Imaging description

Superficial femoral artery (SFA) occlusions may be missed in at least two scenarios at cross-sectional imaging. On standard abdominopelvic CT examinations, the SFAs are often only visualized on the last few slices obtained. In our experience, it is not uncommon for SFA occlusions to go unnoticed, particularly in patients with extensive atherosclerotic disease, given that they are an “edge of the film” finding and may not be included in the typical radiologist search pattern (Figure 85.1). The other scenario where SFA occlusions may be missed occurs with MRA examinations of the lower extremity. Symmetric bilateral occlusions may be difficult to appreciate on coronal maximum intensity projection (MIP) images of the lower extremities, given extensive collateral vascularity from the deep femoral arteries (Figures 85.2 and 85.3). In addition, SFA occlusions often begin at the origin of the vessel and continue for its entire length. In these cases, SFA occlusions must be recognized as the absence of a finding, i.e., the normal vessel, which can be challenging. The normal SFA should be recognized as a medially located vessel free from significant branches along its course through the thigh, unlike the deep femoral artery, which is located laterally and more posterior with numerous branches.

Importance

Occlusions of the SFA can be clinically important, potentially resulting in claudication symptoms, rest pain or, in extreme cases, tissue ischemia. SFA occlusions due to embolic phenomena are important to recognize as patients may require anti-coagulation or thrombectomy and additional imaging studies may be necessary to identify the source of the embolus.

Typical clinical scenario

SFA occlusions may be encountered incidentally in patients with extensive atherosclerotic disease or may be the primary finding in patients being evaluated for suspected peripheral arterial disease (PAD). The prevalence of PAD is approximately 12% in older adults.

Differential diagnosis

In patients with prior surgery for peripheral arterial disease, occlusions of grafts within the thigh may be mistaken for occlusion of the native vessel.