Characterization of Carotid Plaque with Histology and Quantitative Ultrasound
X Wang1*, S Salamat2, T Varghese3, R Dempsey4, (1) University of Wisconsin-Madison, Madison, WI, (2) University of Wisconsin-Madison, Madison, WI, (3) University of Wisconsin, Madison, WI, (4) University of Wisconsin-Madison, Madison, WIWE-E-134-8 Wednesday 2:00PM - 3:50PM Room: 134
Purpose: To compare and correlate localization and registration of calcified, fibrous and lipid regions within heterogeneous plaque using histology and ultrasound quantitative imaging, and to better characterize carotid plaque.
Methods: Atherosclerotic plaque excised after carotid endarterectomy, was imaged ex vivo using a VisualSonics Vevo 770 ultrasound system. Attenuation coefficient images were obtained from the three-dimensional radiofrequency data collected and rendered into a 3D volume. Fixed plaque tissue was then longitudinally sectioned in increments of 5 um, and sections separated by 100 um were acquired. The thickness of each section of the sample was 5 um. Histopathology images were digitized using a PathScan Enabler IV. The two-dimensional histology information obtained were registered using Matlab and reconstructed into a 3D volume. Different regions such as the lumen, calcified, fibrous and lipid region were segmented by a pathologist and digitally color-coded into the 3D histology data. We then compared similar tissue types from the 3D histology volume to the estimated 3D attenuation coefficient using quantitative ultrasound methods.
Results: Our results indicate that calcified, fibrous and lipid regions in the two volumes showed a good correlation. Calcified regions delineated on the histology volume correspond to the high attenuation coefficient region (2.48 dB/cm/MHz) in the 3D attenuation coefficient volume, while lipid regions tend to have lower attenuation coefficient values (1.47 dB/cm/MHz). Fibrous regions in histology, correlate to the lowest attenuation coefficient value (0.86 dB/cm/MHz).
Conclusion: Most plaques are heterogeneous and difficult to characterize precisely. This work demonstrates a direct correlation between pathology and ultrasound quantitative imaging characterization of plaque. It provides a promising way for direct localization of plaque regions and structures, and for improved determination of plaque composition.
Funding Support, Disclosures, and Conflict of Interest: This work was supported in part by NIH grants R21 EB010098-02, R01 NS064034-04, and 2R01 CA112192-06.