Artificial Intelligence for Surgical Safety: Automatic Assessment of the Critical View of Safety in Laparoscopic Cholecystectomy Using Deep Learning.

OBJECTIVE: To develop a deep learning model to automatically segment hepatocystic anatomy and assess the criteria defining the critical view of safety (CVS) in laparoscopic cholecystectomy (LC). BACKGROUND: Poor implementation and subjective interpretation of CVS contributes to the stable rates of bile duct injuries in LC. As CVS is assessed visually, this task can be automated by using computer vision, an area of artificial intelligence aimed at interpreting images. METHODS: Still images from LC videos were annotated with CVS criteria and hepatocystic anatomy segmentation. A deep neural network comprising a segmentation model to highlight hepatocystic anatomy and a classification model to predict CVS criteria achievement was trained and tested using 5-fold cross validation. Intersection over union, average precision, and balanced accuracy were computed to evaluate the model performance versus the annotated ground truth. RESULTS: A total of 2854 images from 201 LC videos were annotated and 402 images were further segmented. Mean intersection over union for segmentation was 66.6%. The model assessed the achievement of CVS criteria with a mean average precision and balanced accuracy of 71.9% and 71.4%, respectively. CONCLUSIONS: Deep learning algorithms can be trained to reliably segment hepatocystic anatomy and assess CVS criteria in still laparoscopic images. Surgical-technical partnerships should be encouraged to develop and evaluate deep learning models to improve surgical safety.

Single Snapshot Imaging of Optical Properties (SSOP) for Perfusion Assessment during Gastric Conduit Creation for Esophagectomy: An Experimental Study on Pigs.

Anastomotic leakage (AL) is a serious complication occurring after esophagectomy. The current knowledge suggests that inadequate intraoperative perfusion in the anastomotic site contributes to an increase in the AL rate. Presently, clinical estimation undertaken by surgeons is not accurate and new technology is necessary to improve the intraoperative assessment of tissue oxygenation. In the present study, we demonstrate the application of a novel optical technology, namely Single Snapshot imaging of Optical Properties (SSOP), used to quantify StO2% in an open surgery experimental gastric conduit (GC) model. After the creation of a gastric conduit, local StO2% was measured with a preclinical SSOP system for 60 min in the antrum (ROI-A), corpus (ROI-C), and fundus (ROI-F). The removed region (ROI-R) acted as ischemic control. ROI-R had statistically significant lower StO2% when compared to all other ROIs at T15, T30, T45, and T60 (p < 0.0001). Local capillary lactates (LCLs) and StO2% correlation was statistically significant (R = -0.8439, 95% CI -0.9367 to -0.6407, p < 0.0001). Finally, SSOP could discriminate resected from perfused regions and ROI-A from ROI-F (the future anastomotic site). In conclusion, SSOP could well be a suitable technology to assess intraoperative perfusion of GC, providing consistent StO2% quantification and ROIs discrimination.

Intraoperative Time-Out to Promote the Implementation of the Critical View of Safety in Laparoscopic Cholecystectomy: A Video-Based Assessment of 343 Procedures.

BACKGROUND: The critical view of safety (CVS) is poorly adopted in surgical practices, although it is recommended ubiquitously to prevent major bile duct injuries during laparoscopic cholecystectomy (LC). This study aimed to investigate whether performing a short intraoperative time-out can improve CVS implementation. STUDY DESIGN: In this before vs after study, surgeons performing LCs at an academic center were invited to use a 5-second long time-out to verify CVS before dividing the cystic duct (5-second rule). The primary aim was to compare the rate of CVS achievement for LC performed in the year before vs the year after implementation of the 5-second rule. The CVS achievement rate was computed after exclusion of bailout procedures using a mediated video-based assessment made by 2 independent reviewers. Clinical outcomes, LC workflows, and postoperative reports were also compared. RESULTS: Three hundred and forty-three of 381 LC performed between December 2017 and November 2019 (171 before and 172 after implementation of the 5-second rule) were analyzed. The 5-second rule was associated with a significantly increased rate of CVS achievement (15.9% vs 44.1% before vs after the 5-second rule, respectively; p < 0.001). Significant differences were also observed with respect to the rate of bailout procedures (8.2% vs 15.7%; p = 0.04), median time (hours:minutes:seconds) to clip the cystic duct or artery (00:17:26; interquartile range 00:11:48 to 00:28:35 vs 00:23:12; interquartile range 00:14:29 to 00:31:45 duration; p = 0.007), and the rate of postoperative CVS reporting (1.3% vs 28.8%; p < 0.001). Postoperative morbidity was comparable (1.8% vs 2.3%; p = 0.68). CONCLUSIONS: Performing a short intraoperative time-out was associated with an improved CVS achievement rate. Systematic intraoperative cognitive aids should be studied to sustain the uptake of guidelines.

