Increased CT Attenuation of Pericolic Adipose Tissue as a Noninvasive Marker of Disease Severity in Ulcerative Colitis

Figures

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  Fig. 1. The patient selection flowchart. UC = ulcerative colitis, UCEIS = ulcerative colitis endoscopic index of severity

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  Fig. 2. The schematic diagram of the four locations where the ROIs were placed. A: Target bowel selection: the most severe bowel was selected to be analyzed (dark red: descending colon), and the axial CT image across the bowel lesion was obtained. B: The axial CT image shows the bowel lesion (dark red). The green ROIs named RS and Sub referred to the ROI located at RS and Sub on axial CT images, respectively. The blue lines referred to mesenteric vessels. C: Oblique sagittal CT images were reconstructed, which was consistent with the direction of the mesenteric vessel. D: The green ROIs named MS and OMS referred to the ROI located at the MS and the OMS around the most severe bowel lesion. ROI = region of interest, RS = retroperitoneal space, Sub = subcutaneous area, MS = mesocolic vascular side, OMS = opposite side of MS, RK = right kidney, LK = left kidney, IVC = inferior vena cava, AO = aortaventralis

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  Fig. 3. Quantitative assessment of fat attenuation from four different locations—MS, OMS (around the most severe bowel lesion), RS, and subcutaneous area. CT images in the non-enhanced phase of a 70-year-old male with severe disease activity (UCEIS = 8). The most severe bowel lesion was located at the sigmoid colon. The FAIMS (29.135 HU) and FAIOMS (15.46 HU) were significantly higher than FAIRS (-2.535 HU). Additionally, the FAIMS significantly increased compared to the FAIOMS. MS = mesocolic vascular side, OMS = opposite side of MS, RS = retroperitoneal space, UCEIS = ulcerative colitis endoscopic index of severity, FAI = fat attenuation index, HU = Hounsfield unit

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  Fig. 4. Quantitative assessment of fat attenuation from four different locations (MS and the OMS around the most severe bowel lesion, RS, and subcutaneous area). CT images in the non-enhanced phase of a 39-year-old female with non-severe disease activity (UCEIS = 2). The most severe bowel lesion was located at the descending colon. The FAIMS (26.705 HU) and FAIOMS (19.46 HU) were significantly higher than FAIRS (-0.26 HU). Additionally, the FAIMS significantly increased compared to the FAIOMS. MS = mesocolic vascular side, OMS = opposite side of MS, RS = retroperitoneal space, UCEIS = ulcerative colitis endoscopic index of severity, FAI = fat attenuation index, HU = Hounsfield unit

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  Fig. 5. Relationships between FAI and endoscopic scores. A-F: Demonstrate a significant positive association between the pericolic FAI and UCEIS scores in three phases. G-L: Demonstrate a significant positive association between the pericolic FAI and Mayo endoscopic scores in three phases. The FAIMS and FAIOMS referred to the fat attenuation of MS and OMS around the most severe bowel lesion minus that of the subcutaneous area. FAI = fat attenuation index, UCEIS = ulcerative colitis endoscopic index of severity, MS = mesocolic vascular side, OMS = opposite side of MS