Evaluation of Electronic Biopsy for Clinical Diagnosis in Virtual Colonoscopy

摘要

Virtual colonoscopy provides techniques not available in optical colonoscopy, an exciting one being the ability to perform an electronic biopsy. An electronic biopsy image is created using ray-casting volume rendering of the CT data with a translucent transfer function mapping higher densities to red and lower densities to blue. The resulting image allows the physician to gain insight into the internal structure of polyps. Benign tissue and adenomas can be differentiated; the former will appear as homogeneously blue and the latter as irregular red structures. Although this technique is now common, is included with clinical systems, and has been used successfully for computer aided detection, there has so far been no study to evaluate the effectiveness of a physician using electronic biopsy in determining the pathological state of a polyp. We present here such a study, wherein an experienced radiologist ranked polyps based on electronic biopsy alone per scan (supine and prone), as well as both combined. Our results show a correct identification 77% of the time using prone or supine images alone, and 80% accuracy using both. Using ROC analysis based on this study with one reader and a modest sample size, the combined score is not significantly higher than using a single electronic biopsy image alone. However, our analysis indicates a trend of superiority for the combined ranking that deserves a follow-up confirmatory study with a larger sample and more readers. This study yields hope that an improved electronic biopsy technique could become a primary clinical diagnosis method.