Classification of variant portal vein anatomy based on three-dimensional CT: surgical implications.

Purposes: The purpose of this study was to develop a new and more comprehensive classification system for portal vein (PV) variations using three-dimensional visualization and evaluation (3DVE) and to discuss the prevalence rates and clinical implications of the variants. Methods: The anatomies of PVs were tracked and analyzed by using three-dimensional visualization of CT images acquired between 2013 and 2022. Scans from 200 adults were evaluated and a total of 178 patients (N = 178) were included in the study. The new classification system, named BLB classification, was developed based on the level of the absent PV branch in each variant anatomy. Results: Using the BLB classification system, PVs were divided into thirteen subtypes. Only 82.6–84.8% of the portal veins of the 178 patients were depicted in Atri's, Cheng's or Covey's classification, compared with 100% identified by the BLB classification. The BLB classification was validated against external data sets from previous studies, with 97.0-98.9% of patients classified by the BLB system. Conclusion: Variant PV anatomies are more commonly seen based on 3DVE than in previous reports. The BLB classification covers almost all portal vein variants and may be used for planning liver surgery. Summary Box: What is already known on this topic: To date, the classification defined by Atri et al. and Covey et al. are mostly used, including four and six subtypes respectively. However, variants and patterns not defined in traditional classifications are frequently encountered during surgery. What this study adds: In this article, we have explored the development of a new classification system (BLB classification) for portal vein anatomies based on three-dimensional visualization and evaluation. The importance of the finding is that the BLB classification covers almost all portal vein variants, which should be much more comprehensive than other reported classification methods and may be used for planning liver surgery. How this study might affect research, practice or policy: The knowledge of variant portal vein subtypes is critically significant in performing safe and efficacious liver surgeries, such as portal vein embolization, liver resection, liver transplantation and TIPS creation. [ABSTRACT FROM AUTHOR]