MRI-based nomogram analysis: recognition of anterior peritoneal reflection and its relationship to rectal cancers

Determination of the positional relationship of the second Houston valve and peritoneal reflection using computed tomographic colonography and magnetic resonance imaging

PURPOSE

The second Houston valve is used as a surrogate for estimating the position of the peritoneal reflection; however, the concordance between the positions of the valve and peritoneal reflection has not been investigated. This study aimed to clarify this positional relationship.

METHODS

The second Houston valve and peritoneal reflection positions were assessed using tomographic colonography and magnetic resonance imaging. In total, 117 patients were enrolled in this study.

RESULTS

The positions of the second Houston valve and peritoneal reflection were nearly concordant, although the space between them ranged from - 20.7 to 33.9 mm. A peritoneal reflection located further from the anal verge than the second Houston valve was defined as a shallow peritoneal reflection. Male sex, high body weight, and a high body mass index were significantly correlated with a shallower peritoneal reflection, as determined by a univariate analysis (sex: P = 0.0138, weight: P = 0.0097, body mass index: P = 0.0311). A multivariate analysis revealed a significantly shallower peritoneal reflection in males than in females (odds ratio: 2.75, 95% confidence interval: 1.15-6.56, P = 0.023).

CONCLUSIONS

The second Houston valve located near the peritoneal reflection can be a useful surrogate marker for estimating its position. In relatively heavy males, the peritoneal reflection is located more cranially than the second Houston valve.