Damien L. Stella

Preoperative imaging for DIEA perforator flaps: a comparative study of computed tomographic angiography and Doppler ultrasound.

BACKGROUND Abdominal donor-site flaps, including the transverse rectus abdominis musculocutaneous (TRAM) and deep inferior epigastric artery (DIEA) perforator flaps, are standard in autologous breast reconstruction. With significant variation in the vascular anatomy of the abdominal wall, preoperative imaging is essential for preoperative planning and reducing intraoperative error. Doppler and color duplex sonography have been used with varying results, and the quest continues for optimal preoperative assessment. Computed tomographic angiography has recently been proposed as a noninvasive modality for this purpose. This is the first study to formally compare preoperative Doppler ultrasound with computed tomographic angiography for imaging the DIEA. METHODS Eight consecutive patients undergoing DIEA perforator flap surgery for breast reconstruction underwent both computed tomographic angiography and Doppler ultrasound preoperatively. All investigations and procedures were performed at the same institution with the same primary and assisting surgeons and the same radiology team. RESULTS Computed tomographic angiography was superior to Doppler ultrasound at identifying the course of the DIEA and its branching pattern, and in visualizing its perforators. Preoperative computed tomographic angiography was highly specific (100 percent) and more sensitive in mapping and visualizing perforators (p = 0.0078). It was also proficient at identifying the superficial epigastric arterial system and for effectively displaying the results intraoperatively. It was substantially quicker and removed the interobserver error associated with Doppler ultrasonography. The study was ceased after eight patients because of the overwhelming benefit of computed tomographic angiography over Doppler ultrasonography. CONCLUSION Computed tomographic angiography is a valuable imaging modality for the preoperative assessment of the donor-site vascular supply for TRAM and DIEA perforator flaps.Background: Abdominal donor-site flaps, including the transverse rectus abdominis musculocutaneous (TRAM) and deep inferior epigastric artery (DIEA) perforator flaps, are standard in autologous breast reconstruction. With significant variation in the vascular anatomy of the abdominal wall, preoperative imaging is essential for preoperative planning and reducing intraoperative error. Doppler and color duplex sonography have been used with varying results, and the quest continues for optimal preoperative assessment. Computed tomographic angiography has recently been proposed as a noninvasive modality for this purpose. This is the first study to formally compare preoperative Doppler ultrasound with computed tomographic angiography for imaging the DIEA. Methods: Eight consecutive patients undergoing DIEA perforator flap surgery for breast reconstruction underwent both computed tomographic angiography and Doppler ultrasound preoperatively. All investigations and procedures were performed at the same institution with the same primary and assisting surgeons and the same radiology team. Results: Computed tomographic angiography was superior to Doppler ultrasound at identifying the course of the DIEA and its branching pattern, and in visualizing its perforators. Preoperative computed tomographic angiography was highly specific (100 percent) and more sensitive in mapping and visualizing perforators (p = 0.0078). It was also proficient at identifying the superficial epigastric arterial system and for effectively displaying the results intraoperatively. It was substantially quicker and removed the interobserver error associated with Doppler ultrasonography. The study was ceased after eight patients because of the overwhelming benefit of computed tomographic angiography over Doppler ultrasonography. Conclusion: Computed tomographic angiography is a valuable imaging modality for the preoperative assessment of the donor-site vascular supply for TRAM and DIEA perforator flaps.

