Measurements on slope parameter mapping based on dual-energy CT enterography for improving Crohn's disease diagnosis and inflammatory activity evaluation

To explore the value of slope parameter images (SPI) derived from the dual-phase dual-energy CT enterography (DE-CTE) in the diagnosis and activity evaluation of Crohn's disease (CD). A retrospective analysis of 76 patients with CD and 53 controls who underwent dual-phase DE-CTE between January 2019 and March 2022. CD lesions were divided into non-moderate-to-severe activity (n = 108) and moderate-to-severe activity (n = 59). Virtual monoenergetic images of 40-100 keV and SPI for energy spectrum curves between 40 and 100 keV (SPI_40-100) were generated. Virtual monoenergetic CT values (HU_40-100keV) and the slope between 40 and 100 keV measured on SPI_40-100 (SP_40-100) on intestinal wall and adjacent mesenteric fat for the dual phases were collected. The performances of quantitative parameters in the diagnosis and activity assessment of CD were evaluated. The dual-phase SP_40-100 and HU_40-100 in the affected intestinal wall and adjacent mesenteric fat were higher than those in the control group (P < 0.001). For CD diagnosis, the area under the curve (AUC) of the arterial phase (AP) SP_40-100 of mesenteric fat was the highest (AUC = 0.969, P < 0.05). The dual-phase SP_40-100 and HU_40-100keV of the intestinal wall and creeping fat in those with moderate-to-severe activity were significantly higher than those with non-moderate-to-severe activity (P < 0.001). For activity assessment, AP-SP_40-100 of creeping fat had the highest AUC among all parameters (AUC = 0.935, P < 0.05). The measurements on SPI_40-100 obtained via dual-phase DE-CTE have high value in CD diagnosis and inflammatory activity evaluation, and the AP SP_40-100 of mesenteric fat has the highest diagnostic efficacy.