Novel Dual-Energy Computed Tomography Enterography Iodine Density Maps Provide Unique Depiction of Crohn Disease Activity

Objective To create a map of iodine densities within affected segments of small-bowel Crohn disease (CD) derived from contrast-enhanced dual-energy computed tomography enterography (DECTE) studies. Methods Twenty CD patients imaged with intravenous contrast-enhanced DECTE between June 2016 and December 2017 were retrospectively identified. Ten patients without clinical evidence of CD and 8 normal-appearing jejunal segments in CD patients were controls. Using prototype software, 8 manual contours were drawn along the mucosa of affected segments. Relatively normal-appearing bowel was included at the edges. These contours served as a basis for iodine density calculation and 3-dimensional iodine density map rendering. Color-coded iodine densities allowed detection and quantification of the most and least dense portion of each segment and also permitted relative comparison between segments. Results The average iodine density per CD involved segment ranged 1.0 to 3.3 mg/mL, which differed significantly from normal ileum (P< 0.0001) and normal-appearing jejunum in patients with CD (P= 0.0009). Standard deviations ranged from 0.8 to 1.7 mg/mL, which differed significantly from normal ileum (P= 0.0039) and normal-appearing jejunum in patients with CD (P= 0.0056). The amplitude of the power spectrum ranged from 0.66 to 3.3 demonstrating patches of iodine rather than uniform distribution. This differed significantly from normal ileum (P= 0.0005) and normal-appearing jejunum in patients with CD (P= 0.0004). Conclusions Heterogeneous CD activity and distribution can be displayed as iodine density maps created from DECTE.