Assessing Water Content of the Human Colonic Chyme Using the MRI Parameter T1: A Key Biomarker of Colonic Function

Area of Science:

• Gastroenterology
• Medical Imaging
• Biophysics

Background:

• The colon processes 2 liters of fluid daily, with absorption efficacy impacting stool consistency.
• Altered colonic water content can lead to diarrhea or constipation.
• Magnetic resonance imaging (MRI) T1 relaxation time can quantify colonic water.

Purpose of the Study:

• To explore regional T1 assessment using MRI for evaluating colonic function disorders.
• To investigate the relationship between colonic T1 values and stool characteristics.
• To assess the potential of MRI T1 as a biomarker for treatment efficacy.

Main Methods:

• Analysis of individual participant data from 12 studies.
• Inclusion of patients with constipation, irritable bowel syndrome with diarrhea (IBS-D), and healthy volunteers (HV).
• Quantification of T1 by measuring tissue signal after magnetization inversion pulses.

Main Results:

• Ascending colon T1 (T1AC) negatively correlated with stool bacterial content during induced diarrhea (r²=0.78).
• Elevated fasting T1AC observed in IBS-D patients compared to HVs; constipation patients showed normal T1AC.
• Mesalazine treatment reduced fasting T1AC in IBS-D patients; dietary fiber intake was associated with higher T1AC.

Conclusions:

• MRI T1 is a viable parameter for assessing colonic water content.
• Regional T1 assessment can differentiate between IBS-D and healthy controls.
• MRI T1 shows potential for monitoring the effectiveness of interventions targeting colonic water and stool consistency.