Imaging in Propeller Flap Surgery

Improving the visualisation of perforator arteries for anterolateral thigh flaps harvest in CT angiography via sublingual glyceryl trinitrate

AIM

To investigate the improvement of image quality and visualisation of the anterolateral thigh (ALT) flap perforators on computed tomography angiography (CTA) after administration of sublingual glyceryl trinitrate (GTN).

MATERIALS AND METHODS

Sixty patients with oral lesions received thigh CTA examinations were divided randomly into two groups after administration of sublingual GTN (GTN group) or without administration of sublingual GTN (non-GTN group). Two radiologists calculated the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and assessed the image quality of each vessel. Besides, the grade of thigh artery, the lumen diameter of deep femoral artery, lateral circumflex femoral artery (LCFA), the descending branch of LCFA and its proximal and distal perforators, and the number and type of visible perforators were evaluated quantitatively.

RESULTS

The SNR and CNR were not significantly different between the two groups (p>0.05). The image quality of CTA in the GTN group was significantly better than that in the non-GTN group (p<0.01). The lumen diameters of the deep femoral artery, LCFA, the descending branch of LCFA and its perforators were significantly larger in the GTN group than those in the non-GTN group (p<0.01). Compared with the non-GTN group, the number of visible perforators and the number of visible septocutaneous perforators were significantly more in the GTN group, and the qualitative grade of visible perforators was significantly higher (p<0.001).

CONCLUSIONS

The administration of sublingual GTN in preoperative thigh CTA can improve the image quality and visualisation of perforator vessels, thus could help surgeons to select the optimum ALT flaps.

Customizing Anterolateral Thigh Flap With Magnetic Resonance Angiography Differential Subsampling With Cartesian Ordering Imaging for Individualized Reconstruction of Extremity Defects

INTRODUCTION

Magnetic resonance angiography (MRA) with the differential subsampling with cartesian ordering (DISCO) imaging technique is rarely used in anterolateral thigh (ALT) flap. In our series, MRA DISCO imaging technique is used as a tool to customize ALT flaps. The aim of this study was to report the accuracy of cutaneous perforators identified by the MRA DISCO imaging.

METHODS

Nineteen patients underwent the MRA DISCO imaging for perforator mapping before the ALT flap transfer. A total of 38 ALT regions were studied on the MRA DISCO images. Flap thinning was performed under the guidance of MRA DISCO imaging.

RESULTS

The lateral circumflex femoral artery (LCFA) most commonly stems from the deep femoral artery (84.2%), followed by the common femoral artery (15.8%). The average number of perforator vessels per LCFA was 10.2 ± 1.7. The distinct oblique branch was observed in 16 out of the 38 ALT regions (42.1%). Among the 19 ALT flaps harvested, 5 were septocutaneous perforator flaps and 14 musculocutaneous perforator flaps. Ten were harvested based on the descending branch, and 3 used the oblique branch as the flap vascular pedicle. In addition, the displayed course and types of perforator vessels on the DISCO images of the 18 skin flaps were consistent with the intraoperative findings, with an accuracy of 94.7%.

CONCLUSIONS

The state of the cutaneous perforators of LCFA can be identified on the MRA DISCO images. The 3D-CE-MRA DISCO imaging is a practical method, which can ameliorate the design and customization of ALT flap for an individualized reconstruction.

Computed Tomography Angiography and B-Mode Ultrasonography under Artificial Intelligence Plaque Segmentation Algorithm in the Perforator Localization for Preparation of Free Anterolateral Femoral Flap

