Mesenteric lymph nodes in MR enterography: are they reliable followers of bowel in active Crohn's disease?

ObjectivesTo demonstrate magnetic resonance enterography (MRE) features of mesenteric lymph nodes (LN) in patients with Crohn's disease (CD) and investigate whether they follow enhancement or apparent diffusion coefficient (ADC) parameters of bowel.MethodsThis study was approved by the institutional review board. A total of 788 MREs from patients with CD were retrospectively reviewed. Eighty-eight patients, aged 16-66 years, including 59 active cases, were enrolled based on inclusion criteria. In each MRE, two segments (normal and abnormal) and two LNs (regional and non-regional) were independently suggested, consensually chosen, and analyzed by two radiologists. Signal-to-noise (SNR) and contrast-to-noise (CNR) ratios were calculated to assess signal intensities (SI) at 30, 60 and 180 s after contrast administration, as well as slope of enhancement (SOE). Enhancement parameters and ADC values were compared.ResultsRegional LNs showed significantly higher SI30, SI60 and SI180 (CNR&SNR) and lower ADC values in active vs. inactive groups (all p<0.05) without significant difference in number or size. Strong correlations were demonstrated between abnormal segments and regional LNs in active group in terms of SI30, SI60, SI180, SOE0-30 and ADC values (r = 0.679 to 0.774, all p<0.001). SI180, SOE60-180 and ADC values were moderately correlated between abnormal segments and regional LNs in inactive group (r = 0.448 to 0.595, all p<0.05). In logistic regression analyses, SOE0-30 and ADC value of regional LNs independently predicted active CD.ConclusionMesenteric LNs follow quantitative enhancement and diffusion parameters of bowel in active CD. SOE0-30 and ADC value of LN could predict disease activity.Key Points center dot Mesenteric LNs may strongly follow enhancement pattern of bowel in active CD.center dot DWI parameters of LNs and bowel were strongly correlated in active CD.center dot SI(180)was moderately correlated between bowel and LNs in inactive CD.center dot DWI parameters were moderately correlated between LNs and bowel in inactive CD.center dot SOE(0-30)and ADC value of mesenteric LN could predict disease activity.