DOES THE PREOPERATIVE IMAGING OF PERFORATORS WITH CT ANGIOGRAPHY IMPROVE OPERATIVE OUTCOMES IN BREAST RECONSTRUCTION

Background: Breast reconstruction is increasingly performed with the use of the abdominal wall donor site, with potential complications including donor site morbidity and impaired flap viability. As a tool for selecting the optimal perforators which will ultimately supply the flap, preoperative imaging with computed tomography angiography (CTA) has become increasingly popular. Potential benefits include reduced intramuscular dissection, with faster and safer dissection, reduced donor site morbidity and improved flap vascularity and survival. Despite the potential for improvements in operative outcome, any benefits are yet to be established. Methods: A cohort study of 104 breast reconstructions in 88 patients was conducted. All patients underwent breast reconstruction based on an abdominal wall free flap. Of these, 40 patients undergoing preoperative imaging with CTA and 48 patients not undergoing CTA were included, with all CTAs undertaken at a single institution. Length of operation, length of stay, and operative complications were assessed. An evaluation of operative stress was achieved with the use of visual analogue scales (VAS) administered to the surgeons. Results: The use of CTA was associated with decreased operating time (mean: 77 min for bilateral cases), significantly decreased complications related to flap viability (particularly partial flap loss), and a statistically significant reduction in donor site morbidity. Psychometric testing of surgeons revealed a statistically significant decrease in operative stress (41% decrease) with the use of preoperative CTA. Conclusion: The use of CTA for preoperative imaging in breast reconstruction is associated with improved operative outcomes.

Abdominal Wall CT Angiography: A Detailed Account of a Newly Established Preoperative Imaging Technique

Institutional review board approval was obtained for this study, and all patients gave written informed consent. Autologous surgical breast reconstruction with use of abdominal wall donor flaps based on the deep inferior epigastric artery (DIEA) and one or more of its anterior musculocutaneous perforating branches (DIEA perforator flap) is being used with increasing frequency instead of breast reconstruction with use of traditional transverse rectus abdominus musculocutaneous and modified muscle-sparing flaps. Preoperative mapping of the DIEA perforators with abdominal wall computed tomographic (CT) angiography may improve patient care by providing the surgeon with additional information that will lead to optimization of the surgical technique, shorter procedure time, and reduction in the frequency of surgical complications. The branching patterns of the DIEA, the segmental anatomy of the anterior adipocutaneous perforating branches of the DIEA, and the importance of these features in pre- and intraoperative surgical planning necessitate a different approach to abdominal wall CT angiography than that used with other abdominal CT angiographic techniques. In abdominal wall CT angiography, the common femoral artery is used as the bolus trigger, CT scanning is performed in the caudocranial direction, the automatic exposure control feature is disabled, a scaled grid overlay tool is used to present information to the surgeons, and radiation dose is minimized (average dose, 6 mSv). The anatomic accuracy of abdominal wall CT angiography has been investigated in cadaveric and surgical studies, with sensitivity of 96%-100% and specificity of 95%-100%. This detailed description will allow other radiologists and surgeons interested in free DIEP flap surgery to incorporate this useful tool into their practice.

Advances in the pre-operative planning of deep inferior epigastric artery perforator flaps: magnetic resonance angiography.

Imaging of the abdominal wall vasculature prior to deep inferior epigastric artery (DIEA) perforator (DIEP) flaps has been shown to significantly improve surgical outcomes. Although computed tomography angiography (CTA) has been shown to be highly accurate, it is associated with radiation exposure, and as such modalities without radiation exposure have been sought. Magnetic resonance angiography (MRA) has been proposed as such an option. We conducted a pilot study comparing MRA with CTA and with operative findings in six consecutive patients undergoing DIEP flaps for breast reconstruction. The DIEA, superficial inferior epigastric artery (SIEA) and perforators were all assessed with each modality. We found that the DIEA and SIEA were accurately imaged with both CTA and MRA, but that while MRA could identify some major perforators, CTA was more accurate than MRA for perforator mapping. As such, while MRA does have a role in the imaging of DIEA perforators, CTA is still the preferred modality. On the basis of these findings, a larger study into the role for MRA in this setting is warranted.

