Perforator flaps are preferable for breast reconstruction after mastectomy in many patients. Preoperative imaging of the perforators and source vessels is desirable to reduce surgeon stress, limit donor and recipient site complications, and minimize operative time and associated costs. Computed tomographic angiography (CTA) has been shown to provide highly accurate representations of vascular anatomy with excellent spatial resolution. A critical review of the currently available literature was performed to identify the benefits of preoperative imaging (specifically CTA) in perforator flap reconstruction.
The benefits of autologous breast reconstruction are well established, particularly in individuals who have failed implant-based reconstruction or require adjuvant radiation. Multiple donor sites are available, providing an abundance of soft tissue similar in texture to the original breast. A natural breast contour can be achieved while avoiding future problems associated with prosthetic, implant-based techniques, such as capsular contracture, implant malposition, or implant rupture. The description of the pedicled transverse rectus abdominis musculocutaneous (TRAM) flap by Hartrampf and colleagues revolutionized breast reconstruction, allowing for total autologous reconstruction with vascularized soft tissue in a single stage. The lower abdomen has since become the preferred donor site for breast reconstruction for surgeons performing autologous procedures. A growing body of literature detailing the anatomy of the integument of the anterior abdominal wall and its underlying source vessels has led to refinements in operative techniques designed to maximize the reconstructive result while minimizing donor site morbidity.
Perforator flaps
In 1967, Fujino reported that the contribution of perforators to the interstitial fluid turnover in axial flaps is approximately equal to the contribution made by the axial artery itself. Twenty years later, Taylor and Palmer performed an anatomic study of human angiosomes and found an average of 374 musculocutaneous and septocutaneous perforators larger than 0.5 mm throughout the body. The perforator flap concept was introduced by Kroll and Rosenfield in 1988, and 1 year later Koshima and Soeda reported 2 abdominal perforator-based flaps to reconstruct a groin and tongue defect, coining the term perforator flap. The deep inferior epigastric artery perforator (DIEP) flap has since gained widespread acceptance as one of the ideal methods of breast reconstruction after its introduction by Allen in 1994. The superficial inferior epigastric artery (SIEA) flap represents the least invasive means of transferring the lower abdominal skin and fat, requiring no dissection within the muscle or fascia. However, the SIEA may not be available in many cases, is not as reliable across the midline, and may have a higher incidence of arterial thrombosis.
The major disadvantage of these flaps is that they can be difficult to harvest. Furthermore, although refinements in the technique have led to improvements in donor site morbidity, there seems to be an inverse relationship between donor site morbidity and flap-specific complications related to flap perfusion. In other words, although donor site morbidity is reduced to a minimum, flap reliability and perfusion can be adversely affected to some degree. In a study of 179 patients, Wu and colleagues demonstrated that the patients perceived a reduced duration of postoperative pain and had improved postoperative abdominal strength when undergoing less-invasive procedures (muscle-sparing TRAM [MS-TRAM] vs DIEP vs SIEA). In this study, DIEP flaps were statistically similar to SIEA flaps. In a meta-analysis of free TRAM and DIEP flaps, Man and colleagues identified a 2-fold increase in the risk of fat necrosis (relative risk [RR], 1.94, confidence interval [CI], 1.28, 2.93) and flap loss (RR, 2.05, CI, 1.16, 3.61) in DIEP flaps compared with free TRAM flaps, whereas the risk of an abdominal bulge or hernia was approximately half (RR, 0.49, CI, 0.28, 0.86). There was no difference in the risk of fat necrosis when the analysis was limited to studies using muscle-sparing free TRAM flaps (RR, 0.91, CI, 0.47, 1.78). Nahabedian and colleagues studied 163 flaps in 135 patients (143 free TRAM and 20 DIEP flaps). In free TRAM flaps, the incidence of postoperative reexploration was 7.7%. Total necrosis occurred in 5 flaps (3.5%), fat necrosis was observed in 14 flaps (9.8%), an abdominal bulge developed in 8 women (6.8%), and no partial necrosis was seen. In the DIEP group, 3 flaps were reexplored (15%), total necrosis occurred in 1 flap (5%), fat necrosis developed in 2 flaps (10%), and no abdominal bulges were encountered.