Endoscopic assessment of morphological and histopathological upper gastrointestinal changes after endoscopic sleeve gastroplasty.

BACKGROUND: Endoscopic sleeve gastroplasty (ESG) is a promising bariatric endoluminal procedure. Restriction and shortening of the stomach are obtained by means of non-resorbable full-thickness sutures, thus inducing the formation of several endoluminal pouches in which food can stagnate. The effect of ESG on the upper gastrointestinal tract has never been investigated. OBJECTIVES: This study objectively evaluates endoscopic macroscopic and histopathologic changes within 12-month follow-up (FU) in patients who underwent ESG. SETTING: Retrospective study on a prospective database of patients who underwent ESG at our tertiary referral center between October 2016 and March 2019. METHODS: All consecutive patients undergoing upper endoscopy (EGD) preoperatively and 6 and 12 months after ESG were included. The upper gastrointestinal tract was evaluated for mucosal abnormalities and biopsies were systematically taken. RESULTS: Eighty-six patients were included. EGD results were as follows: esophagitis decreased from 14% preoperatively to 3.6% and 1.2% at 6- and 12-month FU, respectively (P = .001); 19.8% of patients presented preoperatively a type I hiatal hernia <4 cm and showed no size increment or de novo hiatal hernia at 6- and 12-months. The rate of preoperative hyperemic (23.2%) and erosive (3.5%) gastropathy decreased to 9.5% and 1.2% at 6 months and 17.4% and 1.2% at 12 months, respectively. Gastric ulcer (4.7%), duodenal hyperemic mucosa (1.2%) and duodenal micro-ulcerations (2.3%) detected preoperatively were not present at 6- and 12-month EGD. The rate of histopathological disease, which was 68.1% preoperatively, dropped to 29.2% at 12 months, chronic gastritis decreased from 40.3% to 26.4%, acute gastritis from 9.7% to 0%, and acute inflammation on chronic gastritis from 18% to 2.8% (P < .001). CONCLUSION: ESG is a safe procedure that does not promote the new onset of macroscopic and histopathologic abnormalities within 1-year follow-up.

Intraoperative Perfusion Assessment in Enhanced Reality Using Quantitative Optical Imaging: An Experimental Study in a Pancreatic Partial Ischemia Model.

To reduce the risk of pancreatic fistula after pancreatectomy, a satisfactory blood flow at the pancreatic stump is considered crucial. Our group has developed and validated a real-time computational imaging analysis of tissue perfusion, using fluorescence imaging, the fluorescence-based enhanced reality (FLER). Hyperspectral imaging (HSI) is another emerging technology, which provides tissue-specific spectral signatures, allowing for perfusion quantification. Both imaging modalities were employed to estimate perfusion in a porcine model of partial pancreatic ischemia. Perfusion quantification was assessed using the metrics of both imaging modalities (slope of the time to reach maximum fluorescence intensity and tissue oxygen saturation (StO2), for FLER and HSI, respectively). We found that the HSI-StO2 and the FLER slope were statistically correlated using the Spearman analysis (R = 0.697; p = 0.013). Local capillary lactate values were statistically correlated to the HSI-StO2 and to the FLER slope (R = -0.88; p < 0.001 and R = -0.608; p = 0.0074). HSI-based and FLER-based lactate prediction models had statistically similar predictive abilities (p = 0.112). Both modalities are promising to assess real-time pancreatic perfusion. Clinical translation in human pancreatic surgery is currently underway.

Quantitative serosal and mucosal optical imaging perfusion assessment in gastric conduits for esophageal surgery: an experimental study in enhanced reality.

