Deep Learning-Based Real-time Ureter Identification in Laparoscopic Colorectal Surgery.

BACKGROUND: Iatrogenic ureteral injury is a serious complication of abdominopelvic surgery. Identifying the ureters intraoperatively is essential to avoid iatrogenic ureteral injury. Here, we developed a model that may minimize this complication. IMPACT OF INNOVATION: We applied a deep learning-based semantic segmentation algorithm to the ureter recognition task and developed a deep learning model called UreterNet. This study aimed to verify whether the ureters could be identified in videos of laparoscopic colorectal surgery. TECHNOLOGY MATERIALS AND METHODS: Semantic segmentation of the ureter area was performed using a convolutional neural network-based approach. Feature Pyramid Networks were used as the convolutional neural network architecture for semantic segmentation. Precision, recall, and the dice coefficient were used as the evaluation metrics in this study. PRELIMINARY RESULTS: We created 14,069 annotated images from 304 videos, with 9537, 2266, and 2266 images in the training, validation, and test datasets, respectively. Concerning ureter recognition performance, precision, recall, and the Dice coefficient for the test data were 0.712, 0.722, and 0.716, respectively. Regarding the real-time performance on recorded videos, it took 71 ms for UreterNet to infer all pixels corresponding to the ureter from a single still image and 143 ms to output and display the inferred results as a segmentation mask on the laparoscopic monitor. CONCLUSIONS AND FUTURE DIRECTIONS: UreterNet is a noninvasive method for identifying the ureter in videos of laparoscopic colorectal surgery and can potentially improve surgical safety. Although this could lead to the development of an image-navigated surgical system, it is necessary to verify whether UreterNet reduces the occurrence of iatrogenic ureteral injury.

Cytological Analysis of the Surgical Field During Transanal Total Mesorectal Excision for Rectal Cancer: A Prospective Study.

BACKGROUND: An unexpectedly large number of patients experienced local recurrence with transanal total mesorectal excision in Norway. This appears to be associated with cancer cell spillage during surgery. OBJECTIVE: To investigate the surgical field cytology during transanal total mesorectal excision. DESIGN: This was a prospective cohort study. SETTINGS: This study was conducted at a single center between June and December 2020. PATIENTS: Forty patients with rectal cancer underwent transanal total mesorectal excision. After irrigation of the surgical field, the water specimens were cytologically evaluated at 6 representative steps. The first sample was used as an initial control. The second, third, fourth, fifth, and sixth samples were collected after the first pursestring suture, rectotomy, the second pursestring suture, specimen resection, and anastomosis, respectively. The clinicopathological features and intraoperative complications of the patients were reviewed. MAIN OUTCOME MEASURES: The primary outcome was to evaluate the presence of cancer cells in washing cytological samples. RESULTS: Of the 40 consecutive patients enrolled in this study, 18 patients underwent neoadjuvant chemoradiotherapy. Incomplete first pursestring suture and rectal perforation were observed in 4 (10.0%) and 3 (7.5%) cases, respectively. In the first sample, 31 patients (77.5%) had malignant cells. Malignant findings were detected in 2 patients (5.0%) from the second to fifth samples. None of the sixth sample exhibited any malignant findings. LIMITATIONS: This single-center study had a small sample size. CONCLUSIONS: Cancer cells were initially detected by cytology, but only a few were observed throughout the procedure; however, cancer cells were not detected in the final surgical field. Further follow-up and novel studies are required to obtain clinically significant findings using cytology during transanal total mesorectal excision. See Video Abstract . ANLISIS CITOLGICO DEL CAMPO QUIRRGICO DURANTE LA ESCISIN TOTAL DEL MESORRECTO TRANSANAL PARA EL CNCER DE RECTO UN ESTUDIO PROSPECTIVO: ANTECEDENTES:Un número inesperadamente grande de pacientes experimentó recurrencia local con la escisión total del mesorrecto transanal en Noruega. Esto parece estar asociado con el derrame de células cancerosas durante la cirugía.OBJETIVO:Investigar la citología del campo quirúrgico durante la escisión total del mesorrecto transanal.DISEÑO:Este fue un estudio de cohorte prospectivo.ENTORNO CLINICO:Este estudio se realizó en un solo centro entre junio y diciembre de 2020.PACIENTES:Cuarenta pacientes con cáncer de recto se sometieron a escisión total del mesorrecto transanal. Después de la irrigación del campo quirúrgico, las muestras de agua se evaluaron citológicamente en seis pasos representativos. La primera muestra se utilizó como control inicial. La segunda, tercera, cuarta, quinta y sexta muestras se recolectaron después de la primera sutura en bolsa de tabaco, la rectotomía, la segunda sutura en bolsa de tabaco, la resección de la muestra y la anastomosis, respectivamente. Se revisaron las características clínico-patológicas y las complicaciones intraoperatorias de los pacientes.PRINCIPALES MEDIDAS DE RESULTADO:El resultado primario fue evaluar la presencia de células cancerosas en el lavado de muestras citológicas.RESULTADOS:De los 40 pacientes consecutivos inscritos en este estudio, 18 pacientes se sometieron a quimiorradioterapia neoadyuvante. Se observaron la primera sutura en bolsa de tabaco incompleta y perforación rectal en cuatro (10,0%) y tres (7,5%) casos, respectivamente. En la primera muestra, 31 (77,5%) pacientes tenían células malignas. Se detectaron hallazgos malignos en dos pacientes (5,0%) de la segunda a la quinta muestra. Ninguno de la sexta muestra demostraron hallazgos malignos.LIMITACIONES:Este estudio unicéntrico tuvo un tamaño de muestra pequeño.CONCLUSIONES:Inicialmente se detectaron células cancerosas mediante citología, pero solo se observaron unas pocas durante todo el procedimiento; sin embargo, no se detectaron células cancerosas en el campo quirúrgico final. Se requieren más seguimientos y estudios novedosos para obtener hallazgos clínicamente significativos mediante citología durante la escisión total del mesorrecto transanal. (Traducción- Dr. Francisco M. Abarca-Rendon ).