Selection of flap
The selection of flap type and design should be made based on patient weight, the amount of abdominal fat available, and breast volume requirements. In addition, the number, caliber, and location of the perforating vessels should be considered. Perforator size, location, intramuscular and subcutaneous course, and association with motor nerves are significant factors that can influence operative technique, length of operation, and operative outcomes. The learning curve for this procedure can be relatively steep. Man and colleagues state that “the most important part of that learning curve has not been the technical component of these procedures but rather the development of intraoperative decision making in choosing the appropriate technique in a given patient. The critical element of that decision is predicting high flap reliability based on anatomic findings, simultaneously limiting the potential for abdominal wall complications. Inherent in this decision is the cumulative experience of each surgeon.” Kroll’s series demonstrated an incidence of partial flap loss of 37.5% and of fat necrosis of 62.5% in the first 8 patients, which improved to 8.7% and 17.4%, respectively, when modified selection criteria were used.
The art of this surgical procedure centers on the determination of the perforators that maximally perfuse the transferred flap while minimizing neuromuscular damage to the rectus abdominis muscle. This determination can be difficult considering the variability in the anatomy of the anterior abdominal wall vasculature. The number, location, and course of DIEPs are highly variable among patients as well as between the individual sides of the abdomen. Proponents of the use of lateral row perforators highlight the shorter intramuscular course of these perforators, thereby facilitating shorter operative times and ease of dissection. In angiographic cadaveric studies, however, lateral row perforators have vascular territories similar to that of SIEA flaps, namely, those confined to one side of the abdomen without crossing the midline. Medial perforators have been demonstrated to supply a larger vascular territory compared with lateral perforators (296 cm 2 vs 196 cm 2 ) in an angiographic study and are much more likely to perfuse across the midline, at times even into zone IV. These considerations are important regarding volume requirements and perforator selection in unilateral cases.
The relationship of the deep inferior epigastric perforators and the motor nerves to the rectus abdominis muscle as well as the transverse distance traversed by the perforators used in the flap are also crucial to this procedure. The motor nerves to the rectus abdominis muscle enter into a nerve plexus running with the lateralmost branch of the deep inferior epigastric artery (DIEA), placing the nerves at risk when a lateral perforator is chosen. The medial branches, on the other hand, are devoid of these nerve branches. The DIEA branching pattern is closely correlated with the course of the perforators. A bifurcating (type II) branching pattern of the DIEA has a reduced transverse distance crossed by each perforator through the rectus abdominis muscle compared with a trifurcating (type III) branching pattern (mean, 1.4 cm vs 1.73 cm, respectively). Type I vessels are intermediate in the transverse distance each perforator travels compared with type II and III branching patterns. Another study indicates that the average perforator traverses the muscle at a distance of 1.32 cm in width, thereby requiring a sacrifice of at least that width of muscle to harvest the flap. A perforator with a long intramuscular course (>4 cm) lengthens the time for operative dissection substantially, particularly when the intramuscular course occurs in a stepwise fashion. All these factors should be considered when harvesting a DIEP flap. The largest perforators with the least sacrifice to the neuromuscular anatomy of the rectus abdominis muscle should be chosen.
As experience has been gained in these procedures, the importance of determining an individual’s unique anatomy has become paramount. Preoperative imaging to facilitate flap harvest and determining the proposed operative plan are therefore important to expedite the procedure, reduce complications, and ease decision making, thereby decreasing surgeon stress related to the procedure. Imaging techniques can help avoid catastrophic complications caused by congenital absence or iatrogenic ligation of the deep inferior epigastric source vessels, a condition being encountered more frequently, or aberrant communication of perforators with abnormal underlying source vessels. The authors have encountered both of these conditions intraoperatively as well as on preoperative imaging studies ( Fig. 1 ). Imaging techniques can also determine the feasibility of the procedure after previous abdominal operations, particularly after abdominal suction–assisted lipectomy or abdominoplasty (Krochmal DJ, Rebecca AM, Kalkbrenner KA, et al. Deep inferior epigastric perforator (DIEP) flap breast reconstruction after abdominal suction-assisted lipectomy, submitted for publication).