INTRODUCTION/OBJECTIVE: Gastric conduit (GC) is used for reconstruction after esophagectomy. Anastomotic leakage (AL) incidence remains high, given the extensive disruption of the gastric circulation. Currently, there is no reliable method to intraoperatively quantify gastric perfusion. Hyperspectral imaging (HSI) has shown its potential to quantify serosal StO2. Confocal laser endomicroscopy (CLE) allows for automatic mucosal microcirculation quantification as functional capillary density area (FCD-A). The aim of this study was to quantify serosal and mucosal GC's microperfusion using HSI and CLE. Local capillary lactate (LCL) served as biomarker. METHODS: GC was formed in 5 pigs and serosal StO2% was quantified at 3 regions of interest (ROI) using HSI: fundus (ROI-F), greater curvature (ROI-C), and pylorus (ROI-P). After intravenous injection of sodium-fluorescein (0.5 g), CLE-based mucosal microperfusion was assessed at the corresponding ROIs, and LCLs were quantified via a lactate analyzer. RESULTS: StO2 and FCD-A at ROI-F (41 ± 10.6%, 3.3 ± 3.8, respectively) were significantly lower than ROI-C (68.2 ± 6.7%, p value: 0.005; 18.4 ± 7, p value: 0.01, respectively) and ROI-P (72 ± 10.4%, p value: 0.005; 15.7 ± 3.2 p value: 0.001). LCL value at ROI-F (9.6 ± 4.7 mmol/L) was significantly higher than at ROI-C (2.6 ± 1.2 mmol/L, p value: 0.04) and ROI-P (2.6 ± 1.3 mmol/L, p value: 0.04). No statistically significant difference was found in all metrics between ROI-C and ROI-P. StO2 correlated with FCD-A (Pearson's r = 0.67). The LCL correlated negatively with both FCD-A (Spearman's r = - 0.74) and StO2 (Spearman's r = - 0.54). CONCLUSIONS: GC formation causes a drop in serosal and mucosal fundic perfusion. HSI and CLE correlate well and might become useful intraoperative tools.

Demarcation Line Assessment in Anatomical Liver Resection: An Overview.

Anatomical liver resection (ALR) is the preferred oncological approach for the treatment of primary liver malignancies, such as hepatocellular carcinoma and intrahepatic cholangiocarcinoma. The demarcation line (DL) is formed by means of selective vascular occlusion and is used by surgeons to guide ALR. Emerging intraoperative technologies are playing a major role to enhance the surgeon's vision and ensure a precise oncologic surgery. In this article, a brief overview of modalities to assess the DL during ALRs is presented, from the established conventional techniques to future perspectives.

Does endoscopic sleeve gastroplasty stand the test of time? Objective assessment of endoscopic ESG appearance and its relation to weight loss in a large group of consecutive patients.

INTRODUCTION: Endoscopic sleeve gastroplasty (ESG) is a promising bariatric treatment. Gastric volume reduction and delayed gastric emptying are the probable mechanisms driving weight loss. However, there are concerns regarding the overtime ESG effectiveness. This study aims to evaluate the correlation between endoscopic gastroplasty integrity overtime and weight loss. PATIENTS AND METHODS: Patients undergoing follow-up endoscopy (6 and 12 months) after ESG were included. ESG were classified in three groups according to endoscopic appearance: open when all the stiches were loose; partially intact if at least one stitch was loose; intact if all the stitches were present and tight. Initial BMI, excess weight loss (%EWL) and total weight loss (%TWL) at 6 and 12 months were assessed against gastroplasty endoscopic appearance. RESULTS: From October 2016 to April 2019, 133 patients underwent ESG, 87 (65.4%) had a follow-up EGD at 6 months. ESG was open in six cases (6.9%), partially intact in 38 (43.7%) and intact in 43 (49.4%). The overall %EWL and %TWL was 34.5 ± 19.8 and 13.2 ± 7.4, respectively; 25.7 ± 26.9 and 11.8 ± 11.8 for the open group, 30.8 ± 20.1 and 12.4 ± 7.8 for the partially intact group; 39.1 ± 19.7 and 14.0 ± 6.4 for the intact gastroplasty. Forty-one patients underwent a 12 months endoscopy: 10 (24.4%) had an intact ESG, 24 (58.5%) had a partially intact gastroplasty, and in 7 (17.0%) cases the sutures were lost. Overall %EWL and %TWL at 12 months was 34.3 ± 21.9 and 13.1 ± 8.1: 19.3 ± 13.4 and 8.9 ± 6.1 for the open group; 36.0 ± 24.2 and 13.1 ± 8.9 for the partially intact group; 40.3 ± 17.3 and 17.2 ± 5.4 for the intact group. ESG appearance correlated with preoperative BMI (r 0.34; p 0.001) and %EWL at 6 months (r 0.22; p 0.035) and 12 months (r 0.29; p 0.065). CONCLUSION: This preliminary work shows that weight loss correlates with ESG endoscopic appearance over time. Initial BMI predicts endoscopic suture duration over time. Larger studies and longer follow-up are needed.

