Snapshot Multispectral Imaging Is Not Inferior to SPY Laser Fluorescence Imaging When Predicting Murine Flap Necrosis

Mastectomy Skin Flap Perfusion Assessment Prior to Breast Reconstruction: A Narrative Review

BACKGROUND

Predicting the viability of the skin flaps after mastectomy is of high importance and significance in immediate breast reconstruction. Numerous methods have been used and are readily available. This review aims to describe and compare the current preferred perfusion assessment tools.

METHODS

Four major scientific databases-Web of Science, PubMed, Embase, and Scopus-were consulted to retrieve reviews, meta-analyses, clinical trials, experimental studies, and case reports focused on skin flap perfusion assessment following mastectomy. English-language articles published within the last 10 years were included. The most recent search was conducted on 31 July 2024.

RESULTS

A summary focused on the relevant information of all included studies was drafted, and the results of the studies have been synthetized and compared. A total of 58 studies have been included in this review.

CONCLUSION

Indocyanine green angiography (ICG-A) is the preferred and most-used method of evaluating perfusion, especially in high-risk patients, while new technologies show promising results and might be of great interest in the future. Perfusion assessment tools complement and should not replace clinical evaluation.

Flap Viability Evaluation Using a Tissue Oximetry Camera as an Alternative to Indocyanine Green Fluorescence Imaging

Indocyanine green (ICG) fluorescence imaging is useful for assessing flap viability; however, it is associated with a risk of anaphylactic shock, even in patients with no history of drug allergies. SnapshotNIR is a noncontact, camera-type handheld tissue oximeter that can measure the tissue oxygen saturation of the body surface. The device emits red and near infrared light wavelengths and then optimizes the measurement of the differential reflectance from oxygenated and deoxygenated hemoglobin, and StO2 is calculated. A 20 × 15 cm surgical field can be evaluated in less than 3 seconds by holding the camera at a distance of 30 cm. We applied this device at zone II in a deep inferior epigastric perforator (DIEP) flap, and compared the findings with the border of flap perfusion detected by ICG imaging. Left breast reconstruction using a free DIEP flap was performed for a 60-year-old woman. The DIEP flap was vascularized by a perforator vessel coursing to the right abdominis muscle. First, Diagnogreen (5 mg; Daiichi Sankyo Co., Tokyo, Japan) was intravenously injected, and the ICG fluorescence perfusion border detected by PDE-neo (Hamamatsu Photonics, Hamamatsu City, Shizuoka, Japan) was determined. The ICG border was defined by two reconstructive surgeons after fluorescence had spread out for 2 minutes. Next, zones Ⅱ and Ⅳ of the DIEP flap, contralateral to the perforator, were evaluated using photographs obtained by SnapshotNIR. There were significant StO2 value differences between the ICG-negative area and ICG-positive area. This device can be widely applied in the noninvasive evaluation of flap viability.

Point-of-Care Tissue Oxygenation Assessment with SnapshotNIR for Alloplastic and Autologous Breast Reconstruction

In breast reconstruction, mastectomy and free flaps are susceptible to vascular compromise and tissue necrosis. The SnapshotNIR device (Kent Imaging, Calgary, AB, Canada) utilizes near-infrared spectroscopy to measure tissue oxygen saturation (StO₂) and hemoglobin concentration. Here, we report on the use of this device for StO₂ monitoring among patients receiving alloplastic or autologous breast reconstruction.

Methods

Patients receiving immediate alloplastic reconstruction after mastectomy or autologous reconstruction were enrolled. Preoperative, intraoperative, and postoperative images were taken of the flaps. StO₂ and hemoglobin were measured at the following locations: superior and inferior breast, free flap skin paddle (when applicable), and un-operated control skin. Linear mixed effects model for repeated measurements was used to model measurements to estimate the area effect difference across time, time effect difference across area, and pairwise comparisons between two areas at each time point.

Results

Thirty-two breasts underwent alloplastic reconstruction; 38 breasts underwent autologous reconstruction. No enrollees developed skin necrosis. StO₂ was highest after mastectomy and closure in alloplastic reconstructions. StO₂ was observed to decline at follow-up in autologous reconstructions. Mean preoperative StO₂ was highest in breasts that had previously undergone mastectomy and alloplastic reconstruction.

Conclusions

The SnapshotNIR device detected normal spatial and temporal differences in tissue oxygenation over the operative course of alloplastic and autologous breast reconstruction. A multi-institutional, prospective clinical trial is needed to determine the sensitivity and specificity of this device for detecting skin flap necrosis.

