In Vivo Quantitative Tissue Characterization of Human Coronary Arterial Plaques by Use of Integrated Backscatter Intravascular Ultrasound and Comparison With Angioscopic Findings

Abstract

Background-The purpose of the present study was to define whether integrated backscatter (IB) combined with conventional intravascular ultrasound (IVUS) makes tissue characterization of coronary arterial plaques possible. Methods and Results-IB-IVUS was performed in coronary arteries (total 18 segments) of 9 patients at autopsy, and the findings were compared with the histology. RF signals, which were digitized at 2 GHz in 8-bit resolution, were obtained with an IVUS system with a 40-MHz catheter. IB values of the RF signal from the region of interest (ROI) (100-m depth, 1.4°per line) were calculated by use of a personal computer. IB values on the ROIs were divided into 5 categories, compared with each of the plaque histologies: category 1 (thrombus), Ϫ88 Ͻ IB Յ Ϫ80; category 2 (intimal hyperplasia or lipid core), Ϫ73 Ͻ IB Յ Ϫ63; category 3 (fibrous tissue), Ϫ63 Ͻ IB Յ Ϫ55; category 4 (mixed lesions), Ϫ55 Ͻ IB Յ Ϫ30; and category 5 (calcification), Ϫ30 Ͻ IB Յ Ϫ23. On the basis of these categories, we analyzed 5120 ROIs per segment in each ring-like arterial specimen. Color-coded maps of plaques were constructed by use of these IB data and conventional IVUS data, which reflected the plaque histology of autopsied coronary arteries well. Then, the same method was undertaken in 24 segments with plaque from 12 patients in vivo with angina pectoris. Comparisons between coronary angioscopy and IB-IVUS revealed that the surface color of plaques in angioscopy reflected the thickness of the fibrous cap rather than the size of the lipid core. Conclusions-IB-IVUS represents a new and useful tool for evaluating the tissue structure of human coronary arterial plaques.

Angioscopic Study of Silent Plaque Disruption in Nonischemic Related Coronary Artery in Patients With Stable Ischemic Heart Disease

“…The cap of intense yellow color plaques is very thin 28) and is associated with plaque vulnerability. 29,30) In the present study, for patients with OMI and stable angina, yellow plaques had a higher incidence of silent plaque disruption compared to white plaques. Therefore, through better identification of the yellow plaques, angioscopy would be useful for the detection of patients who are at high risk of suffering plaque disruption in a nonischemic related coronary artery.…”

Impact of Water- and Lipid-Soluble Statins on Nonculprit Lesions in Patients with Acute Coronary Syndrome

“…6,15,16) The system was connected to a conventional IVUS imaging system, and a radiofrequency signal output was acquired. IB-IVUS images were obtained at the same time as conventional IVUS measurements after PCI.…”

“…Captured images have correlated highly with pathological findings. 5,6) Plaque stability can potentially be achieved by a change in plaque contents, such as the removal of lipids from the lipid-rich plaque and an increase in its fibrous tissue, without an improvement in the degree of plaque volume. 7) Using serial IVUS examinations in patients with stable angina pectoris, the Study of Coronary Atheroma by Intravascular Ultrasound: Effect of Rosuvastatin versus Atorvastatin (SATURN) trial revealed that water-soluble and lipid-soluble statins provided comparable benefits in reducing plaque volume.…”

Integrated Backscatter Intravascular Ultrasound

“…In the next generation, this ultrasound IB technique was applied to coronary arteries by use of intravascular ultrasound (IVUS) (Kawasaki et al, 2002). A personal computer (Windows XP Professional, CPU: 3.4 GHz) equipped with newly developed custom software was connected to an IVUS imaging system (VISIWAVE, Terumo, Japan) to obtain the radio frequency signal, signal trigger and video image outputs.…”