Anatomic Imaging of Gluteal Perforator Flaps without Ionizing Radiation: Seeing Is Believing with Magnetic Resonance Angiography Julie V. Vasile, M.D.,1 Tiffany Newman, M.D.,2 David G. Rusch, M.D.,4 David T. Greenspun, M.D.,5 Robert J. Allen, M.D.,1 Martin Prince, M.D.,3 and Joshua L. Levine, M.D.1 ABSTRACT Preoperative imaging is essential for abdominal perforator flap breast reconstruc- tion because it allows for preoperative perforator selection, resulting in improved operative efficiency and flap design. The benefits of visualizing the vasculature preoperatively also extend to gluteal artery perforator flaps. Initially, our practice used computed tomography angiography (CTA) to image the gluteal vessels. However, with advances in magnetic resonance imaging angiography (MRA), perforating vessels of 1-mm diameter can reliably be visualized without exposing patients to ionizing radiation or iodinated intravenous contrast. In our original MRA protocol to image abdominal flaps, we found the accuracy of MRA compared favorably with CTA. With our increased experience with MRA, we decided to use MRA to image gluteal flaps. Technical changes were made to the MRA protocol to improve image quality and extend the field of view. Using our new MRA protocol, we can image the vasculature of the buttock, abdomen, and upper thigh in one study. We have found that the spatial resolution of MRA is sufficient to accurately map gluteal perforating vessels, as well as provide information on vessel caliber and course. This article details our experience with preoperative imaging for gluteal perforator flap breast reconstruction. KEYWORDS: Gluteal artery perforator flap, superior gluteal artery perforator flap, inferior gluteal artery perforator flap, magnetic resonance imaging angiography, preoperative imaging The ability to dissect a perforating vessel of appearance and feel can be created from a patient’s own adequate caliber to provide blood flow to a flap of skin tissue while minimizing injury to the underlying muscle and subcutaneous fat without sacrificing the muscle has at the donor site. In contrast to implant breast recon- advanced breast reconstruction. Breasts with a natural struction, sensation can develop in the reconstructed 1Center for Microsurgical Breast Reconstruction; 2Weill Cornell J Reconstr Microsurg. Copyright # by Thieme Medical Publishers, Imaging at New York Presbyterian; 3Columbia and Cornell Univer- Inc., 333 Seventh Avenue, New York, NY 10001, USA. Tel: +1(212) sities, New York, New York; 4Drucker, Genuth, and Augenstein, P.C., 584-4662. Rockville, New York; 5Greenwich Hospital, Greenwich, Connecticut. Received: February 17, 2009. Accepted after revision: April 13, Address for correspondence and reprint requests: Julie Vasile, 2009. M.D., Center for Microsurgical Breast Reconstruction, 1776 Broad- DOI 10.1055/s-0029-1225535. ISSN 0743-684X. way, Suite 1200, New York, NY 10019 (e-mail: [email protected]). JOURNAL OF RECONSTRUCTIVE MICROSURGERY breast as nerves grow into the autologous tissue and/or traverse through the gluteus maximus and gluteus med- with direct coaptation of a sensory nerve in the perfo- ius muscles at varying angles and for varying distances. rator flap with a sensory nerve in the chest.1,2 The They can even course between or around the gluteal abdomen is our first choice of donor tissue for breast muscles (septocutaneous vessel).6 Superior gluteal artery reconstruction. However, gluteal flaps based on perfo- perforators generally course through the gluteal muscle rating vessels are an excellent alternative for patients at a more vertical angle than inferior gluteal artery with insufficient abdominal tissue, prior abdomino- perforators, which can make dissection shorter, but plasty, extensive abdominal liposuction, or failed ab- produces a shorter SGAP flap pedicle length (6 to dominal flaps. 8 cm). Inferior gluteal artery perforators traverse the Gluteal artery perforator (GAP) flaps are nour- gluteal muscle at a more oblique angle, producing a ished by arteries that perforate through the gluteal longer pedicle (8 to 10 cm), which can make the micro- muscles and are harvested with preservation of the surgical anastomosis and insetting of the flap easier.3,6 muscle and function.3–5 The superior gluteal artery exits The vascular branching pattern of a perforator through the pelvis superior to the piriformis muscle and its subcutaneous fat (arborization) also varies. branches perforate through the gluteus medius and The ability to preoperatively visualize gluteal gluteus maximus muscles. The inferior gluteal artery perforating vessels is especially advantageous because of exits the pelvis inferior to the piriformis muscle, and the high degree of vessel anatomic variability. Prior to its branches perforate through