Which magnetic resonance imaging findings accurately evaluate inflammation in small bowel Crohn's disease? A retrospective comparison with surgical pathologic analysis.

BACKGROUND: The aim was to evaluate the value of magnetic resonance imaging (MRI) findings in Crohn's disease (CD) in correlation with pathological inflammatory score using surgical pathology analysis as a reference method.
METHODS: CD patients who were to undergo bowel resection surgery underwent MR enterography before surgery. The CD pathological inflammatory score of the surgical specimens was classified into three grades: mild or nonactive CD, moderately active CD, and severely active CD; fibrosis was also classified into three grades: mild, moderate, and severe. Mural and extramural MRI findings were correlated with pathological inflammatory and fibrosis grades.
RESULTS: Fifty-three consecutive patients were included retrospectively. The mean delay between MRI and surgery was 24 days (range 1-90, median 14). The CD pathological inflammatory score was graded as follows: grade 0 (11 patients, 21%), grade 1 (15 patients, 28%), and grade 2 (27 patients, 51%). MRI findings significantly associated with pathological inflammatory grading were wall thickness (P < 0.0001), degree of wall enhancement on delayed phase (P < 0.0001), pattern of enhancement on both parenchymatous (P = 0.02), and delayed phase, (P = 0.008), T2 relative hypersignal wall (P < 0.0001), blurred wall enhancement (P = 0.018), comb sign (P = 0.004), fistula (P < 0.0001), and abscess (P = 0.049). The inflammation score correlated with the fibrosis score (r = 0.63, P = 0.0001).
CONCLUSIONS: Our study identified MRI findings significantly associated with surgical pathological inflammation. These lesions are considered potentially reversible and may be efficiently treated medically. We also showed that fibrosis was closely and positively related to inflammation.