Histopathologic Validation of Grayscale Carotid Plaque Characteristics Related to Plaque Vulnerability

Abstract

Inflammation and angiogenesis play major roles in carotid plaque vulnerability. The purpose of this study was to determine if grayscale features of carotid plaques are associated with histological markers for inflammation. Thirty-eight individuals completed a dedicated research carotid ultrasound exam prior to carotid endarterectomy. Grayscale analysis was performed on plaque images to measure plaque echogenicity (grayscale median [GSM] pixel brightness), plaque area, presence of discrete white areas [DWAs], and the percent of black area near the lumen on any one component of the plaque. Plaques with higher ultrasound GSM had greater percent calcification (p=0.013) on histopathology. Presence of an ultrasound DWA was associated with more plaque hemosiderin (p=0.0005) and inflammation (p=0.019) on histopathology examination. The percent of plaque black area in any one component was associated with a higher score for macroscopic ulceration (p=0.028). Ultrasound plaque characteristics (GSM, DWAs and Black areas) represent histopathological markers associated with plaque vulnerability.

Influence of Ultrasound System and Gain on Grayscale Median Values

“…Quantitative grayscale ultrasound (US) can be used to quantify echogenicity and to characterize tissue in anatomic structures . Increasingly, quantitative grayscale US and textural feature extraction are being used to assess characteristics associated with preclinical arterial injury and the risk of cardiovascular disease, including stroke .…”

“…Within studies, the GSM and other textural features have been measured reproducibly with dedicated software analysis programs . Computer‐assisted methods for plaque classification can reduce GSM variability using image normalization procedures, which linearly scale grayscale values in the image between two different reference points available in every subject .…”

Transcranial Doppler and Microemboli Detection: Relationships to Symptomatic Status and Histopathology Findings

“…All carotid endarterectomies and ulceration scores were provided by a board-certified surgeon (Mitchell et al 2017). At the time of carotid endarterectomy, the surgeon scored the plaque on an ordinal scale of 1 to 4.…”

“…Paraffin-embedded plaque sections were stained using standard hematoxylin and eosin methods (Mitchell, et al 2017). Sections were assessed for the percent calcification, cholesterol content, hemorrhage, hemosiderin content, and inflammatory cell infiltration by a single pathologist blinded to subject characteristics.…”

“…Atheromatous plaques were scored for hemorrhage, hemosiderin, inflammation, percent cholesterol and calcium. An ordinal scale (0–3) was used for scoring the presence of hemosiderin and inflammation, with 0 representing no hemosiderin or inflammation, 1 minimal, 2 moderate and 3 representing extensive hemosiderin/inflammation Mitchell et al 2017). …”