Predictive risk factors for resection surface-related complications after laparoscopic simultaneous resection of primary colorectal tumor and synchronous liver metastases: a single-center retrospective study.

BACKGROUND: Laparoscopic simultaneous resection (LSR) of primary colorectal tumors and synchronous colorectal liver metastases (sCRLM) has been recently performed. This study aimed to evaluate the postoperative outcomes after LSR and determine the risk factors for resection surface-related complications (RSRC), such as postoperative biliary fistula and liver-transection surface abscess. METHODS: Between 2009 and 2022, consecutive patients with sCRLM who underwent LSR were included. We retrospectively analyzed clinicopathological data, including intraoperative factors and postoperative outcomes. The difficulty level of all liver resections was classified according to the IWATE difficulty scoring system (DSS). We then performed univariate and multivariate analyses to identify the risk factors for RSRC. RESULTS: Of the 112 patients, 94 (83.9%) underwent partial hepatectomy and colorectal surgery. The median DSS score was 5 points (1-11), with 12 (10.7%) patients scoring ≥ 7 points. Postoperative complications were observed in 41 (36.6%) patients, of whom 16 (14.3%) experienced severe complications classified as Clavien-Dindo grade IIIa or higher. There was no postoperative mortality. The most common complication was RSRC (19 patients, 17.0%). Multivariate analysis identified American Society of Anesthesiologists (ASA) classification ≥ 3 [odds ratio (OR) 10.3, 95% confidence interval (CI) 1.37-77.8; P = 0.023], DSS score ≥ 7 points (OR 5.08, 95% CI 1.17-20.0; P = 0.030), and right-sided colectomy (OR 4.67, 95% CI 1.46-15.0; P = 0.009) as independent risk factors for RSRC. Postoperative hospital stays were significantly longer for patients with RSRC than for those without RSRC (22 days vs. 11 days; P < 0.001). CONCLUSION: Short-term outcomes of LSR for patients with sCRLM were acceptable in an experienced center. RSRC was the most common complication, and high-difficulty hepatectomy, right-sided colectomy, and ASA classification ≥ 3 were independent risk factors for RSRC.

Deep learning-based vessel automatic recognition for laparoscopic right hemicolectomy.

BACKGROUND: In laparoscopic right hemicolectomy (RHC) for right-sided colon cancer, accurate recognition of the vascular anatomy is required for appropriate lymph node harvesting and safe operative procedures. We aimed to develop a deep learning model that enables the automatic recognition and visualization of major blood vessels in laparoscopic RHC. MATERIALS AND METHODS: This was a single-institution retrospective feasibility study. Semantic segmentation of three vessel areas, including the superior mesenteric vein (SMV), ileocolic artery (ICA), and ileocolic vein (ICV), was performed using the developed deep learning model. The Dice coefficient, recall, and precision were utilized as evaluation metrics to quantify the model performance after fivefold cross-validation. The model was further qualitatively appraised by 13 surgeons, based on a grading rubric to assess its potential for clinical application. RESULTS: In total, 2624 images were extracted from 104 laparoscopic colectomy for right-sided colon cancer videos, and the pixels corresponding to the SMV, ICA, and ICV were manually annotated and utilized as training data. SMV recognition was the most accurate, with all three evaluation metrics having values above 0.75, whereas the recognition accuracy of ICA and ICV ranged from 0.53 to 0.57 for the three evaluation metrics. Additionally, all 13 surgeons gave acceptable ratings for the possibility of clinical application in rubric-based quantitative evaluations. CONCLUSION: We developed a DL-based vessel segmentation model capable of achieving feasible identification and visualization of major blood vessels in association with RHC. This model may be used by surgeons to accomplish reliable navigation of vessel visualization.

