Quantitative MRI in murine radiation‐induced rectocolitis:
comparison with histopathological inflammation score
Bernard E. Van Beers
Hôpitaux Universitaires Beaujon, Radiology,
Université Paris VII, Clichy, France
Laboratory of Imaging Biomarkers, Center of
Research on Inflammation, UMR 1149,
INSERM, University Paris‐Diderot, Paris,
Hopital Beaujon, Pathology, Université Paris
VII, Clichy, France
Laboratory of Intestinal Inflammation, Center
of Research on Inflammation, UMR 1149,
INSERM, University Paris Diderot, Paris,
Institute for Radiological Protection and
Nuclear Safety (IRSN), Research Laboratory in
Radiobiology and Radiopathology, Fontenay‐
Magaly Zappa, Hôpitaux Universitaires
Beaujon, Radiology, Université Paris VII,
France Life Imaging, Grant/Award Number:
Murine radiation‐induced rectocolitis is considered to be a relevant animal model of gastrointes-
tinal inflammation. The purpose of our study was to compare quantitative MRI and histopatho-
logical features in this gastrointestinal inflammation model.
Radiation rectocolitis was induced by localized single‐dose radiation (27 Gy) in Sprague‐Dawley
‐weighted and diffusion‐weighted MRI was performed at 7 T in 16 rats
between 2 and 4 weeks after irradiation and in 10 control rats. Rats were sacrificed and the his-
topathological inflammation score of the colorectal samples was assessed.
The irradiated rats showed significant increase in colorectal wall thickness (2.1 ± 0.3 mm versus
0.8 ± 0.3 mm in control rats, P < 0.0001), normalized T
signal intensity (4 ± 0.8 versus 2 ±
0.4 AU, P < 0.0001), normalized T
signal intensity (1.4 ± 0.1 versus 1.1 ± 0.2 AU, P = 0.0009)
and apparent and pure diffusion coefficients (ADC and D) (2.06 × 10
± 0.34 versus 1.51 ×
± 0.23 mm
/s, P = 0.0004, and 1.97 × 10
± 0.43 mm
/s versus 1.48 × 10
/s, P = 0.008, respectively). Colorectal wall thickness (r = 0.84, P < 0.0001), normalized
signal intensity (r = 0.85, P < 0.0001) and ADC (r = 0.80, P < 0.0001) were strongly correlated
with the histopathological inflammation score, whereas normalized T
signal intensity and D were
moderately correlated (r = 0.64, P = 0.0006, and r = 0.65, P = 0.0003, respectively).
High‐field MRI features of single‐dose radiation‐induced rectocolitis in rats differ significantly
from those of control rats. Quantitative MRI characteristics, especially wall thickness, normalized
signal intensity, ADC and D, are potential markers of the histopathological inflammation score.
colitis, inflammation, MRI, pathology, radiation‐induced, rats
Gastrointestinal inflammation, including idiopathic intestinal inflammatory diseases and radiation enteropathy, results in significant morbidity and
mortality, with compromised quality of life and life expectancy.
To explore the pathophysiological mechanisms of gastrointestinal inflammation
and to serve as tools for the preclinical evaluation of new drug efficacy, various animal models of gastrointestinal inflammation have been devel-
oped, including chemically induced, spontaneous, genetically engineered and transgenic models.
The MRI signs of some animal models have been
However, these animal models are limited by their variability and their dissimilarity to human inflammatory bowel disease.
In contrast, as highlighted by Hauer‐Jensen et al., radiation enteropathy could be considered a nearly ideal model of gastrointestinal inflamma-
tion for several reasons.
First, radiation enteropathy is highly clinically relevant and the prevalence of radiation‐induced gastrointestinal dysfunc-
tion is higher than that of inflammatory bowel disease. Second, animal models and patients have identical pathophysiology; therefore, the
translational value of the observations made in the animal model is clear. Third, animal models of radiation enteropathy have made it possible to
Abbreviations used: ADC, apparent diffusion coefficient; IVIM, intra‐voxel incoherent motion; ROI, region of interest
Received: 16 March 2017 Revised: 17 December 2017 Accepted: 26 December 2017
NMR in Biomedicine. 2018;31:e3897.
Copyright © 2018 John Wiley & Sons, Ltd.wileyonlinelibrary.com/journal/nbm 1of8