Hybrid Intravascular Imaging: Recent Advances, Technical Considerations, and Current Applications in the Study of Plaque Pathophysiology

Christos V. Bourantas; Farouc A. Jaffer; Frank J. Gijsen; Gijs van Soest; Sean P. Madden; Brian K. Courtney; Ali M. Fard; Erhan Tenekecioglu; Yaping Zeng; Antonius F.W. van der Steen; Stanislav Emelianov; James Muller; Peter H. Stone; Laura Marcu; Guillermo J. Tearney; Patrick W. Serruys

Disclosures

Eur Heart J. 2017;38(6):400-412. 

In This Article

Abstract and Introduction

Abstract

Cumulative evidence from histology-based studies demonstrate that the currently available intravascular imaging techniques have fundamental limitations that do not allow complete and detailed evaluation of plaque morphology and pathobiology, limiting the ability to accurately identify high-risk plaques. To overcome these drawbacks, new efforts are developing for data fusion methodologies and the design of hybrid, dual-probe catheters to enable accurate assessment of plaque characteristics, and reliable identification of high-risk lesions. Today several dual-probe catheters have been introduced including combined near infrared spectroscopy-intravascular ultrasound (NIRS-IVUS), that is already commercially available, IVUS-optical coherence tomography (OCT), the OCT-NIRS, the OCT-near infrared fluorescence (NIRF) molecular imaging, IVUS-NIRF, IVUS intravascular photoacoustic imaging and combined fluorescence lifetime-IVUS imaging. These multimodal approaches appear able to overcome limitations of standalone imaging and provide comprehensive visualization of plaque composition and plaque biology. The aim of this review article is to summarize the advances in hybrid intravascular imaging, discuss the technical challenges that should be addressed in order to have a use in the clinical arena, and present the evidence from their first applications aiming to highlight their potential value in the study of atherosclerosis.

Introduction

Intravascular imaging was introduced in the clinical setting in the beginning of 1990s and enabled for the first time in vivo evaluation of the atheroma burden and detection of plaque characteristics associated with increased vulnerability.[1] The first clinical applications of intravascular imaging techniques [i.e. intravascular ultrasound (IVUS) and optical coherence tomography (OCT)] demonstrated their potential value in assessing plaque morphology and pathophysiology and generated optimism that intravascular imaging would enable accurate detection of high-risk plaques likely to cause clinical events.[2,3] However, recent histology-based studies and large-scale studies of coronary atherosclerosis revealed significant limitations of existing imaging modalities in detecting vulnerable plaque characteristics and high-risk lesions (i.e. in the PROSPECT study the positive predictive value of IVUS-derived variables in detecting lesions that caused events was 18.2% while in the PREDICTION the positive predictive value of IVUS-derived variables and of the local haemodynamic forces in detecting lesions that progressed and required revascularization was 41%) and highlighted the need to design alternative invasive imaging techniques that would allow complete and accurate evaluation of plaque morphology and pathobiology.[4–7]

The miniaturization of medical devices and advances in image and signal processing permitted the development of novel modalities [e.g. near infrared spectroscopy (NIRS), intravascular photoacoustic (IVPA) imaging, near infrared fluorescence (NIRF) molecular imaging, and time-resolved fluorescence spectroscopy (TRFS), or fluorescence lifetime imaging (FLIm)] that appear able to address certain limitations of either IVUS or OCT and provide additional information about plaque morphology and pathobiology. Nevertheless, no single existing technique enables a complete assessment of the plaque (Supplementary material online, file). To address this challenge, hybrid imaging has been suggested. Hybrid intravascular imaging can be obtained either through the development of methodologies that allow reliable offline co-registration of data acquired by different modalities with complementary strengths, or through the design of dual-probe catheters that enable simultaneous assessment of plaque morphology by two different imaging techniques.[8] Over the recent years, significant advances have occurred in this field and accumulating evidence indicates the potential value of hybrid imaging in research. The aim of this article is to present the latest developments in hybrid intravascular imaging, describe the technical challenges and limitations of the available data fusion methodologies and dual-probe catheters, summarize the evidence from their first applications, and discuss their future role in the study of coronary atherosclerosis ( Table 1 ).

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