Wenli Cai PhD, Presenter: Nothing to Disclose

Se Hyung Kim, Abstract Co-Author: Research Grant, Mallinckrodt plc Research Grant, Samsung Electronics Co Ltd

Michael Ethan Zalis MD, Abstract Co-Author: Co-founder, QPID Health Inc Chief Medical Officer, QPID Health Inc Stockholder, QPID Health Inc

The purpose of this study was to evaluate a novel dual-energy electronic cleansing (DE-EC) method: virtual-colon-tagging EC (VCT-EC), in cleansing fecal-tagging CT colonography (CTC). We assessed the performance of polyp detection and the conspicuity of polyps after the application of VCT-EC.

Twenty-one patients underwent a bowel preparation with a low-fiber, low-residue diet, and oral administration of iodine contrast agents. Dual-energy CT scanning (SOMATOM Definition Flash) was performed at two photon voltages of 140 kVp and 80 kVp with the automatic dose exposure control module (CARE Dose 4D) in both supine and prone positions. Resulting DE-CTC data were subjected to VCT-EC scheme. Each subject had video-assisted optical colonoscopy as reference standard. The performance of polyp detection in VCT-EC was assessed by two experienced radiologists, who were blind to the pathology reports and the original fecal-tagging CTC images. They read the 21 cleansed DE-CTC cases by the proposed VCT-EC scheme to find the polyps by recording the size and location of each finding, as well as the confidence score regarding whether each finding is a polyp ≥6 mm (range: 1 [definitely no ployp] - 10 [definitely a polyp]); a score of ≥5 indicates a polyp finding).

The per-patient analysis revealed that VEC-EC yielded an average sensitivity of 90.6%, 93.3% and 95.0% for polyps ≥6mm, ≥8mm, and ≥10mm respectively. The per-polyp analysis indicated that for 6 missed polyps ≥8mm (false-negative) (5 from reader 1 and 1 from reader 2), only 1 of them was submerged in tagged materials at prone position and thus was a cleansed polyp by VCT-EC. Five (5) of 6 false-negative findings were sessile-flat morphology. The t-test of confidence scores between “Cleansed Polyps” and “Air-Exposed” non-submerged polyps showed no statistically significant difference for all 33 polyps (p=0.73) and 13 polyps submerged in one position and air-exposed in another position (p=0.60).

Our VCT-EC scheme provides an effective solution for the artifacts-free visualization of fecal-tagging CTC images.

New dual-energy EC method can substantially reduce EC artifacts and it may lead to artifact-free visualization of the colon.

Cai, W, Kim, S, Zalis, M, Evaluation of the Performance and Conspicuity of Polyps Detection by Virtual Colon Tagging Method in Dual-energy Fecal-tagging CT Colonography.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045727.html