Measurement of oro-caecal transit time by magnetic resonance imaging

Abstract

OBJECTIVES To assess prospectively the agreement of orocaecal transit time (OCTT) measurements by lactulose hydrogen breath test (LHBT) and magnetic resonance imaging (MRI) in healthy subjects. METHODS Volunteers underwent abdominal 1.5-T MRI using axial and coronal single-shot fast-spin-echo T2-weighted sequences, having fasted and after lactulose ingestion (10 g/125 mL). Imaging and H2 excretion gas-chromatography were performed concurrently every 15 min up to 180 min. MR images were analyzed using semiautomatic segmentation to calculate small bowel gas volume (SBGV) and visually to detect bolus arrival in the caecum. Agreement between MRI-and LHBT-OCTT was assessed. RESULTS Twenty-eight subjects (17 men/11 women; mean age ± standard deviation 30 ± 8 years) were evaluated. Two H2 non-producers on LHBT were excluded. OCTT measured by MRI and LHBT was concordant in 18/26 (69 %) subjects (excellent agreement, k = 0.924). Median SBGV was 49.0 mL (interquartile interval 44.1 -51.6 mL). In 8/26 (31 %) subjects, MRI showed that the lactulose bolus was in the terminal ileum and not the caecum when H2E increased on LHBT. Median OCTT measured by MRI was significantly longer than OCTT measured by LHBT [135 min (120 -150 min) vs. 127.5 min (105 -150 min); p = 0.008]. Above baseline levels, correlation between [H2] and SBGV was significant (r = 0.964; p < 0.001). CONCLUSIONS MRI provides valid measurements of OCTT and gas production in the small bowel. KEY POINTS • MRI is a valid technique to measure OCTT. • Excellent agreement between MRI and LHBT was found. • Measuring gas production using MRI may provide evidence of small bowel fermentation. Methods: Volunteers underwent abdominal 1.5-T MRI using axial and coronal single-shot fast-spin-echo T2-weighted sequences in the fasted condition and after lactulose ingestion (10g/125mL). Imaging and H 2 excretion gas-cromatography were performed concurrently every 15 minutes up to 180 minutes. MR images were analyzed using semiautomatic segmentation to calculate small bowel gas volume (SBGV) and visually to detect bolus arrival in the cecum.Agreement between MRI-and LHBT-OCTT was assessed.Results: Twenty-eight subjects (17 males/11 females;mean age±standard deviation 30±8 years) were evaluated. Two H 2 non-producers on LHBT were excluded. OCTT measured by MRI and LHBT was concordant in 18/26 (69%) subjects (excellent agreement,k=0.924). Median SBGV was 49.0 mL (interquartile interval 44.1-51.6 mL). In 8/26 (31%) subjects, MRI showed the lactulose bolus was in the terminal ileum and not the cecum when H 2 E increased on LHBT. Thus, median OCTT measured by MRI was significantly longer than that measured by min)vs.127.5(105-150min);p=0.008]. Above baseline levels, correlation between [H 2 ] and SBGV was significant (r=0.964;p<0.001).Conclusions: MRI provides valid measurements of OCTT and gas production in the small bowel. Keypoints: MRI is a valid technique to measure OCTT.  Excellent agreement between MRI and LHBT was found. Measuring gas production using MRI may pro...

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Will MRI of gastrointestinal function parallel the clinical success of cine cardiac MRI?

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