Endoscopy 2004; 36 - 25
DOI: 10.1055/s-2004-834513

Use of Magnetic Resonance Imaging (MRI) to Determine the 3D Geometry in the Human Rectum

BP McMahon 1, JB Frøkjær 1, A Bergmann 1, DH Liao 1, E Steffensen 1, AM Drewes 1, H Gregersen 1
  • 1Center of Excellence in Visceral Biomechanics and Pain and Radiology Department, Aalborg University Hospital, Denmark and Center for Sensory-Motor Interactions, Aalborg University, Denmark

Aim: To develop an analytical method to describe the 3D geometry of the human rectal wall.

Methods: A dedicated balloon was positioned inside the rectal ampulla. Stepwise distension was performed inside the bore of a 1.5T magnetic resonance scanner during dedicated high quality image acquisition. The pressure was recorded using a low compliance perfusion manometric system. MR images of one healthy volunteer were analyzed. Using computer software the curvatures were computed throughout the rectal surface and using the transmural pressure the wall tension was computed using the law of Laplace.

Results: The spatial distributions of principal curvatures, wall thickness, tensions and stresses were non-homogeneous in the rectal wall due to its complex geometry. 3D figures of curvature and tension in the rectum during distension were computed and displayed.

Conclusions: This work provides an analytical tool for characterizing the complex in-vivo 3D geometry including tension distribution of a human rectum from a clinical imaging modality. The very complex geometry and non-homogenous spatial curvature distribution suggests that this type of 3D rendering may prove more useful than barostat or impedance planimetry technique.