the gluteus maximus the era of preoperative perforator imaging, a surgeon had muscle.6 Superior gluteal artery perforator (SGAP) flaps little knowledge of an individual patient’s anatomy until harvest the superior buttock tissue. Inferior gluteal artery surgery was well underway. As a result, perforator perforator (IGAP) flaps harvest the inferior buttock selection could be a tedious decision process that oc- tissue. The in-the-crease IGAP flap is designed to curred in the operating room at the expense of operating remove the inferior buttock tissue ‘‘saddle bags’’ and time and general anesthetic requirement. Our favored hide most of the scar in the inferior gluteal crease.3 modality for GAP flap imaging has changed as technol- The decision to choose an SGAP or IGAP flap is based ogy has advanced. Initially, we only used a handheld on each individual patient’s preference and anatomy. Doppler ultrasound. A Doppler ultrasound is portable A patient’s preference toward an SGAP or IGAP and simple to use but cannot differentiate perforating flap is influenced by the trade-offs of each gluteal flap vessels from superficial and deep axial vessels, robust procedure. The scar from an SGAP flap can be covered perforators from miniscule ones, or accurately locate by a bathing suit, but the scar is prominent on the perforators that do not exit perpendicular from the buttock. In addition, harvesting an SGAP flap can fascia.8,9 Furthermore, Doppler ultrasound does not disturb the superior fullness of the buttock, which is provide any information about the anatomic course of considered the aesthetic unit of the buttock. The scar a vessel. from an IGAP flap is located in a less prominent area of In comparison, color Duplex sonography provides the buttock in the inferior gluteal crease or where the more detailed information about the anatomy of the shadow falls, but the lateral portion of the scar can be vessels. In addition, Duplex sonography can assess vessel visible in a bathing suit. Harvesting an IGAP flap caliber and hemodynamic flow. Unfortunately, color removes the ‘‘saddlebags,’’ commonly an area of abun- Duplex has some significant shortcomings. This method dant fat deposition in women. of preoperative vascular evaluation requires highly The highly variable anatomy of gluteal vessels can trained technicians with knowledge of perforator anat- be challenging when designing an SGAP or IGAP flap. omy and is time-consuming.9 The technique’s most Cadaveric dissection studies show that the number and crucial drawback is an inability to produce anatomic location of gluteal perforators from the superior gluteal images in a format that a surgeon can easily and artery and inferior gluteal artery vary greatly. The aver- independently view. As a result, we do not use this age number of relatively large perforators from the modality for imaging perforator flaps in our patients. superior gluteal artery is reported to be between three Increasingly, computed tomographic angiography to five (range, one to seven), and most of the perforators (CTA) is used to image perforator flaps because this are located in a zone extending along the superior two- technique can demonstrate vessel anatomy, assess vessel thirds of a line from the posterior superior iliac spine to caliber, accurately locate perforators, and produce ana- the greater trochanter.6,7 The average number of rela- tomic images in a format that a surgeon can easily and tively large perforators from the inferior gluteal artery is independently view. Although CTA can be performed eight (range, 4 to 12), and most of the perforators are quickly,8,9 patients must be exposed to ionizing radia- located in a zone extending along the middle third of the tion. Recent articles in the medical literature and lay lower buttock.6 press warn that physicians may be exposing patients to The varying course of perforators adds another excessive and potentially unnecessary radiation and ques- challenge to the difficulty of flap harvest. Perforators can tion the long-term effects of such exposure.10,11 Patients IMAGING OF GLUTEAL PERFORATOR FLAPS WITHOUT RADIATION/VASILE ET AL with breast cancer often have a heightened concern for of energy as hydrogen atoms return to their relaxed state. any factor that can potentially increase the risk of MRI coils detect the released energy, and computer developing a second cancer and may perceive the risks software processes the data into anatomic images. Ex- of radiation exposure even more negatively. A subset of posure to a magnetic field or radiofrequency pulse with our patients with breast cancer gene (BRCA) mutations, MRI has not been linked to the development of cancer.20 which confer an increased risk of developing both breast Furthermore, the risks of anaphylaxis and nephrotoxicity