Intravascular Imaging Modalities Research Articles

Wall shear stress and evolution of coronary atherosclerosis: an emerging intravascular imaging modality

Wall shear stress and evolution of coronary atherosclerosis: an emerging intravascular imaging modality

Impact of Frequency-Domain Optical Coherence Tomography Guidance for Optimal Coronary Stent Implantation in Comparison With Intravascular Ultrasound Guidance

Frequency-domain optical coherence tomography (FD-OCT) is a novel, high resolution intravascular imaging modality. Intravascular ultrasound (IVUS) is a widely used conventional imaging modality for achieving optimal stent deployment. The aim of this study was to evaluate the impact of FD-OCT guidance for coronary stent implantation compared with IVUS guidance. A total of 70 patients with de novo coronary artery lesions and either unstable or stable angina pectoris were enrolled in this randomized study (optical coherence tomography [OCT] group: n=35, IVUS group: n=35). In the OCT group, stent implantation was performed under FD-OCT guidance alone and final stent expansion was evaluated by IVUS. In the IVUS group, conventional IVUS guidance was used and final stent apposition was evaluated by FD-OCT. There were no significant differences regarding the procedural, fluoroscopy time, and contrast volume. Although device and clinical success rates also were similar, the visibility of vessel border was significantly lower in the OCT group (P<0.05). Minimum and mean stent area and focal and diffuse stent expansion were smaller (6.1±2.2 mm versus 7.1±2.1 mm, 7.5±2.5 versus 8.7±2.4 mm, 64.7±13.7% versus 80.3±13.4%, 84.2±15.8% versus 98.8±16.5%, P<0.05, respectively), and the frequency of significant residual reference segment stenosis at the proximal edge was higher in the OCT group (P<0.05). Incomplete apposed struts in both groups were similar (P=0.34). FD-OCT guidance for stent implantation was associated with smaller stent expansion and more frequent significant residual reference segment stenosis compared with conventional IVUS guidance.

Application of Optical Coherence Tomography in Percutaneous Coronary Intervention

Optical coherence tomography (OCT) is a high resolution imaging technique that offers microscopic visualization of the coronary artery. The fast scanning speed and simple imaging procedure of new-generation frequency-domain OCT make this technology easy to use in the clinical setting. The OCT examination is useful for guidance and risk stratification of percutaneous coronary intervention (PCI). OCT-derived thin-cap fibroatheroma, which is characterized by large lipid-core and thin fibrous cap <65 μm, is a predictor of peri-PCI complications, such as angiographic no-reflow, microvascular obstruction, and post-PCI cardiac troponin I elevation. Stent malapposition, tissue protrusion, and stent edge dissection are assessed in more detail by OCT than with conventional intravascular imaging modalities. Neointimal coverage at strut level assessed by OCT could be a surrogate endpoint for quickly scrutinizing safety after drug-eluting stent implantation. The OCT findings of in-stent neoatherosclerosis, such as lipid-rich neointima, microvascular proliferation, and neointimal plaque rupture, are associated with very late stent failure, including thrombosis and restenosis. With its excellent ability to assess coronary atherosclerosis and to guide PCI, OCT provides new insights into interventional cardiology.

Optical coherence tomography assessment of calcified plaque modification after rotational atherectomy

Rotational atherectomy (RA) facilitates stent delivery in highly calcified coronary plaques (CCP). However, lesion ablation by RA in angulated segments may be affected by guidewire bias, leading to a non-uniform plaque modification. Intravascular optical coherence tomography (iOCT) is the highest resolution (∼10 μm axial) intravascular imaging modality available for clinical use; furthermore, near infrared light easily penetrates calcium, with significantly fewer artifacts, including no "blooming effect" as seen by intravascular ultrasound. Therefore, it may pose as a unique tool for serial calcium quantification, as related in this article with pre- and post-RA assessment, allowing accurate characterization of plaque modification, as well as quality of stent deployment. The effects of guidewire bias in the debulking process have not been well documented by iOCT. We present a case of lesion preparation by RA affected by guidewire bias in which iOCT revealed unique insights into CCP modification.

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

Optical coherence tomography (OCT) is an increasingly used intravascular imaging modality to assess coronary stent implantation and vessel healing. A recently developed catheter (C7 Dragonfly; LightLab Imaging Inc.,Westford, MA, USA) allows visualisation of peripheral arteries up to 10 mm of diameter with high speed pullback. Safety, feasibility and the technique of OCT following carotid artery stenting (CAS) were evaluated in the present study. OCT was performed in seven consecutive patients following successful CAS using proximal cerebral protection devices, occluding the common and external carotid artery and gentle manual injection of a total of 8-14 ml of 50% diluted contrast media with normal saline in order to displace the blood from the artery. Once the blood was displaced, pullback was started through the stented segment continuing the gentle contrast injection. After completion of the pullback all injected contrast was aspirated and discarded. In the first three patients, OCT was also performed without internal carotid artery flow blockage. Due to the high blood flow in the ICA it was not possible to replace all residual blood and obtain adequate OCT images. No procedural, in-hospital, or 30-day follow-up complications occurred. One patient experienced transient intolerance to vessel occlusion without any neurological sequels. OCT images were of good quality providing important information regarding stent geometry, presence and lack of strut apposition, plaque fracture, and plaque prolapse. Intravascular OCT under occlusive proximal protection appears feasible and safe to assess stent implantation in carotid arteries.