Doppler Ultrasonography
Acoustic Doppler sonography has been used for a considerable period of time to facilitate flap harvest and to aid in preoperative flap planning. The advantages include the technique’s simplicity of use, ready availability, and high sensitivity. However, this technique provides very little anatomic detail. In a study of 38 abdominally based free flaps (32 DIEP and 6 MS-TRAM flaps), Giunta and colleagues reported a low false-negative rate for preoperative localization of perforators with a hand-held Doppler (14 of 127; 11%); however, the false-positive results were very high (127 perforators identified intraoperatively of the 219 marked with Doppler preoperatively; false-positive rate 42%). Doppler ultrasonography is thought to be sufficient to demonstrate an overall view of the distribution of the individual perforating vessels, and this speeds the surgical dissection and eases the intraoperative localization of the vessels.
Multidetector row computed tomography (MDCT) and computed tomographic angiography (CTA) have revolutionized anatomic imaging throughout the body. MDCT allows for rapid acquisition of a large volume of information that can be used to construct multidimensional images of small vessels. CTA has been used effectively to map the vasculature in many anatomic regions of the body, including the head and lower limbs. The images obtained provide accurate and detailed representations of the source vessels, the perforators and associated side branches, their relationship to the muscle and fascia, and their subcutaneous branching pattern ( Fig. 2 ). MDCT is touted as being significantly more accurate in localizing the site of musculocutaneous and septocutaneous perforators compared with Doppler ultrasonography. In a study of 5 adult men, Imai and colleagues detected 83 perforators originating from the deep inferior epigastric system using MDCT. Of these, only 35 perforators were identified using Doppler ultrasonography. MDCT was able to precisely localize the site of fascial penetration of the perforator, whereas Doppler ultrasonography was less accurate, with the location marked with Doppler found at an average of 7.6 mm away from the actual site based on MDCT images (range, 0–22.5 mm). In a study of 8 patients undergoing DIEP flap surgery, Rozen and colleagues compared the abilities of CTA and Doppler ultrasonography to localize and characterize the proposed perforators to use in the flap design. CTA was highly specific (100%) and more sensitive in mapping and visualizing perforators ( P = .0078). CTA was good at identifying the SIEA system, effectively demonstrated major branches of the DIEA and perforators, and was useful in providing the images intraoperatively if needed, whereas Doppler was not. CTA was thought to be quicker to perform (15 minutes vs up to 2 hours) and removed interobserver error associated with Doppler ultrasonography. Because the clinical dissection of perforators often proved to be discordant from unidirectional Doppler flowmetry findings, Vandevoort and colleagues did not use this technique for preoperative mapping of the perforators.
Duplex Ultrasonography
Duplex ultrasonography is thought to be superior to hand-held acoustic Doppler sonography in the mapping of perforator vessels. This technique combines gray-scale ultrasonography to visualize the architecture of the body part as well as color Doppler ultrasonography to estimate blood flow velocities within the vessels. This combination can assist the surgeon in locating the surface location of the proposed perforator via a simple noninvasive modality that does not require ionizing radiation or contrast material. Blondeel and colleagues report a positive predictive value of almost 100% and true positive rate with the use of duplex ultrasonography in the planning of perforator flaps. However, this study does not comment on the rate of false-negative results. Duplex ultrasonography has the disadvantage of requiring skilled technicians to complete and interpret the study, and the images are not available to the operating surgeon at the time of the procedure. CTA, on the other hand, can be read by the surgeon and provides images that can be referenced at the time of surgery ( Fig. 3 ). Duplex ultrasonography also tends to have poor test-retest reliability. Other concerns pertain to the technique’s inability to accurately study the branching pattern of the DIEA system, poor identification of major branches associated with the perforators, and poor visualization of the SIEA system.
