Do we really need contrast medium? Quantitative measurement of ADC for disease activity assessment in paediatric Inflammatory Bowel Disease

Abstract

Objective To establish an ADC cut-off value to classify active and non-active lesions in inflammatory bowel disease (IBD). Methods and Materials We reviewed 167 paediatric Magnetic resonance enterographies (MREs) executed for suspected IBD. Data such as bowel wall thickness, DWI restriction, stenosis and pre-stenotic dilatation, comb sign, fat stranding, reactive lymph nodes, and contrast enhancement pattern were collected. In the ADC map, quantitative assessment of disease activity was measured (max 3 lesions/exam) placing 3 regions of interest (ROIs) in the areas of highest inflammation (based on qualitative analysis of the DWI sequence) and the mean ADC value was calculated. Similarly, we assessed ADC values of the bowel wall in those patients were no IBD lesions were found, placing the ROIs at a standardised site. Ileocolonoscopy, esophagogastroduodenoscopy or surgery with histology and video-capsule endoscopy were used as the standards of reference. Results Due to rigid inclusion criteria only 34 patients were eventually enrolled in the study. Radiological findings of IBD were identified in 29 MREs and 44 lesions were detected, using two different MRI scanners (1.5- and 3-tesla). The remaining 6 patients had negative MRE. A total of 56 bowel segments were included in the study. Acute disease was found in 39 lesions (69.6%), whereas 17 (30.4%) were classified as non-active lesions or healthy segments. Active ADC values were lower compared to the ones of non-active portions. For each scanner an ADC cut-off value to discern active and non-active segments was found. Sensitivity was 0.91 for both the MREs, and specificity was 0.89 and 0.81 for 1.5T and 3T respectively. Inter-rater agreement on disease activity between ADC values and MRE results and between ADC values and the standard of reference were very good for both 1.5T and 3T. Conclusions DWI is a powerful tool to detect IBD involvement of a bowel segment and ADC map can provide a scanner-based quantitative measurement of disease activity to separate active and non-active lesions