title: Diffusion-weighted imaging for evaluating inflammatory activity in Crohn's disease: comparison with histopathology, conventional MRI activity scores, and faecal calprotectin.
abstract: To evaluate whether the extent of enteric diffusion-weighted imaging (DWI) signal abnormality reflects inflammatory burden in Crohn's disease (CD), and to compare qualitative and quantitative grading.
  
  
  
  69 CD patients (35 male, age 16-78) undergoing MR enterography with DWI (MRE-D) and the same-day faecal calprotectin (cohort 1) were supplemented by 29 patients (19 male, age 16-70) undergoing MRE-D and terminal ileal biopsy (cohort 2). Global (cohort 1) and terminal ileal (cohort 2) DWI signal was graded (0 to 3) by 2 radiologists and segmental apparent diffusion coefficient (ADC) calculated. Data were compared to calprotectin and a validated MRI activity score [MEGS] (cohort 1), and a histopathological activity score (eAIS) (cohort 2) using nonparametric testing and rank correlation.
  
  
  
  Patients with normal (grades 0 and 1) DWI signal had lower calprotectin and MEGS than those with abnormal signal (grades 2 and 3) (160 vs. 492 μg/l, p = 0.0004, and 3.3 vs. 21, p < 0.0001), respectively. Calprotectin was lower if abnormal DWI affected <10 cm of small bowel compared to diffuse small and large bowel abnormality (236 vs. 571 μg, p = 0.009). The sensitivity and specificity for active disease (calprotectin > 120 μg/l) were 83% and 52%, respectively. There was a negative correlation between ileal MEGS and ADC (r = -0.41, p = 0.017). There was no significant difference in eAIS between qualitative DWI scores (p = 0.42). Mean ADC was not different in those with and without histological inflammation (2077 vs. 1622 × 10-6mm2/s, p = 0.10) CONCLUSIONS: Qualitative grading of DWI signal has utility in defining the burden of CD activity. Quantitative ADC measurements have poor discriminatory ability for segmental disease activity.
authors: University College London Hospitals NHS Foundation Trust, London, UK.|Centre for Medical Imaging, University College London, London, UK.
authors: D A
authors: 0000-0002-6326-4658
authors: DA
authors: Pendsé
authors: University College London Hospitals NHS Foundation Trust, London, UK.|Centre for Medical Imaging, University College London, London, UK.
authors: J C
authors: JC
authors: Makanyanga
authors: University College London Hospitals NHS Foundation Trust, London, UK.|Centre for Medical Imaging, University College London, London, UK.
authors: A A
authors: AA
authors: Plumb
authors: University College London Hospitals NHS Foundation Trust, London, UK.|Centre for Medical Imaging, University College London, London, UK.
authors: G
authors: G
authors: Bhatnagar
authors: University College London Hospitals NHS Foundation Trust, London, UK.|Centre for Medical Imaging, University College London, London, UK.
authors: D
authors: D
authors: Atkinson
authors: University College London Hospitals NHS Foundation Trust, London, UK.|Research Department of Pathology, Cancer Institute, UCL, London, UK.
authors: Manuel
authors: M
authors: Rodriguez-Justo
authors: University College London Hospitals NHS Foundation Trust, London, UK.|Centre for Medical Imaging, University College London, London, UK.
authors: S
authors: S
authors: Halligan
authors: University College London Hospitals NHS Foundation Trust, London, UK. stuart.taylor@uclh.nhs.uk.|Centre for Medical Imaging, University College London, London, UK. stuart.taylor@uclh.nhs.uk.
authors: S A
authors: SA
authors: Taylor
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis; D001706:Biopsy; D003424:Crohn Disease / Q000000981:diagnostic imaging* / Q000473:pathology; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005243:Feces / Q000737:chemistry; D005260:Female; D006801:Humans; D039841:Leukocyte L1 Antigen Complex / Q000032:analysis*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity
chemical_list: D014408:Biomarkers, Tumor; D039841:Leukocyte L1 Antigen Complex
keywords: Crohns disease; Diffusion; Imaging; Inflammatory bowel disease (IBD); Magnetic resonance imaging (MRI)