E. Buc

Deformable Registration of a Preoperative 3D Liver Volume to a Laparoscopy Image Using Contour and Shading Cues.

The deformable registration of a preoperative organ volume to an intraoperative laparoscopy image is required to achieve augmented reality in laparoscopy. This is an extremely challenging objective for the liver. This is because the preoperative volume is textureless, and the liver is deformed and only partially visible in the laparoscopy image. We solve this problem by modeling the preoperative volume as a Neo-Hookean elastic model, which we evolve under shading and contour cues. The contour cues combine the organ’s silhouette and a few curvilinear anatomical landmarks. The problem is difficult because the shading cue is highly nonconvex and the contour cues give curve-level (and not point-level) correspondences. We propose a convergent alternating projections algorithm, which achieves a (4%) registration error.

Effects of clamping procedures on central venous pressure during liver resection

BACKGROUNDnVarious clamping procedures are used to decrease bleeding during liver resections but their effect on central venous pressure (CVP) remains unclear. The aim of this study was to assess the variations of the CVP during two different clamping procedures.nnnMETHODSnWe retrospectively reviewed 29 patients (19 males, 10 females) who had Pringle maneuver (PM) and clamping of the inferior vena cava below the liver (IVCC) during major liver resections.nnnRESULTSnMean decrease of the CVP after PM, IVCC, and PM+IVCC was 0.84 ± 1.37, 2.17 ± 2.13 and 3.17 ± 2.56 cmH20, respectively (P=0.02, P<0.0001 and P<0.0001, respectively). IVCC was more effective in inducing a decrease of the CVP than PM alone (P<0.05). The combination of both PM and IVCC induced the greatest decrease but not to a level of significance compared to IVCC alone (P=0.25).nnnCONCLUSIONnIVCC remains the more efficient procedure to lower the CVP. However, although PM is commonly used to control vascular inflow within the liver its significant influence on the CVP could participate to the reduction of bleeding during liver resections.

Feasibility prospective study of laparoscopic cholecystectomy with suprapubic approach.

BACKGROUNDnSince the publication of laparoscopic cholecystectomy (LC) using three ports instead of four, no significant evolution has impacted on our clinical practice in order to improve length of stay, postoperative pain, time of recovery and cosmetic results. Recently, a renewed interest has been observed with the suprapubic approach, called occult scar laparoscopic cholecystectomy (OSLC). The aim of this prospective multicentric study was to evaluate the feasibility of OSLC in 2 French centers.nnnMETHODSnFrom March to September 2014, 60 patients were prospectively included in this study. The operation incisions consisted of an umbilical incision for camera; an incision in the right groin for maneuvers of exposition and a suprapubic incision for instrumental dissection and clipping. Outcome was by operative time, operative complications, hospital length of stay, analgesia required after surgery, and cosmetic outcomes. The Patient Satisfaction Scale and Visual Analog Score (VAS) also were used to evaluate the level of cosmetic result and postoperative pain.nnnRESULTSnNo laparoscopy was converted to an open procedure, the mean operative time was 53±20min. No patient had intraoperative bile duct injury or significant bleeding. The mean length of stay was 1.70±0.76 days. Two patients (3%) experienced postoperative complication (1 intra-abdominal abscess treated by antibiotics and 1 subcutaneous seroma of the 11-mm port wound treated successfully by needle aspiration).nnnCONCLUSIONnThe technique proved to be safe and feasible with no specific complication and without specific instrument. It offers satisfactory postoperative pain level and good cosmetic results.

Non-lethal Right Liver Atrophy After TIPS Occlusion in A Cirrhotic Patient: Introducing The Hepatic Biembolization

BackgroundTransjugular intrahepatic portosystemic shunt (TIPS) is the standard procedure in the treatment of refractory ascites and variceal bleeding in the setting of portal hypertension. Secondary obstruction of the shunt is a classic but potentially lethal complication.MethodsWe present here the case of a cirrhotic patient that underwent a TIPS for refractory ascites, with early complete thrombosis without lethal complication.ResultsObstruction of the TIPS led to thrombosis of both the right hepatic and the right portal veins with progressive total atrophy of the right liver and marked hypertrophy of the left liver. Despite initial poor liver function, biological hepatic markers improved slowly until complete recovery.ConclusionHence, we suggest the concept of combined right portal and hepatic vein embolization as a new procedure to induce partial liver hypertrophy before major liver resection, even in cirrhotic patients.

