Robust and fast laparoscopic vision-based ultrasound probe tracking using a binary dot array marker.

Laparoscopic vision-based ultrasound probe tracking systems have gained considerable attention in ultrasound-guided laparoscopic surgeries as replacements for external tracking systems (e.g. optical tracking and electromagnetic tracking systems), which increase cost and setting time, require additional operation space, and introduce new limitations. Most existing laparoscopic ultrasound (LUS) probe tracking systems rely on fiducial markers, which cannot easily realise fast and robust vision-based tracking in laparoscopic surgery owing to their design limitations. Therefore, we propose a novel binary dot array marker to realise a robust and fast LUS probe tracking system. The binary dot array marker comprises two dots (green and blue), which form multiple unique identification dot subarrays in the binary dot array. The binary dot array marker can be tracked when one of the identification dot subarrays is detected and identified; this novel design makes the binary dot array marker-based probe tracking system robust against occlusions during surgery. The evaluation results indicate that the proposed binary dot marker performs better in terms of robustness, computational efficiency, and tracking accuracy compared to the state-of-the-art fiducial markers used for vision-based probe tracking.

Deformation of the Pelvic Arteries Caused by Pneumoperitoneum and Postural Changes in an Animal Model.

BACKGROUND/AIM: We investigated pelvic arterial deformation and shift due to intraoperative pneumoperitoneum and postural changes in an animal model. MATERIALS AND METHODS: Computed tomography images of pigs were acquired in different body positions (supine, head down at 5° and 10°, right lateral recumbent at 5° and 15°) before and after insufflation. We used a free software (3D Slicer) for image analysis. After landmark registration using 10 markers inserted into the pelvis, pelvic arterial deformation and shift of seven arterial bifurcation points were evaluated. The distance moved was the target registration error (TRE) from the points registered in the supine position. Fiducial registration error (FRE) was measured using the 10 pelvic markers. RESULTS: TRE average from postural changes ranged from 0.7 to 1.2 mm and was 1.4 mm due to pneumoperitoneum. TRE and FRE averages were 2.1 mm and 0.2 mm, respectively. CONCLUSION: The pelvis was useful for registering anatomical landmarks.

Surgical navigation system for laparoscopic lateral pelvic lymph node dissection in rectal cancer surgery using laparoscopic-vision-tracked ultrasonic imaging.

BACKGROUND: Laparoscopic lateral pelvic lymph node dissection (LPLND) in rectal cancer surgery requires considerable skill because the pelvic arteries, which need to be located to guide the dissection, are covered by other tissues and cannot be observed on laparoscopic views. Therefore, surgeons need to localize the pelvic arteries accurately before dissection, to prevent injury to these arteries. METHODS: This report proposes a surgical navigation system to facilitate artery localization in laparoscopic LPLND by combining ultrasonic imaging and laparoscopy. Specifically, free-hand laparoscopic ultrasound (LUS) is employed to capture the arteries intraoperatively in this approach, and a laparoscopic vision-based tracking system is utilized to track the LUS probe. To extract the artery contours from the two-dimensional ultrasound image sequences efficiently, an artery extraction framework based on local phase-based snakes was developed. After reconstructing the three-dimensional intraoperative artery model from ultrasound images, a high-resolution artery model segmented from preoperative computed tomography (CT) images was rigidly registered to the intraoperative artery model and overlaid onto the laparoscopic view to guide laparoscopic LPLND. RESULTS: Experiments were conducted to evaluate the performance of the vision-based tracking system, and the average reconstruction error of the proposed tracking system was found to be 2.4 mm. Then, the proposed navigation system was quantitatively evaluated on an artery phantom. The reconstruction time and average navigation error were 8 min and 2.3 mm, respectively. A navigation system was also successfully constructed to localize the pelvic arteries in laparoscopic and open surgeries of a swine. This demonstrated the feasibility of the proposed system in vivo. The construction times in the laparoscopic and open surgeries were 14 and 12 min, respectively. CONCLUSIONS: The experimental results showed that the proposed navigation system can guide laparoscopic LPLND and requires a significantly shorter setting time than the state-of-the-art navigation systems do.

Mesalazine-induced Pleuropericarditis in a Patient with Crohn's Disease.

A 16-year-old boy was diagnosed with Crohn's disease. Treatment with oral mesalazine was started at 3 g per day; however, he complained of high fever, a nonproductive cough, and left shoulder pain after 2 weeks. His chest radiography and chest computed tomography showed cardiomegaly and left pleural effusion, while an echocardiogram revealed pericardial effusion. Because no infection was detected by thoracentesis and the drug lymphocyte stimulation tests for mesalazine were positive, the patient was diagnosed with mesalazine-induced pleuropericarditis. After the cessation of mesalazine, the clinical symptoms and laboratory findings quickly improved.