Equilibrium-phase high spatial resolution contrast-enhanced MR angiography at 1.5T in preoperative imaging for perforator flap breast reconstruction

Reconstructive flap surgery in head and neck cancer patients: an interdisciplinary view of the challenges encountered by radiation oncologists in postoperative radiotherapy

Background

Major advances have been made in reconstructive surgery in the last decades to reduce morbidity in head and neck cancer. Flaps are now present in 80% of patients with oral cavity cancer to cover anatomic, functional, and cosmetic needs. However, gaps in interdisciplinary innovation transfer from surgery to postoperative radiotherapy (poRT) remain challenging. We aimed to provide an interdisciplinary view of the challenges encountered by radiation oncologists in planning head and neck postoperative radiotherapy.

Methods

A systematic and critical review was conducted to address areas of optimization in surgery and radiology that may be relevant to poRT.

Results

Despite extensive surgical literature on flap techniques and salvage surgery, 13 retrospective series were identified, where flap outcomes were indirectly compared between surgery alone or poRT. These low-evidence studies suggest that radiotherapy accelerates flap atrophy, fibrosis, and osteoradionecrosis and deteriorates functional outcomes. Preliminary evidence suggests that tumor spread occurs at the flap-tissue junction rather than in the flaps. One prospective 15-patient study showed 31.3% vs. 39.2% flap volume reduction without or with poRT. In an international consensus, experts recognized the needs for optimized flap-sparing poRT against flap-related functional deterioration and bone damage. CT, MRI, and PET-CT modalities show potential for the delineation of the junction area between native tissues and flap for flap segmentation and to characterize flap-specific changes quantitatively and correlate them with patterns of relapse or complications.

Conclusion

Flap management in poRT is insufficiently documented, but poRT seems to damage flaps. Current gaps in knowledge underscore the need for prospective flap assessment and interdisciplinary trials investigating flap morbidity minimization by flap-sparing poRT planning.

ACR Appropriateness Criteria® Imaging of Deep Inferior Epigastric Arteries for Surgical Planning (Breast Reconstruction Surgery): 2022 Update

Breast cancer is the most common malignancy in women in the United States, with surgical options including lumpectomy and mastectomy followed by breast reconstruction. Deep inferior epigastric perforator (DIEP) flap is a muscle-sparing perforator free flap breast reconstruction technique, which uses the deep inferior epigastric artery (DIEA) perforators to create a vascular pedicle. Multiple perforators are identified by preoperative imaging, which are typically ranked based on size, location, and intramuscular course. The goal of preoperative imaging is to aid the surgical team in preoperative planning given the variability of the DIEA perforator branches anatomy between patients. The objective of this document is to review the imaging modalities that can be used preoperatively to identify the optimal perforator and thereby reduce intraoperative complications, reduce postoperative complications, and improve clinical outcomes. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

The accuracy of different modalities of perforator mapping for unilateral DIEP flap breast reconstruction: A systematic review and meta-analysis

BACKGROUND

Perforator mapping may be performed prior to deep inferior epigastric perforator (DIEP) flap breast reconstruction to guide perforator selection. However, the accuracy of different imaging modalities remains unknown. This review aimed to evaluate the accuracy of different modalities for locating perforators for unipedicled DIEP flap breast reconstruction.

METHODS

MEDLINE and EMBASE were searched from inception to 24th September 2019 for studies concerning adult women undergoing DIEP flap breast reconstruction with preoperative perforator mapping. The index test was pre-operative imaging and the reference standard was intraoperative identification.

RESULTS

21 articles with 1146 women were included. Six methods were described; handheld doppler, colour doppler (duplex) ultrasonography, computed tomography angiography, magnetic resonance angiography (MRA), direct infrared thermography with and without doppler. Meta-analysis revealed 94% (95% CI 88-99%) of DIEPs identified as the 'dominant perforator' on imaging were chosen as dominant perforators intraoperatively. Colour doppler (Duplex) ultrasonography had the lowest agreement (mean 74% [95% CI 67-81%]) whilst MRA had the highest agreement (mean 97% [95% CI 86-100%]). There was no statistically significant difference in the performance of different tests. All studies were subject to bias as the operators had knowledge of the index test prior to conducting the reference standard.

CONCLUSIONS

Based upon limited evidence, cross sectional (CT/MR) imaging modalities for preoperative DIEP mapping appear to have similar accuracy and perform better than ultrasound.

Identification of Ulnar Artery Perforators Using Color Doppler Ultrasonography

BACKGROUND

 The ulnar artery perforator (UAP) flap, which is hairless, thin, and pliable, has been used for the reconstruction of soft tissues from the finger to the elbow. Preoperative planning is essential for a perforator flap surgery, and there are some tests to identify perforators. Color Doppler ultrasonography (US) with a high-frequency transducer helps in detecting decreased flow in smaller vessels, such as perforators. The purpose of this study was to determine the anatomical locations and origins of perforators arising from the ulnar artery using color Doppler US in healthy volunteers.

