Can High Frequency Ultrasound and MRI Diagnose Malignant Atheromatous Plaque in Vitro?

Abstract

It remains a vital clinical issue how to diagnose malignant atheromatous plaques consisting of ulcerative plaque and hemorrhagic plaque, which are potential risks for thrombosis and the arterial spasm. This study proposes further investigations to develop mediods in order to detect this type of lesions by echocardiography. In this study, we tested high frequency (7.5 MHz) US and 1.0 T MRI (Tl weighted SE, STIR; short time inversion recovery sequence, and T1 weighted fat suppression technique) for their precision in the diagnosis of atheromatous plaque as malignant or benign in post mortem human aorta. Ten hemorrhagic plaques were imaged as heterogeneous echo- pattern in die shoulder of plaques covered with high-echo capsule with US; however, these findings were also obtained from 2 of 16 non-hemorrhagic plaques. With T1SE, hemorrhagic plaques were revealed as mixed areas of reduced intensity and high intensity which were differentiated from fatty deposition with Tl weighted fat suppression technique. Ulcerative plaques were revealed as concave shaped plaques and diagnosed correcdy with bodi methods. US was superior to MRI from the viewpoints of examination time and measuring wall thickness. US indicated intimal plus medial thickness of hemorrhagic plaque and non-hemorrhagic plaque at 4.3+ 1.1 mm and 3.0+ 1.0 mm (p<0.05) respectively. MRI was vulnerable to artifacts and its image was poorer in quality due to its lower resolution: however, probably because of its superior ability to distinguish fatty deposition from hemorrhage, MRI ultimately enabled more accurate diagnosis than US, as long as its image was fairly clear. The overall accuracies were 80% with US and 85.7% with MRI as confirmed by histological tests. From these results, die careful analysis of the two images obtained from US and MRI enables clinical diagnosis of malignant atheromatous plaques. (Jpn. Heart J 36: 235-245, 1995). © 1995, International Heart Journal Association. All rights reserved.