Fat embolism in the popliteal vein detected on CT: Case report and review of the literature

Abstract

Fat emboli are a common phenomenon, but are rarely detected or reported on extremity CT imaging. We present a case of fat embolus in the popliteal vein in the setting of a femoral fracture. This is the most distal fat embolus described in the literature. There are no guidelines regarding intervention if a fat embolus is detected in a peripheral vein on CT. A review of all the previous cases of peripheral fat emboli is presented for reference.

Keywords: CT; Fat embolism; Fracture; IVC filter; Trauma.

Fig. 1

Three-dimensional volume-rendered reconstruction of CT showing comminuted and displaced intra-articular distal femoral fracture from a posterior view. Traction pin is present in the tibia.

Fig. 2

Axial CT image at the level of the proximal tibia and fibula. Macroscopic fat within the popliteal vein compatible with fat embolus (straight arrow). Other than small foci of peripheral atherosclerotic calcification, the adjacent popliteal artery (lateral to the vein at this level) appears normal on this non-contrast CT (curved arrow).

Fig. 3

Sagittal CT image. Fat embolus within the popliteal vein (straight arrow), posterior to the level of the proximal tibia. Compression of the popliteal vein by a posteriorly displaced femoral fracture fragment, above the level of the embolus (curved arrow). Gas within the femoral fracture and knee joint (*).

Fig. 4

Axial CT image at the level of the distal femur. Severe compression of the popliteal vein by a posteriorly displaced femoral fracture fragment, with the popliteal vein assuming a linear slit-like appearance (straight arrow). Adjacent popliteal artery (medial to the vein at this level) is patent and round (curved arrow). Gas within the femoral fracture compatible with open fracture (*). Small lipoma in the semimembranosus muscle (arrowhead). Hemorrhage within the suprapatellar knee joint is partially imaged.

Fig. 5

(A) Ultrasound image of the right popliteal vein demonstrates a patent vein without evidence of thrombosis or intraluminal fat. (B) Corresponding Doppler image of the right popliteal vein demonstrates normal blood flow.