT systems required the removal of blood during OCT examinations. A recently developed frequency-domain OCT system has a faster frame rate and pullback speed, making the OCT procedure more user-friendly and not requiring proximal balloon occlusion. During percutaneous coronary intervention (PCI), OCT can provide detailed information (dissection, tissue prolapse, thrombi, and incomplete stent apposition [ISA]). At follow-up examinations after stent implantation, stent strut coverage and ISA can be assessed. Several OCT studies have demonstrated delayed neointimal coverage following drug-eluting stent (DES) implantation vs. bare metal stent (BMS) placement. While newer DESs promote more favorable vascular healing, the clinical implications remain unknown. Recent OCT studies have provided insights into restenotic tissue characteristics; DES restenotic morphologies differ from those with BMSs. OCT is a novel, promising imaging modality; with more in-depth assessments of its use, it may impact clinical outcomes in patients with symptomatic coronary artery disease.     

Fully automatic three‐dimensional quantitative analysis of intracoronary optical coherence tomography

Objectives and background : Quantitative analysis of intracoronary optical coherence tomography (OCT) image data (QOCT) is currently performed by a time‐consuming manual contour tracing process in individual OCT images acquired during a pullback procedure (frame‐based method). To get an efficient quantitative analysis process, we developed a fully automatic three‐dimensional (3D) lumen contour detection method and evaluated the results against those derived by expert human observers. Methods : The method was developed using Matlab (The Mathworks, Natick, MA). It incorporates a graphical user interface for contour display and, in the selected cases where this might be necessary, editing. OCT image data of 20 randomly selected patients, acquired with a commercially available system (Lightlab imaging, Westford, MA), were pulled from our OCT database for validation. Results : A total of 4,137 OCT images were analyzed. There was no statistically significant difference in mean lumen areas between the two methods (5.03 ± 2.16 vs. 5.02 ± 2.21 mm²; P = 0.6, human vs. automated). Regression analysis showed a good correlation with an r value of 0.99. The method requires an average 2–5 sec calculation time per OCT image. In 3% of the detected contours an observer correction was necessary. Conclusion : Fully automatic lumen contour detection in OCT images is feasible with only a select few contours showing an artifact (3%) that can be easily corrected. This QOCT method may be a valuable tool for future coronary imaging studies incorporating OCT. © 2009 Wiley‐Liss, Inc.     

High-resolution cross-sectional imaging of the gastrointestinal tract using optical coherence tomography: preliminary results

Background: Optical coherence tomography (OCT) is a novel technique for noninvasive cross-sectional imaging with high spatial resolution (10 to 20 μm). OCT is similar to B-mode ultrasound except that it uses infrared light rather than ultrasound. We studied OCT imaging of the gastrointestinal (GI) tract in vitro to analyze the potential of this technique for endoscopic applications. Methods: Human gastrointestinal tissues harvested from surgical resection and autopsy specimens were used. Specimens were imaged within 5 hours of resection or snap frozen in liquid nitrogen. After imaging, OCT scan locations were carefully marked using dye microinjections, fixed, and prepared for routine histologic processing. OCT images were then compared and correlated with the histologic sections. Results: OCT images demonstrated clear delineation of the mucosa and submucosa in most specimens. Furthermore, microscopic structures such as crypts, blood vessels, or esophageal glands in the submucosa and lymphatic nodules were observed. Conclusions: The resolution of OCT images of GI wall is sufficient to delineate the microscopic structure of the mucosa and submucosa. Potentially, OCT would allow in vivo imaging at endoscopy of the microstructure of the mucosa and submucosa. This would be particularly useful in the detection and staging of small lesions such as early stage cancers.     

Advantage of next‐generation frequency‐domain optical coherence tomography compared with conventional time‐domain system in the assessment of coronary lesion

Background : Intracoronary optical coherence tomography (OCT) is a high‐resolution imaging modality used for evaluation of coronary lesion morphology. However, current time‐domain OCT (TD‐OCT) have a number of limitations with regard to both procedural usage and safety in the clinical setting. The next‐generation frequency‐domain OCT (FD‐OCT), which has a much faster frame rate and pullback speed than TD‐OCT, is expected to overcome these limitations. The aim of this study was to evaluate the feasibility and usability of next generation FD‐OCT in the assessment of coronary lesions. Methods : A comparison study was performed between FD‐OCT and TD‐OCT from the aspect of usability (set‐up time), qualitatively (rate of clear image segment), and safety (adverse event) in 14 ischemic heart disease patients with 20 previously implanted coronary stents. Results : The mean time of the OCT procedure in this study from setup to completion of image acquisition was 3.2 ± 0.8 min for FD‐OCT and 11.2 ± 2.5 min for TD‐OCT (P < 0.01). In qualitative image assessment, FD‐OCT has the potential to yield a higher rate of clear image segments (CIS) than TD‐OCT (99.4% vs. 80.8%, respectively; P < 0.01). In addition to these improved characteristics, there were no ischemic ECG changes or arrhythmia associated with FD‐OCT. Conclusions : The next‐generation intracoronary FD‐OCT has better performance in the clinical setting and the potential to overcome several limitations of conventional TD‐OCT systems. © 2009 Wiley‐Liss, Inc.     

