SRS270 - Difficulty in assessing chronicity of arterial occlusions on CT imaging

Abstract Background Lower limb ischaemia can be caused by different pathophysiologies including atherosclerosis, thrombosis and neointimal hyperplasia. Successful treatment requires appropriate treatment strategy selection based on underlying pathophysiology and lesion chronicity. CT angiography (CTA) is the most commonly used imaging modality for assessing lower limb ischaemia. The aim of this study was to understand the limitations of CTA in arterial lesion characterisation. Methods Vascular surgeons and interventional radiologists retrospectively reviewed pre-operative CTAs of 50 patients admitted with lower limb ischaemia. This was done without and with key clinical information. A standardised protocol was used identify key imaging features. Clinicians characterised lesion pathophysiology and chronicity (acute, sub-acute, chronic) and proposed a treatment strategy accordingly. These were then compared to intra-operative findings, including guidewire escalation strategy, qualitative assessment of haptic feedback when crossing the lesion, and the eventual successful strategy employed. Results Acute and chronic lesions were the most accurately identified, matching both clinical information and intraoperative findings. However, sub-acute and acute-on-chronic cases were more challenging. CT images of patients who had previously undergone revascularisation, and had stents in place, were also challenging to interpret, even with clinical history. Conclusions CTA remains an important diagnostic tool but has limitations in the accurate assessment of lesion chronicity. Clinical history facilitates the interpretation of disease duration but can be difficult to illicit in emergent settings. Intra-operative findings such as guidewire passage resistance play an essential role in treatment strategy selection. Augmenting CTA with complementary imaging and sensing modalities may improve its utility in this setting.