==== Front Intest ResIntest ResIRIntestinal Research1598-91002288-1956Korean Association for the Study of Intestinal Diseases 10.5217/ir.2018.16.3.445Original ArticleMagnetic resonance enterography predicts the prognosis of Crohn's disease Lee Ji Hoon 1Park Yong Eun 1Seo Nieun 2Lee Hyun Jung 1Park Soo Jung 1Kim Tae Il 1Kim Won Ho 1Lim Joon Seok 2Cheon Jae Hee 131 Department of Internal Medicine and Institute of Gastroenterology, Yonsei University College of Medicine, Seoul, Korea.2 Department of Radiology, Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, Korea.3 Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea.Correspondence to Jae Hee Cheon, Department of Internal Medicine and Institute of Gastroenterology, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea. Tel: +82-2-2228-1990, Fax: +82-2-393-6884, GENIUSHEE@yuhs.acCo-Correspondence to Joon Seok Lim, Department of Radiology, Research Institute of Radiological Science, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea. Tel: +82-2-2228-7400, Fax: +82-2-393-3035, JSLIM1@yuhs.ac7 2018 27 7 2018 16 3 445 457 25 8 2017 16 10 2017 19 10 2017 © Copyright 2018. Korean Association for the Study of Intestinal Diseases.2018Korean Association for the Study of Intestinal DiseasesThis is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.Background/Aims Magnetic resonance enterography (MRE) has emerged as an important tool in the diagnosis and follow-up of Crohn's disease (CD). The aim of this study was to evaluate whether MRE findings could predict the prognosis of CD. Methods In this retrospective study, a total of 173 patients with clinical remission of CD (n=61) or active CD (n=112) were identified. The outcomes of clinical relapse, admission, surgery, and need for other medications according to the MRE findings were evaluated. Results The presence of active inflammation on MRE was observed in 93 (83%) patients with clinically active CD and in 44 (72.1%) patients with clinical remission of CD, without a statistically significant difference (P=0.091). In multivariate analysis, active inflammation on MRE increased the risk for clinical relapse (hazard ratio [HR], 6.985; 95% confidence interval [CI], 1.024–47.649) in patients with clinical remission of CD. In patients with clinically active CD, active inflammation on MRE increased the risk for CD-related hospitalization (HR, 2.970; 95% CI, 1.006–8.772). Conclusions The presence of active inflammation on MRE was significantly associated with poor prognosis both in patients with clinical remission of CD and in those with active CD. Magnetic resonance enterographyPrognosisCrohn diseaseKorea Health Industry Development Institutehttp://dx.doi.org/10.13039/501100003710A120176HI13C1345National Research Foundation of Koreahttp://dx.doi.org/10.13039/501100003725NRF-2013R1A2A2A01067123NRF-2014R1A1A1008096 ==== Body INTRODUCTION Crohn's disease (CD) is a chronic transmural IBD that can occur throughout the gastrointestinal tract. It is characterized by repeated episodes of exacerbation and regression. Approximately 70% of patients with CD have small-bowel involvement, and 30% of them have disease limited to the small bowel.1 Mucosal healing has become the treatment target in the management of CD.2 However, it is difficult to recognize mucosal lesions in patients with small-bowel lesions using conventional endoscopic methods. The CDAI is widely used in assessing disease activity; however, clinical symptoms scored by CDAI are not reliable measures of mucosal inflammation.3 Computerized tomography enterography (CTE) imaging is useful for assessing disease activity in CD but exposes patients to a large dose of radiation during each evaluation, therefore preventing repeated examinations.4 In recent years, magnetic resonance enterography (MRE) has emerged as an important tool in the diagnosis and follow-up of CD.5 MRE can provide information on the deep small intestine and extraluminal manifestations of CD.6 MRE is preferred because it does not expose patients to ionizing radiation, has a high tissue contrast, and uses safe gadolinium-based contrast media.7 A correlation between MRE imaging and the disease activity of CD has been established.8 In a meta-analysis study, the sensitivity and specificity of MRI for the detection of CD were found to be 93.0% and 92.8%, respectively.9 In other study, MRE detected ulcerative lesions in the small intestine with 82.4% sensitivity and 87.6% specificity.10 In another study assessing ileocolonic CD, MRE imaging was superior to CTE in detecting intestinal strictures and ileal wall enhancement.11 In a recent study, Deepak et al.12 revealed that radiological response detected with CTE or MRE was associated with a reduction in the long-term risk of hospitalization, surgery, or corticosteroid use among patients with small-bowel CD. However, few studies have evaluated the prognosis of patients with CD in terms of the first MRE findings both at the time of clinical remission and during the clinically active state. Therefore, the purpose of our study was to evaluate the usefulness of MRE imaging in assessing the prognosis of CD. We hypothesized that active inflammatory findings on MRE would be