Abstract
Introduction: Barostat is an equipment for studying sensory thresholds in the gastrointestinal (GI) tract. Moreover barostat is one of the most important procedures for studying gastrointestinal function. On the other hand, barostat is so expensive that any limited facilities use barostat for research. In this study, it is examined whether functional MRI without Barostat system tolerates to evaluate brain-gut interaction in irritable bowel syndrome. Method: Eleven right-handed male subjects, aged 20-21 years, were recruited for this study. Six subjects were healthy control and 5 subjects were non-patient IBS who met the Rome II criteria for IBS. None of the subjects were on pain medications, serotonin re-uptake inhibitors, serotonin antagonists, or tricyclic antidepressants. The tube and balloon were inserted into the rectum. The rectal distention protocol consisted of 3 sets of repeated 30-seconds rectal distentions separated by a 30-seconds rest period in the following order: There was a lag time of 10 second to reach peak pressure and to deflate down to the baseline. All images were acquired on a SIGNA MR/I Echospeed 1.5T, GE. A SPM2 was used to analyze images. Result: In the control subjects, the insular cortex and the posterior cingulated cortex (PCC) were activated while in the non-patient IBS, the insular cortex, the anterior cingulated cortex (ACC), and PCC were activated. For both of the control subjects and the non-patient IBS, significant activation was observed in the insular cortex and PCC during stimulation. Conclusion: Visceral and emotional stimulation significantly correlates with activation of specific regions in the brain including the limbic system and the association cortex, especially ACC, the prefrontal cortex, and the insular cortex. This study showed that the insular cortex, ACC and PCC were activated in the visceral stimulation without Barostat system. We conclude that the distension protocol without Barostat system is one of the practical ways in evaluating the brain-gut interaction by functional MRI.