CONTRAST‐ENHANCED ENDOSCOPIC ULTRASONOGRAPHY IN THE DIAGNOSIS OF PANCREATO‐BILIARY DISEASES

In diagnostic imaging, techniques represented by computed tomography (CT) and magnetic resonance imaging (MRI), diagnosis by evaluation of plain images in combination with contrast‐enhanced images is considered important. Recently, the ultrasound contrast media that can be administered from peripheral veins have been developed, and their utility is reported not only for the circulatory organ area but also the digestive organ area, mainly for liver diseases. As for the pancreato‐biliary diseases, there often are the cases that visualization of the diseases itself is not easy by transabdominal ultrasonography, so, the evaluation of contrast‐enhanced ultrasonography remains difficult. In contrast, endoscopic ultrasonography (EUS) is thought to be one of the most valuable modality for those diseases. The mainstream of an operation method of EUS was mechanical radial type, but in late years, endoscopic ultrasonography of an electronic linear method and an electronic radial method have been developed. Because an electronic scan method was adopted, we get possible to apply technology of color Doppler flow imaging and power Doppler flow imaging and harmonic imaging methods to EUS. We would like to outline the usefulness of contrast‐enhanced color/power Doppler EUS and contrast‐enhanced harmonic EUS, moreover, tissue harmonic imaging and three dimensional imaging, on the basis of our experiences.     

Mandatory Diagnostic Angiography for Carotid Artery Stenosis Prior to Carotid Artery Intervention

Introduction: Revascularization is an important strategy for reducing stroke risk in patients with severe carotid atherosclerosis. Magnetic resonance angiography (MRA) and/or carotid ultrasound have traditionally been used as the only diagnostic modalities prior to revascularization. Patients undergoing CEA frequently have no further assessments of carotid anatomy prior to surgery. Evaluation with carotid ultrasound and MRA can often overestimate the degree of stenosis. We sought to determine if noninvasive imaging was sufficient for determining whether a patient should be referred for carotid intervention.
Methods: We performed an analysis of 101 patients referred for carotid artery stenting (CAS). All patients had previously been evaluated with carotid ultrasound and 94% had undergone MRA as well. We sought to determine if noninvasive diagnostic imaging for carotid stenosis was sufficient to determine the necessity for endovascular intervention.
Results: Of the 101 patients referred for carotid intervention, 36 (36%) were shown to have <70% stenoses and did not require intervention. Of those who had significant disease, 49 (75%) underwent successful CAS, 15 (23%) underwent CEA, and 1 patient was treated medically for a total occlusion. Three of the 36 patients not requiring carotid intervention were found to have subclavian stenosis. Two (4%) of the patients undergoing CAS and 4 (27%) of the patients undergoing CEA had minor complications. No patients suffered a major stroke, MI, or death at follow-up.
Conclusion: This analysis demonstrates that 36% of patients referred for endovascular intervention based on noninvasive imaging did not meet criteria by angiography. This emphasizes the need for carotid angiography prior to carotid intervention.     

Use of intravascular imaging in managing coronary artery disease

For many years,coronary angiography has been considered "the gold standard" for evaluating patients with coronary artery disease. However,angiography only provides a planar two-dimensional silhouette of the lumen and is unsuitable for the precise assessment of atherosclerosis. With the introduction of intravascular imaging,direct visualization of the arterial wall is now feasible. Intravascular imaging modalities extend diagnostic information,thereby enabling more precise evaluation of plaque burden and vessel remodeling. Of all technologies,intravascular ultrasound(IVUS) is the most mature and widely used intravascular imaging technique. Optical coherence tomography(OCT) is an evolving technology that has the highest spatial resolution of existing imaging methods,and it is becoming increasingly widespread. These methods are useful tools for planning interventional strategies and optimizing stent deployment,particularly when stenting complex lesions. We strongly support the mandatory use of IVUS for left main percutaneous coronary intervention(PCI). In addition,it can be used to evaluate vascularresponses,including neointimal growth and strut apposition,during follow-ups. Adequately powered randomized trials are needed to support IVUS or OCT use in routine clinical practice and to answer whether OCT is superior to IVUS in reducing adverse events when used to guide PCI. The current perception and adoption of innovative interventional devices,such as bioabsorbable scaffolds,will increase the need for intravascular imaging in the future.     

A unique stenosis in saphenous vein graft visualized by optical coherence tomography

We present a case of a unique stenosis in a 12-year-old saphenous vein graft (SVG), to the right coronary artery, which was visualized by optical coherence tomography (OCT), before percutaneous coronary intervention. The patient was an 80-year-old man in whom the stenosis was documented by area-detector coronary computed tomography. OCT imaging demonstrated that the culprit lesion was a venous valve containing a thrombus before preintervention imaging. Coronary stenting was performed with a distal protection device, and pathologic examination of the aspirate verified the OCT findings. Coronary angiography 12 years previously, just after coronary artery bypass surgery (CABG), had shown a completely normal SVG without any suspicion of a venous valve. These OCT images suggested the possibility that the culprit lesion was an “upside down” venous valve that was not visualized by angiography just after surgery, but could be a cause of late SVG stenosis following CABG. OCT imaging is very useful for clarifying the etiology of the stenosis in cases of ambiguous angiographic lesions.     

Serial optical coherence tomography images of trapped balloon catheter after bailout stenting

The increased use of endovascular interventions has resulted in a growing number of complications pertaining to unretrievable devices. We report a case of balloon dislodgement in a coronary artery during percutaneous coronary intervention (PCI) with bailout stenting using bare metal stent (BMS). We could not retrieve the remnant despite several attempts and techniques. Thereafter, we deployed BMS to bail out thrombus to recover the coronary flow. Emergency surgery was not considered because of high perioperative mortality (EuroSCORE II 55.91%). We did careful follow‐up with frequency domain optical coherence tomography images, which revealed thick neointima hyperplasia that completely covered the BMS over the balloon. On the other hand, relevant amounts of thrombus remained on the proximal shaft. In cases where remnants are difficult to retrieve using a percutaneous transcatheter technique and the patients are high‐risk for surgery, sealing whole remnants with a BMS is a feasible treatment option. © 2014 Wiley Periodicals, Inc.