The Future in Perforator Flap Imaging: A New Technique to Substantially Reduce Radiation Dose with Computed Tomographic Angiography

Sir: The use of preoperative imaging in perforator flap surgery has been a recent advance that has been shown to improve a range of operative outcome measures.1 In deep inferior epigastric artery perforator flap surgery, flap survival, donor-site morbidity, and length of operation have all been shown to be significantly reduced with the use of preoperative computed tomographic angiography. The use of computed tomographic angiography has thus been incorporated as routine in many centers internationally. Despite these clear benefits of its use, hesitation still exists toward its inherent association with ionizing radiation. Several techniques have recently been described in a move to minimize this radiation exposure. Changes in scanning protocols have achieved substantial dose reduction, with initial scanning techniques using scanning protocols similar to computed tomographic angiography of the abdomen for intraabdominal abnormalities, with calculated radiation doses of up to 10 mSv being received.2 By modifying the protocols specifically for flap planning, the radiation dose of computed tomographic angiography was able to be reduced by 40 percent to 6 mSv.3 To eliminate this exposure completely, the use of magnetic resonance angiography has been investigated; however, descriptions of its use do not yet match those of computed tomographic angiography, and certainly no outcome studies have been reported.4,5 Given that computed tomographic angiography is thus still considered the standard means of preoperative imaging, we describe a recent advance in computed tomographic angiography thus substantially reduces the radiation exposure with its use. Although the use of multidetector row computed tomography scanners has been a great advance in imaging technologies, all previously reported scanners used for perforator imaging have required movement of the computed tomography scanning table to achieve the multiple slices that the computed tomographic scanner acquires (four-slice, 16-slice, and 64-slice multidetector rows). This movement involves some time delay. The capture of multiple slices with these scanners also requires some overlap between adjacent slices. A new advance in computed tomography hardware is the 320-slice multidetector row computed tomographic angiography scanner. This scanner enables 320 data sets to be acquired simultaneously in a single-image “volume” capture, eliminating the need for table movement or multiple slices. These both serve to substantially reduce radiation exposure to the patient. In our experience with the 320 multidetector row computed tomography scanner (Aquilion One; Toshiba America Medical Systems, Tustin, Calif.), we have been able to achieve perforator imaging of the same resolution and quality as previously reported, and with axial slices of 0.5 mm (compared with 0.63 mm with 64-slice scanners), the resolution of three-dimensional reconstructions may in fact be enhanced (Fig. 1). In performing this new technique of “single-volume acquisition” scanning, the radiation dose is substantially reduced to 1.78 mSV. This is equivalent to the radiation dose of approximately three plain abdominal radiographs.2Fig. 1.: (Above) Preoperative computed tomographic angiography, volume-rendered reconstruction of the abdominal wall vasculature, using a 320-slice multidetector row computed tomography scanner (Aquilion One, Toshiba, Calif.), highlighting a single, large, 1.5-mm perforator (blue arrow). (Center) Grid based at the umbilicus applied for localization. (Below) Maximum intensity projection view of perforators relative to the deep inferior epigastric arteries.Since the first reports of computed tomographic angiography for perforator imaging only 3 years ago, there has been a revolution in advanced imaging technologies for perforator flap imaging. With ongoing research, these techniques have continued to become safer and provide growing levels of anatomical detail. Through increasing patient accessibility to imaging technologies, ongoing validation of the benefits from the use of these tools will be increasingly available. DISCLOSURE The authors have no financial interest to declare in relation to the content of this article. Warren M. Rozen, M.B.B.S., B.Med.Sc., Ph.D. Daniel Chubb, M.B.B.S., B.Med.Sc. Jack Brockhoff Reconstructive Plastic Surgery Research Unit University of Melbourne Parkville, Victoria, Australia Marcus Crossett, Ba.App.Ph. Monash Heart Department of Radiology Monash Medical Center Clayton, Victoria, Australia Mark W. Ashton, M.B.B.S., M.D. Jack Brockhoff Reconstructive Plastic Surgery Research Unit University of Melbourne Parkville, Victoria, Australia