En-Haw Wu MD, Presenter: Nothing to Disclose

So Yeon Kim MD, Abstract Co-Author: Nothing to Disclose

Zhen Jane Wang MD, Abstract Co-Author: Nothing to Disclose

Wei-Chou Chang MD, Abstract Co-Author: Nothing to Disclose

Liqin Zhao MD, Abstract Co-Author: Nothing to Disclose

Benjamin M. Yeh MD, Abstract Co-Author: Research Grant, General Electric Company Consultant, General Electric Company

To describe the appearance and incidence of gas interface artifacts in the small bowel that may mimic bowel disease at iodine map reformations with rapid kVp switching Dual Energy CT (rsDECT) .

We retrospectively identified 99 consecutive patients (M:F= 51: 48, age 59.3 ± 14.4 years) who underwent abdominal rsDECT scans obtained with oral water and IV contrast. At an AW workstation up to three representative jejunal segments in a patient were chosen to include segments with full gas-distension, partial gas-distension, or absent gas. For each jejunal segment, readers recorded the presence of image artifacts seen in the iodine maps that were not seen on the corresponding 140 kVp or 65 keV images. Iodine map artifacts were classified as: 1) Pseudo-stratified bowel wall artifact, defined as three or more thin alternating parallel bands of bright and dark signal; 2) Pseudo-pneumatosis, defined as irregular small beaded signal voids adjacent to bowel mucosa; and 3) Pseudo-hyperenhancement, defined as intense high signal of the bowel folds brighter than that of blood vessels .

Iodine map bowel artifacts appeared in 82 of 99 patients (83%). Of a total of 242 representative jejunal segments evaluated (full gas-distension: 54, partial gas-distension: 89, absent gas: 99), the artifacts were observed in 134 (55.4%) jejunal segments. Bowel image artifacts were more frequently seen in fully gas-distended 54 of 54 (100%) and partially gas-distended 80 of 89 (90%) jejunum than in and absent gas segments 0 of 99 (0%), p<0.001 for both. For all cases, the artifacts were seen only along the air-bowel interface. In full and partial gas-distended segments (n=143), 114 segments had two or more artifacts (totally, 105 pseudo-stratified bowel wall, 21 pseudo-pneumatosis, and 125 pseudo-hyperenhancement). The presence of pseudo-stratified bowel wall and pseudo-hyperenhancement were significantly associated (r=0.697, p = 0.02).

Image artifacts on iodine map of rsDECT are common at gas interfaces in the bowel. Knowledge of these artifacts is helpful to accurately interpret DECT scans with possible bowel disease.

When evaluating dual energy CT iodine map images, one whould recognize that gas interface artifact is common and has characteristic image appearances.

Wu, E, Kim, S, Wang, Z, Chang, W, Zhao, L, Yeh, B, Frequency and Appearance of Small Bowel Image Artifacts in the Iodine Map Images of Rapid kVp Switching Dual-energy CT.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14015821.html