New developments in the detection of vulnerable plaque

Abstract

Failure of coronary angiography (luminography) in prediction of future acute coronary syndromes has cast a shadow of doubt over the value of this old gold-standard technique. The fact that angiographically invisible or nonsignificant lesions cause the majority of acute coronary syndromes has driven scientists to develop new diagnostic methods. In this article, we review the ongoing worldwide research on both invasive techniques (such as intravascular angioscopy and colorimetry, ultrasound, thermography, optical coherence tomography, near infrared spectroscopy, Raman spectroscopy, fluorescence emission spectroscopy, elastography, magnetic resonance imaging and spectroscopy, nuclear immunoscintigraphy, electrical impedance imaging, vascular tissue doppler, and shear stress imaging) and noninvasive techniques (such as MRI, contrast-enhanced MRI with and without immunolabeled agents, electron beam computed tomography, multi-slice spiral / helical computed tomography, and nuclear imaging, including positron emission tomography). Each of these techniques and their potential combination holds promise for characterization of plaques responsible for acute coronary syndromes, namely vulnerable plaque.

Detection of Lipid Pool, Thin Fibrous Cap, and Inflammatory Cells in Human Aortic Atherosclerotic Plaques by Near-Infrared Spectroscopy

“…Other techniques such as intravascular MRI and Raman spectroscopy are under intense investigation for human implementation. 7,8,14 An important feature of the present in vitro study is the high likelihood that the method can be adapted for coronary plaque characterization in living patients. Of foremost importance is that NIR light can be safely delivered to the human coronary by a fiberoptic catheter.…”

“…Spectroscopic information is dependent on a range of variables including temperature, pH, and breakdown of tissue. 7 Hence, this promising in vitro ability of NIR spectroscopy to detect signs associated with vulnerability must be tested in vivo in an animal model and in living patients. Furthermore, validation of these results in coronary plaques is also needed.…”

“…4 -6 Multiple techniques are being tested to identify such plaques before they disrupt and cause thrombosis. [7][8][9][10][11][12][13][14] Identification of these potentially lethal plaques before they disrupt will facilitate the development of therapeutic strategies to prevent acute coronary events.…”

Inflammation as a Cardiovascular Risk Factor

“…24,25 Two imaging techniques, MRI (MRI) and computed tomography (CT), have been used successfully for this purpose. High-resolution, multicontrast MRI is currently the leading imaging modality for plaque characterization in vivo; it can differentiate plaque components based on both physical and chemical variables, provide high-resolution images of the coronary artery wall, and identify thin fibrous caps and lipid cores of atherosclerotic plaques.…”

Vulnerable Atherosclerotic Plaque

“…Clinical trials are likely to demonstrate that such plaques can be detected with some combination of MRI or computed tomography (CT) with contrast, angiography, thermography, ultrasound or optical coherence tomography (OCT) (either of which could incorporate elastography or integrated backscatter), near-infrared spectroscopy, and/or angioscopy. 42,43 Such an approach would be expensive, but could prove useful. For example, if a patient is found to be at greater risk than predicted by office or bedside techniques, including serum CRP level, this information may lead the patient to reschedule a physically or mentally stressful task in lieu of rest, or of a critical family meeting or reconciliation.…”