Normal Anatomy Figs 1

The abdominal aorta bifurcates at L4 level into the common iliac arteries. The common iliac artery bifurcates into internal iliac and external iliac arteries in front of the sacro-iliac joints at the level of L5/S1. The internal iliac artery travels inferiorly towards the sciatic foramen and divides into the anterior trunk (which supplies via numerous named arteries the pelvic viscera) and the posterior trunk (which supplies the muscles of the lateral pelvis). The external iliac artery becomes the common femoral artery where it crosses under the inguinal ligament, approximately half way between the anterior superior iliac spine and pubic tubercle. There are three branches of the external iliac artery, the superficial pudendal and superficial in ferior epigastric arteries which arise medially (rarely identified on moving table MRA), and the superficial circumflex epigastric artery which arises laterally, and which is usually identified on MRA especially in patients with PAOD as it forms one of the collateral pathways that typically enlarges in response to significant stenoses or occlusions of the iliac arteries. The common femoral artery, a short artery of 4-6 cms only, is the continuation of the external iliac artery but no identifiable anatomic landmark separates these structures on MRA. The common femoral artery divides into the profunda femoris artery, a medium sized artery arising from the lateral aspect and which typically gives 4 perforating muscular branches to the thigh in addition to the medial and lateral circumflex arteries, and the superficial femoral artery, the direct

Moving Table Mra

Fig. 2. Normal anatomy: Moving table CE-MRA of the lower extremity arteries gives adequate anatomic coverage of the relevant anatomy with three overlapping coronally oriented acquisitions. Note that different imaging volumes have been used for each of the three anatomic regions (demonstrated on lateral MIPs)

continuation of the CFA, which has no branches in the thigh. The SFA becomes the popliteal artery on passing through the adductor hiatus in the distal thigh, approximately at the junction of the upper two thirds and lower third of the femur. Upon entering the adductor canal the SFA gives rise to the medial and lateral genicular branches, which typically enlarge and form collateral channels in patients with severe stenosis or occlusion of the SFA.

Below the knee, the popliteal artery gives rise to the anterior tibial artery, usually the largest of the infrapopliteal arteries, and the peroneal (typically the smallest) and posterior tibial arteries, which arise from a common stem, the tibio-peroneal trunk. These arteries are collectively known as the "trifurcation" or "run-off" vessels.

The anatomy of the pedal arch and foot vessels will be described in the foot chapter.

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