Intraoperative artificial intelligence system identifying liver vessels in laparoscopic liver resection: a retrospective experimental study.

BACKGROUND: The precise recognition of liver vessels during liver parenchymal dissection is the crucial technique for laparoscopic liver resection (LLR). This retrospective feasibility study aimed to develop artificial intelligence (AI) models to recognize liver vessels in LLR, and to evaluate their accuracy and real-time performance. METHODS: Images from LLR videos were extracted, and the hepatic veins and Glissonean pedicles were labeled separately. Two AI models were developed to recognize liver vessels: the "2-class model" which recognized both hepatic veins and Glissonean pedicles as equivalent vessels and distinguished them from the background class, and the "3-class model" which recognized them all separately. The Feature Pyramid Network was used as a neural network architecture for both models in their semantic segmentation tasks. The models were evaluated using fivefold cross-validation tests, and the Dice coefficient (DC) was used as an evaluation metric. Ten gastroenterological surgeons also evaluated the models qualitatively through rubric. RESULTS: In total, 2421 frames from 48 video clips were extracted. The mean DC value of the 2-class model was 0.789, with a processing speed of 0.094 s. The mean DC values for the hepatic vein and the Glissonean pedicle in the 3-class model were 0.631 and 0.482, respectively. The average processing time for the 3-class model was 0.097 s. Qualitative evaluation by surgeons revealed that false-negative and false-positive ratings in the 2-class model averaged 4.40 and 3.46, respectively, on a five-point scale, while the false-negative, false-positive, and vessel differentiation ratings in the 3-class model averaged 4.36, 3.44, and 3.28, respectively, on a five-point scale. CONCLUSION: We successfully developed deep-learning models that recognize liver vessels in LLR with high accuracy and sufficient processing speed. These findings suggest the potential of a new real-time automated navigation system for LLR.

Development of a laparoscopic sigmoidectomy simulator: Sigmaster.

The sigmoid colon simulator was designed to accurately reproduce the anatomical layer structure and the arrangement of characteristic organs in each layer, and to have conductivity so that energy devices can be used. Dry polyester fibers were used to reproduce the layered structures, which included characteristic blood vessels, nerve sheaths, and intestinal tracts. The adhesive strength of the layers was controlled to allow realistic peeling techniques. The features of the Sigmaster are illustrated through a comparison of simulated sigmoidectomy using Sigmaster and actual surgery. We developed a laparoscopic sigmoidectomy simulator called Sigmaster. Sigmaster is a training device that closely reproduces the membrane structures of the human body and allows surgeons to experience the entire laparoscopic sigmoidectomy process.

Two-team lateral lymph node dissection assisted by the transanal approach for locally advanced lower rectal cancer: comparison with the conventional transabdominal approach.

BACKGROUND: An optimal surgical approach to lateral lymph node dissection (LLND) remains controversial. With the recent popularity of transanal total mesorectal excision, a two-team procedure combining the transabdominal and transanal approaches was established as a novel approach to LLND. This study aimed to clarify the safety and feasibility of two-team LLND (2team-LLND) and compare its short-term outcomes with those of conventional transabdominal LLND (Conv-LLND). METHODS: Between April 2013 and March 2020, 463 patients diagnosed with primary locally advanced rectal cancer underwent a transanal total mesorectal excision; among them, 93 patients who underwent bilateral prophylactic LLND were included in this single-center, retrospective study. Among these patients, 50 and 43 patients underwent Conv-LLND (the Conv-LLND group) and 2team-LLND (the 2team-LLND group), respectively. The short-term outcomes, including the operation time, blood loss volume, number of complications, and number of harvested lymph nodes, were compared between the two groups. RESULTS: The intraoperative and postoperative complications in the 2team-LLND group were equivalent to those in the Conv-LLND group; furthermore, the incidence of postoperative urinary retention in the 2team-LLND group was acceptably low (9%). Compared with the Conv-LLND group, the 2team-LLND group had a significantly shorter operation time (P = 0.003), lower median blood loss (P = 0.02), and higher number of harvested lateral lymph nodes (P = 0.0005). CONCLUSION: The intraoperative and postoperative complications of 2team-LLND were comparable with those of Conv-LLND. Thus, 2team-LLND was safe and feasible for advanced lower rectal cancer. Moreover, it was superior to Conv-LLND in terms of the operation time, blood loss volume, and number of harvested lateral lymph nodes. Therefore, it can be a promising LLND approach.

Single-center comparative study of short-term outcomes of transanal and laparoscopic total mesorectal excisions for low and middle rectal cancers.