Scott and colleagues prospectively studied 30 flaps (4 MS-TRAM, 18 DIEP, and 8 SIEA flaps) in 22 patients. All patients underwent preoperative imaging with both CTA and duplex ultrasonography. The two largest perforators visualized with each study were chosen on both sides of the abdomen and compared based on intraoperative findings. CTA identified 83 perforators. Only 55 (66%) were demonstrated via duplex ultrasonography. Eight SIEA flaps were transferred during the study, all of which were visible with preoperative CTA. No superficial inferior epigastric systems were identified preoperatively with duplex ultrasonography. Based on the superior anatomic detail provided by CTA, the ability to characterize the SIEA system, and the significant number of clinically important perforators missed with duplex ultrasonography, the investigators conclude that CTA is a more-valuable resource for the preoperative planning of perforator flaps.
MDCT/CTA
In 2006, Masia and colleagues introduced the use of MDCT for the preoperative planning of DIEP flaps. In a prospective study by Rozen and colleagues, CTA was found to be highly accurate in identifying and mapping the perforators of the DIEA system. A total of 279 perforators were accurately recorded with only 1 false-positive and 1 false-negative, producing a sensitivity of 99.6% and a positive predictive value of 99.6%. All the perforators used in the flap harvest had been identified preoperatively via CTA imaging. In this study, there were no partial or total flap losses, there was no reported donor site morbidity, and there was a fat necrosis rate of 7%. MDCT/CTA provides extraordinarily high resolution, enabling the demonstration of perforators as small as 0.3 mm. This high resolution is important in not only identifying the perforator itself and its communication with the underlying source vessel but also outlining its branching pattern and the linking vessels that allow communication with adjacent vascular territories to maximize the perfusion of the flap. This identification and outlining becomes critical when designing the adipocutaneous flap island to minimize fat necrosis and partial flap loss. Ohjimi and colleagues critically studied the vascular architecture of deep inferior epigastric–based oblique free flaps radiographically. An average of 2.1 large deep inferior epigastric perforators was included in each of 11 flaps. In 9 of the 11 flaps, the axial artery was visible. Three flaps developed partial necrosis. In 2 flaps, no axial vessels were visible, and in the third, only 1-sided distribution of the axial vessel was noted. This information further supports the idea that preoperative identification of not only the perforator itself but also its associated area of perfusion is important, which can now be defined preoperatively.
Alonso-Burgos and colleagues suggested the benefits of preoperative CTA in the planning and execution of DIEP flap reconstruction early in the history of its use. In 2006, the investigators reported their experience in 6 patients. Accurate identification of the main perforators was achieved in all cases with very satisfactory concordance between CTA and the surgical findings. No unreported vessels were found. The investigators were also pleased with the characterization of the SIEA system and the fine detail provided even in the case of very small perforators. They stated that preoperative localization of adequate vessels would make the procedure easier and would decrease morbidity by preventing unnecessary perforator dissections and therefore allow the flap harvest to proceed in a faster and safer way. However, surgical outcomes and operative time were not formally studied.
To adopt CTA for routine use in perforator flap planning, its benefits must outweigh its disadvantages and risks. CTA requires the infusion of intravenous contrast. As such, those with contrast or iodine allergies or those with renal impairment have contraindications for the use of CTA. CTA also exposes the patient to ionizing radiation. Recent literature cautions against the rising number of computed tomography (CT) scans performed because of the associated radiation exposure. With the use of MDCT, the effective dose of radiation is relatively low. This dose has been reported to be between 4.8 and 6 mSv, which is less than that of a conventional abdominal CT scan. The cost can also be prohibitive and ranges from ¥1000 (approximately $150) to £350 (approximately $556) to $1734 (United States in 2008) for combined hospital and professional charges. The estimated savings due to reduced operative times alone has been quoted as £1750 (approximately $2779) by expediting flap harvest times based on the information that CTA provides. Uppal and colleagues reported a mean reduction in the operative time of 76 minutes for unilateral DIEP flap transfer using CTA compared with duplex ultrasonography. Although the cost of the CTA was £176 (approximately $275), the 21% reduction in operative time resulted in a savings of £471 (approximately $732) from anesthesia and facility costs alone. The investigators then made reference to a study by Jenkins and Baker, pointing out that prolonged operative time can increase postoperative recovery and may increase complications such as atelectasis and deep vein thrombosis. Reduction in operative time for these intricate procedures may minimize the risk of these complications. It is for these reasons that detailed outcome studies are important to validate the use of CTA in the planning of perforator flaps.
