Résumé
Objective: to compare objective and subjective image quality between virtual monoenergetic images (VMI) and mixed images (120 kvP) in patients with colitis or bowel obstruction in the emergency department.Methods: retrospective monocentric analysis of patients with bowel obstruction and colitis in different mono energetic levels (40, 50, 60 and 70 keV) and mixed images (120 kvP) in portal time abdominopelvic CT. Objective criterias (CNR) and subjective criterias like noise, smoothing, overall quality and diagnostic quality were evaluated.Results: sixty-four patients were reviewed, 33 with bowel occlusion (mean age 65+/-20 yo) and colitis (mean age 49+/-22 yo). The maximum CNR value was observed at 60 keV in the 2 groups with respectively no significant difference between the different levels except between 70 and 60 keV (-4.7% and p<0.05) for bowel occlusion and significant difference with 40 and 70 levels for colitis. The subjective evaluation showed a superiority of 60 keV images compared to the others mono energetic levels and mixed images for all criterions. Inter-observer agreement for the analysis of the different criteria showed a kappa of 0.95 for noise, 0.89 for smoothing, 0.88 for overall quality, 0.91 for diagnostic quality and 0.99 for diagnostic confidence.Conclusions: 60 keV seems to be the most suitable mono energetic level for analyzing the digestive tract since subjective evaluation found less noise and better appreciation of image quality and objective evaluation found a maximum CNR.