associated with poor prognosis such as relapse, admission, surgery, need for corticosteroids, need for adding other medications, or need for increasing the dose of current medications even in patients with clinical remission of CD. METHODS 1. Patients In this retrospective study, we reviewed the medical records of patients with CD who underwent MRE imaging at Severance Hospital, Yonsei University College of Medicine, Seoul, Korea, between December 2012 and March 2016. The purposes of MRE imaging evaluation were divided into 2 categories: evaluation of current CD activity at the time of clinical remission and that during the clinically active state. MRE was performed in order to follow-up after the treatment. The indications for MRE were when the symptoms persisted despite treatment, complications were suspected, inflammatory markers were elevated even with clinical remission, and determination of the appropriateness of current treatment. The CDAI according to the criteria of Best et al.13 was used to assess the disease activity of patients with CD. A CDAI score <150 was considered to indicate clinical remission. Clinical relapse was defined as the occurrence or worsening of symptoms, accompanied by an increase in the CDAI score to >150.14 Descriptions of patient age at CD diagnosis, disease location, and phenotype were based on the Montreal classification.15 Previous surgery was defined as a prior CD-related surgery that includes major surgeries such as ileocecectomy and small-bowel resection. The exclusion criteria were patient age <18 years, inaccurate diagnosis of CD, <3 months of follow-up, and any contraindications to MRE imaging such as the presence of a pacemaker in patients. Admission was defined as hospitalization for >1 day through the emergency room or outpatient clinic. Surgery was defined as any CD-related surgeries such as small-bowel resection and ileocecectomy. The need for corticosteroids was defined as the addition of any amount of corticosteroids in patients who were not steroid users during the follow-up period after MRE examination. The need for adding other medications or increasing the dose of current medications was defined as the addition of another type of CD medication or increasing the dose of medications used after MRE examination including corticosteroids, respectively. The study was approved by the Institutional Review Board of Severance Hospital (IRB No. 4-2016-0857) and performed in accordance with the principles of the Declaration of Helsinki. The informed consent was waived. 2. MRE Technique We used very low concentration of barium suspension (easy Mark 0.1; Taejoon Pharmaceutical, Seoul, Korea) for luminal distension of small bowel. Patients were given 1,350 mL of this solution orally 60 minutes before MRI. A 3-T imaging unit (Achieva 3T; Philips, Best, the Netherlands or Discovery 750; GE Healthcare, Milwaukee, WI, USA) was used. Briefly, the following sequences were performed: coronal T2-weighted half-Fourier sequences with and without fat suppression; coronal and axial T2-like steady-state gradient-echo sequences with fat suppression; coronal free breathing diffusion-weighted imaging (with b factors of 0, 500, and 800 s/mm2) and apparent diffusion coefficient mapping; and coronal T1-weighted spoiled gradient-echo sequences with fat suppression, including unenhanced imaging and dynamic phases sequences performed after intravenous administration of gadolinium-based contrast material (Gadovist; Schering, Berlin, Germany) (0.2 mmol/kg at a rate of 2 mL/s) followed by a saline bolus injection and an axial delayed contrast-enhanced T1-weighted spoiled gradient-echo sequence with fat suppression. To avoid bowel peristalsis, 10 mg scopolamine-N-butyl bromide (Buscopan; Boehringer-Ingelheim, Ingelheim, Germany) was administered intravenously, immediately before imaging. An additional same dose of scopolamine was injected immediately before the contrast-enhanced T1-weighted imaging. 3. Image Analysis The MRE images were reviewed retrospectively by 2 experienced radiologists (J.S.L. and N.S.) who were blinded to the clinical and laboratory findings of the patients. Active inflammation on MRE was defined as the presence of more than one of the following findings: mural thickening >3 mm, mural hyperenhancement, mural edema (increased signal intensity on T2-weighted images), comb sign (sign of engorged vasa recta), penetration (sinus tract, fistula, abscess), or restricted diffusion on diffusion-weighted images.1617181920 Mucosal healing was defined as the absence of any findings of active inflammation. 4. End Points The end points were the rates of clinical relapse, admission, surgery, need for corticosteroids, need for adding other medications, or need for increasing the dose of current medications according to the purpose of the MRE examination. 