MDCT/CTA Operative Time
One of the primary advantages of using CTA in the preoperative planning of perforator flaps centers around shortening the learning curve for the procedure and reducing operative time to harvest and transfer the flap. CTA may flatten the learning curve and shorten the time to proficiency for less-experienced surgeons. This may limit flap-specific complications (partial/complete flap loss, fat necrosis, or anastomotic complications) and donor site complications (abdominal bulges, hernias, abdominal weakness, or abdominal wounds) early in a surgeon’s experience with perforator flaps. Reducing operative time directly reduces the cost of the procedure by decreasing anesthesia and facility costs. Reducing flap-specific and donor site complications can also reduce costs by reducing hospital length of stay, secondary procedures, and the supplies required to address a complication.
Casey and colleagues demonstrated a reduction in operative time in unilateral DIEP flap transfer from 459 minutes to 370 minutes following the routine use of CTA compared with hand-held Doppler interrogation alone. In bilateral cases, operative times were reduced from 657 minutes to 515 minutes. The decreased operative time in this retrospectively designed study was thought to be because of a more-directed dissection to the dominant perforator with the most direct intramuscular course as compared with a blind exploration of the anterior abdominal wall when a hand-held Doppler was used alone. A correlation between surgeon experience and operative time was also performed in this study. With the use of CTA, the surgeon with the least experience was quickly able to match the operative times of the most senior surgeon with similar overall flap and donor site complication rates. This information supports the benefits of CTA in shortening the learning curve for DIEP flap reconstruction.
Uppal and colleagues prospectively studied 26 patients scheduled to undergo perforator flap breast reconstruction (unilateral/bilateral DIEP, superior gluteal artery perforator [SGAP] flaps). Mean operative times for unilateral DIEP, bilateral DIEP, and SGAP flap reconstruction were 4 hours and 49 minutes, 7 hours and 23 minutes, and 4 hours and 56 minutes, respectively. Compared with 15 unilateral DIEP duplex controls, operative time was shorter by 1 hour and 16 minutes (21% reduction) in the CTA group. Minqiang and colleagues specifically studied the time required to harvest a DIEP flap. Between December 2006 and May 2008, 22 consecutive patients who underwent CTA before DIEP breast reconstruction were compared with 22 previous patients who did not undergo CTA. The time required to harvest a DIEP flap was 2.8 ± 0.2 hours in the CTA group compared with 4.4 ± 0.2 hours in the control group (no CTA).
Smit and colleagues performed a chart review of 138 DIEP breast reconstructions. Of these, 70 were performed after preoperative CTA and were compared with 68 flap reconstructions that were performed the previous year using Doppler examination alone. Operative time in the CTA group was 264 minutes compared with 354 minutes in the Doppler control group. Rozen and colleagues prospectively studied 40 patients who underwent breast reconstruction after CTA between March 2006 and November 2007. These patients were compared with 48 patients who had previously undergone breast reconstruction without CTA. CTA resulted in a reduction in operative time by 77 minutes and was noted to be even more beneficial in bilateral cases. This study also included a psychometric assessment of operative stress for the operating surgeon during perforator dissection with and without the use of CTA. A statistically significant reduction of 41% in the mean stress level experienced by the operating surgeon was encountered with the use of CTA. Masia and colleagues reported on 90 patients and found an average operating time savings of 1 hour and 40 minutes when CTA was used preoperatively. In a follow-up study, Masia and colleagues confirmed these findings in 357 patients, showing a significant decrease in the time needed for DIEP flap harvest from 3 hours and 20 minutes to 1 hour and 40 minutes.
