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Virtual tagging for laxative‐free CT colonography: Pilot evaluation
Author(s) -
Näppi Janne,
Yoshida Hiroyuki
Publication year - 2009
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3113893
Subject(s) - virtual colonoscopy , false positive paradox , laxative , feces , medicine , computed tomographic , partial volume , true positive rate , artificial intelligence , radiology , nuclear medicine , computer science , colonoscopy , computed tomography , colorectal cancer , constipation , cancer , paleontology , biology
Laxative‐free computed tomographic colonography ( lf CTC) could significantly improve patient adherence to colorectal screening. However, the interpretation of lf CTC data is complicated by the presence of poorly tagged feces and partial‐volume artifacts that imitate colorectal lesions. The authors developed a method for virtual tagging of such artifacts. A probabilistic model of colonic wall was developed, and virtual tagging was performed on artifacts that were identified by the model. The method was evaluated with 46 clinical lf CTC cases that were prepared with dietary fecal tagging only. Visual examples show that the method can label partial‐volume artifacts, poorly tagged feces, nonadhering completely untagged feces, and artifacts such as rectal tubes. The effect of virtual tagging was evaluated by comparing the detection accuracy of a fully automated polyp detection scheme without and with the method. With virtual tagging, the per‐lesion detection sensitivity was 100% for lesions ⩾ 10 mm( n = 4 ) with 3.8 false positives per patient (per two CT scan volumes) and 90% for lesions ⩾ 6 mm( n = 10 ) with 5.4 false positives per patient on average. The improvement in detection performance by virtual tagging was statistically significant ( p = 0.03 ; JAFROC and JAFROC‐1).