Diagnostic Challenges and Pitfalls in MR Imaging with Hepatocyte-specific Contrast Agents

The use of gadolinium-based hepatocyte-specific contrast agents (HSCAs) has increased markedly since their introduction, and hepatocellular phase imaging performed with an HSCA is now a key part of the standard magnetic resonance (MR) imaging work-up for focal liver lesions. An understanding of the mechanisms of action of HSCAs helps ensure their effective use. The optimal delay for hepatocellular phase image acquisition differs between the two currently available HSCAs, gadoxetic acid and gadobenate dimeglumine, and MR imaging protocols must be adjusted accordingly. In addition, familiarity with typical and atypical appearances of benign and malignant focal liver lesions at HSCA-enhanced hepatocellular phase MR imaging, along with knowledge of the processes that are most likely to produce atypical appearances, is required to achieve optimal diagnostic accuracy.

The accuracy of computed tomographic angiography for mapping the perforators of the deep inferior epigastric artery: a blinded, prospective cohort study.

Background: The deep inferior epigastric artery perforator flap is increasingly used for autologous breast reconstruction, with low donor-site morbidity cited as a major advantage of this operation. Preoperative imaging of the donor-site vasculature is frequently used as a further means of improving operative outcome. Computed tomographic angiography has been increasingly described as a preferred imaging modality; however, its formal evaluation has not been described in a clinical setting. Methods: A prospective, single-blind, cohort study was undertaken on 60 consecutive patients for whom deep inferior epigastric artery perforator flap surgery had been planned. Patients who did not undergo the procedure during the study period were excluded, with 42 patients ultimately included in the study. All computed tomographic angiography scans were obtained at a single institution. Perforators were mapped both on angiography and intraoperatively using a grid of 4-mm squares centered on the umbilicus. Only perforators larger than 1 mm were included in the study. All imaging findings were recorded by a single operator, and all intraoperative findings were recorded by the operating surgeon. Results: Computed tomographic angiography identified 280 major perforators in 42 patients. It was highly accurate, demonstrating 279 perforators recorded accurately, with one false-positive and one false-negative. Its sensitivity for mapping perforators was thus 99.6 percent, with a positive predictive value of 99.6 percent. Conclusions: Computed tomographic angiography is highly accurate in identifying and mapping the perforators of the deep inferior epigastric artery. Its accuracy is superior to that of the previous modalities used in this role and suggests the usefulness of this technique before deep inferior epigastric artery perforator flap surgery for breast reconstruction.

Establishing the case for CT angiography in the preoperative imaging of abdominal wall perforators

Preoperative imaging of the donor site vasculature for deep inferior epigastric artery (DIEA) perforator flaps and other abdominal wall reconstructive flaps has become more commonplace. Abdominal wall computed tomography angiography (CTA) has been described as the most accurate and reproducible modality available for demonstrating the location, size, and course of individual perforators. We drew on our experience of 75 consecutive patients planned for DIEA‐based flap surgery undertaking CTA at a single institution. Seven of these cases have been reported to highlight the utility of CTA for preoperative planning, emphasizing the unique information supplied by CTA that may influence operative outcome. Among all cases that underwent preoperative imaging with CTA, there was 100% flap survival, with no partial or complete flap necrosis. We found that in three of the cases described, the choice of operation was necessarily selected based on CTA findings (DIEA perforator flap, transverse rectus abdominis myocutaneous flap, and superficial superior epigastric artery flap). In addition, three cases demonstrate that CTA findings may dictate the decision to operate at all, and one case demonstrates the utility of CTA for evaluating the entire abdominal contents for comorbid conditions. Our experience with CTA for abdominal wall perforator mapping has been highly beneficial. CTA may guide operative technique and improve perforator selection in uncomplicated cases, and in difficult cases it can guide the most appropriate operation or indeed if an operation is appropriate at all. This is particularly the case in the setting of comorbidities or previous abdominal surgery.