Superior outcomes (but at higher costs) of non-operative management with interval appendectomy over immediate surgery in appendicitis with abscess: Results from a large adult population cohort.

INTRODUCTION: The aim of this study was to compare surgical outcomes and hospitalization costs between immediate surgery and non-operative management followed by interval appendectomy in adults presenting with appendicitis with abscess. METHODS: From 2003 to 2015, 3316 patients presented with appendicitis, including 101 who presented with appendicular abscess. Between 2003 and 2006, 33 patients with appendicular abscess were managed with emergency operations (emergency group). Non-operative management followed by interval appendectomy was implemented in 2007 and offered to 68 patients during the study period. Of these patients, 64 patients underwent the procedure (interval group), and 4 patients refused. RESULTS: Non-operative management was successful in 76.6% of cases (49/64 patients) in the interval group. Operative time and length of hospital stay were similar between the emergency and interval groups. In the interval group, blood loss, the need for extended resection, and overall postoperative morbidity were significantly lower than in the emergency group (P < 0.01, respectively). Medical costs for surgery in the interval group were lower than in the emergency group ($4512 vs $6888, P = 0.002), but this group's total medical costs were higher ($9591 vs $6888, P < 0.01). CONCLUSION: The interval strategy is associated with a reduced need for extended resection, lower postoperative morbidity, and a shorter length of hospital stay. However, total medical costs for the interval strategy are higher than those for emergency operations in cases of appendicular abscess in adults.

Fluorescence-enabled assessment of adrenal gland localization and perfusion in posterior retroperitoneoscopic adrenal surgery in a preclinical model.

BACKGROUND: The posterior retroperitoneoscopic adrenal access represents a challenge in orientation and working space creation. The aim of this experimental acute study was to evaluate the impact of computer-assisted quantitative fluorescence imaging on adrenal gland identification and assessment of intraoperative remnant perfusion for adrenal resection in the posterior retroperitoneoscopic approach. METHODS: Six pigs underwent simultaneous (n = 5) or sequential (n = 1) bilateral posterior retroperitoneoscopic adrenalectomy (n = 12). Fluorescence imaging was obtained via intravenous administration of 3 mL of Indocyanine Green (ICG) and by switching the camera systems to near-infrared mode (D-LIGHT P, KARL STORZ; Germany). Fluorescence-based visualization of adrenal glands before vascular division (n = 4), after the main vascular pedicle ligation (negative control, n = 1) or after adrenal resection (n = 7), was followed by completion adrenalectomy. The fluorescence signal intensity dynamics were recorded and analyzed using proprietary software. For each pixel, the slope of fluorescence signal intensity evolution over time was translated into a color-coded perfusion cartography, which was superimposed onto real-time images obtained with the corresponding left and right camera systems. Quantitative fluorescence signal analysis in the regions of interest (ROIs) served to assess adrenal remnant perfusion in divided adrenal glands. RESULTS: In the retroperitoneum, the vascular anatomy was illuminated in fluorescence imaging first. The adrenal glands were promptly highlighted after primary intravenous ICG administration (n = 9) or showed a fluorescence signal intensity increase upon reinjection (n = 3). Quantitative fluorescence analysis showed a statistically significant difference between perfused and ischemic segments in divided glands (p = 0.0156). CONCLUSIONS: Fluorescence imaging provides real-time guidance during minimally invasive adrenal surgery. Prior to dissection, it allows to easily discriminate the adrenal gland from surrounding retroperitoneal structures. After adrenal gland division, ICG injection associated with a computer-assisted quantitative analysis helps to distinguish between well-perfused and ischemic segments. Further studies are underway to establish the correlation between remnant perfusion and viability.

Simultaneous computer-assisted assessment of mucosal and serosal perfusion in a model of segmental colonic ischemia.

