The observation of below-the-knee artery by optical frequency domain image and angioscopy: a case series.

All patients had multiple risk factors for atherosclerosis and stenosis/occlusion of the SFA and ipsilateral BTK arteries. Furthermore, some patients had several other atherosclerotic vascular diseases suggesting the presence of advanced systemic atherosclerosis. On the other hand, some patients with multiple BTK artery stenosis/occlusion did not have advanced atherosclerosis in the examined BTK artery. The absence of significant atherosclerosis in a BTK artery in patients with multiple stenoses or occlusion in other ipsilateral BTK arteries may suggest some mechanism of vessel occlusion other than atherosclerosis. Further investigations are needed to clarify the mechanism.