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Carotid plaque movement from B-mode ultrasound images: a feasibility study
European Journal of Ultrasound 6 Suppl. 1 (1997) S1 – S51
Supplement
Abstracts of the 28th Annual Meeting of the British Medical Ultrasound Society, Edinburgh, 11–13 December 1996
Carotid plaque movement from B-mode ultrasound images: a feasibility study Gorman S.T.; Pugh N.D.; Woodcock J.P. Department of Bioengineering, Uni6ersity Hospital of Wales, Heath Park, Cardiff CF4 4XW, UK In recent years there has been renewed interest in the role of plaque morphology in the aetiology of carotid disease. As well as plaque composition, deformation and motion of the carotid plaque have been suggested as significant risk factors in the development of ischemic disease. While there are commercially available systems for investigating movement perpendicular to the artery lumen during the cardiac cycle (i.e. artery distension), plaque motion is also likely to have a significant component parallel to the direction of blood flow. There is, at present, no method for quantifying this 2-D motion. B-mode image sequences of carotid arteries were obtained using a 7.5 MHz linear array ultrasound transducer and digitised using a PC equipped with a frame grabber card. Commercial software (MATLAB) was used to apply a 2-D cross-correlation to the speckle patterns obtained from the B-mode images. This gave quantification of perpendicular and parallel carotid wall motion during systole, with a theoretical resolution of 0.07 mm (compared with a typical carotid artery distension of 0.4 mm). To confirm the accuracy of the tracking system, the measured perpendicular displacement was compared with the distension measured with a commercially available wall tracking system in ten normal carotid arteries. The results show good agreement (correlation=0.82, P= 0.005). Initial studies of carotid artery movement with this system have given promising results and several examples of plaque motion will be discussed. This feasibility study has demonstrated that plaque motion can be tracked using a cross-correlation technique. This offers another method of plaque characterisation which may prove important in identifying patients at high risk of developing embolic events.
What important pathological components of carotid atheroma can be reliably detected using ultrasound Wardlaw J.M.a; Lammie G.A.b; Allan P.L.c; Ruckley C.V.daDepartment of Clinical Neurosciences, Uni6ersity of Edinburgh, Bramwell Dott Building, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK b Neuropathology, Uni6ersity of Edinburgh, Bramwell Dott Building, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK c Medical Radiology, Uni6ersity of Edinburgh, Bramwell Dott Building, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK d Vascular Surgery, Uni6ersity of Edinburgh, Bramwell Dott Building, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK Introduction: Various scales have been devised for categorising the ultrasound appearance of carotid atheromatous plaques compared with pathological specimens, but these are only useful if they have good observer reliability and can identify pathological markers of plaque activity. The fact that there are several of these scales suggests that none are perfect. It is not yet entirely certain why an atheromatous plaque causes a stroke, apart from the degree of stenosis it produces. But work in the coronary arteries has demonstrated that features thought to be connected with an ‘unstable’ plaque (i.e. likely to cause symptoms) include a large necrotic core, a thin fibrous cap, and high macrophage density. Such plaques are liable to ulcerate and thrombose. Method: In a prospective study, patients with TlAs had carotid Doppler ultrasound (Acuson 128 × P10V, 7.5 MHz probe): the appearance of any atheroma was coded for necrosis (0 to + + + ), fibrous cap (thin or thick), surface contour (regular or irregular), ulceration (fissure, small or large) and haemorrhage on the surface or within the atheroma (no to + + +). Endarterectomy specimens from patients subsequently operated on were similarly coded, histologically.
0929-8266/97/$17.00 © 1997 Elsevier Science Ireland Ltd. All rights reserved. PII S 0 9 2 9 - 8 2 6 6 ( 9 7 ) 1 0 0 0 8 - 8
Supplement
Abstracts of the 28th Annual Meeting of the British Medical Ultrasound Society, Edinburgh, 11–13 December 1996
Carotid plaque movement from B-mode ultrasound images: a feasibility study Gorman S.T.; Pugh N.D.; Woodcock J.P. Department of Bioengineering, Uni6ersity Hospital of Wales, Heath Park, Cardiff CF4 4XW, UK In recent years there has been renewed interest in the role of plaque morphology in the aetiology of carotid disease. As well as plaque composition, deformation and motion of the carotid plaque have been suggested as significant risk factors in the development of ischemic disease. While there are commercially available systems for investigating movement perpendicular to the artery lumen during the cardiac cycle (i.e. artery distension), plaque motion is also likely to have a significant component parallel to the direction of blood flow. There is, at present, no method for quantifying this 2-D motion. B-mode image sequences of carotid arteries were obtained using a 7.5 MHz linear array ultrasound transducer and digitised using a PC equipped with a frame grabber card. Commercial software (MATLAB) was used to apply a 2-D cross-correlation to the speckle patterns obtained from the B-mode images. This gave quantification of perpendicular and parallel carotid wall motion during systole, with a theoretical resolution of 0.07 mm (compared with a typical carotid artery distension of 0.4 mm). To confirm the accuracy of the tracking system, the measured perpendicular displacement was compared with the distension measured with a commercially available wall tracking system in ten normal carotid arteries. The results show good agreement (correlation=0.82, P= 0.005). Initial studies of carotid artery movement with this system have given promising results and several examples of plaque motion will be discussed. This feasibility study has demonstrated that plaque motion can be tracked using a cross-correlation technique. This offers another method of plaque characterisation which may prove important in identifying patients at high risk of developing embolic events.
What important pathological components of carotid atheroma can be reliably detected using ultrasound Wardlaw J.M.a; Lammie G.A.b; Allan P.L.c; Ruckley C.V.daDepartment of Clinical Neurosciences, Uni6ersity of Edinburgh, Bramwell Dott Building, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK b Neuropathology, Uni6ersity of Edinburgh, Bramwell Dott Building, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK c Medical Radiology, Uni6ersity of Edinburgh, Bramwell Dott Building, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK d Vascular Surgery, Uni6ersity of Edinburgh, Bramwell Dott Building, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK Introduction: Various scales have been devised for categorising the ultrasound appearance of carotid atheromatous plaques compared with pathological specimens, but these are only useful if they have good observer reliability and can identify pathological markers of plaque activity. The fact that there are several of these scales suggests that none are perfect. It is not yet entirely certain why an atheromatous plaque causes a stroke, apart from the degree of stenosis it produces. But work in the coronary arteries has demonstrated that features thought to be connected with an ‘unstable’ plaque (i.e. likely to cause symptoms) include a large necrotic core, a thin fibrous cap, and high macrophage density. Such plaques are liable to ulcerate and thrombose. Method: In a prospective study, patients with TlAs had carotid Doppler ultrasound (Acuson 128 × P10V, 7.5 MHz probe): the appearance of any atheroma was coded for necrosis (0 to + + + ), fibrous cap (thin or thick), surface contour (regular or irregular), ulceration (fissure, small or large) and haemorrhage on the surface or within the atheroma (no to + + +). Endarterectomy specimens from patients subsequently operated on were similarly coded, histologically.
0929-8266/97/$17.00 © 1997 Elsevier Science Ireland Ltd. All rights reserved. PII S 0 9 2 9 - 8 2 6 6 ( 9 7 ) 1 0 0 0 8 - 8