5. Statistical Analysis Statistical analyses were conducted by using SPSS version 18.0 (SPSS Inc., Chicago, IL, USA). Continuous variables were compared by using the two-sample t-test or the Mann-Whitney U-test. The chi-square test or Fisher exact test was used to analyze categorical data. The cumulative probabilities of clinical relapse, admission, CD-related surgery, need for corticosteroids, need for adding other medications, or need for increasing the dose of current medications were estimated by using the Kaplan-Meier method and the log-rank test. A Cox proportional hazards model was used for assessing the risk of clinical relapse, admission, CD-related surgery, need for corticosteroids, need for adding other medications, or need for increasing the dose of current medications. A P-value of <0.05 was considered statistically significant. RESULTS A total of 173 consecutive patients with CD who met the inclusion criteria were included in this study (Fig. 1). The baseline characteristics of the patients on the day of MRE examination are summarized in Table 1. There were 127 male (73.4%) and 46 female (26.6%) patients whose median age at diagnosis was 21 years (interquartile range [IQR], 18–27 years). The median BMI was 20 kg/m2 (IQR, 18–22 kg/m2), and the median duration of disease was 7 years (IQR, 4–11 years). The median CDAI on the day of MRE examination was 95 (IQR, 61–122) in patients with clinical remission of CD and 228 (IQR, 187–277) in patients with clinically active CD (P<0.001). The median CRP level and ESR were higher in patients with clinically active CD than in those with clinical remission of CD (P<0.001 and P=0.003, respectively), and the median albumin level was lower in patients with clinically active CD (P<0.001). Almost half of the patients (49.7%) had perianal lesions, and 71 patients (41%) had a previous CD-related surgery. The median follow-up period after MRE was 14.4 months (IQR, 9.9–20.1 months) in patients with clinical remission of CD and 17.7 months (IQR, 12.3–22.9 months) in those with clinically active CD (P<0.001). The presence of active inflammation on MRE was observed in 93 (83.0%) patients with clinically active CD and in 44 (72.1%) patients with clinically remission of CD, with no statistically significant difference (P=0.091). More than 72% of patients with clinical remission of CD still had active inflammation on MRE examination. A total of 61 patients were in the clinical remission state, and their baseline characteristics according to the MRE results are detailed in Table 2. Forty-four patients (72.1%) had active inflammation on MRE, and their median CRP was higher than that of patients with no active inflammation on MRE (P=0.003). The median albumin level was significantly lower in the group with active inflammation than in the group without (P=0.008). A total of 112 patients were in the clinically active state, and their baseline characteristics are summarized in Table 3. The median CRP level and ESR were higher in the group with active inflammation (P<0.001 and P<0.001, respectively), and the median albumin level was higher in the group without active inflammation (P<0.001). 1. Medication Use The medications used at the time of MRE examination among patients with clinical remission of CD were 5-aminosalicylic acid (5-ASA) in 56 patients (91.8%), azathioprine in 34 patients (55.7%), tumor necrosis factor α (TNF-α) inhibitors in 10 patients (16.4%), corticosteroids in 1 patient (1.6%), methotrexate in 1 patient (1.6%), and none in 1 patient (1.6%). Among 61 patients in the clinical remission state, the need for adding other medications or increasing the dose of current medications was observed in 24 patients (39.3%), and of these, addition of corticosteroids was observed in 5 patients (8.2%). The medications used at the clinically active state of CD were 5-ASA in 95 patients (84.8%), azathioprine in 64 patients (57.1%), TNF-α inhibitors in 27 patients (24.1%), corticosteroids in 7 patients (6.3%), methotrexate in 2 patients (1.8%), and none in 1 patient (0.9%). Among 112 patients with clinically active CD, the need for adding other medications or increasing the dose of current medications was observed in 77 patients (68.8%), and addition of corticosteroids was observed in 37 patients (33%). 2. Outcomes of Patients with Clinical Remission of CD In multivariate analysis, active inflammation on MRE increased the risk for relapse (hazard ratio [HR], 6.985; 95% CI, 1.024–47.649), and the risk for the need for adding other medications or increasing the dose of current medications (HR, 6.440; 95% CI, 1.432–28.966) in patients with clinical remission of CD (Table 4). The age at diagnosis of CD and the median albumin level were related to the risk for the need for adding other medications or increasing the dose of current medications. In the Kaplan-Meier analysis with the log-rank test, the presence of active inflammation on MRE imaging was significantly associated with higher cumulative probabilities of relapse (P=0.025), or the need for adding other medications or increasing the dose of current medications (P=0.029), compared with the absence of active inflammation on MRE (Fig. 2). 