Preoperative liver registration for augmented monocular laparoscopy using backward–forward biomechanical simulation

PurposeAugmented reality for monocular laparoscopy from a preoperative volume such as CT is achieved in two steps. The first step is to segment the organ in the preoperative volume and reconstruct its 3D model. The second step is to register the preoperative 3D model to an initial intraoperative laparoscopy image. To date, there does not exist an automatic initial registration method to solve the second step for the liver in the de facto operating room conditions of monocular laparoscopy. Existing methods attempt to solve for both deformation and pose simultaneously, leading to nonconvex problems with no optimal solution algorithms.MethodsWe propose in contrast to break the problem down into two parts, solving for (i)xa0deformation and (ii)xa0pose. Part (i)xa0simulates biomechanical deformations from the preoperative to the intraoperative state to predict the liver’s unknown intraoperative shape by modeling gravity, the abdominopelvic cavity’s pressure and boundary conditions. Part (ii)xa0rigidly registers the simulated shape to the laparoscopy image using contour cues.ResultsOur formulation leads to a well-posed problem, contrary to existing methods. This is because it exploits strong environment priors to complement the weak laparoscopic visual cues.ConclusionQuantitative results with in silico and phantom experiments and qualitative results with laparosurgery images for two patients show that our method outperforms the state-of-the-art in accuracy and registration time.

Preliminary trial of augmented reality performed on a laparoscopic left hepatectomy

BackgroundLaparoscopic liver surgery is seldom performed, mainly because of the risk of hepatic vein bleeding or incomplete resection of the tumour. This risk may be reduced by means of an augmented reality guidance system (ARGS), which have the potential to aid one in finding the position of intrahepatic tumours and hepatic veins and thus in facilitating the oncological resection and in limiting the risk of operative bleeding.MethodsWe report the case of an 81-year-old man who was diagnosed with a hepatocellular carcinoma after an intraabdominal bleeding. The preoperative CT scan did not show metastases. We describe our preferred approach for laparoscopic left hepatectomy with initial control of the left hepatic vein and preliminary results of our novel ARGS achieved postoperatively. In our ARGS, a 3D virtual anatomical model is created from the abdominal CT scan and manually registered to selected laparoscopic images. For this patient, the virtual model was composed of the segmented left liver, right liver, tumour and median hepatic vein.ResultsThe patient’s operating time was summed up to 205xa0min where a blood loss of 300xa0cc was recorded. The postoperative course was simple. Histopathological analysis revealed the presence of a hepatocellular carcinoma with free margins. Our results of intrahepatic visualization suggest that ARGS can be beneficial in detecting the tumour, transection plane and medial hepatic vein prior to parenchymal transection, where it does not work due to the substantial changes to the liver’s shape.ConclusionsAs of today, we have performed eight similar left hepatectomies, with good results. Our ARGS has shown promising results and should now be attempted intraoperatively.

Liver hypertrophy: Underlying mechanisms and promoting procedures before major hepatectomy

Various procedures can promote hypertrophy of the future liver remnant (FLR) before major hepatectomy to prevent postoperative liver failure. The pathophysiological situation following portal vein embolization (PVE), hepatic artery ligation/embolization or hepatectomy remains unclear. On one hand, the main mechanisms of hepatic regeneration appear to be driven by hepatic hypoxia (involving the hepatic arterial buffer response), an increased portal blood flow inducing shear stress and the involvement of several mediators (inflammatory cytokines, vasoregulators, growth factors, eicosanoids and several hormones). On the other hand, several factors are associated with impaired liver regeneration, such as biliary obstruction, malnutrition, diabetes mellitus, male gender, age, ethanol and viral infection. All these mechanisms may explain the varying degrees of hypertrophy observed following a surgical or radiological procedure promoting hypertrophy the FLR. Radiological procedures include left and right portal vein embolization (extended or not to segment 4), sequential PVE and hepatic vein embolization (HVE), and more recently combined PVE and HVE. Surgical procedures include associated liver partition and portal vein ligation for staged hepatectomy, and more recently the combined portal embolization and arterial ligation procedure. This review aimed to clarify the pathophysiology of liver regeneration; it also describes radiological or surgical procedures employed to improve liver regeneration in terms of volumetric changes, the feasibility of the second step and the benefits and drawbacks of each procedure.