CT angiography to evaluate hemodynamic changes in popliteal artery aneurysms during flexion and extension of the knee joint.

ABSTRACT

AIM: The aim of this study was to find out which characteristics of an asymptomatic popliteal artery aneurysm (PAA) will increase the risk for acute thrombosis. METHODS: This was a single-center prospective study of consecutive patients with asymptomatic PAAs presenting from January 2010 to April 2012. Computed tomography angiography was used to perform measurements of the PAA during 0º extension and 90º flexion of the knee. After semi-automated segmentation of the popliteal artery (PA) lumen, a center lumen line (CLL) was automatically constructed. RESULTS: The study included 16 asymptomatic PAAs. Median lumen area of the PA was directly proximal and distal of the PAA 57 mm2 (IQR, 44-87 mm2) and 46 mm2 (IQR, 32-66 mm2) in extension vs. 51 mm2 (IQR, 38-73 mm2) and 38 mm2 (IQR, 30-62 mm2) during 90º flexion, respectively (P=0.007) and (P=0.03). The median of the greatest decrease in lumen area after flexion and extension of the knee was 36 mm (IQR, 28-48 mm) in PAAs≥30 mm compared with 11 mm (IQR, 4-18 mm) in PAAs<30 mm (P<0.05). The proximal angulation was a median 48° in extension (IQR, 27-61º) and 75° during flexion (IQR, 46-99º; P=0.02). Distal angulation was a median of 31° (IQR, 21-42º) after extension vs. 62° (IQR, 33-81º) during flexion (P=0.03). CONCLUSION: Knee bending in patients with PAAs will lead to a reduction in the lumen area of the PAA and a change in the degree of angulation of the PAA. A significant decrease in lumen area was seen in PAAs≥30 mm compared with PAAs<30 mm after flexion of the knee.