Real-time continuous image guidance for endoscopic retrograde cholangiopancreatography based on 3D/2D registration and respiratory compensation.

BACKGROUND: It has been confirmed that three-dimensional (3D) imaging allows easier identification of bile duct anatomy and intraoperative guidance of endoscopic retrograde cholangiopancreatography (ERCP), which reduces the radiation dose and procedure time with improved safety. However, current 3D biliary imaging does not have good real-time fusion with intraoperative imaging, a process meant to overcome the influence of intraoperative respiratory motion and guide navigation. The present study explored the feasibility of real-time continuous image-guided ERCP. AIM: To explore the feasibility of real-time continuous image-guided ERCP. METHODS: We selected 2 3D-printed abdominal biliary tract models with different structures to simulate different patients. The ERCP environment was simulated for the biliary phantom experiment to create a navigation system, which was further tested in patients. In addition, based on the estimation of the patient's respiratory motion, preoperative 3D biliary imaging from computed tomography of 18 patients with cholelithiasis was registered and fused in real-time with 2D fluoroscopic sequence generated by the C-arm unit during ERCP. RESULTS: Continuous image-guided ERCP was applied in the biliary phantom with a registration error of 0.46 mm ± 0.13 mm and a tracking error of 0.64 mm ± 0.24 mm. After estimating the respiratory motion, 3D/2D registration accurately transformed preoperative 3D biliary images to each image in the X-ray image sequence in real-time in 18 patients, with an average fusion rate of 88%. CONCLUSION: Continuous image-guided ERCP may be an effective approach to assist the operator and reduce the use of X-ray and contrast agents.

Correction to: Nitric Oxide Participates in the Brain Ischemic Tolerance Induced by Intermittent Hypobaric Hypoxia in the Hippocampal CA1 Subfield in Rats.

The order of corresponding author was inadvertently published. Hence, the first and the second corresponding authors should be Min Zhang (hebmuzhangmin@163.com) and Jing-Ge Zhang (zhangjg001@163.com).

Nitric Oxide Participates in the Brain Ischemic Tolerance Induced by Intermittent Hypobaric Hypoxia in the Hippocampal CA1 Subfield in Rats.

Previous studies have shown that intermittent hypobaric hypoxia (IH) preconditioning protected neurons survival from brain ischemia. However, the mechanism remains to be elucidated. The present study explored the role of nitric oxide (NO) in the process by measuring the expression of NO synthase (NOS) and NO levels. Male Wistar rats (100) were randomly assigned into four groups: sham group, IH + sham group, ischemia group and IH + ischemia group. Rats for IH preconditioning were exposed to hypobaric hypoxia mimicking 5000 m high-altitude (PB = 404 mmHg, PO2 = 84 mmHg) 6 h/day, once daily for 28 days. Global brain ischemia was established by four-vessel occlusion that has been created by Pulsinelli. Rats were sacrificed at 7th day after the ischemia for neuropathological evaluation by thionin stain. In addition, the expression of neuronal NOS (nNOS), inducible NOS (iNOS), and NO content in the hippocampal CA1 subfield were measured at 2nd day and 7th day after the ischemia. Results revealed that global brain ischemia engendered delayed neuronal death (DND), both nNOS and iNOS expression up-regulated, and NO content increased in the hippocampal CA1 subfield. IH preconditioning reduced neuronal injury induced by the ischemia, and prevented the up-regulation of NOS expression and NO production. In addition, L-NAME + ischemia group was designed to detect whether depressing NO production could alleviate the DND. Pre-administration of L-NAME alleviated DND induced by the ischemia. These results suggest that IH preconditioning plays a protective role by inhibiting the over expression of NOS and NO content after brain ischemia.