Dynamic Imaging is the Ideal Modality for the Diagnosis of Popliteal Artery Entrapment Syndrome

Abstract

Popliteal Artery Entrapment Syndrome (PAES) is a rare vascular condition with significant equipoise on how to properly diagnose and evaluate relevant imaging. This can lead to misdiagnosis and delay in surgical management. The objective of this study is to describe and compare distinct imaging features of dynamic versus static images to help determine the ideal imaging modality for diagnosis of PAES. This is a retrospective review of patients referred for PAES at a single institution. We reviewed non-invasive imaging studies, diagnostic arteriograms, and cross-sectional images which include computed tomography angiography (CTA) or magnetic resonance angiography (MRA). For each affected and unaffected extremity, the characteristic collaterals for PAES were named and measured on arteriogram using Picture Archiving and Communication Software (PACS). Available cross-sectional images were also analyzed and compared with arteriogram and intraoperative findings during surgical exploration. There were 23 patients referred for PAES who underwent diagnostic evaluation and surgical management between 2013 and 2022. All patients had a duplex ultrasound that revealed a mean popliteal peak-systolic velocity (PSV) of 78 cm/sec at rest. With forced plantar flexion, the PSV increased to a mean 175 cm/sec. A total of 12 extremities had complete loss of flow with provocation during duplex ultrasound. All patients underwent diagnostic angiography of 46 extremities. All limbs with PAES (n=35) exhibited complete popliteal artery occlusion during angiography with forced plantar flexion. Distinct angiographic findings on resting images included a well-developed medial sural artery in 100% of limbs with PAES with a mean diameter of 2.7 mm. In limbs without PAES, only 80% had a visualized medial sural artery on arteriogram with a mean diameter of 2.0 mm (p=0.1). A lateral sural artery was seen in 85% of affected extremities (mean diameter of 1.8 mm) while an anterior tibial recurrent artery was seen in 59% of affected extremities (mean diameter of 1.3 mm). In unaffected limbs, there were no visible lateral sural or anterior tibial recurrent arteries. The mean contrast used with diagnostic arteriograms was 58 milliliters (range 10-100 milliliters). Axial imaging was available for 9 affected extremities. Five had a previous MRA with only 1 being truly positive for arterial compression. Four extremities had previous CTA with 3 being falsely negative despite having type 3 PAES discovered during surgical exploration. Dynamic imaging with angiography provides immediate surgeon feedback by visualizing popliteal artery compression and enlarged sural collaterals during resting arteriography. The medial sural collateral is enlarged in patients with PAES and often the lateral sural and anterior tibial recurrent arteries can be visualized as well. CTA and MRA are associated with high false-negative rates and therefore cause delays in diagnosis and surgical management of PAES. Dynamic imaging should therefore be the gold standard for the diagnosis of PAES.