Anatomical variations in the harvest of anterolateral thigh flap perforators: A cadaveric and clinical study

Background: The anterolateral thigh (ALT) flap has become increasingly popular due to its versatility and minimal donor site morbidity. Its major limitation has been uncertainty in predicting perforator anatomy, with the occasional absence of suitable perforators and high variability in their size and course. The variability of this anatomy has not been adequately explored previously. Methods: A cadaveric study was undertaken, in which 19 thighs (from 10 fresh cadavers) underwent contrast injection and angiographic imaging. Anatomical variations of the vasculature were recorded. A clinical study of 44 patients undergoing ALT flap reconstruction was also undertaken. Perforator anatomy was described in the first 32 patients, and the subsequent 12 patients underwent computed tomography angiography with a view to predicting individual anatomy and improving operative outcome. Results: Cadaver angiography was able to highlight and classify the variations in arterial anatomy, with four patterns observed and marked variability between cases. In 32 patients undergoing ALT flaps without preoperative CT angiography (CTA), five patients (16%) did not have any suitable perforators from the descending branch of the lateral circumflex femoral artery. By selecting the limb of choice with preoperative CTA, the incidence of flap unsuitability was reduced to 0%. Comparing CTA with Doppler, CTA was more accurate (sensitivity 100%) and provided more information. Conclusion: The perforators supplying the ALT flap show significant variability in location and course, with the potential for unsuitable perforators limiting flap success. Preoperative CTA can demonstrate the vascular anatomy and can aid perforator selection and operative success.

Developments in perforator imaging for the anterolateral thigh flap: CT angiography and CT‐guided stereotaxy

Introduction: The anterolateral thigh flap is an increasingly popular reconstructive option despite uncertainty in its perforator anatomy. Perforators are not always present, vary in size and intramuscular course, and have variable cutaneous courses and supply. As such, preoperative imaging has become favored. Methods: The current study describes the preliminary use of two new modalities for preoperative imaging: computed tomography (CT) Angiography and CT‐guided stereotaxy. These have been utilized in the preoperative imaging of two patients undergoing ALT flap reconstruction. Each patient underwent each of these techniques combined with Doppler ultrasound, the previous standard modality. The size, location, and course of perforators were explored and compared with operative findings. Results: Both techniques are technically feasible, highly accurate, and provide more information to the surgeon than ultrasound. Conclusion: CT Angiography and CT‐guided stereotaxy are useful adjuncts to Doppler ultrasound for imaging perforators prior to ALT flaps. A larger study is suggested to quantify the accuracy of these techniques.

The Accuracy of Computed Tomographic Angiography for Mapping the Perforators of the Diea: A Cadaveric Study

Background: The deep inferior epigastric artery (DIEA) perforator flap is increasingly used for breast reconstruction, with preoperative imaging sought as a means of improving operative outcome. Computed tomographic angiography has been recently described as the preferred imaging modality; however, formal evaluation of computed tomographic angiography has not been described. A cadaveric study was undertaken to evaluate the accuracy of computed tomographic angiography for perforator mapping. Methods: Ten cadaveric hemiabdominal walls from five fresh cadavers underwent contrast injection of each DIEA and subsequent computed tomographic scanning, with each DIEA and all perforating branches documented. Dissection was then performed, with the recording of the course of the DIEA and the course of all perforators in each specimen. The concordance of computed tomographic angiography with dissection findings was evaluated. Results: Cadaveric computed tomographic angiography identified 154 perforators in 10 hemiabdominal walls. Computed tomographic angiography was highly accurate, with eight false-positives and six false-negatives on cadaveric computed tomographic angiography, establishing an overall sensitivity of 96 percent and a positive predictive value of 95 percent for mapping perforators. For perforators greater than 1 mm in diameter, the sensitivity was 100 percent and the positive predictive value was 100 percent. Conclusions: Computed tomographic angiography is a highly accurate tool for identifying the perforators of the DIEA before DIEA perforator flaps for breast reconstruction. Preoperative identification of these vessels can aid planning for the preferred hemiabdomen for dissection, and may save operative time, angst, and potentially complications.