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Accurate segmentation of the mandibular canal is essential in dental implant and maxillofacial surgery, which can help prevent nerve or vascular damage inside the mandibular canal. Achieving this is challenging because of the low contrast in CBCT scans and the small scales of mandibular canal areas. Several innovative methods have been proposed for mandibular canal segmentation with positive performance. However, most of these methods segment the mandibular canal based on sliding patches, which may adversely affect the morphological integrity of the tubular structure. In this study, we propose whole mandibular canal segmentation using transformed dental CBCT volume in the Frenet frame. Considering the connectivity of the mandibular canal, we propose to transform the CBCT volume to obtain a sub-volume containing the whole mandibular canal based on the Frenet frame to ensure complete 3D structural information. Moreover, to further improve the performance of mandibular canal segmentation, we use clDice to guarantee the integrity of the mandibular canal structure and segment the mandibular canal. Experimental results on our CBCT dataset show that integrating the proposed transformed volume in the Frenet frame into other state-of-the-art methods achieves a 0.5%∼12.1% improvement in Dice performance. Our proposed method can achieve impressive results with a Dice value of 0.865 (±0.035), and a clDice value of 0.971 (±0.020), suggesting that our method can segment the mandibular canal with superior performance.

Purpose: To analyze whether HBV infection can reduce the risk of colorectal liver metastasis (CRLM) in stage 2 colorectal cancer (CRC)., Methods: The data of postoperative pathological stage 2 CRC patients treated at the Sixth Affiliated Hospital of Sun Yat-sen University between 2013 and 2015 were analyzed. The patients were divided into an infection group (group A) and a non-infection group (group B). The correlations between HBV infection and CRLM, 5-year liver disease-free survival, and 5-year overall survival were compared., Results: A total of 884 patients who met the inclusion criteria were included in the study. Group A included 297 patients (33.60%), and 5 patients (1.68%) had CRLM. Group B included 587 patients (66.40%), and 31 patients (5.28%) had CRLM. The results of correlation analysis and logistic regression analysis showed that HBV infection (P = 0.013, HR = 0.29, 95% CI 0.11-0.77) was a protective factor for CRLM, while CEA > 5 ng/ml (P = 0.002, HR = 3.12, 95% CI 1.51-6.47) and hypertension (P = 0.010, HR = 3.50, 95% CI 1.34-9.09) were risk factors for CRLM. Group A had a significantly better 5-year liver disease-free survival than group B (P = 0.011, HR = 0.31, 95% CI 0.16-0.63), but there was no significant difference in the 5-year overall survival (P = 0.433)., Conclusion: HBV infection may reduce the risk of metachronous liver metastasis in stage 2 colorectal cancer.