BACKGROUND: Fluorescence-based enhanced reality (FLER) enables the quantification of fluorescence signal dynamics, which can be superimposed onto real-time laparoscopic images by using a virtual perfusion cartogram. The current practice of perfusion assessment relies on visualizing the bowel serosa. The aim of this experimental study was to quantify potential differences in mucosal and serosal perfusion levels in an ischemic colon segment. METHODS: An ischemic colon segment was created in 12 pigs. Simultaneous quantitative mucosal and serosal fluorescence imaging was obtained via intravenous indocyanine green injection (0.2 mg/kg), using two near-infrared camera systems, and computer-assisted FLER analysis. Lactate levels were measured in capillary blood of the colonic wall at seven regions of interest (ROIs) as determined with FLER perfusion cartography: the ischemic zone (I), the proximal and distal vascularized areas (PV, DV), and the 50% perfusion threshold proximally and distally at the mucosal and serosal side (P50M, P50S, D50M, D50S). RESULTS: The mean ischemic zone as measured (mm) for the mucosal side was significantly larger than the serosal one (56.3 ± 21.3 vs. 40.8 ± 14.9, p = 0.001) with significantly lower lactate values at the mucosal ROIs. There was a significant weak inverse correlation between lactate and slope values for the defined ROIs (r = - 0.2452, p = 0.0246). CONCLUSIONS: Mucosal ischemic zones were larger than serosal zones. These results suggest that an assessment of bowel perfusion from the serosal side only can underestimate the extent of ischemia. Further studies are required to predict the optimal resection margin and anastomotic site.

Which method of distal pancreatectomy is cost-effective among open, laparoscopic, or robotic surgery?

BACKGROUND: The aim of this study was to analyze the clinical and economic impact of robotic distal pancreatectomy, laparoscopic distal pancreatectomy, and open distal pancreatectomy. METHODS: All consecutive patients who underwent distal pancreatic resection for benign and malignant diseases between January 2012 and December 2015 were prospectively included. Cost analysis was performed; all charges from patient admission to discharge were considered. RESULTS: There were 21 robotic (RDP), 25 laparoscopic (LDP), and 43 open (ODP) procedures. Operative time was longer in the RDP group (RDP =345 minutes, LDP =306 min, ODP =251 min, P=0.01). Blood loss was higher in the ODP group (RDP =192 mL, LDP =356 mL, ODP =573 mL, P=0.0002). Spleen preservation was more frequent in the RDP group (RDP =66.6%, LDP =61.9%, ODP =9.3%, P=0.001). The rate of patients with Clavien-Dindo > grade III was higher in the ODP group (RDP =0%, LDP =12%, ODP =23%, P=0.01), especially for non-surgical complications, which were more frequent in the ODP group (RDP =9.5%, LDP =24%, ODP =41.8%, P=0.02). Length of hospital stay was increased in the ODP group (ODP =19 days, LDP =13 days, RDP =11 days, P=0.007). The total cost of the procedure, including the surgical procedure and postoperative course was higher in the ODP group (ODP =30,929 Euros, LDP =22,150 Euros, RDP =21,219 Euros, P=0.02). CONCLUSIONS: Cost-effective results of RDP seem to be similar to LDP with some better short-term outcomes.

Linearly chirped fiber Bragg grating response to thermal gradient: from bench tests to the real-time assessment during in vivo laser ablations of biological tissue.

The response of a fiber optic sensor [linearly chirped fiber Bragg grating (LCFBG)] to a linear thermal gradient applied on its sensing length (i.e., 1.5 cm) has been investigated. After these bench tests, we assessed their feasibility for temperature monitoring during thermal tumor treatment. In particular, we performed experiments during ex vivo laser ablation (LA) in pig liver and in vivo thermal ablation in animal models (pigs). We investigated the following: (i) the relationship between the full width at half maximum of the LCFBG spectrum and the temperature difference among the extremities of the LCFBG and (ii) the relationship between the mean spectrum wavelength and the mean temperature acting on the LCFBG sensing area. These relationships showed a linear trend during both bench tests and LA in animal models. Thermal sensitivity was significant although different values were found with regards to bench tests and animal experiments. The linear trend and significant sensitivity allow hypothesizing a future use of this kind of sensor to monitor both temperature gradient and mean temperature within a tissue undergoing thermal treatment.

Precision real-time evaluation of bowel perfusion: accuracy of confocal endomicroscopy assessment of stoma in a controlled hemorrhagic shock model.