Multispectral Image under Tissue Classification Algorithm in Screening of Cervical Cancer

The objectives of this study were to improve the efficiency and accuracy of early clinical diagnosis of cervical cancer and to explore the application of tissue classification algorithm combined with multispectral imaging in screening of cervical cancer. 50 patients with suspected cervical cancer were selected. Firstly, the multispectral imaging technology was used to collect the multispectral images of the cervical tissues of 50 patients under the conventional white light waveband, the narrowband green light waveband, and the narrowband blue light waveband. Secondly, the collected multispectral images were fused, and then the tissue classification algorithm was used to segment the diseased area according to the difference between the cervical tissues without lesions and the cervical tissues with lesions. The difference in the contrast and other characteristics of the multiband spectrum fusion image would segment the diseased area, which was compared with the results of the disease examination. The average gradient, standard deviation (SD), and image entropy were adopted to evaluate the image quality, and the sensitivity and specificity were selected to evaluate the clinical application value of discussed method. The fused spectral image was compared with the image without lesions, it was found that there was a clear difference, and the fused multispectral image showed a contrast of 0.7549, which was also higher than that before fusion (0.4716), showing statistical difference (P < 0.05). The average gradient, SD, and image entropy of the multispectral image assisted by the tissue classification algorithm were 2.0765, 65.2579, and 4.974, respectively, showing statistical difference (P < 0.05). Compared with the three reported indicators, the values of the algorithm in this study were higher. The sensitivity and specificity of the multispectral image with the tissue classification algorithm were 85.3% and 70.8%, respectively, which were both greater than those of the image without the algorithm. It showed that the multispectral image assisted by tissue classification algorithm can effectively screen the cervical cancer and can quickly, efficiently, and safely segment the cervical tissue from the lesion area and the nonlesion area. The segmentation result was the same as that of the doctor's disease examination, indicating that it showed high clinical application value. This provided an effective reference for the clinical application of multispectral imaging technology assisted by tissue classification algorithm in the early screening and diagnosis of cervical cancer.

Hyperintensity of integrin-targeted fluorescence agent IntegriSense750 accurately predicts flap necrosis compared to Indocyanine green

BACKGROUND

Flap necrosis is a feared complication of reconstructive surgery. Current methods of prediction using Indocyanine green (ICG) lack specificity. IntegriSense750 is a fluorescence agent that binds sites of vascular remodeling. We hypothesized that IntegriSense750 better predicts flap compromise compared to ICG.

METHODS

Fifteen mice underwent lateral thoracic artery axial flap harvest. Mice received an injection of ICG (n = 7) or IntegriSense750 (n = 8) daily from postoperative days (POD) 0-3 and were imaged daily. Mean signal-to-background ratios quantified the change in fluorescence as necrosis progressed.

RESULTS

Mean signal-to-background ratio was significantly higher for IntegriSense750 compared to ICG on POD0 (1.47 ± 0.17 vs. 0.86 ± 0.21, p = 0.01) and daily through POD3 (2.12 ± 0.70 vs. 0.96 ± 0.29, p < 0.001).

CONCLUSIONS

IntegriSense750 demonstrates increased signal-to-background ratio at areas of flap distress compared to ICG which may increase identification of flap necrosis and improve patient outcomes.

The Use of Multispectral Imaging in DIEP Free Flap Perforator Selection: A Case Study

Perforator selection is of paramount importance when performing a Deep Inferior Epigastric Perforator flap. Technological advancements within imaging modalities have proved invaluable in preoperative planning and intraoperative assessment. Computed tomographic angiography remains the gold standard for preoperative perforator mapping, while color ultrasound Doppler is considered more reliable for determining vessel caliber. Intraoperatively, an imaging modality that provides sequential, real-time assessment of various perforators’ supply to the flap would provide helpful insight to determine which perforator will optimize flap viability, especially of the most distal, lateral margins. Multispectral imaging, a variant of near infrared imaging, has emerged as an alternative method to assess tissue viability in the operating room as well as postoperatively. Unlike Spy technology, which is invasive and cost ineffective, the Snapshot_NIR (KD203) is a handheld multispectral imaging device utilizing NIR to measure the oxygenation of the hemoglobin in the area to calculate the tissue oxygen content (S_tO₂) displayed in a color image. The following case of a 46-year-old woman undergoing tertiary breast reconstruction for treatment of progressive grade 2 capsular contracture illustrates the utility and ease of KD203 application to intra-operative perforator determination in deep inferior epigastric perforator flap assessment.