BACKGROUND: Transanal total mesorectal excision is a promising surgical treatment for rectal cancer. However, evidence regarding the differences in outcomes between the transanal and laparoscopic total mesorectal excisions is scarce. We compared the short-term outcomes of transanal and laparoscopic total mesorectal excisions for low and middle rectal cancers. METHODS: This retrospective study included patients who underwent low anterior or intersphincteric resection for middle (5-10 cm) or low (< 5 cm) rectal cancer at the National Cancer Center Hospital East, Japan, from May 2013 to March 2020. Primary rectal adenocarcinoma was confirmed histologically. Circumferential resection margins (CRMs) of resected specimens were measured; margins ≤ 1 mm were considered positive. The operative time, blood loss, hospitalization length, postoperative readmission rate, and short-term treatment results were compared. RESULTS: Four hundred twenty-nine patients were divided into two mesorectal excision groups: transanal (n = 295) and laparoscopic (n = 134). Operative times were significantly shorter in the transanal group than in the laparoscopic group (p < 0.001). The pathological T stage and N status were not significantly different. The transanal group had significantly lower positive CRM rates (p = 0.04), and significantly lower incidence of the Clavien-Dindo grade III (p = 0.02) and IV (p = 0.03) complications. Both groups had distal margin positivity rates of 0%. CONCLUSIONS: Compared to laparoscopic, transanal total mesorectal excision for low and middle rectal cancers has lower incident postoperative complication and CRM-positivity rates, demonstrating the safety and usefulness of local curability for middle and low rectal cancers.

Efficacy of transperineal minimally invasive surgery with laparoscopic abdominoperineal excision for lower rectal cancer.

PURPOSE: In abdominoperineal excision (APE), the advantages of the "down-to-up" approach are expected to be more obvious when performed as a two-team approach, including transperineal minimally invasive surgery (TpMIS). We investigated the efficacy of TpMIS with laparoscopic APE for lower rectal cancer. METHODS: Patients who underwent laparoscopic APE with (n = 20) or without (n = 30) TpMIS between December 2013 and April 2020 were retrospectively reviewed. Patient and tumor characteristics, intraoperative outcome, short-term outcome, and pathological findings were compared. Additional subgroup analyses were performed in technically challenging cases, including male patients, obese patients, and patients with tumors located at the anterior wall. RESULTS: There was no marked difference in the patient or tumor characteristics or short-term outcomes, including morbidity and mortality between the two groups. Pathological results were comparable, and the circumferential resection margin (CRM) positive rate was 10% in both groups. TpMIS achieved a significant reduction in operative time (p = 0.02). In a subgroup analysis, the amount of blood loss was also smaller in males (p = 0.02) and patients with a high BMI (> 25) (p = 0.005) than in others. CONCLUSION: Simultaneously performing TpMIS and laparoscopic APE is feasible owing to the favorable complication and CRM-positive rates. In terms of operative time and blood loss, TpMIS is expected to be advantageous in both easy and challenging cases.

Novel external reinforcement device for gastrointestinal anastomosis in an experimental study.

BACKGROUND: Anastomotic leakage has been reported to occur when the load on the anastomotic site exceeds the resistance created by sutures, staples, and early scars. It may be possible to avoid anastomotic leakage by covering and reinforcing the anastomotic site with a biocompatible material. The aim of this study was to evaluate the safety and feasibility of a novel external reinforcement device for gastrointestinal anastomosis in an experimental model. METHODS: A single pig was used in this non-survival study, and end-to-end anastomoses were created in six small bowel loops by a single-stapling technique using a circular stapler. Three of the six anastomoses were covered with a novel external reinforcement device. Air was injected, a pressure test of each anastomosis was performed, and the bursting pressure was measured. RESULTS: Reinforcement of the anastomotic site with the device was successfully performed in all anastomoses. The bursting pressure was 76.1 ± 5.7 mmHg in the control group, and 126.8 ± 6.8 mmHg in the device group, respectively. The bursting pressure in the device group was significantly higher than that in the control group (p = 0.0006). CONCLUSIONS: The novel external reinforcement device was safe and feasible for reinforcing the anastomoses in the experimental model.

Anastomosis-Related Complications After Stapled Anastomosis With Reinforced Sutures in Transanal Total Mesorectal Excision for Low Rectal Cancer: A Retrospective Single-Center Study.