Intravascular Imaging Tools in the Cardiac Catheterization Laboratory: Comprehensive Assessment of Anatomy and Physiology

Intravascular imaging modalities have an imperative role in contemporary cardiovascular research. Currently, there are several invasive imaging modalities available in the cardiac catheterization laboratory and new technologies are under development. In the current review, we aimed to provide an update on the research applications of contemporary intravascular imaging tools in the cardiac catheterization laboratory. For the purpose of this review, we separately discuss imaging tools for assessment of epicardial disease (fractional flow reserve and hyperemic stenosis resistance), microvascular function (coronary flow reserve, hyperemic microvascular resistance, and index of microcirculatory resistance), endothelial function, atherosclerotic plaque and vascular remodeling (intravascular ultrasound, optical coherence tomography, angioscopy, and near-infrared spectroscopy), and finally the emerging modalities (palpography and wall shear stress profiling).

Characteristics of in vivo images from an in-stent restenosis lesion of a saphenous vein graft after bare-metal stent implantation: Assessment using optical coherence tomography

Restenosis of saphenous vein grafts (SVG) after bare-metal stent (BMS) implantation remains a clinical problem. Recently, intravascular optical coherence tomography (OCT) has been proposed as a high resolution intravascular imaging modality, and is able to distinguish several components of intracoronary structures. In vivo images of in-stent restenosis (ISR) lesions in an SVG using OCT have not been reported. In this case report, we present the characteristics of in vivo OCT images from an ISR lesion of an SVG after BMS implantation.

Can an Intravascular Imaging Modality Detect Really Vulnerable Plaque?

Can an Intravascular Imaging Modality Detect Really Vulnerable Plaque?

Expert review document on methodology, terminology, and clinical applications of optical coherence tomography: physical principles, methodology of image acquisition, and clinical application for assessment of coronary arteries and atherosclerosis

Optical coherence tomography (OCT) is a novel intravascular imaging modality, based on infrared light emission, that enables a high resolution arterial wall imaging, in the range of 10-20 microns. This feature of OCT allows the visualization of specific components of the atherosclerotic plaques. The aim of the present Expert Review Document is to address the methodology, terminology and clinical applications of OCT for qualitative and quantitative assessment of coronary arteries and atherosclerosis.

S22-4 New Intravascular Imaging Modality to Detect Vulnerable Plaque

S22-4 New Intravascular Imaging Modality to Detect Vulnerable Plaque

Harmonic scalpel versus electrocautery for harvest of radial artery conduits: Reduced risk of spasm and intimal injury on optical coherence tomography

Vasospasm is the primary obstacle to widespread adoption of the radial artery as a conduit in coronary artery bypass grafting. We used optical coherence tomography, a catheter-based intravascular imaging modality, to measure the degree of radial artery spasm induced by means of harvest with electrocautery or a harmonic scalpel in patients undergoing coronary artery bypass grafting. Radial arteries were harvested from 44 consecutive patients with a harmonic scalpel (n = 15) or electrocautery (n = 29). Vessels were imaged before harvesting and after removal from the arm, with saphenous vein tracts serving as internal controls. Optical coherence tomographic findings for the degree of harvesting-induced injury were validated against histologic measures. Optical coherence tomographic measures of endovascular dimensions and injury correlated strongly with histologic findings. Mean luminal volume, a measure of vasospasm, decreased significantly less after harvesting with a harmonic scalpel (9% +/- 7%) than with electrocautery (35% +/- 6%, P = .015). Completely intact intima was present in 11 (73%) of 15 radial arteries harvested with a harmonic scalpel (73%) compared with 9 of 29 arteries harvested by means of electrocautery (31%, P = .011). Intraoperative flow measurements and patency rates at 5 days postoperatively were not significantly different among groups. Optical coherence tomography provides a level of speed and accuracy for quantifying endothelial injury and vasospasm that has not been described for any other modality, suggesting potential as an intraoperative quality assurance tool. Our optical coherence tomographic findings suggest that the harmonic scalpel induces less spasm and intimal injury compared with electrocautery.

