Relative Value of Normalized Sonographic In Vitro Analysis of Arteriosclerotic Plaques of Internal Carotid Artery

Abstract

Background and Purpose-A close correlation between B-mode sonography and the histopathology and surface structure of plaque is rarely seen in vivo with high-grade stenoses of the extracranial carotid artery. The goal of this study was to determine whether normalized gray scale analysis and surface analysis of the plaque are capable of characterizing the attributes correctly. Methods-Optimized B-mode images of 107 carotid endarterectomy specimens were captured, and the gray scale median (GSM) was calculated. The specimens were classified histologically into 3 groups: (1) calcium-rich hard plaques, (2) lipid-rich soft plaques, and (3) combined plaques. The surfaces of the plaques were classified as smooth or rough on the basis of standardized reference samples. The endoluminal surface was digitally documented in vitro by videoendoscopy and again classified into the same categories. All stages of the investigation were performed by 2 observers at 2 different times. Results-Evaluation of the GSM showed close interobserver and intraobserver correlation (PϽ0.01, RϾ0.8). However, there was only 46% agreement between the GSM and the histopathological findings. In both in vitro angioscopy (ϭ0.936, PϽ0.001) and sonographic evaluation (ϭ0.842, PϽ0.001), there was a high correlation between the observers with regard to the evaluable specimens. In 73%, agreement was observed between the sonographic image and angioscopy. Conclusions-Normalized gray scale analysis and evaluation of the plaque surface in an in vitro study make possible observer-independent evaluation. The composition of the plaque cannot be visualized with sufficient accuracy by sonographic GSM analysis. This also applies to the correlation between sonography and actual surface composition of the plaque.

Current imaging modalities to visualize vulnerability within the atherosclerotic carotid plaque

“…Only 46% of the cases showed agreement between the GSM and the histopathologic findings. 30 Correlation of PDA with histology showed similar results. 25,32,33 Currently, it seems that the ability of ultrasound scan to predict signs of vulnerability in the preoperative phase is limited.…”

“…Moreover, in up to 37% of cases, it is not possible to evaluate the plaque surface due to acoustic shadowing or a high degree of stenosis. 29,30 With the development of computer-assisted image analysis, inter-observer variability of ultrasound scan analysis has decreased. The Imaging in Carotid Angioplasty and Risk of Stroke (ICAROS) trial showed that increased echolucency of the carotid plaque, defined as a GSM of less than 25, is a risk factor for stroke during and immediately after carotid artery stenting.…”

Ultraschall in der Gefäßchirurgie

“…Die Übereinstimmung der Untersucher ist trotz Differenzierung sehr gut (Übersicht bei Denzel [7]). Diese Methodik setzt eine relativ aufwändige Standardisierung mit externer Bildbearbeitung (Histogrammfunktion des Adobe® Photoshop® CS) voraus (.…”

PTA oder Operation bei der Therapie von Karotisstenosen?

“…HITS ("high-intensity transient signals") nachweisen [11,34,35,39,46,61,75]. Auch die Angiographie und die Angioskopie spielen eine Rolle, ebenso die Doppler-Sonographie zur Aufdeckung möglicher Turbulenzphänome-ne oder die Duplexsonographie [7,10,29,30]. Die Verfechter der Operation an der Arteria carotis in Lokalanästhesie weisen darauf hin, dass in diesem Fall die neurologische Kontrolle des Patienten besonders einfach und zuverlässig durch direkte Kommunikation möglich ist [40,76].…”

“…The study of Alberts is not published and the inclusion criteria for the SAPPHIRE trial were restricted to the group of high-risk patients, which were not suitable for an operative treatment. [27][28][29][30].…”