3. Outcomes of Patients with Clinically Active CD In multivariate analysis, active inflammation on MRE increased the risk for CD-related admission (HR, 2.970; 95% CI, 1.006–8.772) in patients with clinically active CD (Table 5). According to the Montreal classification, patients who were diagnosed as having CD at age between 17 and 40 years (A2) had a lower risk for the need for corticosteroids (HR, 0.413; 95% CI, 0.185–0.923) and for adding other medications or increasing the dose of current medications (HR, 0.373; 95% CI, 0.197–0.707). Stricturing disease (B2) (HR, 2.383; 95% CI, 1.005–5.383) or penetrating disease (B3) (HR, 2.795; 95% CI, 1.207–6.476) increased the risk for admission, compared with nonstricturing or nonpenetrating disease (B1). Penetrating disease (B3) increased the surgical risk (HR, 5.454; 95% CI, 1.094–27.178), and structuring disease (B2) showed a trend toward an increased risk of surgery (P=0.056). The cumulative probability of admission (P=0.009) was higher in patients with active inflammation on MRE imaging than in those without (Fig. 3). DISCUSSION Regular evaluation of disease activity in patients with CD is important to allow providing adequate medical or surgical therapy, and monitoring drug efficacies.212223 Until recently, the goal of therapy for CD was only to eliminate disease-related symptoms, improve the quality of life of patients, and maintain general wellness by minimizing adverse effects and long-term sequelae.24 In recent studies, the efficacy of CDAI as an indicator of disease severity has been found to be inconclusive.2526 In our study, the CDAI score was not well correlated with the risk for relapse, surgery, or the need for other medications, except for the risk of admission (HR, 1.005; 95% CI, 1.000–1.009) in patients with clinically active CD. Moreover, the CDAI score was not correlated with relapse, admission, surgery, or the need for other medications in patients with clinical remission of CD. The new goal of treatment is no longer only clinical remission indicated by a CDAI score of <150, but also the induction and maintenance of mucosal healing.2427 Patients with both deep remission (defined as CDAI scores <150) and mucosal healing seem to have better outcomes than patients with only clinical remission or only mucosal healing.2829 Mucosal healing detected with MRE imaging was well correlated with the disease activity of CD.8 In our study, mucosal healing detected with MRE was found in only 17 (27.9%) patients with clinical remission of CD and 19 (17%) patients with clinically active CD; however, there was no statistically significant difference (P=0.091). This implies that clinical symptoms according to the CDAI score are not correlated with the actual mucosal state detected with MRE imaging. Forty-four (72.1%) patients with clinical remission assessed according to clinical symptoms had active inflammation on MRE, which suggests that many patients without symptoms might have active intestinal inflammation. MRE is now recommended as a new diagnostic tool in the management of CD.30 MRE is a radiation-free imaging technique used to obtain cross-sectional images of the small bowel, and can describe the whole of the gastrointestinal tract, including mucosal, mural, and extramural tissues.30 Cross-sectional imaging is important in assessing diseases in parts of the small bowel that are difficult to reach by using enteroscopy.31 MRE also has a role in the detection of complications of small-bowel CD and postoperative CD recurrence.32 CD involvement of the proximal small bowel has a higher risk of stricturing behavior and the requirement for multiple surgeries.33 In our study, stricturing disease (B2) and penetrating disease (B3) according to the Montreal classification increased the risk for hospitalization by more than two times, compared with nonstricturing or nonpenetrating disease (B1) in patients with clinically active CD. Moreover, penetrating disease (B3) increased the risk for surgery by more than five times. The current retrospective study provides evidence of the usefulness of MRE in assessing the prognosis of CD. The presence of active inflammation on MRE increased the risk (by more than six times) for relapse and the need for adding other medications or increasing the dose of current medications in patients with clinical remission of CD. Moreover, the presence of active inflammation on MRE increased the risk for CD-related admission in patients with clinically active CD. In a recent study, the radiologic response with CTE or MRE was associated with significant reductions in the long-term risk of hospitalization, surgery, or corticosteroid use among patients with small-bowel CD, supporting our results.12 Complete radiologic response, defined as improvement of all lesions at a second imaging study, decreased the risk for steroid use and surgery by >60% and the risk for hospitalization by 70%.12 In our study, we focused on the effects of the first findings of MRE imaging at the time of clinical remission and during the clinically active state in patients with CD, separately. Moreover, we included patients with L2 disease (colonic lesion) according to the Montreal classification, and analyzed the risk of clinical relapse and the need for adding other medications or increasing the dose of current medications. In this study, the risk of surgery and need for corticosteroids were not correlated with the initial MRE findings; however, the risk for clinical relapse, hospitalization, and the need for adding other