Imaging findings in irritable bowel syndrome and their diagnostic value: a systematic review
Abdominal and brain MRI identifies morphofunctional abnormalities in IBS patients, but heterogeneity of findings and absence of meta-analysis preclude routine diagnostic use.
| Population | Adults diagnosed with IBS (all subtypes) |
|---|---|
| Intervention | Abdominal and brain imaging modalities (MRI, CT, ultrasound) |
| Comparator | Healthy controls and patients with functional constipation |
| Outcome | Colonic and rectal volume; Brain activity in pain-modulation areas (fMRI); Cerebral cortical thickness (static MRI); Volume of brain pain-modulation regions (static MRI); Diagnostic accuracy of MRI vs Rome Criteria |
Summary of findings
| Outcome | Effect | 95% CI | Certainty | Clinical relevance | Notes |
|---|---|---|---|---|---|
| Colonic and rectal volume | No quantified effect size reported; narrative finding: smaller in IBS vs healthy controls and functional constipation | — | Low | — | |
| Brain activity in pain-modulation areas (fMRI) | No quantified effect size reported; narrative finding: increased activity in pain-modulation regions in IBS vs controls | — | Low | — | |
| Cerebral cortical thickness (static MRI) | No quantified effect size reported; narrative finding: cortical thinning in specific pain-modulation areas in IBS | — | Low | — | |
| Volume of brain pain-modulation regions (static MRI) | No quantified effect size reported; narrative finding: increased volumes in specific brain regions in IBS | — | Low | — | |
| Diagnostic accuracy of MRI vs Rome Criteria | Not reported; in the sensitivity, specificity, AUC or LR data available in this review | — | Very low | — |
Context
IBS diagnosis relies on subjective Rome Criteria, which are unsuitable for patients with cognitive decline. Overlap with organic and other functional disorders demands objective markers. Imaging tools could fill this gap, but diagnostic validation remains uncertain.
What the study showed
IBS patients showed smaller colonic and rectal volumes compared to healthy controls and functional constipation patients. Dynamic and static brain MRI demonstrated increased activity, cortical thinning, and increased volumes in pain-modulation regions. Findings varied by IBS subtype, symptom duration and intensity, sex, and cultural background. No absolute numbers, 95% CI, or effect sizes were reported by the authors.
How it was done
Narrative systematic review searching three databases (June–July 2024), no time restriction, English only. Of 679 identified articles, 578 remained after deduplication; 50 full texts were included. No protocol registration, no formal risk-of-bias assessment (e.g., AMSTAR-2), and no meta-analysis were performed.
Effect magnitude
No quantified effect measures (RR, OR, SMD, MD) were reported. The review is descriptive; magnitude and precision of individual findings cannot be determined from this document.
Risk of bias
AMSTAR-2 was not applied, undermining methodological quality assessment. Inclusion of only 50 of 578 eligible articles without explicit exclusion criteria and without quantitative synthesis raises selection and reporting bias risk. Brain imaging findings are highly heterogeneous across IBS subtype, sex, and cultural context, limiting generalizability.
What this study does NOT prove
This review does not prove that MRI has sufficient diagnostic accuracy to replace or complement Rome Criteria in clinical practice. It does not establish causality between imaging abnormalities and IBS pathophysiology.
In clinical practice
MRI should not be incorporated into the standard IBS diagnostic algorithm based on this review. Clinicians should maintain Rome IV Criteria as the diagnostic reference. In patients with cognitive decline or atypical presentation, imaging may exclude organic disease but cannot confirm IBS.
Limitations
AMSTAR-2 was not applied, undermining methodological quality assessment. Inclusion of only 50 of 578 eligible articles without explicit exclusion criteria and without quantitative synthesis raises selection and reporting bias risk. Brain imaging findings are highly heterogeneous across IBS subtype, sex, and cultural context, limiting generalizability.
What is still missing
Prospective controlled studies with adequate sample sizes, standardized MRI protocols, and validated diagnostic thresholds are required before any clinical recommendation.
Technical appendix
Version history
- 1.0 · 2026-06-21 — Auto-generated under Evidence Standard v1.0