BACKGROUND: The International Transanal Total Mesorectal Excision Registry group showed that transanal total mesorectal excision included clinical issues regarding anastomosis-related complications. OBJECTIVE: This study evaluated anastomotic complications in patients whose anastomoses were created with the stapler plus reinforced sutures procedure after transanal total mesorectal excision for low rectal cancer. DESIGN: This was a retrospective single-center study. SETTING: The study was conducted at the National Cancer Center Hospital East, Japan. PATIENTS: Between June 2016 and December 2019, 150 patients underwent transanal total mesorectal excision for low rectal cancer. Stapled anastomosis was performed for 55 patients, and coloanal handsewn anastomosis was performed for 95 patients. Blood perfusion of the colon was routinely evaluated with intraoperative indocyanine green fluorescence angiography. All patients who underwent stapled anastomosis received additional handsewn sutures on all rounds of the stapled line. Patients who underwent intersphincteric resection were excluded. MAIN OUTCOME MEASURES: The anastomosis-related complications were compared between the groups. RESULTS: Early anastomotic leakage was found in one (1.8%) and eight (8.4%) patients in the stapled group and handsewn group. Overall anastomosis-related complications, pelvic abscess, and anastomotic stenosis were significantly less frequent in the stapled group (p < 0.001, p < 0.048, and p < 0.032). Incomplete donuts after the stapled anastomosis were observed in 9 patients (16.4%); however, we reinforced all around the stapled line in these patients, and this reduced the subsequent occurrence of anastomotic leakage. LIMITATIONS: First, this was a retrospective single-center study that was not randomized or controlled. Second, there were chronological differences regarding the anastomotic method between the two groups. Third, our study included a relatively small number of patients who received preoperative chemoradiotherapy. CONCLUSIONS: Stapled anastomosis with reinforced handsewn sutures resulted in fewer anastomosis-related complications than did coloanal handsewn anastomosis after transanal total mesorectal excision for low rectal cancer; thus, the former may be superior and should be the preferred method, when technically possible. See Video Abstract at http://links.lww.com/DCR/B749.COMPLICACIONES RELACIONADAS CON LAS ANASTOMOSIS ENGRAMPADAS Y REFORZADAS CON SUTURAS EN LA EXCISIÓN TOTAL DEL MESORRECTO POR VÍA TRANSANAL EN CASOS DE CÁNCER DE RECTO BAJO: ESTUDIO RETROSPECTIVO UNICÉNTRICO. ANTECEDENTES: El grupo del Registro Internacional de Excisión Total del Mesorrecto por vía Transanal mostró que la excisión total mesorrectal transanal incluía problemas clínicos relacionados a las complicaciones involucradas con la anastomosis. OBJETIVO: Se evaluaron las complicaciones anastomóticas en pacientes cuyas anastomosis se realizaron con engrampadora reforzada de suturas después de la excisión total de l mesorrecto por vía transanal en casos de cáncer de recto bajo. DISEO: Estudio retrospectivo unicéntrico. AJUSTE: El Hospital del Centro Nacional del Cáncer del Este, Japón. PACIENTES: Entre junio de 2016 y diciembre de 2019, 150 pacientes se sometieron a excisión total del mesorrecto por vía transanal en casos de cáncer de recto bajo. Se realizó anastomosis con engrampadora en 55 y anastomosis coloanal suturada a mano en 95 pacientes. La perfusión tisular sanguínea del colon operado se evaluó de forma rutinaria con angiografía de fluorescencia con verde de indocianina intraoperatoria. Todos los pacientes que se sometieron a anastomosis con grapas recibieron suturas realizadas a mano adicionales sobre la totalidad de la línea de grapas. Se excluyeron los pacientes sometidos a resección interesfintérica. PRINCIPALES MEDIDAS DE RESULTADO: Las complicaciones relacionadas con la anastomosis se compararon entre los grupos. RESULTADOS: Se encontró fuga anastomótica temprana en 1 (1.8%) y 8 (8.4%) pacientes en el grupo de engrampado y en el grupo suturado a mano, respectivamente. En general, las complicaciones relacionadas con la anastomosis, el absceso pélvico y la estenosis anastomótica fueron significativamente menos frecuentes en el grupo con grapas (p < 0.001, p < 0.048, p < 0.032, respectivamente). Se observaron donas incompletas después de la anastomosis grapada en 9 pacientes (16,4%); sin embargo, reforzamos todo alrededor de la línea de grapas en estos pacientes, y esto redujo la aparición posterior de fugas anastomóticas. LIMITACIONES: Inicialmente, este fue un estudio retrospectivo de un solo centro que no fue aleatorizado ni controlado. En segundo lugar, hubo diferencias cronológicas con respecto al método anastomótico entre los dos grupos. En tercer lugar, nuestro estudio incluyó un número relativamente pequeño de pacientes que recibieron quimiorradioterapia preoperatoria. CONCLUSIONES: La anastomosis engrapada reforzada con suturas realizadas a mano dio como resultado menos complicaciones relacionadas con la anastomosis que la anastomosis coloanal suturada a mano después de la excisión total del mesorrecto por vía transanal en casos de cáncer de recto bajo; por tanto, el primero puede ser superior y debería ser el método preferido, cuando sea técnicamente posible. Consulte Video Resumen en http://links.lww.com/DCR/B749. (Traducción-Dr. Xavier Delgadillo).

