Dataset Information

Magnetisation transfer imaging adds information to conventional MRIs to differentiate inflammatory from fibrotic components of small intestinal strictures in Crohn's disease.

ABSTRACT:

Objectives

Identifying inflammation- or fibrosis-predominant strictures in Crohn's disease (CD) is crucial for treatment strategies. We evaluated the additive value of magnetisation transfer (MT) to conventional MRI for differentiating CD strictures using surgical histopathology as a reference standard.

Methods

Twenty-eight consecutive CD patients who underwent MRI preoperatively were recruited. MRI parameters included T2-weighted imaging (T2WI) hyperintensity, bowel wall thickness, enhancement pattern changes over time, enhancement pattern and gain ratio in dynamic contrast-enhanced phases, and MT ratio. Correlation analysis was performed using Spearman's rank test. Receiver operating characteristic curve analysis and Cohen's κ were used. A model with combined MRI variables characterising intestinal strictures was proposed and validated in 14 additional CD patients.

Results

Significant correlations with histological inflammation scores were shown for wall thickness (r = 0.361, p = 0.001) and T2WI hyperintensity (r = 0.396, p < 0.001), whereas histological fibrosis scores were significantly correlated with MT ratio (r = 0.681, p < 0.001) and wall thickness (r = 0.461, p < 0.001). T2WI hyperintensity could differentiate mild from moderate-to-severe inflammation with a sensitivity of 0.871 and a specificity of 0.800. MT ratio could discriminate mild from moderate-to-severe fibrosis with a sensitivity and a specificity of 0.913 and 0.923, respectively. Combining MT ratio and T2WI hyperintensity, the MRI classification moderately agreed with the pathological stricture classification (p < 0.01, κ = 0.549). In the validation set, the diagnostic accuracy of T2WI hyperintensity and MT ratio were 86% and 89%, with good agreement between MRI and histopathological classification (p < 0.01, κ = 0.665).

Conclusions

MT ratio combined with conventional MRI improves the differentiation of fibrotic from inflammatory components of small-bowel strictures in CD patients.

Key points

• MT ratio from magnetisation transfer imaging combined with T2WI from conventional MRI can simultaneously characterise bowel fibrosis and inflammation in adult Crohn's disease.

SUBMITTER: Fang ZN

PROVIDER: S-EPMC7760892 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:AimTo develop a new rat model we wanted to gain a better understanding of stricture formation in Crohn's disease (CD).MethodsChronic colitis was induced locally by the administration of 2,4,6-trinitrobenzenesulfonic acid (TNBS). The relapsing inflammation characteristic to CD was mimicked by repeated TNBS treatments. Animals were randomly divided into control, once, twice and three times TNBS-treated groups. Control animals received an enema of saline. Tissue samples were taken from the strictured colonic segments and also adjacent proximally and distally to its 60, 90 or 120 d after the last TNBS or saline administrations. The frequency and macroscopic extent of the strictures were measured on digital photographs. The structural features of strictured gut wall were studied by light- and electron microscopy. Inflammation related alterations in TGF-beta 2 and 3, matrix metalloproteinases 9 (MMP9) and TIMP1 mRNA and protein expression were determined by quantitative real-time PCR and western blot analysis. The quantitative distribution of caspase 9 was determined by post-embedding immunohistochemistry.ResultsIntestinal strictures first appeared 60 d after TNBS treatments and the frequency of them increased up to day 120. From day 90 an intact lamina epithelialis, reversible thickening of lamina muscularis mucosae and irreversible thickening of the muscularis externa were demonstrated in the strictured colonic segments. Nevertheless the morphological signs of apoptosis were frequently seen and excess extracellular matrix deposition was recorded between smooth muscle cells (SMCs). Enhanced caspase 9 expression on day 90 in the SMCs and on day 120 also in myenteric neurons indicated the induction of apoptosis. The mRNA expression profile of TGF-betas after repeated TNBS doses was characteristic to CD, TGF-beta 2, but not TGF-beta 3 was up-regulated. Overexpression of MMP9 and down-regulation of TIMP1 were demonstrated. The progressive increase in the amount of MMP9 protein in the strictures was also obvious between days 90 and 120 but TIMP1 protein was practically undetectable at this time.ConclusionThese findings indicate that aligned structural and molecular changes in the gut wall rather than neuronal cell death play the primary role in stricture formation.