This research was aimed to investigate the accuracy of U-shaped network (UNet)-based computed tomography angiography (CTA) and B-mode ultrasonography (US) in the perforator localization of free anterolateral thigh flap (ALTF). Based on UNet, a fusion of deep supervision mechanism, squeeze-and-excitation module, and attention mechanism was introduced to optimize the algorithm. Then, a CTA segmentation model, DA-UNet, was established. The segmentation performance of DA-UNet and other algorithms was compared under the same conditions. 30 patients who were planned to receive ALTF surgery were selected as the research objects. According to different preoperative localization methods, they were divided into group A (CTA) and group B (B-mode US), 15 cases in each group. Combined with the actual situation during surgery, the diagnostic accordance rate, sensitivity (Sen), specificity, and the distance between the perforator location and the actual location were compared between the two groups. The Dice coefficient, Jaccard index, Sen, the area under curve (AUC), and average Hausdorff distance (AVD) of the DA-UNet segmentation algorithm were 80.70%, 69.97%, 77.56%, 0.887, and 2.48, respectively. These results were significantly better than those of other algorithms (P < 0.05). In group A, the diagnostic accordance rate, Sen, and specificity of patients were 96.55%, 90.52%, and 73.58%, respectively, which were higher than 91.53%, 81.36%, and 15.60% of patients in group B significantly (P < 0.05). There was no statistical difference in the distance between the perforator location and the actual location (P > 0.05). It showed that the accuracy of CTA under the UNet-based DA-UNet segmentation model in the perforator localization of ALTF was better than that of B-mode US. Thus, a reference could be provided for the preparation of free ALTF and its clinical application.

A three-dimensional visualization of the full-field surgical region based on thin-slice MRI: A helpful approach for simultaneously guiding tumor resection and perforator flap elevation

Background

The goal of the current study was to explore the application of preoperative three-dimensional reconstruction (3DR) based on thin-slice magnetic resonance imaging (MRI) in the simultaneous guidance of en bloc tumor resection and adjacent perforator flap elevation.

Methods

The prospective cohort included 35 patients diagnosed with either soft tissue sarcoma or squamous cell skin cancer between 2019 and 2021. The preoperative 3DR based on thin-slice MRI illustrated the spatial anatomical relationship among the tumor, underlying muscle, adjacent perforator vessels, and bone around the surgical region. The accuracy of preoperative imaging data was verified by intraoperative vessel dissection and postoperative pathological measurements.

Results

Tumor size from 3DR data showed relatively high concordance rates with pathological measurements within the 95% limits of agreement. An average of three perforators (range: 1–7) with a mean diameter of 0.32 cm (range: 0.18–0.74 cm) from the 3DR were present in our study. The average distance between tumor boundary and perforator piercing sites on the 3DR was 2.2 cm (range: 1.2–7.7 cm). The average length of artery perforator coursing along the subcutaneous tissue was 5.8 cm (range: 3.3–25.1 cm). The mean flap harvest time was 55 mins (range: 36–97 min). The average flap size was 92.2 cm² (range: 32–126 cm²). One perforator flap occurred distal partial necrosis.

Conclusion

A thorough understanding of anatomical structures in the surgical region according to full-field 3DR based on thin-slice MRI can improve the performance of radical resection of the tumor and adjacent perforator flap transfer, especially for junior surgeons with a poor experience.

Computed tomography angiography-aided individualized anterolateral thigh flap design in the reconstruction of oral and maxillofacial soft tissue defects

PURPOSE

To evaluate a novel method and computed tomography angiography (CTA) for locating anterolateral thigh flap (ALTF) perforators to design individualized ALTFs to reconstruct maxillofacial soft tissue defects.

STUDY DESIGN

This study comprised a group of 36 patients (CTA group) with malignant oral and maxillofacial tumors who underwent CTA and who received individualized ALTFs and a group of 28 patients (control group) with the same condition but without preoperative CTA examination and with nonindividualized ALTFs. ALTFs in the CTA group were designed and harvested using the locating device and CTA, whereas ALTFs in the control group were designed and harvested according to each surgeon's experience.

RESULTS

Fifty perforators were located and 36 ALTFs harvested in the CTA group. In the control group, 34 perforators were located and 28 ALTFs harvested. Less time was required to locate the perforators in the CTA group. Moreover, the CTA group had a higher flap survival rate and better patient satisfaction regarding the postoperative aesthetics and phonetic and swallowing functions.

CONCLUSIONS

The results suggest that CTA and the locating device can be used to accurately locate ALTF perforators and that this method aids in the design and harvesting of individualized ALTFs to achieve good functional and aesthetic outcomes.

Microsurgical Anterolateral Thigh Flap for Reconstruction of Extremity Soft Tissue Defects in Pediatric Patients

BACKGROUND

The anterolateral thigh flap is one of the most widely used flaps because it has the advantages of less damage to the donor site, no sacrifice of main blood vessels, and abundant soft tissue. However, the application of anterolateral thigh flap in children is relatively rare because of small blood vessels and rapid physiological changes. The aim of this study was to explore the effectiveness and characteristics of free anterolateral thigh flaps for the reconstruction of extremity soft tissue defects in pediatric patients.