medications or increasing the dose of current medications were significantly related to the findings of active inflammation on the initial MRE study. This study has some limitations. As this was a retrospective study with a chart review, there was a timing difference between remission or relapse and MRE imaging in each patient. MRE imaging was done during a long-standing clinical remission state in some patients, whereas other patients underwent imaging study immediately after clinical remission. We did not analyze the MRE findings with regard to mural thickening or edema because we only focused on the prognostic significance of the mucosal healing phase against active inflammation. Furthermore, MRE activity was not classified into specific degrees using previous alleged scoring systems such as magnetic resonance index of activity (MaRIA), Crohn's disease activity score (CDAS), or magnetic resonance enterography global score (MEGS). Prognosis could be affected by change of treatment options or physician's decisions, but these factors were not considered. In addition, pediatric patients <18 years old were excluded, and we were not able to analyze the effects of anti-Saccharomyces cerevisiae antibody and fecal calprotectin level because of a lack of data. Colonoscopic findings were not analyzed with MRE findings because there was a time difference between the days of colonoscopic examination and MRE imaging examination, and most patients had small-bowel involvement. Further studies about the correlation between endoscopic and MRE imaging findings are needed. In another study, high CRP at the time of CD diagnosis was risk factor for hospitalization;34 however, we were not able to find a relationship between CRP level and prognosis. This report is the first study to evaluate the clinical outcomes of findings of active inflammation on MRE imaging in patients with CD. In conclusion, the presence of active inflammation on MRE in patients with CD at the time of clinical remission was significantly associated with a high risk of relapse and the need for adding other medications or increasing the dose of current medications. Moreover, the presence of active inflammation during the clinically active state was significantly associated with an increased risk of hospitalization. MRE might be a useful technique in monitoring disease activity in patients with CD. FINANCIAL SUPPORT: This research was supported by two grants (A120176, HI13C1345) from the Korean Health Technology R&D Project through the Korea Health Industry Development Institute, which is funded by the Ministry of Health and Welfare, Republic of Korea, and two grants (NRF-2013R1A2A2A01067123, NRF-2014R1A1A1008096) from the Basic Science Research Program through the National Research Foundation of Korea, which is funded by the Ministry of Science, ICT and Future Planning. CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported. AUTHOR CONTRIBUTION: Guarantor of the article: Jae Hee Cheon and Joon Seok Lim. Specific author contributions: Ji Hoon Lee: acquisition of data; analysis and interpretation of data; drafting of the manuscript. Yong Eun Park: acquisition of data; study concept and design. Nieun Seo: acquisition of data; study concept and design. Hyun Jung Lee: acquisition of data; study concept and design. Soo Jung Park: study concept and design; critical revision of the manuscript for important intellectual content. Tae Il Kim: study concept and design; critical revision of the manuscript for important intellectual content. Won Ho Kim: study concept and design; critical revision of the manuscript for important intellectual content. Jae Hee Cheon and Joon Seok Lim: acquisition of data; study concept and design; critical revision of the manuscript for important intellectual content. All authors approved the final version of the article, including the authorship list. Fig. 1 Recruitment algorithm. A total of 243 consecutive patients with magnetic resonance enterography (MRE) were enrolled. After 70 patients were excluded according to our exclusion criteria, a total of 173 patients were selected for statistical analysis. Fig. 2 Cumulative probabilities of a change in relapse (A) and the need for adding other medications or increasing the dose of current medications (B) according to magnetic resonance enterography (MRE) findings at the time of clinical remission. Fig. 3 Cumulative probabilities of a change in admission according to the magnetic resonance enterography (MRE) findings during the clinically active state. Table 1 Baseline Characteristics of Patients with CD on the Day of MRE Examination Characteristics Total patients (n=173) Clinical remission state (n=61) Clinically active state (n=112) P-value Male sex 127 (73.4) 45 (73.8) 82 (73.2) 0.937 Age (yr) 29 (24–37) 27 (23–38) 30 (24–36) 0.787 Age at diagnosis of CD (yr) 21 (18–27) 20 (17–27) 21 (18–27) 0.702 Age at diagnosis of CD 0.104  A1 31 (17.9) 14 (23.0) 17 (15.2)  A2 134 (77.5) 42 (68.9) 92 (82.1)  A3 8 (4.6) 5 (8.2) 3 (2.7) BMI (kg/m2) 20 (18–22) 21 (19–24) 19 (18–22) 0.012 Disease duration (yr) 7 (4–11) 8 (4–12) 7 (3–11) 0.694 Smoking 0.109  Current 22 (12.7) 7 (11.5) 15 (13.4)  Former 31 (17.9) 16 (26.2) 15 (13.4)  Never 120 (69.4) 38 (62.3) 82 (73.2) Baseline CDAI score 183 (117–249) 95 (61–122) 228 (187–277) <0.001 Baseline CRP level (mg/L) 6.2 (1.1–20.6) 2.8 (0.7–8.8) 11.1 (2.3–25.8) <0.001 Baseline ESR level (mm/hr) 27 (13–49) 23 (12–38) 30 (13–57) 0.003 Baseline albumin level (g/dL) 4.1 (3.7–4.3) 4.2 (4.0–4.5) 3.9 (3.6–4.2) <0.001 Disease localization 0.045  L1 56 (32.4) 23 (37.7) 33 (29.5)  L2 18 (10.4) 10 (16.4) 8 (7.1)  L3 99 (57.2) 28 (45.9) 71 (63.4)  L4 0 0 0 Disease behavior 0.784  B1 65 (37.6) 25 (40.9) 40 (35.7)  B2 44 (25.4) 15 (24.6) 29 (25.9)  B3 64 (36.9) 21 (34.4) 43 (38.4) Perianal lesion 86 (49.7) 30 (49.2) 56 (50.0) 0.918 Previous surgery 48 (27.7) 17 (27.9) 31 (27.7) 0.979 Family history of IBD 5 (2.9) 1 (1.6) 4 (3.6) 0.658 Median follow-up period (mo) 15.9 (11.8–22.3) 14.4 (9.9–20.1) 17.7 (12.3–22.9) 0.002 MRE findings 0.091  Active inflammation 137 (79.2) 44 (72.1) 93 (83.0)  Inactive 36 (20.8) 17 (27.9) 19 (17.0) Values are presented as median (interquartile range) or number (%). MRE, magnetic resonance enterography. Table 2 Baseline Characteristics of Patients with Clinical Remission of CD: Comparison between Patients with and Those without Active Inflammation Characteristics Total patients (n=61) Active inflammation group (n=44) Inactive group (n=17) P-value Male sex 45 (73.8) 34 (77.3) 11 (64.7) 0.344 Age (yr) 27 (23–38) 27 (23–37) 31 (20–46) 0.760 Age at diagnosis of CD (yr) 20 (17–27) 20 (17–25) 21 (16–33) 0.608 Age at diagnosis of CD 0.344  A1 14 (23.0) 8 (18.2) 6 (35.3)  A2 42 (68.9) 32 (72.7) 10 (58.8)  A3 5 (8.2) 4 (9.1) 1 (5.9) BMI (kg/m2) 21 (19–24) 21 (19–23) 21 (20–24) 0.729 Disease duration (yr) 8 (4–12) 7.5 (4–11) 9 (4–13) 0.353 Smoking 0.834  Current 7 (11.5) 6 (13.6) 1 (5.9)  Former 16 (26.2) 11 (25.0) 5 (29.4)  Never 38 (62.3) 27 (61.4) 11 (64.7) Baseline CDAI score 95 (61–122) 96 (61–120) 82 (62–128) 0.888 Baseline CRP level (mg/L) 2.8 (0.7–8.8) 4.3 (1.0–10.5) 0.8 (0.5–3.2) 0.003 Baseline ESR level (mm/hr) 23 (12–38) 25 (16–41) 11 (4–31) 0.052 Baseline albumin level (g/dL) 4.2 (4.0–4.5) 4.2 (3.8–4.4) 4.4 (4.2–4.6) 0.008 Disease localization 0.001  L1 23 (37.7) 19 (43.2) 4 (23.5)  L2 10 (16.4) 2 (4.5) 8 (47.1)  L3 28 (45.9) 23 (52.3) 5 (29.4)  L4 0 0 0 Disease behavior 0.584  B1 25 (40.9) 16 (36.4) 9 (52.9)  B2 15 (24.6) 12 (27.3) 3 (17.6)  B3 21 (34.4) 16 (36.4) 5 (29.4) Perianal lesion 30 (49.2) 24 (54.5) 6 (35.3) 0.178 Previous surgery 17 (27.9) 11 (25.0) 6 (35.3) 0.527 Family history of IBD 1 (1.6) 1 (2.3) 0 1.000 Median follow-up period (mo) 14.4 (9.9–20.1) 14.0 (10.3–19.0) 14.5 (8.6–21.7) 0.737 Values are presented as median (interquartile range) or number (%). Table 3 Baseline Characteristics of Patients with Clinically Active CD: Comparison between Patients with and Those without Active Inflammation Characteristics Total patients (n=112) Active inflammation group (n=93) Inactive group (n=19) P-value Male sex 82 (73.2) 70 (75.3) 12 (63.2) 0.277 Age (yr) 30 (24–36) 30 (24–37) 28 (25–34) 0.944 Age at diagnosis of CD (yr) 21 (18–27) 21 (18–27) 21 (18–25) 0.946 Age at diagnosis of CD 0.413  A1 17 (15.2) 16 (17.2) 1 (5.3)  A2 92 (82.1) 74 (79.6) 18 (94.7)  A3 3 (2.7) 3 (3.2) 0 BMI (kg/m2) 19.3 (17.7–21.6) 19.4 (17.6–21.6) 19.1 (18.3–23.1) 0.673 Disease duration (yr) 7 (3–11) 7 (3–11) 6 (4–13) 0.985 Smoking 0.149  Current 15 (13.4) 12 (12.9) 3 (15.8)  Former 15 (13.4) 15 (16.1) 0  Never 82 (73.2) 66 (71.0) 16 (84.2) Baseline CDAI score 228 (187–277) 221 (185–280) 248 (210–277) 0.550 Baseline CRP level (mg/L) 11.1 (2.3–25.8) 14 (4.2–28.2) 2 (0.6–7.4) <0.001 Baseline ESR level (mm/hr) 30 (13–57) 32 (18–60) 13 (8–30) <0.001 Baseline albumin level (g/dL) 3.9 (3.6–4.2) 3.9 (3.5–4.2) 4.3 (4.1–4.4) <0.001 Disease localization 0.163  L1 33 (29.5) 24 (25.8) 9 (47.4)  L2 8 (7.1) 7 (7.5) 1 (5.3)  L3 71 (63.4) 62 (66.7) 9 (47.4)  L4 0 0 0 Disease behavior 0.733  B1 40 (35.7) 33 (35.5) 7 (36.8)  B2 29 (25.9) 23 (24.7) 6 (31.6)  B3 43 (38.4) 37 (39.8) 6 (31.6) Perianal lesion 56 (50.0) 48 (51.6)) 8 (42.1) 0.450 Previous surgery 31 (27.7) 23 (24.7) 8 (42.1) 0.123 Family history of IBD 4 (3.6) 4 (4.3) 0 1.000 Median follow-up period (mo) 17.7 (12.3–22.9) 18.1 (12.4–22.9) 17.2 (12.0–23.5) 0.824 Values are presented as median (interquartile range) or number (%). Table 4 Univariate and Multivariate HR for Relapse and Need for Adding Other Medications or Increasing the Dose of Current Medications in Patients with Clinical Remission of CD Outcomes Variable Univariate Multivariate HR (95% CI) P-value HR (95% CI) P-value Relapse Male sex 0.531 (0.222–1.267) 0.154 0.337 (0.105–1.084) 0.068 Age 1.019 (0.994–1.045) 0.140 - - Age at diagnosis of CD 1.030 (1.003–1.058) 0.031 - - Age at diagnosis of CD -  A1 (Reference) (Reference)  A2 1.738 (0.501–6.032) 0.384 0.821 (0.181–3.718) 0.799  A3 4.010 (0.894–17.994) 0.070 0.252 (0.019–3.352) 0.297 BMI 1.012 (0.891–1.150) 0.851 - - Disease duration 0.975 (0.903–1.052) 0.508 0.998 (0.901–1.105) 0.967 Smoking - -  Current 1.895 (0.616–5.828) 0.265  Former 0.950 (0.338–2.668) 0.922  Never (Reference) Baseline CDAI score 1.007 (0.996–1.019) 0.223 1.010 (0.994–1.026) 0.241 Baseline CRP level 1.023 (0.998–1.049) 0.077 - - Baseline CRP >20 mg/dL 1.657 (0.556–4.944) 