Avoiding contrast-enhanced sequences does not compromise the precision of the simplified MaRIA for the assessment of non-penetrating Crohn's disease activity
Agnès Fernàndez-Clotet, Víctor Sapena, Nunzia Capozzi, Sonia Rodríguez, Maria-Carme Masamunt, Elena Ricart, Ingrid Ordás, Julian Panés, Jordi Rimola
Eur Radiol 2022 May;32(5):3334-3345; doi: 10.1007/s00330-021-08392-w. Epub 2022 Jan 15.
Magnetic resonance enterography (MRE) has gained a central role in the evaluation of small bowel in patients affected by Crohn’s disease; it is widely accepted as an imaging method with good ability to provide a detailed assessment of small bowel involvement [1]. MRE has been recently proposed as an alternative to ileocolonscopy, which could be often incomplete, and not able to describe transmural involvement and eventual presence of abdominal abscesses [2]. Moreover, MRE has a pivotal role in measuring therapeutic response, representing a noninvasive imaging tool to guide the clinicians in the decision-making process [3]. The use of contrast enhancement is a cornerstone in current MRE protocols, and it is also required for the Magnetic Resonance Index of Activity (MaRIA), one of the major MR grading systems to evaluate the response to therapy in Crohn’s disease [4]. However, MaRIA is a time consuming classification, and the recent evidence of gadolinium deposits in the brain concerns the clinicians, especially in young patients [5]. Then, to overcome these shortcomings and to make the score assessment easier, a novel simplified version of MaRIA (sMaRIA) has been proposed [6].
This study aimed to test the performance, in terms of accuracy, of sMARIA calculated with and without contrast-enhanced sequences, with the goal to assess the biologic therapeutic response in patients affected by Crohn’s disease. Authors prospectively enrolled 46 patients, selected according to the presence of endoscopic ulcerations in at least two intestinal segments, and eligible to be treated with biologic therapy. All patients underwent MRE and ileocolonoscopy within 1 month before starting therapy and they repeated the follow-up examinations (MRE and ileocolonoscopy) at 46 weeks. Ileocolonoscopy was considered the reference standard to assess disease activity by using Simple Endoscopic Score for Crohn’s Disease (SES-CD) [7]. The evaluation of inflammatory changes was conducted on five tracts of colon and terminal ileum. This approach was built to compare in a structured manner the MRE with ileocolonoscopy. Two abdominal radiologists, blinded to clinical and endoscopy results, classified the sMaRIA descriptors in the first round by using the unenhanced sequences (T2-sMaRIA) and in the second round, 1 month later, with all set of sequences (CE-sMaRIA). They calculated the agreement for both T2-sMaRIA and CE-sMaRIA to classify the biologic response in each intestinal tract and per-patient. In per-patient analysis, three different endpoints were evaluated for T2-sMaRIA and CE-sMaRIA: the MRE ability to identify patients with ulcer healing, MRE accuracy in decrease ≥50% of global scores, and MRE performance in identifying endoscopic remission. Overall, in identifying ulcer healing in per-patient analysis the agreement of T2-sMaRIA and CE-sMaRIA was comparable with ileocolonoscopy (sensibility = 80 and 76%; specificity = 95.2 and 95.2%; kappa = 0.74 [0.55-0.93] and 0.70 [0.5-0.9], respectively). Both T2-sMaRIA and CE-sMaRIA identified better the ulceration in the colon in comparison with the ileal segments (Cochran’s Q test <0.001 for both tests). Concerning the therapeutic assessment T2-sMaRIA and CE-sMaRIA were also like ileocolonoscopy for both treatment response (kappa = 0.44 [0.17 - 0.71] and 0.53 [0.28-0.79]) and remission (kappa = 0.43 [0.17-0.69] and 0.48 [0.22-0.73]). The standardized effect size was moderate for both CE-sMaRIA = 0.63 ([0.41-0.85] p < 0.001) and T2-sMaRIA = 0.58 ([0.36-0.80] p < 0.001) when was considered an improvement of at least 0.5 standard deviation in endoscopic evaluation (SES-CD), this cut-off was used as criterion for radiological changes.
Despite the interesting results, limits of the study include the single-institution origin of the radeaders and the possible cohort bias with a few patients with isolated colonic disease, less prone to undergo MRE for treatment assessment during follow-up.
To sum up, sMaRIA calculated with and without contrast-enhanced sequences showed similar performance in classifying the activity, severity, and biologic therapeutic response in patients with Crohn disease. Only few cases of disagreement were observed by the authors to assess therapeutic response, the endpoint with lower accuracy was the assessment of remission. In conclusion, the acceptance and safety of MRE can increase by avoiding the use of contrast medium, without the risk of reducing accuracy.
References:
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- Capozzi, N., et al., Validation of the Simplified Magnetic Resonance Index of Activity [sMARIA] Without Gadolinium-enhanced Sequences for Crohn's Disease. J Crohns Colitis, 2020. 14(8): p. 1074-1081.
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Dr. Michela Polici is a radiology resident at "Sapienza" University of Rome - Sant'Andrea University Hospital in Rome, attending the third year of residency. Her main fields of interest are radiomics and diagnostic imaging, with a particular attention to the Gastrointestinal tract Abdominal parenchyma. She has also been actively involved in clinical imaging research, and she has contributed as a co-author in some publications.
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