BACKGROUND AND AIMS: Confocal laser endomicroscopy (CLE) can provide real-time evaluation of bowel perfusion. We aimed to evaluate CLE perfusion imaging in a hemorrhagic shock model. MATERIALS AND METHODS: Five pigs were equipped to ensure hemodynamic monitoring. Three ileostomies per animal (total n = 15) were randomly created (T0). Blood was withdrawn targeting a mean arterial pressure of 40 mmHg (shock phase, T1), for 90 min. Infusion of Ringer's lactate was started and continued for 90 min (T2). At the different time points: (a) stomas' mucosa was scanned with CLE; (b) capillary lactates were measured on blood obtained by puncturing stomas' mucosa; and (c) full-thickness stomas' biopsies were sampled for histology, mitochondrial respiratory rate (V 0 = basal and V ADP = respiratory rate in excess of adenosine diphosphate), and levels of superoxide anion evaluation. Functional capillary density (FCD) was measured using ad hoc software. RESULTS: Confocal scanning provided consistent and specific imaging of bowel hypoperfusion at T1: vascular hyperpermeability (blurred and enlarged capillaries) and edema (enhanced visualization of the brush border due to increased intercellular spaces and fluorescein leakage). At the end of T2, there was an improved capillary flow. FCD-A index expressed statistically significant correlation with (1) stoma capillary lactates (p = 0.023); (2) systemic capillary lactates (p = 0.031); (3) inflammation pathology score (p = 0.048); (4) central venous pressure (p = 0.0043); and (5) pulmonary artery pressure (p = 0.01). Stoma capillary lactates (mmol/L) were significantly increased at T1 (8.81 ± 4.23; p < 0.0001) and at T2 (4.77 ± 3.13; p < 0.01) when compared to T0 inclusion values (1.86 ± 0.56). V 0 and V ADP (pmol O2/min/mg tissue) were both significantly decreased at T1 versus T0 (p < 0.007 and p < 0.01, respectively) and recovered by the end of reanimation (T2 vs. T0, p = n.s.). Mean O 2·- production (µmol/min/mg/dry tissue) increased at T1 and significantly decreased at T2. CONCLUSIONS: Confocal laser endomicroscopy (CLE) imaging could identify morphological signs congruent with biochemical markers of bowel perfusion and could be useful for assessment of stomas.

Robotic hepatectomies: advances and perspectives.

INTRODUCTION: Over recent years, minimally invasive hepatic resections have increasingly been reported in the literature. Even though hepatic surgery is still considered a challenge for surgeons due to its technical difficulties and high morbidity, the development and spread of robotic surgery has highlighted a new interest, which has induced a rapid dissemination of robotic approaches for hepatic pathologies. This article presents a systematic review of the literature regarding robotic hepatectomy in order to assess the safety and feasibility of robotic hepatic surgery. EVIDENCE ACQUISITION: All eligible studies in robotic liver surgery which were published between January 2001 and January 2016 were reviewed systematically. Only series of ten patients and more were chosen in order to consider the experience of high-volume centers. In case of multiple articles on the same centers, the study including the largest number of patients was considered for the study. Overall, 18 studies, involving a total of 572 robotic liver resection (RLR) were finally analyzed. EVIDENCE SYNTHESIS: All articles in this review demonstrate that robotic liver surgery must be performed by surgeons trained in open liver surgery and skilled in minimally invasive techniques. CONCLUSIONS: RLR and laparoscopic liver resection (LLR) were comparable in terms of safety, feasibility, and outcome for hepatectomies. However, RLR is more expensive than LLR. Further studies are required before any final conclusion can be drawn.

Probe-based confocal laser endomicroscopy and fluorescence-based enhanced reality for real-time assessment of intestinal microcirculation in a porcine model of sigmoid ischemia.

BACKGROUND AND AIM: Surgeons currently rely on visual clues to estimate the presence of sufficient vascularity for safe anastomosis. We aimed to assess the accuracy of endoluminal confocal laser endomicroscopy (CLE) and laparoscopic fluorescence-based enhanced reality (FLER), using near-infrared imaging and fluorescence from injected Indocyanine Green, to identify the transition from ischemic to vascular areas in a porcine model of mesenteric ischemia. METHODS: Six pigs underwent 1-h sigmoid segmental ischemia. The ischemic area was evaluated by clinical assessment and FLER to determine presumed viable margins. For each sigmoid colon, 5 regions of interest (ROIs) were identified: ischemic (ROI 1), presumed viable margins ROI 2a (distal) and 2b (proximal), and vascular areas 3a (distal) and 3b (proximal). After injection of fluorescein, CLE scanning of the mucosa from the ischemic area toward viable margins was performed. Capillary blood samples were obtained by puncturing the serosa at the ROIs, and capillary lactates were measured with the EDGE(®) analyzer. RESULTS: Capillary lactates were significantly higher at ROI 1 (4.91 mmol/L) when compared to resection margins (2.8 mmol/L; mean difference: 2.11; p < 0.05) identified by FLER. There was no significant difference in lactates between ROI1 and resection margins identified by clinical evaluation. In 50 % of cases, ROI 2aCLINIC-2bCLINIC were considered to match (<1 cm distance) with ROI 2aFLER-2bFLER. Confocal analysis revealed specific clues to identify the transition from ischemic to viable areas corresponding to those assessed by FLER in 11/12 cases versus 7/12 for those identified by clinical evaluation. CONCLUSIONS: In this experimental model, FLER and CLE were more accurate than clinical evaluation to delineate bowel vascularization.

