Contemporary endoscopic Simultaneous Localization And Mapping (SLAM) methods accurately compute endoscope poses, however, they only provide a sparse 3D reconstruction that poorly describes the surgical scene. We propose a novel dense SLAM method whose qualities are: 1) Monocular, requiring only RGB images of a hand-held monocular endoscope. 2) Fast, providing endoscope positional tracking and 3D scene reconstruction, running in parallel threads. 3) Dense, yielding an accurate dense reconstruction. 4) Robust, to the severe illumination changes, poor texture and small deformations that are typical in endoscopy. 5) Self-contained, without needing any fiducials nor external tracking devices, therefore it can be smoothly integrated into the surgical workflow. It works as follows. Firstly, accurate cluster frame poses are estimated using the sparse SLAM feature matches. The system segments clusters of video frames according to a parallax criteria. Next, dense matches between cluster frames are computed in parallel by a variational approach that combines Zero Mean Normalized Cross Correlation (ZNCC) and a gradient Huber norm regularizer. This combination copes with challenging lighting and textures at an affordable time budget on a modern GPU. It can outperform pure stereo reconstructions because the frames cluster can provide larger parallax from the endoscope's motion. We provide an extensive experimental validation on real sequences of the porcine abdominal cavity, both in-vivo and exvivo. We also show a qualitative evaluation on human liver. Additionally, we show a comparison with other dense SLAM methods showing the performance gain in terms of accuracy, density and computation time.

We aim to track the endoscope location inside the surgical scene and provide 3D reconstruction, in real-time, from the sole input of the image sequence captured by the monocular endoscope. This information offers new possibilities for developing surgical navigation and augmented reality applications. The main benefit of this approach is the lack of extra tracking elements which can disturb the surgeon performance in the clinical routine. It is our first contribution to exploit ORBSLAM, one of the best performing monocular SLAM algorithms, to estimate both of the endoscope location, and 3D structure of the surgical scene. However, the reconstructed 3D map poorly describe textureless soft organ surfaces such as liver. It is our second contribution to extend ORBSLAM to be able to reconstruct a semi-dense map of soft organs. Experimental results on in-vivo pigs, shows a robust endoscope tracking even with organs deformations and partial instrument occlusions. It also shows the reconstruction density, and accuracy against ground truth surface obtained from CT.

Purpose: To compare safety and efficacy of combined therapy with conventional transarterial chemoembolization (cTACE)þmicrowave ablation (MWA) versus only TACE or MWA for treatment of hepatocellular carcinoma (HCC) >3-<5 cm. Methods: This randomized controlled trial (NCT04721470) screened 278 patients with HCC >3-<5 cm. Patients were randomized into three groups: 90 underwent TACE (Group 1); 95 underwent MWA (Group 2); and 93 underwent combined therapy (Group 3). Patients were followed-up with contrastenhanced CT or MRI. Images were evaluated and compared for treatment response and adverse events based on modified response evaluation criteria in solid tumor. Serum alpha-fetoprotein (AFP) concentration was measured at baseline and during every follow-up visit. Results: Final analysis included 265 patients (154 men, 111 women; mean age ¼ 54.5 ± 11.8 years; range ¼ 38-76 years). Complete response was achieved by 86.5% of patients who received combined therapy compared with 54.8% with only TACE and 56.5% with only MWA (p ¼ 0.0002). The recurrence rate after 12 months was significantly lower in Group 3 (22.47%) than Groups 1 (60.7%) and 2 (51.1%) (p ¼ 0.0001). The overall survival rate (three years after therapy) was significantly higher in Group 3 (69.6%) than Groups 1 (54.7%) and 2 (54.3%) (p ¼ 0.02). The mean progression-free survival was significantly higher in Group 3 than groups 1 and 2 (p < 0.001). A decrease in AFP concentration was seen in 75%, 63%, and 48% patients of Group 3, 2, and 1, respectively. Conclusions: Combined therapy with cTACE þ MWA is safe, well-tolerated, and more effective than TACE or MWA alone for treatment of HCC >3-<5 cm.

The proposed system can be smoothly integrated into the surgical workflow because it: (1) operates in real time, (2) requires minimal additional hardware only a tablet-PC with camera, (3) is robust to occlusion, (4) requires minimal interaction from the medical staff.