Steven Rogers ^{a, b}, Joao Carreira ^b, Alison Phair ^a, Christabel Olech ^a, Jonathan Ghosh ^c, 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 Independent Vascular Services Ltd, Wythenshawe Hospital, Manchester University NHS Foundation Trust, Southmoor Road, Wythenshawe, Manchester, UK, M23 9LT.

^c Department of Vascular and Endovascular Surgery, Wythenshawe Hospital, Manchester University NHS Foundation Trust, Manchester Academic Health Science Centre, Southmoor Road, Manchester, UK, M23 9LT.

Background

Clear imaging of below-knee and foot arteries is essential to plan distal reconstructions. Contrast-enhanced tomographic ultrasound (CEtUS) is novel and entirely safe with no exposure to ionising radiation or nephrotoxic contrast. We compared below knee CEtUS with angiography.

Methods

In the same week as CT, MR or catheter angiography, CEtUS was performed using intravenous 1.2mL bolus injections of Sonovue with a maximum of 5mL administered/patient. CEtUS was reported by a Vascular Scientist blinded to the angiograms reported by a Consultant Radiologist. We compared images using a modified Society of Vascular Surgery (SVS) run-off score.

Results

We recruited 181 PAD patients where 20 were excluded from analysis. In the remaining 161 patients there were 175 comparative patient images split into two groups. 81 had calf imaging and 94 had pedal imaging representing, 405 and 198 imaged arteries respectively. Weighted quadratic Kappa/ICC values for intra- and inter-observer agreement were excellent (k/ICC=0.83 to 0.95) and had narrow confidence intervals indicating precision, in both groups. When comparing angiography and CEtUS, weighted quadratic Kappa/ICC agreement was moderate with acceptable confidence intervals in both groups ([Calf k/ICC=0.54], [Pedal k/ICC=0.53). Agreement decreased from Popliteal to pedal vessels as diameter decreased. Agreement between CEtUS and DSA was best and CTA the weakest.

Conclusions

CEtUS is a novel imaging modality with strong observer agreement that achieves clear peripheral and foot images without ionising radiation exposure or nephrotoxic X-ray contrast media. CEtUS enhances visualisation of run-off vessels which may play a role in planning of limb salvage or targeted assessment.

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