Published online Sep 28, 2020. doi: 10.3748/wjg.v26.i36.5484
Peer-review started: June 12, 2020
First decision: July 25, 2020
Revised: July 27, 2020
Accepted: September 4, 2020
Article in press: September 4, 2020
Published online: September 28, 2020
Symptoms in the gastrointestinal tract are common and nonspecific. Magnetic resonance enterography (MRE) is therefore often used to diagnose or exclude the presence of structural lesions related to inflammatory bowel disease (IBD). If MRE does not show any organic lesions, the patients are suspected to be healthy or are diagnosed as irritable bowel syndrome (IBS). Dysmotility of the small bowel is observed both as a primary disease and secondary to several common diseases such as diabetes and neurological diseases. Dysmotility may cause similar symptoms as IBD, but dysmotility is difficult to diagnose and the condition is often over-looked. In the absence of proper investigation, which are often invasive and not easily available, patients with gastrointestinal dysmotility may be without any treatment.
Studies have described that MRE also can be used to assess motility by calculating motility index (MI), based on displacement mapping. If MRE could be used also to assess gastrointestinal motility, patients with dysmotility could possibly be identified earlier in the disease course, and selected patients could be referred to further examinations. Thus, patients with gastrointestinal dysmotility could be treated appropriately.
The objective of the present study was to evaluate the usefulness and potential of the MI in a large cohort of unselected patients and healthy controls to examine whether the MI could be helpful to identify also altered motility patterns in addition to morphological MRE changes. The main focus was to examine the association between the MI and basal characteristics and gastrointestinal symptoms.
All consecutive patients referred for MRE during a 2-year period were asked to participate. Healthy volunteers were included as controls. MRE was prepared and conducted in accordance with clinical routines. All the participants had to complete the visual analog scale for IBS and IBS-symptom severity scale to assess gastrointestinal symptoms and all medical records were scrutinized. Maps of MI were calculated from dynamic MR images. ANOVA was used to evaluate differences in MI between groups, classified as healthy, Crohn’s disease, ulcerative colitis, IBS, other assorted disorders and dysmotility. Logistic and linear regression were applied to the MI values.
There was a difference in MI between the disease groups in jejunum and terminal ileum (P = 0.021 and P = 0.07), which was explained by a difference between controls and other assorted diseases (P = 0.043 and P = 0.059). The weight was higher in men than in women (OR = 1.056; 95%CI: 1.035-1.081; P < 0.001), and MI of the terminal ileum tended to be lower in men than in women (OR = 0.035; 95%CI: 0.001-1.086; P = 0.056). In men, MI of the terminal ileum was inversely associated with increased mural thickness (P < 0.001). There was a tendency to association between MI and constipation (P = 0.053) and weight (P = 0.081). In women, MI of the jejunum was inversely associated with diarrhea (P = 0.029) and MI of the terminal ileum was associated with constipation (P = 0.039). There was a tendency to inverse association between MI of the terminal ileum and mural thickness (P = 0.063).
Although MIs differ across diseases, the most important findings of the present study are that a lower MI of the terminal ileum is mainly associated with male sex and an increased mural thickness. Symptoms are weakly associated with the MI.
Before introduction of this technique in the daily clinical practice, the MI should be less affected by mural thickness, sex and weight or classified by proper criteria for different weights and sexes. Additional techniques probably need to be developed to identify motility patterns by MRE, less influenced by basal characteristics. Furthermore, this method should be compared with other established modalities such as antroduodenal manometry and wireless capsules to evaluate motility.