Steven Rogers a, b, Alison Phair a, Joao Carriera b, Christabel Olecha, Jonathan Ghosh b, Charles McCollum a
a Academic Surgery Unit, Division of Cardiovascular Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Wythenshawe Hospital, Southmoor Road, Wythenshawe, Manchester, UK, M23 9LT.
b Department of Vascular and Endovascular Surgery, Wythenshawe Hospital, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Southmoor Road, Manchester, UK, M23 9LT.
c Independent Vascular Services Ltd, Wythenshawe Hospital, Manchester University NHS Foundation Trust, Southmoor Road, Wythenshawe, Manchester, UK, M23 9LT.
A <2% risk of ipsilateral stroke/year in asymptomatic patients demonstrates that carotid stenosis severity is a poor predictor of stroke. We know that carotid plaques undergo outward remodelling to preserve luminal diameter, adding further evidence that plaques should be assessed in terms of vulnerability and not stenosis. This study has utilised a novel 3D tomographic ultrasound (tUS) system, with and without microbubble-contrast to establish the most accurate method for calculating Carotid Plaque Volume (CPV) non-invasively.
Pre-operatively, B-mode and CEUS scans were performed by an experienced Vascular Scientist. B-mode, CEUS and fused tUS scans were used to measure CPV by two observers using a standardised technique. The precise volume of the endarterectomised plaque was measured using immersion.
149 patients undergoing endarterectomy for >50%NASCET stenosis were recruited. Minimal bias was identified for intra-observer B-mode, CEUS and fused tUS scans, 0.09(0.23) [95%CI -0.36 to 0.53]cm3, 0.08(0.24) [95%CI -0.38 to 0.54]cm3 and 0.06(0.22) [95%CI -0.37 to 0.48]cm3. Minimal bias was identified for inter-observer B-mode, CEUS and Fused tUS scans; -0.05(0.26) [95%CI -0.53 to 0.43]cm3, -0.02(0.25) [95%CI -0.50 to 0.47]cm3 and -0.07(0.19) [95%CI -0.44 to 0.30]cm3. B-mode, CEUS and fused tUS methods had minimal bias when compared with endarterectomy volume; -0.13(0.23) [95%CI -0.59 to 0.32]cm3, – 0.01(0.20) [95%CI -0.41 to 0.39]cm3 and -0.08(0.20) [95%CI -0.46 to 0.31]cm3.
CPV can be accurately measured by tUS with excellent intra- and inter-observer agreement and minimal bias when compared to endarterectomy volume. The highest degree of precision was seen with CEUS and fused images but B-mode tUS scans have sufficient precision for Carotid screening.
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