PATIENTS AND METHODS

This study included 26 pediatric patients, with an average age of 6.7 years (range, 2-13 years). There were 5 cases of upper limb defects and 21 cases of lower limb defects, all of which were accompanied by exposed bones or tendons. The causes of defects included traffic injury in 9 cases, mechanical injury in 7 cases, collision injury in 4 cases, spoke injury in 3 cases, cicatricial contracture in 2 cases, and fibroma in 1 case. All defects were reconstructed with free anterolateral thigh flaps.

RESULTS

Twenty-six anterolateral thigh flaps were harvested, including 15 fasciocutaneous flaps and 11 musculocutaneous flaps. The mean size of the flap was 73.4 cm2 (range, 4 × 3 to 24 × 8 cm). The donor sites were sutured directly in 19 cases and underwent split-thickness skin grafting in 7 cases. There were 3 cases of vascular crisis, 3 cases of flap edge necrosis, 3 cases of infection, 1 case of pressure ulcer, and 1 case of dehiscence after surgery. Eleven patients had scar hyperplasia in the donor site. A total of 34 reoperations were performed, including 14 flap debulking, 7 debridement, 4 skin graft, 3 vascular crisis re-exploration, and 6 other procedures.

CONCLUSIONS

Free anterolateral thigh flap was a safe and reliable option for reconstructing soft tissue defects of extremities in pediatric patients. Notably, the incidence of scar hyperplasia in the donor site and the possibility of reoperation in pediatric patients were higher than those in adult patients.

Analysis of risk factors for complications of perforator propeller flaps used for soft tissue reconstruction after malignant tumor resection: A systematic review and meta-analysis

BACKGROUND

Perforator propeller flaps (PPFs) have been widely used due to their numerous advantages; however, they were also associated with various complications. Herein, we analyzed the risk factors for complications of PPFs used for soft tissue reconstruction after malignant tumor resection.

METHODS

We searched databases for articles on soft tissue reconstruction using PPFs after malignant tumor resection published between January 1991 and April 2021. Studies were selected according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement. Fixed effects models and relative risks were used for data analysis. Funnel plots and Begg's test were used to evaluate publication bias.

RESULTS

Twenty-six articles met the inclusion criteria. Complications were found in 24.7% of all patients. The four significant risk factors were age equal or older than 60 years (pooled relative risk, 1.83; p = .04), smoking (pooled relative risk, 2.32; p = .03), diabetes (pooled relative risk, 2.59; p = .01) and radiotherapy (pooled relative risk, 2.09; p = .01). Hypertension, defects located in the extremities, flap size equal or greater than 100 cm² , and pedicle rotation equal or greater than 120 degrees were not significant risk factors for complications. No publication bias was found in the included articles.

CONCLUSION

Age equal or older than 60 years, smoking, diabetes and radiotherapy are four risk factors for complications when PPFs are used to reconstruct soft tissue defects resulting from malignant tumor resection.

Color Doppler Ultrasound versus Computed Tomography Angiography for Preoperative Anterolateral Thigh Flap Perforator Imaging: A Systematic Review and Meta-Analysis

BACKGROUND

 The anterolateral thigh (ALT) perforator flap is a commonly used flap with a predictable, though often variable, perforator anatomy. Preoperative imaging with color Doppler ultrasound (CDU) and computed tomography angiography (CTA) of ALT flap perforators can be a useful tool for flap planning. This study provides a complete review and analysis of the relevant preoperative ALT imaging literature.

METHODS

 Studies related to preoperative CDU and CTA imaging were reviewed, and information related to imaging method, sensitivity, false-positive rates, and perforator course identification (musculocutaneous vs. septocutaneous) were analyzed.