0.365 0.647 (0.111–3.780) 0.629 Baseline ESR level 1.012 (0.992–1.032) 0.237 - - Baseline albumin level 0.302 (0.125–0.730) 0.008 - - Baseline albumin ≤3.5 g/dL 3.900 (1.427–10.659) 0.008 7.968 (1.008–62.969) 0.049 Disease localization  L1 (Reference) (Reference)  L2 0.112 (0.014–0.911) 0.041 0.017 (0.000–0.686) 0.031  L3 0.552 (0.230–1.325) 0.183 0.815 (0.249–2.662) 0.735 Disease behavior  B1 (Reference) (Reference)  B2 2.119 (0.711–6.315) 0.178 0.912 (0.122–6.806) 0.928  B3 2.026 (0.720–5.705) 0.181 1.446 (0.370–5.649) 0.596 Perianal lesion 0.677 (0.289–1.589) 0.370 0.378 (0.090–1.593) 0.185 Previous surgery 1.155 (0.471–2.835) 0.753 1.618 (0.396–6.610) 0.503 Family history of IBD 1.751 (0.230–13.352) 0.589 - - MRE findings  Active inflammation 4.555 (1.063–19.511) 0.041 8.603 (1.026–72.138) 0.047  Inactive (Reference) (Reference) Adding other medications or increasing the dose of current medications Male sex 1.085 (0.433–2.719) 0.862 0.699 (0.238–2.049) 0.514 Age 0.981 (0.947–1.016) 0.288 - - Age at diagnosis of CD 0.978 (0.935–1.024) 0.346 - - Age at diagnosis of CD -  A1 (Reference) (Reference)  A2 0.761 (0.315–1.835) 0.543 0.407 (0.134–1.231) 0.111  A3 0.340 (0.042–2.774) 0.314 0.147 (0.008–2.595) 0.191 BMI 1.024 (0.898–1.168) 0.719 - - Disease duration 0.977 (0.911–1.048) 0.518 0.971 (0.889–1.061) 0.518 Smoking - -  Current 1.400 (0.407–4.813) 0.593  Former 0.924 (0.361–2.365) 0.870  Never (Reference) Baseline CDAI score 1.000 (0.990–1.011) 0.974 1.006 (0.992–1.020) 0.406 Baseline CRP level 1.003 (0.975–1.032) 0.841 - - Baseline CRP >20 mg/dL 1.026 (0.307–3.431) 0.967 0.747 (0.152–3.672) 0.720 Baseline ESR level 0.998 (0.979–1.019) 0.882 - - Baseline albumin level 0.527 (0.231–1.200) 0.127 - - Baseline albumin ≤3.5 g/dL 0.903 (0.213–3.834) 0.890 0.915 (0.140–5.969) 0.926 Disease localization  L1 (Reference) (Reference)  L2 0.514 (0.141–1.872) 0.313 0.973 (0.184–5.149) 0.974  L3 0.897 (0.387–2.081) 0.800 0.678 (0.241–1.902) 0.460 Disease behavior  B1 (Reference) (Reference)  B2 1.001 (0.356–2.814) 0.998 1.572 (0.333–7.421) 0.568  B3 1.283 (0.521–3.157) 0.588 1.757 (0.540–5.717) 0.349 Perianal lesion 1.685 (0.757–3.753) 0.202 1.271 (0.451–3.582) 0.650 Previous surgery 0.830 (0.331–2.079) 0.691 0.659 (0.180–2.417) 0.530 MRE findings  Active inflammation 3.515 (1.051–11.755) 0.041 5.113 (1.187–22.029) 0.029  Inactive (Reference) (Reference) HR, hazard ratio; MRE, magnetic resonance enterography. Table 5 Univariate and Multivariate HR for Admission in Patients with Clinically Active CD Outcomes Variable Univariate Multivariate HR (95% CI) P-value HR (95% CI) P-value Admission Male sex 0.845 (0.483–1.477) 0.554 1.098 (0.600–2.013) 0.761 Age 0.977 (0.947–1.008) 0.140 - - Age at diagnosis of CD 0.961 (0.924–1.000) 0.051 - - Age at diagnosis of CD -  A1 (Reference) (Reference)  A2 0.571 (0.301–1.082) 0.086 0.547 (0.264–1.134) 0.105  A3 0.345 (0.045–2.660) 0.307 0.092 (0.009–0.902) 0.041 BMI 0.963 (0.886–1.047) 0.381 - - Disease duration 1.011 (0.965–1.059) 0.659 0.930 (0.867–0.997) 0.041 Smoking - -  Current 0.587 (0.233–1.479) 0.258  Former 0.697 (0.298–1.632) 0.405  Never (Reference) Baseline CDAI score 1.004 (1.000–1.007) 0.034 1.005 (1.000–1.009) 0.034 Baseline CRP level 1.008 (1.000–1.017) 0.055 - - Baseline CRP >20 mg/dL 1.586 (0.933–2.696) 0.088 0.696 (0.353–1.374) 0.296 Baseline ESR level 1.009 (1.000–1.018) 0.060 - - Baseline albumin level 0.477 (0.299–0.759) 0.002 - - Baseline albumin ≤3.5 g/dL 2.528 (1.443–4.428) 0.001 1.923 (0.890–4.153) 0.096 Disease localization  L1 (Reference) (Reference)  L2 1.140 (0.322–4.042) 0.839 2.250 (0.560–9.042) 0.253  L3 1.748 (0.920–3.321) 0.088 1.739 (0.796–3.800) 0.165 Disease behavior  B1 (Reference) (Reference)  B2 1.862 (0.907–3.819) 0.090 2.454 (1.096–5.493) 0.029  B3 2.190 (1.147–4.184) 0.018 2.753 (1.196–6.336) 0.017 Perianal lesion 0.723 (0.428–1.220) 0.224 0.489 (0.276–0.868) 0.015 Previous surgery 0.595 (0.314–1.126) 0.110 - - Family history of IBD 8.974 (2.918–27.596) <0.001 12.823 (3.469–47.391) >0.001 MRE findings  Active inflammation 3.485 (1.259–9.649) 0.016 3.171 (1.092–9.204) 0.034  Inactive (Reference) (Reference) HR, hazard ratio; MRE, magnetic resonance enterography. ==== Refs 1 Martin DR Lauenstein T Sitaraman SV Utility of magnetic resonance imaging in small bowel Crohn's disease Gastroenterology 2007 133 385 390 17681157 2 Peyrin-Biroulet L Sandborn W Sands BE Selecting therapeutic targets in inflammatory bowel disease (STRIDE): determining therapeutic goals for treat-to-target Am J Gastroenterol 2015 110 1324 1338 26303131 3 Peyrin-Biroulet L Reinisch W Colombel JF Clinical disease activity, C-reactive protein normalisation and mucosal healing in Crohn's disease in the SONIC trial Gut 2014 63 88 95 23974954 4 Maglinte DD Chernish SM Kelvin FM O'Connor KW Hage JP Crohn disease of the small intestine: accuracy and relevance of enteroclysis Radiology 1992 184 541 545 1620862 5 Sinha R Verma R Verma S Rajesh A MR enterography of Crohn disease: part 1, rationale, technique, and pitfalls AJR Am J Roentgenol 2011 197 76 79 21701013 6 Ohtsuka K Takenaka K Kitazume Y Magnetic resonance enterography for the evaluation of the deep small intestine in Crohn's