Optical Coherence Tomography in the Setting of an Acute Anterior Myocardial Infarction

HomeCirculationVol. 116, No. 14Optical Coherence Tomography in the Setting of an Acute Anterior Myocardial Infarction Free AccessReview ArticlePDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessReview ArticlePDF/EPUBOptical Coherence Tomography in the Setting of an Acute Anterior Myocardial Infarction Ravinay Bhindi, Shahzad M. Munir and Keith M. Channon Ravinay BhindiRavinay Bhindi From the Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom. Search for more papers by this author , Shahzad M. MunirShahzad M. Munir From the Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom. Search for more papers by this author and Keith M. ChannonKeith M. Channon From the Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom. Search for more papers by this author Originally published2 Oct 2007https://doi.org/10.1161/CIRCULATIONAHA.107.722769Circulation. 2007;116:e366–e367An 82-year-old man presented with an acute anterior myocardial infarction and was treated with intravenous reteplase with successful reperfusion. Forty-eight hours later, however, he developed further chest pain and ST-segment elevation. He was referred for salvage percutaneous coronary intervention.The left anterior descending artery was completely occluded proximally (Figure, A) with no detectable collateral flow, and the remainder of the coronary circulation showed diffuse nonsignificant disease. The left anterior descending artery was engaged with a JL4 guide catheter and wired with a Whisper J wire. The lesion was predilated with a 1.5-mm noncompliant balloon that restored flow to the left anterior descending artery and demonstrated a tight culprit lesion in the left anterior descending artery (Figure, B). This was then imaged with optical coherence tomography (OCT), which was facilitated by bolus contrast injection instead of proximal vessel occlusion. Panel C of the Figure demonstrates the composition of the plaque, which was disrupted with fibrocalcific material in the wall and thrombus in the vessel lumen. The lesion was then further dilated with a 2.5/12-mm balloon, stented with a 3.5/12-mm drug-eluting stent, and finally postdilated with a 3.5/9-mm balloon with an excellent angiographic result (Figure, D). OCT was then performed with proximal balloon occlusion at the end of the case, which showed a widely patent vessel, good stent apposition, and no luminal thrombus (Figure, E). Download figureDownload PowerPointA, Coronary angiography demonstrates a totally occluded left anterior descending artery proximally (arrow). B, After predilatation of the left anterior descending artery, the culprit lesion is identified (arrow). C, OCT of the lesion demonstrates a stenosed lumen with a predominantly fibrocalcific plaque (L), which shows evidence of disruption and intraluminal thrombus (arrow). D, Angiographic image after stent deployment (arrow) shows a widely patent vessel. E, OCT after stent deployment demonstrates a widely patent lumen with no intraluminal thrombus and good stent apposition (arrow).OCT is a novel, high-resolution, intravascular imaging modality that provides “optical biopsies” of the vascular wall.1,2 Because blood interferes with the imaging capabilities of the OCT probe, vessel occlusion followed by saline injection is generally performed to permit viewing. An alternative strategy is concurrent imaging during the injection of a contrast bolus to displace blood; this alternative technique was adopted in the present case during the initial sequence of imaging, when blood flow was diminished as a result of the recently ruptured plaque. Adequate images were obtained with no significant delay using this procedure. The present case shows the OCT images of a ruptured plaque detected during salvage percutaneous coronary intervention after an anterior myocardial infarction, which was performed in a hemodynamically stable patient with failed thrombolysis, to characterize the culprit lesion. Such an approach could potentially be used to broaden the application of OCT.DisclosuresNone.FootnotesCorrespondence to Dr Ravinay Bhindi, Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom. E-mail [email protected]References1 Yabushita H, Bouma BE, Houser SL, Aretz HT, Jang IK, Schlendorf KH, Kauffman CR, Shishkov M, Kang DH, Halpern EF, Tearney GJ. Characterization of human atherosclerosis by optical coherence tomography. Circulation. 2002; 106: 1640–1645.LinkGoogle Scholar2 Jang IK, Tearney GJ, MacNeill B, Takano M, Moselewski F, Iftima N, Shishkov M, Houser S, Aretz HT, Halpern EF, Bouma BE. In vivo characterization of coronary atherosclerotic plaque by use of optical coherence tomography. Circulation. 2005; 111: 1551–1555.LinkGoogle Scholar Previous Back to top Next FiguresReferencesRelatedDetailsCited By Lee R, Antoniades C, Adlam D and Channon K (2012) Treatment of recurrent vein graft “stent-in-stent” re-stenosis guided by optical coherence tomography, International Journal of Cardiology, 10.1016/j.ijcard.2011.08.007, 156:1, (e20-e21), Online publication date: 1-Apr-2012. October 2, 2007Vol 116, Issue 14 Advertisement Article InformationMetrics https://doi.org/10.1161/CIRCULATIONAHA.107.722769PMID: 17909111 Originally publishedOctober 2, 2007 PDF download Advertisement SubjectsCatheter-Based Coronary and Valvular InterventionsImagingMyocardial Infarction