Artificial Intelligence-Based Total Mesorectal Excision Plane Navigation in Laparoscopic Colorectal Surgery.

BACKGROUND: Total mesorectal excision is the standard surgical procedure for rectal cancer because it is associated with low local recurrence rates. To the best of our knowledge, this is the first study to use an image-guided navigation system with total mesorectal excision. IMPACT OF INNOVATION: The impact of innovation is the development of a deep learning-based image-guided navigation system for areolar tissue in the total mesorectal excision plane. Such a system might be helpful to surgeons because areolar tissue can be used as a landmark for the appropriate dissection plane. TECHNOLOGY, MATERIALS, AND METHODS: This was a single-center experimental feasibility study involving 32 randomly selected patients who had undergone laparoscopic left-sided colorectal resection between 2015 and 2019. Deep learning-based semantic segmentation of areolar tissue in the total mesorectal excision plane was performed. Intraoperative images capturing the total mesorectal excision scene extracted from left colorectal laparoscopic resection videos were used as training data for the deep learning model. Six hundred annotation images were created from 32 videos, with 528 images in the training and 72 images in the test data sets. The experimental feasibility study was conducted at the Department of Colorectal Surgery, National Cancer Center Hospital East, Chiba, Japan. Dice coefficient was used to evaluate semantic segmentation accuracy for areolar tissue. PRELIMINARY RESULTS: The developed semantic segmentation model helped locate and highlight the areolar tissue area in the total mesorectal excision plane. The accuracy and generalization performance of deep learning models depend mainly on the quantity and quality of the training data. This study had only 600 images; thus, more images for training are necessary to improve the recognition accuracy. CONCLUSION AND FUTURE DIRECTIONS: We successfully developed a total mesorectal excision plane image-guided navigation system based on an areolar tissue segmentation approach with high accuracy. This may aid surgeons in recognizing the total mesorectal excision plane for dissection.

Trans-anal surgery with the taTME technique for rectal gastrointestinal stromal tumors: a retrospective study.

PURPOSE: Rectal gastrointestinal stromal tumors (GISTs) surgery is often challenging owing to the anatomical constraints of the narrow pelvis and tumor hugeness. Despite the increasing number of patients undergoing trans-anal total mesorectal excision (taTME) globally, the feasibility of trans-anal surgery with the taTME technique for rectal GISTs remains unclear. We aimed to evaluate the feasibility of trans-anal surgery with the taTME technique for rectal GISTs. METHODS: Using a prospectively collected database, we retrospectively analyzed the clinical findings, surgical outcomes, pathological outcomes, urinary and anal functions, and prognoses of patients who underwent trans-anal surgery with the taTME technique for primary rectal GISTs at the National Cancer Center Hospital East from September 2014 to March 2020. RESULTS: Twenty-one patients with primary rectal GISTs were included in this study. The median distance from the anal verge to the lower edge of the tumor was 40 mm (range, 15-60 mm), and the median tumor size was 59 mm (range, 11-175 mm). Moreover, seven and 14 patients underwent one-team and two-team surgeries, respectively, with curative intent. Nineteen patients (90.5%) underwent anus-preserving surgery, and the urinary tracts were preserved in all cases. Two-team surgery showed a significantly lower blood loss volume and shorter operation time than one-team surgery (58 vs. 222 mL, P = 0.017; 184 vs 356 min, P = 0.041, respectively). The pathological negative-margin resection rate was 100%. During the follow-up period, no patient developed local GIST recurrence and one (4.8%) developed distant metastasis. CONCLUSION: Trans-anal surgery with the taTME technique is feasible for rectal GISTs, and two-team surgery may be more advantageous than one-team surgery in terms of operation time and blood loss.

Deep learning-based automatic surgical step recognition in intraoperative videos for transanal total mesorectal excision.

BACKGROUND: Dividing a surgical procedure into a sequence of identifiable and meaningful steps facilitates intraoperative video data acquisition and storage. These efforts are especially valuable for technically challenging procedures that require intraoperative video analysis, such as transanal total mesorectal excision (TaTME); however, manual video indexing is time-consuming. Thus, in this study, we constructed an annotated video dataset for TaTME with surgical step information and evaluated the performance of a deep learning model in recognizing the surgical steps in TaTME. METHODS: This was a single-institutional retrospective feasibility study. All TaTME intraoperative videos were divided into frames. Each frame was manually annotated as one of the following major steps: (1) purse-string closure; (2) full thickness transection of the rectal wall; (3) down-to-up dissection; (4) dissection after rendezvous; and (5) purse-string suture for stapled anastomosis. Steps 3 and 4 were each further classified into four sub-steps, specifically, for dissection of the anterior, posterior, right, and left planes. A convolutional neural network-based deep learning model, Xception, was utilized for the surgical step classification task. RESULTS: Our dataset containing 50 TaTME videos was randomly divided into two subsets for training and testing with 40 and 10 videos, respectively. The overall accuracy obtained for all classification steps was 93.2%. By contrast, when sub-step classification was included in the performance analysis, a mean accuracy (± standard deviation) of 78% (± 5%), with a maximum accuracy of 85%, was obtained. CONCLUSIONS: To the best of our knowledge, this is the first study based on automatic surgical step classification for TaTME. Our deep learning model self-learned and recognized the classification steps in TaTME videos with high accuracy after training. Thus, our model can be applied to a system for intraoperative guidance or for postoperative video indexing and analysis in TaTME procedures.