METHODS

 Forty forearms of 20 healthy volunteers were included in the study. Perforators arising from the ulnar artery, within 100 mm proximal to the pisiform, were investigated using color Doppler US with a high-frequency transducer.

RESULTS

 A total of 205 perforators were identified. On comparing the locations in each 20 mm section from the pisiform, the largest number of perforators was 58 (28%), within 20 mm proximal to the pisiform. The axial view demonstrated 44 (21%), 64 (31%), 32 (16%), and 65 (32%) perforators in the radial, ulnar, superficial, and deep aspects of the ulnar artery, respectively. Fifty-two and 28 essential perforators were supplied by the UAPs arising from the superficial and ulnar aspect within 20 mm proximal to the pisiform and between 21 and 40 mm proximal to the pisiform, respectively, while elevating the UAP flap.

CONCLUSION

 This is the first study to assess the UAP using color Doppler US. Identification of UAP using color Doppler US can be used as a preoperative assessment for reliable elevation of a UAP flap.

ACR Appropriateness Criteria® Imaging of Deep Inferior Epigastric Arteries for Surgical Planning (Breast Reconstruction Surgery)

Breast cancer is the most common malignancy in women in the United States. Breast reconstruction surgery is a commonly used therapy for patients with breast cancer. The technique for the deep inferior epigastric perforator flap uses a preserved rectus muscle, which decreases donor site morbidity. Accurate identification and measurement of the perforator branches of the deep inferior epigastric artery is pivotal during pre-operative planning so that the surgeon can prioritize the best vessel to use and ultimately improve clinical outcome. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Advances in imaging technologies for planning breast reconstruction

The role and choice of preoperative imaging for planning in breast reconstruction is still a disputed topic in the reconstructive community, with varying opinion on the necessity, the ideal imaging modality, costs and impact on patient outcomes. Since the advent of perforator flaps their use in microsurgical breast reconstruction has grown. Perforator based flaps afford lower donor morbidity by sparing the underlying muscle provide durable results, superior cosmesis to create a natural looking new breast, and are preferred in the context of radiation therapy. However these surgeries are complex; more technically challenging that implant based reconstruction, and leaves little room for error. The role of imaging in breast reconstruction can assist the surgeon in exploring or confirming flap choices based on donor site characteristics and presence of suitable perforators. Vascular anatomical studies in the lab have provided the surgeon a foundation of knowledge on location and vascular territories of individual perforators to improve our understanding for flap design and safe flap harvest. The creation of a presurgical map in patients can highlight any abnormal or individual anatomical variance to optimize flap design, intraoperative decision-making and execution of flap harvest with greater predictability and efficiency. This article highlights the role and techniques for preoperative planning using the newer technologies that have been adopted in reconstructive clinical practice: computed tomographic angiography (CTA), magnetic resonance angiography (MRA), laser-assisted indocyanine green fluorescence angiography (LA-ICGFA) and dynamic infrared thermography (DIRT). The primary focus of this paper is on the application of CTA and MRA imaging modalities.

Comparative analysis of fluorescent angiography, computed tomographic angiography and magnetic resonance angiography for planning autologous breast reconstruction

BACKGROUND

The high incidence of breast cancer and growing number of breast cancer patients undergoing mastectomy has led to breast reconstruction becoming an important part of holistic treatment for these patients. In planning autologous reconstructions, preoperative assessment of donor site microvascular anatomy with advanced imaging modalities has assisted in the appropriate selection of flap donor site, individual perforators, and lead to an overall improvement in flap outcomes. In this review, we compare the accuracy of fluorescent angiography, computed tomographic angiography (CTA), and magnetic resonance angiography (MRA) and their impact on clinical outcomes.

METHODS

A review of the published English literature dating from 1950 to 2015 using databases, such as PubMed, Medline, Web of Science, and EMBASE was undertaken.

RESULTS

Fluorescent angiography is technically limited by its inability to evaluate deep-lying perforators and hence, it has a minimal role in the preoperative setting. However, it may be useful intraoperatively in evaluating microvascular anastomotic patency and the mastectomy skin perfusion. CTA is currently widely considered the standard, due to its high accuracy and reliability. Multiple studies have demonstrated its ability to improve clinical outcomes, such as operative length and flap complications. However, concerns surrounding exposure to radiation and nephrotoxic contrast agents exist. MRA has been explored, however despite recent advances, the image quality of MRA is considered inferior to CTA.

CONCLUSIONS

Preoperative imaging is an essential component in planning autologous breast reconstruction. Fluorescent angiography presents minimal role as a preoperative imaging modality, but may be a useful intraoperative adjunct to assess the anastomosis and the mastectomy skin perfusion. Currently, CTA is the gold standard preoperatively. MRA has a role, particularly for women of younger age, iodine allergy, and renal impairment.