Intravascular optical coherence tomography: Cellular imaging

The vast majority of acute coronary events are attributed to rupture or erosion of high-risk or vulnerable plaques. Novel imaging techniques are being actively sought that can detect quiescent vulnerable features within coronary plaque and thereby identify populations at risk, monitor plaque progression, and target therapy appropriately. Optical coherence tomography is an intravascular imaging modality capable of detecting and characterizing coronary plaque in vivo. Recently, optical coherence tomography quantification of macrophage infiltration within atherosclerotic plaque ex vivo was demonstrated. Application of this technique to clinical practice yields a hybrid image incorporating plaque morphology with a measure of biologic activity. In a recently conducted clinical study assessing macrophage distributions in patients, evidence supporting both the vulnerable plaque model and the hypothesis of multifocal inflammatory risk, linked by the common thread of increased macrophage infiltration, has been found. These results suggest that elevated multifocal coronary macrophage content, present both in culprit lesions and at remote sites, serves as a background for heightened risk. Superimposed on this inflammatory background, local increases in macrophage content, particularly at the cap surface and at areas at high risk for rupture, further promote the instability of individual lesions.

Characterization of Human Atherosclerosis by Optical Coherence Tomography

High-resolution visualization of atherosclerotic plaque morphology may be essential for identifying coronary plaques that cause acute coronary events. Optical coherence tomography (OCT) is an intravascular imaging modality capable of providing cross-sectional images of tissue with a resolution of 10 micro m. To date, OCT imaging has not been investigated in sufficient detail to assess its accuracy for characterizing atherosclerotic plaques. The aim of this study was to establish objective OCT image criteria for atherosclerotic plaque characterization in vitro. OCT images of 357 (diseased) atherosclerotic arterial segments obtained at autopsy were correlated with histology. OCT image criteria for 3 types of plaque were formulated by analysis of a subset (n=50) of arterial segments. OCT images of fibrous plaques were characterized by homogeneous, signal-rich regions; fibrocalcific plaques by well-delineated, signal-poor regions with sharp borders; and lipid-rich plaques by signal-poor regions with diffuse borders. Independent validation of these criteria by 2 OCT readers for the remaining segments (n=307) demonstrated a sensitivity and specificity ranging from 71% to 79% and 97% to 98% for fibrous plaques, 95% to 96% and 97% for fibrocalcific plaques, and 90% to 94% and 90% to 92% for lipid-rich plaques, respectively (overall agreement, kappa=0.83 to 0.84). The interobserver and intraobserver reliabilities of OCT assessment were high (kappa values of 0.88 and 0.91, respectively). Objective OCT criteria are highly sensitive and specific for characterizing different types of atherosclerotic plaques. These results represent an important step in validating this new intravascular imaging modality and will provide a basis for the interpretation of intracoronary OCT images obtained from patients.

INTRAVASCULAR ULTRASOUND: The Role in Diagnostic and Therapeutic Procedures

Intravascular ultrasound (IVUS), a relatively new imaging modality, has become part of the expanding armamentarium of imaging devices used during both coronary and peripheral interventions.72, 73 In the past 5 years IVUS has made large strides in improvement of resolution, gray scale, and overall image quality. This, in combination with the development of more user friendly and reliable IVUS units, has allowed for significant expansion of the potential roles for IVUS during catheter directed interventions.72 As percutaneous interventions become more complex, imaging with various modalities other than angiography becomes more important. Endovascular graft placement and aortic fenestration for dissections are two examples of newer imaging guided procedures that rely on specific information obtained either prior to or during the intervention that cannot be obtained with angiography alone.65, 68 Results, outcomes, and patency projections of more conventional interventions such as percutaneous transluminal angioplasty (PTA), atherectomy, and stent placement may be betterpredicted with the additional information provided by IVUS. Angiography has been and will most probably remain the indispensable reference standard for vascular evaluation, especially during interventional procedures. Advances in catheter technology, digital imaging systems, and contrast technology have allowed angiography to evolve into a relatively safe, time efficient, and reproducible diagnostic tool that is universally accepted by physicians of all specialties who interrogate vascular anatomy. Nonetheless, significant limitations exist with angiography and discrepancies between pathologically proven specimens and angiography have long been recognized.14, 16, 22, 30, 53, 59, 64, 68, 75 Angiography provides two-dimensional (2-D) longitudinal images of patent vessel lumens. It provides no information regarding the vessel wall, morphology of plaque, etiology of stenoses, occlusions or perivascular structures. Angioscopy, another intravascular imaging tool, allows direct visualization of the vessel lumen but provides no cross-sectional information and is inundated with technical difficulties. Table 1 summarizes the three intravascular imaging modalities. Intraobserver and interobserver variations also may tend to make angiographic interpretation less accurate (Table 2).3, 12