Flap-related Complications
CTA has the theoretical advantage of being able to preoperatively localize the dominant perforators based on their relative size and branching patterns that adequately supply a flap. This ability is particularly important in unilateral cases. In bilateral cases, the perforators can be approached both laterally as well as medially once the 2 sides of the abdominal skin is divided in the midline. In unilateral cases, however, it can be difficult to visualize medial row perforators without sacrificing their lateral counterparts. Without this information preoperatively, a truly dominant lateral perforator may be sacrificed to visualize what are later found to be less-suitable medial row vessels. In a collective experience of 600 flaps over a span of 12 months, Massey and colleagues report a total flap failure rate of 1%. These excellent results highlight that CTA is unlikely to result in a significant improvement in the rate of total flap loss. This technique is likely to have more of an effect on the rate of fat necrosis and partial flap loss by maximizing the perfusion of the distal segments of the flap by designing the flap around the best perforasome.
Rozen and colleagues evaluated 75 patients prospectively to highlight the utility of CTA. In this series, there was a flap survival of 100% with no partial or complete flap losses. In 3 cases, CTA dictated whether an operation was appropriate at all. Seven unique cases were presented to demonstrate the importance of CTA, which included cases in which previous surgery altered or disrupted the vascular anatomy; cases in which small perforators were seen, therefore dictating that an MS-TRAM should be performed; a case in which a DIEP flap could be harvested despite a ventral hernia; and cases in which CTA identified comorbid conditions that influenced the decision to proceed. In 15 cases (20%), the expected operation was directly changed because of the imaging results. Minqiang and colleagues experienced an incidence of 22.7% of preoperative flap redesign based on CTA findings. The intraoperative plan remained the same in all patients in the CTA group, whereas the intraoperative plan changed in 13.6% in those who did not have a preoperative CTA. There was 1 case of partial flap loss in the CTA group, and 1 complete loss and 2 partial flap losses in the control group.
In a study of 287 DIEP flap breast reconstructions, Casey and colleagues reported a fat necrosis rate of 10.9% in procedures performed after CTA. Although this rate was better than the 13.4% experienced in cases performed with Doppler examination alone, this did not reach statistical significance. The incidence of anastomotic complications and total flap loss was also similar between the CTA and Doppler groups (6.9% vs 8.1% and 2% vs 3.8%, respectively). Uppal and colleagues evaluated 17 unilateral and 12 bilateral DIEP flap reconstructions after CTA. Fat necrosis was noted in 1 bilateral case and in none of the unilateral cases. Only 1 postoperative reexploration was necessary in 1 of the bilateral cases. Smit and colleagues identified fewer complications in a CTA group compared with the non-CTA control group (20% vs 25%). The CTA group had 6 infections, 4 hematomas, 2 superficial necroses, 2 seromas, and 2 anastomotic complications. The control group included 6 infections, 4 hematomas, 6 superficial necroses, and 6 anastomotic complications. All flap reconstructions were successful in the CTA group, whereas 1 flap reconstruction failed and partial necrosis occurred in 3 flaps in the control group.
In a study by Rozen and colleagues of 40 patients following CTA and 48 prior patients without CTA, no partial flap losses were encountered in the CTA group, whereas 5 occurred in the control group. Fat necrosis was also less common in the CTA group (3/40, 7.5% vs 8/48, 16.7%). No complete flap losses occurred in either group. In the largest study to date, Masia prospectively evaluated 357 patients scheduled for DIEP flap breast reconstruction. Total flap loss was reduced from 4% to 1% after the introduction of CTA. In addition, partial flap loss greater than 20% and partial flap loss less than 20% were reduced from 6% to 2% and 6% to 0%, respectively.