disease Intest Res 2016 14 120 126 27175112 7 Fornasa F Benassuti C Benazzato L Role of magnetic resonance enterography in differentiating between fibrotic and active inflammatory small bowel stenosis in patients with Crohn's disease J Clin Imaging Sci 2011 1 35 21966632 8 Koh DM Miao Y Chinn RJ MR imaging evaluation of the activity of Crohn's disease AJR Am J Roentgenol 2001 177 1325 1332 11717076 9 Horsthuis K Bipat S Bennink RJ Stoker J Inflammatory bowel disease diagnosed with US, MR, scintigraphy, and CT: meta-analysis of prospective studies Radiology 2008 247 64 79 18372465 10 Takenaka K Ohtsuka K Kitazume Y Comparison of magnetic resonance and balloon enteroscopic examination of the small intestine in patients with Crohn's disease Gastroenterology 2014 147 334 342 24732015 11 Fiorino G Bonifacio C Peyrin-Biroulet L Prospective comparison of computed tomography enterography and magnetic resonance enterography for assessment of disease activity and complications in ileocolonic Crohn's disease Inflamm Bowel Dis 2011 17 1073 1080 21484958 12 Deepak P Fletcher JG Fidler JL Radiological response is associated with better long-term outcomes and is a potential treatment target in patients with small bowel Crohn's disease Am J Gastroenterol 2016 111 997 1006 27166131 13 Best WR Becktel JM Singleton JW Rederived values of the eight coefficients of the Crohn's disease activity index (CDAI) Gastroenterology 1979 77 4 Pt 2 843 846 467941 14 Costa F Mumolo MG Ceccarelli L Calprotectin is a stronger predictive marker of relapse in ulcerative colitis than in Crohn's disease Gut 2005 54 364 368 15710984 15 Silverberg MS Satsangi J Ahmad T Toward an integrated clinical, molecular and serological classification of inflammatory bowel disease: report of a Working Party of the 2005 Montreal World Congress of Gastroenterology Can J Gastroenterol 2005 19 Suppl A 5A 36A 16 Masselli G Gualdi G MR imaging of the small bowel Radiology 2012 264 333 348 22821694 17 Tolan DJ Greenhalgh R Zealley IA Halligan S Taylor SA MR enterographic manifestations of small bowel Crohn disease Radiographics 2010 30 367 384 20228323 18 Grand DJ Beland M Harris A Magnetic resonance enterography Radiol Clin North Am 2013 51 99 112 23182510 19 Steward MJ Punwani S Proctor I Non-perforating small bowel Crohn's disease assessed by MRI enterography: derivation and histopathological validation of an MR-based activity index Eur J Radiol 2012 81 2080 2088 21924572 20 Rimola J Rodriguez S García-Bosch O Magnetic resonance for assessment of disease activity and severity in ileocolonic Crohn's disease Gut 2009 58 1113 1120 19136510 21 Singleton JW Clinical activity assessment in inflammatory bowel disease Dig Dis Sci 1987 32 12 Suppl 42S 45S 3319457 22 Carter MJ Lobo AJ Travis SP IBD Section, British Society of Gastroenterology Guidelines for the management of inflammatory bowel disease in adults Gut 2004 53 Suppl 5 V1 V16 15306569 23 Kim DH Cheon JH Intestinal Behçet's disease: a true inflammatory bowel disease or merely an intestinal complication of systemic vasculitis? Yonsei Med J 2016 57 22 32 26632379 24 Lichtenstein GR Hanauer SB Sandborn WJ Practice Parameters Committee of American College of Gastroenterology Management of Crohn's disease in adults Am J Gastroenterol 2009 104 465 483 19174807 25 Lémann M Mary JY Colombel JF A randomized, double-blind, controlled withdrawal trial in Crohn's disease patients in long-term remission on azathioprine Gastroenterology 2005 128 1812 1818 15940616 26 Colombel JF Sandborn WJ Reinisch W Infliximab, azathioprine, or combination therapy for Crohn's disease N Engl J Med 2010 362 1383 1395 20393175 27 Rutgeerts P Diamond RH Bala M Scheduled maintenance treatment with infliximab is superior to episodic treatment for the healing of mucosal ulceration associated with Crohn's disease Gastrointest Endosc 2006 63 433 442 16500392 28 Colombel JF Rutgeerts PJ Sandborn WJ Adalimumab induces deep remission in patients with Crohn's disease Clin Gastroenterol Hepatol 2014 12 414 422.e5 23856361 29 Colombel JF Louis E Peyrin-Biroulet L Sandborn WJ Panaccione R Deep remission: a new concept? Dig Dis 2012 30 Suppl 3 107 111 23295700 30 Makanyanga JC Taylor SA Current and future role of MR enterography in the management of Crohn disease AJR Am J Roentgenol 2013 201 56 64 23789658 31 Fowler KJ Dassopoulos T Raptis C Magnetic resonance enterography in the evaluation of Crohn's disease: a primer for the gastroenterologist Inflamm Bowel Dis 2014 20 2179 2188 25054338 32 Greenup AJ Bressler B Rosenfeld G Medical imaging in small bowel Crohn's disease-computer tomography enterography, magnetic resonance enterography, and ultrasound: “Which One Is the Best for What?” Inflamm Bowel Dis 2016 22 1246 1261 27070909 33 Lazarev M Huang C Bitton A Relationship between proximal Crohn's disease location and disease behavior and surgery: a cross-sectional study of the IBD Genetics Consortium Am J Gastroenterol 2013 108 106 112 23229423 34 Kwon JH Im JP Ye BD Disease phenotype, activity and clinical course prediction based on C-reactive protein levels at diagnosis in patients with Crohn's disease: results from the CONNECT study Gut Liver 2016 10 595 603 27021506