Real-time vascular anatomical image navigation for laparoscopic surgery: experimental study.

BACKGROUND: Recognition of the inferior mesenteric artery (IMA) during colorectal cancer surgery is crucial to avoid intraoperative hemorrhage and define the appropriate lymph node dissection line. This retrospective feasibility study aimed to develop an IMA anatomical recognition model for laparoscopic colorectal resection using deep learning, and to evaluate its recognition accuracy and real-time performance. METHODS: A complete multi-institutional surgical video database, LapSig300 was used for this study. Intraoperative videos of 60 patients who underwent laparoscopic sigmoid colon resection or high anterior resection were randomly extracted from the database and included. Deep learning-based semantic segmentation accuracy and real-time performance of the developed IMA recognition model were evaluated using Dice similarity coefficient (DSC) and frames per second (FPS), respectively. RESULTS: In a fivefold cross-validation conducted using 1200 annotated images for the IMA semantic segmentation task, the mean DSC value was 0.798 (± 0.0161 SD) and the maximum DSC was 0.816. The proposed deep learning model operated at a speed of over 12 FPS. CONCLUSION: To the best of our knowledge, this is the first study to evaluate the feasibility of real-time vascular anatomical navigation during laparoscopic colorectal surgery using a deep learning-based semantic segmentation approach. This experimental study was conducted to confirm the feasibility of our model; therefore, its safety and usefulness were not verified in clinical practice. However, the proposed deep learning model demonstrated a relatively high accuracy in recognizing IMA in intraoperative images. The proposed approach has potential application in image navigation systems for unfixed soft tissues and organs during various laparoscopic surgeries.

Endoscopic resection combined with the Cryoballoon focal ablation system in the porcine normal esophagus: a preclinical study.

BACKGROUND: The Cryoballoon focal ablation system (CbFAS) for dysplastic Barrett's esophagus is simple, time-saving and has high therapeutic efficacy. This study aimed to evaluate the technical feasibility and tissue damage with combination therapy of endoscopic resection (ER) and CbFAS in porcine models. METHODS: Three pigs (A, B, and C) were included, and all ER procedures were performed by endoscopic mucosal resection using the Cap method (EMR). Combination therapy for each pig was performed as follows: (a) CbFAS was performed for a post-EMR mucosal defect for Pig A; (b) CbFAS for post-EMR scar for Pig B, and (c) EMR for post-CbFAS scar for Pig C. All pigs were euthanized at 32 days after the initial procedure, and the tissue damage was evaluated. RESULTS: All endoscopic procedures were followed as scheduled. None of the subjects experienced anorexia, rapid weight loss, bleeding, and perforation during the observation period. They were euthanized at 32 days after the initial endoscopic procedure. On histological assessment, there was little difference between the tissue that was treated with CbFAS alone and that treated with CbFAS in combination with ER. CONCLUSION: Combination therapy with ER and CbFAS can be technically feasible, and its outcome was not significantly different from CbFAS alone in terms of tissue damage.

Computer-assisted real-time automatic prostate segmentation during TaTME: a single-center feasibility study.

BACKGROUND: Urethral injuries (UIs) are significant complications pertaining to transanal total mesorectal excision (TaTME). It is important for surgeons to identify the prostate during TaTME to prevent UI occurrence; intraoperative image navigation could be considered useful in this regard. This study aims at developing a deep learning model for real-time automatic prostate segmentation based on intraoperative video during TaTME. The proposed model's performance has been evaluated. METHODS: This was a single-institution retrospective feasibility study. Semantic segmentation of the prostate area was performed using a convolutional neural network (CNN)-based approach. DeepLab v3 plus was utilized as the CNN model for the semantic segmentation task. The Dice coefficient (DC), which is calculated based on the overlapping area between the ground truth and predicted area, was utilized as an evaluation metric for the proposed model. RESULTS: Five hundred prostate images were randomly extracted from 17 TaTME videos, and the prostate area was manually annotated on each image. Fivefold cross-validation tests were performed, and as observed, the average DC value equaled 0.71 ± 0.04, the maximum value being 0.77. Additionally, the model operated at 11 fps, which provides acceptable real-time performance. CONCLUSIONS: To the best of the authors' knowledge, this is the first effort toward realization of computer-assisted TaTME, and results obtained in this study suggest that the proposed deep learning model can be utilized for real-time automatic prostate segmentation. In future endeavors, the accuracy and performance of the proposed model will be improved to enable its use in practical applications, and its capability to reduce UI risks during TaTME will be verified.

