GASTROINTESTINAL Time-efficient CT colonography interpretation using an advanced image-gallery-based, computer-aided “first-reader” workflow for the detection of colorectal adenomas Thomas Mang & Gerardo Hermosillo & Matthias Wolf & Luca Bogoni & Marcos Salganicoff & Vikas Raykar & Helmut Ringl & Michael Weber & Christina Mueller-Mang & Anno Graser Received: 26 February 2012 / Revised: 19 April 2012 / Accepted: 25 April 2012 / Published online: 18 August 2012 # European Society of Radiology 2012 Abstract Objectives To assess the performance of an advanced “first- reader” workflow for computer-aided detection (CAD) of colorectal adenomas ≥ 6 mm at computed tomographic colonography (CTC) in a low-prevalence cohort. Methods A total of 616 colonoscopy-validated CTC patient- datasets were retrospectively reviewed by a radiologist us- ing a “first-reader” CAD workflow. CAD detections were presented as galleries of six automatically generated two- dimensional (2D) and three-dimensional (3D) images to- gether with interactive 3D target views and 2D multiplanar views of the complete dataset. Each patient-dataset was interpreted by initially using CAD image-galleries followed by a fast 2D review to address unprompted colonic areas. Per-patient, per-polyp, and per-adenoma sensitivities were calculated for lesions ≥ 6 mm. Statistical testing employed Fisher ’ s exact and McNemar tests. Results In 91/616 patients, 131 polyps (92 adenomas, 39 non-adenomas) ≥ 6 mm and two cancers were identified by reference standard. Using the CAD gallery-based first- reader workflow, the radiologist detected all adenomas ≥ 10 mm (34/34) and cancers. Per-patient and polyp sensitivities for lesions ≥ 6 mm were 84.3 % (75/89), and 83.2 % (109/131), respectively, with 89.1 % (57/64) and 85.9 % (79/92) for adenomas. Overall specificity was 95.6 % (504/527). Mean interpretation time was 3.1 min per patient. Conclusions A CAD algorithm, applied in an image- gallery-based first-reader workflow, can substantially de- crease reading times while enabling accurate detection of colorectal adenomas in a low-prevalence population. Key Points • Computer-aided detection (CAD) is increasingly used to help interpret CT colonography (CTC) • An image-gallery first-reader CAD-workflow is feasible for detection of colorectal adenomas ≥ 6 mm • Image-gallery first-reader CAD yields per-patient sensi- tivity of 89.1 % and specificity of 95.6 % • The mean reading time for CTC was 3.1 min, making screening feasible • No large adenoma was missed by the radiologist who reviewed with CAD galleries Keywords CT colonography . Virtual colonoscopy . CAD . First-reader paradigm . Colorectal adenoma T. Mang (*) : H. Ringl : M. Weber : C. Mueller-Mang Department of Radiology, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria e-mail: thomas.mang@meduniwien.ac.at G. Hermosillo : M. Wolf : L. Bogoni : M. Salganicoff : V. Raykar Siemens Healthcare, Siemens Medical Solutions, H IM SY CAD R&D, 51 Valley Stream Parkway, E-51, Malvern, PA 19355, USA A. Graser Department of Clinical Radiology, University of Munich—Grosshadern Campus, Marchioninistr. 15, 81377 Munich, Germany Eur Radiol (2012) 22:2768–2779 DOI 10.1007/s00330-012-2522-2