With recent advances, magnetic resonance imaging angiography (MRA) has sufficient spatial resolution to visualize 1 mm vessels without exposing patients to radiation or iodinated intravenous contrast used with computed tomography angiography.The purpose of the study was to analyze the accuracy of our new MRA protocol that images multiple donor sites in one exam.
24 patients were imaged with MRA from September 2008 to February 2009. Exclusion criteria were a metal foreign body, inability to receive gadolinium contrast, and inability to travel to the one radiological center using our MRA protocol. Patients were imaged in the prone position on a 1.5 T MR scanner from 3 cm above the umbilicus to the mid-thigh. Slice thickness was 3 mm with 1.5 mm overlap and 3D reconstruction was performed. The radiologist identified the location and course of all relatively large intramuscular (IM) perforating and septocutaneous (SC) vessels in the multiple donor sites. The radiologist calculated a predicted flap weight for the abdomen donor site based on a typical elliptical flap excision. The surgeon reviewed the MRA images and the radiologist report to preoperatively select a donor site and a vessel on which to design the flap in the office. Immediately after the operation, the surgeon completed a survey.
18 patients underwent 30 deep inferior epigastric artery perforator (DIEP) flaps, based on a single IM perforator in 23 flaps, two joining IM perforators in 5 flaps, and a SC vessel in 1 flap. 2 patients underwent 3 superior gluteal artery perforator (SGAP) flaps, based on an IM perforator in 2 flaps and a SC vessel one flap. 1 patient underwent 2 inferior gluteal flaps based on an IM inferior gluteal artery perforator (IGAP) in 1 flap, and a SC deep femoral artery in 1 flap. 1 patient underwent 1 lumbar artery perforator (LAP) flap based on a SC lumbar vessel. 1 patient underwent 1 transverse upper thigh (TUT) flap based on a SC medial circumflex femoral artery.
The predicted location of the vessels was accurate to within 0.5 cm. There were no false positives (i.e. large vessel identified on MRA that was not found intraoperatively) and no false negatives (i.e. large vessel found intraoperative that was not seen on MRA). The surgeon used the preoperatively selected vessel(s) to base the flap in all 37 flaps; however in 1 DIEP flap, a second perforator, which joined the originally selected perforator was also used. To capture the selected vessel, the surgeon preoperatively moved the design of the abdominal flap cephalad or caudal from the standard position in 13 of 18 patients (72%). The preoperatively selected vessel determined the location and design of all the non abdominal flaps. The predicted abdominal flap weight correlated with the actual flap weight on average within 43 grams. Beveling outside the skin flap design and harvest of inguinal lymph nodes in 2 flaps increased the actual flap weights.
MRA provides accurate information for the preoperative identification of the optimal perforator flap vessel, resulting in improved operative efficiency and flap design.