Donor Site Complications
Another advantage of CTA lies in its ability to identify a suitable perforator with an intramuscular course, which on harvesting minimizes the neuromuscular damage to the rectus abdominis muscle. Finding a dominant medial row perforator with a paramuscular or paraneural anatomic course can be ideal, allowing for a more simplified harvest and minimal trauma to the rectus abdominis muscle. This was found to occur in 11% of cases in the largest series of DIEP flap reconstructions after CTA to date. If this anatomic configuration does not exist, then CTA can demonstrate a perforator with the shortest transverse intramuscular course with the fewest associated side branches. By limiting the division of rectus muscle fibers and preserving the motor nerves, complications such as bulges, hernias, and abdominal weakness can be minimized. CTA can potentially increase a surgeon’s comfort in the inclusion of less perforators in the flap design, thereby limiting the division of intervening muscle fibers between neighboring vessels.
Casey and colleagues demonstrated a significant reduction in the number of incorporated perforators in DIEP flap design after the introduction of preoperative CTA perforator mapping. The incidence of postoperative abdominal bulges dropped precipitously once a CTA protocol was instituted. Using hand-held Doppler alone, the rate of abdominal bulges after DIEP flap transfer was 9.1%. After CTA, this rate dropped to 1% with similar abdominal closure techniques. When the analysis was limited to a single surgeon, the incidence of postoperative abdominal wound complications was also significantly reduced in the CTA group compared with the group that used hand-held Doppler only (3/41, 7% vs 12/41, 29%, respectively). In Rozen and colleagues’ prospective study of 104 DIEP flaps in 88 patients (40 with CTA, 48 without CTA), a significant reduction in donor site morbidity was encountered in the CTA group (0/40, 0% vs 7/48, 14.6%). Abdominal bulges were reduced from 2.1% to 0%, and abdominal hernias dropped from 12.5% to 0%.
Future Modalities
CTA has become an invaluable tool in the preoperative planning of perforator flaps. At present, 7 of 10 investigators in a large series recently published use some form of preoperative imaging routinely for every case of perforator flap breast reconstruction. As technology advances, our search for less invasive means to provide more detailed and accurate information continues. Virtual reality software can improve the accuracy of perforator localization. Magnetic resonance angiography has the benefit of requiring no iodinated intravenous contrast material and does not subject the patient to ionizing radiation. Preliminary experience with this technique is encouraging ; however, this study is more expensive, less reproducible, and not as good at providing fine anatomic detail of smaller perforators compared with CTA at present. Although these modalities have shown promise, at present, CTA remains the gold standard for perforator mapping. All these imaging techniques provide important information to the operating surgeon regarding the perforators; however, they do not provide all the information needed to complete the procedure. Although the general relationships regarding the DIEA branches, perforators, and the motor nerves to the rectus abdominis muscle have been described, the actual association between individual nerves and vessels in any given patient cannot yet be determined based on current imaging techniques. These techniques also fail to account for physiologic changes related to blood flow and perfusion. These studies are meant as an adjunct, not a replacement for surgical judgment.
Conclusions for Autologous Breast Reconstruction
The lower abdomen has become the preferred donor site for autologous breast reconstruction. Significant variability in the anatomy of the deep inferior epigastric source vessels and their associated perforators has made preoperative imaging for perforator mapping and planning desirable. CTA has emerged as the gold standard for this purpose. CTA can accurately select the optimal perforators to maximize flap perfusion while minimizing donor site morbidity related to neuromuscular damage to the rectus abdominis muscle. The information allows a more directed dissection to the dominant perforators that have the most direct course through or around the rectus abdominis muscle to the underlying deep inferior epigastric pedicle. Preoperative imaging with CTA has been demonstrated to expedite flap harvest. This imaging decreases operative time and associated costs, reduces flap-specific complications (particularly fat necrosis and partial flap loss), and helps minimize donor site problems such as bulges and hernias. Although arterial inflow in perforator flaps is important, venous outflow issues are reported to be more critical. Improved spatial resolution with current imaging techniques allows for better anatomic detail of the relationship between neighboring perforators and the communication between the superficial and deep systems ( Fig. 4 ). This information is now being used to minimize flap complications and predict a successful outcome. CTA is currently the imaging modality of choice for preoperative perforator mapping; however, many other options are available, each offering certain advantages.
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Noncontrast Magnetic Resonance Imaging for Preoperative Perforator Mapping
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