RESULTS

 A total of 23 studies related to preoperative ALT flap CDU and CTA imaging were included for review and analysis. Intraoperative perforator identification was compared with those found preoperatively using CDU (n = 672) and CTA (n = 531). Perforator identification sensitivity for CDU was 95.3% (95% CI: 90.9-97.6%) compared with the CTA sensitivity of 90.4% (95% confidence interval [CI]: 74.4-96.9%). The false-positive rate for CDU was 2.8% (95% CI: 1.1-4.5%) compared with 2.4% (95% CI: 0.7-4.1%) for CTA. Accuracy of perforator course identification was 95.5% (95% CI: 93.6-99.2%) for CDU and 96.9% (95% CI: 92.7-100.1%) for CTA.

CONCLUSION

 CDU provides the reconstructive surgeon with greater preoperative perforator imaging sensitivity compared with CTA; however, false-positive rates are marginally higher with preoperative CDU. Preoperative imaging for ALT flap design is an effective tool, and the reconstructive surgeon should consider the data presented here when selecting a flap imaging modality.

Thermal, Hyperspectral, and Laser Doppler Imaging: Non-Invasive Tools for Detection of The Deep Inferior Epigastric Artery Perforators-A Prospective Comparison Study

Perforator flaps have become one of the leading procedures in microsurgical tissue transfer. Individual defects require a tailored approach to guarantee the most effective treatment. A thorough understanding of the individual vascular anatomy and the location of prominent perforators is of utmost importance and usually requires invasive angiography or at least acoustic Doppler exploration. In this study, we aimed at evaluating different non-invasive imaging modalities as possible alternatives for perforator location detection. After a cooling phase, we performed thermal, hyperspectral and Laser Doppler imaging and visually evaluated a possible detection of the perforator for a period of five minutes with an image taken every minute. We identified the most prominent perforator of the deep inferior epigastric artery by handheld acoustic Doppler in 18 patients. The detected perforator locations were then correlated. Eighteen participants were assessed with six images each per imaging method. We could show a positive match for 94.44%, 38.89%, and 0% of patients and 92.59%, 25.93%, and 0% of images for the methods respectively compared to the handheld acoustic Doppler. Sex, age, abdominal girth, and BMI showed no correlation with a possible visual detection of the perforator in the images. Therefore, thermal imaging can yield valuable supporting data in the individualized procedure planning. Future larger cohort studies are required to better assess the full potential of modern handheld thermal imaging devices.

How to Design and Harvest a Propeller Flap

Propeller flaps are local flaps based either on a subcutaneous pedicle, a single perforator, or vessels entering the flap in such a way so as to allow the flap to rotate on their axis. Depending on the kind of pedicle and the anatomical area, the preoperative investigation and the harvesting techniques may vary. An adequate knowledge of skin and subcutaneous tissue perfusion in the different areas of the body is very important to plan a propeller flap to be successful. The surgeon should begin by finding the most suitable perforators in the area surrounding the defect using available technology. The position, size, and shape of the flap are planned about this point. For perforator-pedicled propeller flaps, the procedure starts with an exploration from the margins of the defect or through a dedicated incision to visualize any perforators in the surroundings. The most suitable perforator is selected and isolated, the skin island is replanned, and the flap is harvested and rotated into the defect. The variations in surgical technique for other types of propellers and in specific anatomical areas are also described. Compared with free flaps, propeller flaps have the advantage of a simpler, shorter operation, without the need for a recipient vessel for microanastomosis. Yet, from a technical point of view, an adequate experience in dissecting perforators and the use of magnifying glasses are almost always required.

Perforator-Pedicled Propeller Flaps for Lower Extremity Reconstruction

Reconstruction of the lower extremity is considered a major challenge due to frequent bone exposure and the absence of local tissue redundancy, as well as often due to the presence of vascular insufficiency. Many surgeons have preferred free flaps especially for reconstructing the more distal lower limb defects until the evolution of pedicled perforator flaps and propeller flaps in particular provided a like-with-like reconstruction of the lower extremity without affecting the main vessels of the limb or the underlying muscles, and without the risk of any microanastomosis especially in patients with multiple comorbidities. Perforator-pedicled propeller flaps as local flaps in the lower extremity are best suited for small- and medium-sized defects with minimal donor-site morbidity, regardless of the cause of the defect. Any of the three source vessels of the leg can provide reliable perforators for propeller flap coverage of the distal leg and foot. The three main risk factors that are relative contraindications may be advanced age, diabetes mellitus, and atherosclerotic peripheral vascular disease.