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Background: High visceral adipose tissue (VAT) and creeping fat (CrF) in Crohn's disease (CD) have been widely recognized. The VAT to subcutaneous adipose tissue (SAT) ratio and sarcopenia have been associated with CD complications. Studies regarding the influence of body composition predictors on CD complications assessed with magnetic resonance enterography (MRE) are scarce. Aim: Assessment of the body composition parameters and CrF in opportunistic MRE as predictors of complicated CD. Methods: This was a retrospective study of 114 patients with inflammatory (n = 54) and complicated (n = 60) CD. The semi-automated assessment of body composition and the qualitative evaluation of CrF were performed. Results: Body composition parameters did not differ between both groups regarding the body mass index (BMI) (p =0.50), total adipose tissue index (TATI) (p =0.14), subcutaneous adipose tissue index (SATI) (p =0.17), visceral adipose tissue index (VATI) (p =0.33), VAT/SAT ratio (p =0.77), intramuscular adipose tissue (IMAT) (p =0.64), skeletal muscle index (SMI) (p =0.22), and sarcopenia (p =0.50). 47 strictures, 18 fistulae, and seven abscesses were identified. Fistulae were more likely to occur in patients with CrF (odds ratio [OR] 5.07, 95% confidence interval [CI] 1.76–14.56; p=<0.001) and high VAT/SAT ratio (OR: 3.82, 95% CI 1.34–10.85; p=0.01). Conclusion: Body composition measurements in CD patients displayed no statistically significant difference between the groups of inflammatory and complicated disease. Nonetheless, CD patients stratified in the group of high VAT/SAT ratio and the presence of CrF should be recognized as risk groups for the occurrence of fistulae.

Photoionization modelling allows to follow the transport, the emergence, and the absorption of photons taking into account all important processes in nebular plasmas. Such modelling needs the spatial distribution of density, chemical abundances and temperature, that can be provided by chemo-dynamical simulations (ChDS) of dwarf galaxies. We perform multicomponent photoionization modelling (MPhM) of the ionized gas using 2-D ChDSs of dwarf galaxies. We calculate emissivity maps for important nebular emission lines. Their intensities are used to derive the chemical abundance of oxygen by the so-called T e − and R 23 −methods. Some disagreements are found between oxygen abundances calculated with these methods and the ones coming from the ChDSs. We investigate the fraction of ionizing radiation emitted in the star-forming region which is able to leak out the galaxy. The time-and direction-averaged escape fraction in our simulation is 0.35-0.4. Finally, we have calculated the total Hα luminosity of our model galaxy using Kennicutt's calibration to derive the star-formation rate. This value has been compared to the 'true' rate in the ChDSs. The Hα -based star-formation rate agrees with the true one only at the beginning of the simulation. Minor deviations arise later on and are due in part to the production of high-energy photons in the warm-hot gas, in part to the leakage of energetic photons out of the galaxy. The effect of artificially introduced thin dense shells (with thicknesses smaller than the ChDSs spatial resolution) is investigated, as well.

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