Three-dimensional Computed Tomographic Images of Pelvic Muscle in Anorectal Malformations

Purpose: The anatomy of the pelvic flower muscles based on investigation of gross section slides of a specimen does not always correspond with those described by Pena. Therefore, we restudied the anatomy with 3-dimensional (3D) images of the pelvic muscle produced with computed tomography.

Methods: Thirty-eight patients with anorectal malformations before anorectoplasty were investigated with a multi-detector row helical computed tomography (MRH-CT). Images of the pelvic part were obtained with a slice thickness of 1 mm and a reconstruction pitch of 0.5 mm. A 3D reconstruction was made with the volume rendering method. Lateral views of the 3D CT reconstructed images of the pelvic muscle were compared with the same views of the type corresponding to Pena's schematic drawings in the literature.

Results: Study of the 3D reconstructions demonstrated that the pelvic muscles of each type were less uniform than the ones described by Pena. There was a great difference even in the same type of anatomy. The differences between the 3D image and the description by Pena were most notable in the high type and particularly in the description of the vertical fibers and the parasagittal muscles.

Conclusions: A 3D image with MRH-CT can provide useful preoperative information about the anatomy of the pelvic flower muscles in each case.