Sacral neuromodulation for the prevention of a permanent stoma in patients with severe defecation disorder following intersphincteric resection.

PURPOSE: Severe defecation disorder occurs frequently in coloanal anastomosis for low rectal cancer, and may affect quality of life. Sacral neuromodulation (SNM) has been reported to be successful after rectal resection, but there are no results for patients treated with intersphincteric resection (ISR). METHODS: A retrospective single-center study of SNM was performed for patient with defecation disorder following ISR. Pre- and post-treatment bowel frequencies, fecal incontinence episodes, and Wexner, LARS and FIQL scores were assessed to evaluate the efficacy. A good response was defined as ≥ 50% reduction of bowel frequency per day or fecal incontinence episodes per week. RESULTS: 10 patients (7 males, mean age 67.5 years) underwent SNM. All patients had severe fecal incontinence with a median Wexner score of 15 (13-20) and a median LARS score of 41 (36-41). The Wexner score improved after SNM, but not significantly (p = 0.06). LARS and FIQL scores significantly improved after SNM (p = 0.02, p = 0.01). At the end of follow-up, the good response rate was 40%. Three cases without a good response required creation of a permanent stoma. CONCLUSION: Seven out of 10 patients did not require a permanent colostomy after SNM. SNM should be considered before performing a permanent colostomy.

Delorme surgery for colonic mucosal prolapse after intersphincteric resection.

PURPOSE: Mucosal prolapse at the site of anastomosis is a long-term complication unique to ISR. It reduces the QOL of patients due to a worsened anal function and local symptoms around the anus. We herein sought to assess the surgical outcomes after Delorme surgery for these patients. METHODS: ISR was performed in 720 patients with low rectal cancer between January 2001 and March 2019 at the National Cancer Center Hospital East. Among these patients, the 33 (4.5%) who underwent initial Delorme surgery for postoperative colonic mucosal prolapse were identified from the medical records and then were analyzed retrospectively. We estimated the anal function using Wexner's incontinence score and assessed whether local anal symptoms due to the prolapse improved postoperatively. RESULTS: Stoma closure was performed before Delorme surgery in 15 (45.5%) patients, and we compared the preoperative and postoperative anal function in these patients. The average Wexner's incontinence score changed from 15.1 before to 12.9 after Delorme surgery. Local symptoms around the anus improved in all 33 (100%) patients. Recurrence of colonic mucosal prolapse occurred in 5 patients (15%), and Delorme surgery was reperformed in these cases. CONCLUSION: Delorme surgery for colonic mucosal prolapse following ISR has clinical benefits for both improving anal local symptoms and slightly improving the anal function.

Impact of intraoperative indocyanine green fluorescence angiography on anastomotic leakage after laparoscopic sphincter-sparing surgery for malignant rectal tumors.

PURPOSE: Whether indocyanine green fluorescence angiography (ICG-FA) during rectal surgery is effective in reducing anastomotic leakage remains unclear. This study aimed to investigate the effect of intraoperative ICG-FA on anastomotic leakage after sphincter-sparing surgery for malignant rectal tumors. METHODS: This was a retrospective, single-center cohort study conducted on 852 consecutive patients who underwent laparoscopic sphincter-sparing surgery from January 2007 to June 2017 at our institution. The incidence of anastomotic leakage was compared between patients who underwent ICG-FA to determine the proximal resection margin and those in whom this technique was not performed, using logistic regression analysis, including propensity score. RESULTS: A total of eight patients were excluded (one patient with previous low anterior resection and seven patients who underwent simultaneous resection for other primary cancers), resulting in 844 patients being analyzed. Before propensity score matching, 141 patients (16.7%) who underwent ICG-FA were compared with 703 patients (83.3%) in whom ICG-FA was not performed. The incidence of anastomotic leakage was 2.8% (4/141) in the ICG-FA group and 12.4% (87/703) in the control group (p = 0.001). After propensity score matching (n = 420), the patient characteristics between the two groups were well balanced, and the incidence of anastomotic leakage was 2.8% (4/141) in the ICG-FA group and 13.6% (38/279) in the control group (p = 0.001). Logistic regression analyses using propensity score showed that patients who underwent ICG-FA had significantly lower odds of anastomotic leakage. CONCLUSION: Intraoperative ICG-FA is a promising method to reduce anastomotic leakage after laparoscopic rectal surgery.