Enhanced-reality video fluorescence: a real-time assessment of intestinal viability.

OBJECTIVE: Our aim was to evaluate a fluorescence-based enhanced-reality system to assess intestinal viability in a laparoscopic mesenteric ischemia model. MATERIALS AND METHODS: A small bowel loop was exposed, and 3 to 4 mesenteric vessels were clipped in 6 pigs. Indocyanine green (ICG) was administered intravenously 15 minutes later. The bowel was illuminated with an incoherent light source laparoscope (D-light-P, KarlStorz). The ICG fluorescence signal was analyzed with Ad Hoc imaging software (VR-RENDER), which provides a digital perfusion cartography that was superimposed to the intraoperative laparoscopic image [augmented reality (AR) synthesis]. Five regions of interest (ROIs) were marked under AR guidance (1, 2a-2b, 3a-3b corresponding to the ischemic, marginal, and vascularized zones, respectively). One hour later, capillary blood samples were obtained by puncturing the bowel serosa at the identified ROIs and lactates were measured using the EDGE analyzer. A surgical biopsy of each intestinal ROI was sent for mitochondrial respiratory rate assessment and for metabolites quantification. RESULTS: Mean capillary lactate levels were 3.98 (SD = 1.91) versus 1.05 (SD = 0.46) versus 0.74 (SD = 0.34) mmol/L at ROI 1 versus 2a-2b (P = 0.0001) versus 3a-3b (P = 0.0001), respectively. Mean maximal mitochondrial respiratory rate was 104.4 (±21.58) pmolO2/second/mg at the ROI 1 versus 191.1 ± 14.48 (2b, P = 0.03) versus 180.4 ± 16.71 (3a, P = 0.02) versus 199.2 ± 25.21 (3b, P = 0.02). Alanine, choline, ethanolamine, glucose, lactate, myoinositol, phosphocholine, sylloinositol, and valine showed statistically significant different concentrations between ischemic and nonischemic segments. CONCLUSIONS: Fluorescence-based AR may effectively detect the boundary between the ischemic and the vascularized zones in this experimental model.

Follow-up of tumor development in the colons of living rats and implications for chemoprevention trials: assessment of aspirin-difluoromethylornithine combination.

We aimed to establish a reliable procedure allowing the follow-up of tumor development by computed tomographic (CT) colonography in an animal model of colon carcinogenesis in order to assess the chemopreventive efficacy of aspirin and difluoromethylornithine (DFMO) given in combination. Fischer rats received an intraperitoneal injection (25 mg/kg) of dimethylhydrazine (DMH) once a week for two weeks in order to initiate colon carcinogenesis. Five months after the last injection of DMH, a first CT colonography was performed and rats were then randomly separated into two groups (control and experimental). The experimental group received a 0.1% mixture of aspirin and DFMO in drinking water. CT colonography was performed at 6, 7 and 8 months. Data showed a precise correlation between location and size of tumors found at autopsy and those detected by CT colonography at 8 months. All tumors were also detected on the CT views obtained previously. Animals of the aspirin/DFMO group exhibited an inactivation of ornithine decarboxylase, a key enzyme in polyamine biosynthesis, and a two-fold reduction in the prostaglandin E2 content of the colonic mucosa (p<0.01). In rats with tumors at the start of the aspirin/DFMO treatment, a significant slow-down of tumor development was observed. In contrast, in rats where no tumors were detected at the start of the treatment, tumor formation was inhibited. Our data show that CT colonography represents a reliable method to assess in a living animal the efficacy of chemopreventive agents.