Noncontrast Magnetic Resonance Imaging of Perforators for Preoperative Evaluation of Anterolateral Thigh Flaps

The anterolateral thigh (ALT) flap is a commonly utilized perforator-based flap in reconstructive surgery. Although previous studies have used various angiographic techniques to preoperatively image ALT perforators, none have investigated the efficacy of noncontrast magnetic resonance imaging (MRI). Our study investigates the efficacy of our institutional fat suppression noncontrast MRI sequence to characterize the number, location, and course of dominant skin perforators in the ALT for preoperative planning. METHODS: We queried our institutional database for 100 noncontrast thigh MRIs from July 2013 to July 2018 that included an axial fat suppression sequence with visualization from the lesser trochanter to the distal musculotendinous junction of the rectus femoris. Perforator course, size, and location relative to bony landmarks were determined. RESULTS: Of the 100 examinations, 70 included bilateral thighs for a total of 170 thighs for perforator analysis. An estimated 277 perforators were identified, of which 101 were septocutaneous (36.5%) and 176 were musculocutaneous (63.5%). An average of 1.63 perforators were visualized in each thigh (min, 1; max, 4). The average perforator diameter at exit from the anterior thigh compartment fascia was 2.5 mm (SD, 0.5). Perforator exit location along the anterior superior iliac spine- or lesser trochanter-patella line could be determined for n = 57 perforators and mapped into 3 predictable clusters. CONCLUSIONS: At least 1 perforator was found in each of 170 thighs imaged. Perforator course, size, and location measured with noncontrast MRI are consistent with prior literature. Noncontrast MRI is a low-morbidity imaging modality that may serve as an effective tool in preoperative planning of the ALT flap.