MR imaging of the retrorectal-presacral tumors: an algorithmic approach.

The retrorectal-presacral space is located posterior to the mesorectum and anterior to the sacrum, and can harbor a heterogeneous group of uncommon masses. Retrorectal-presacral tumors may be classified as congenital, neurogenic, osseous, and miscellaneous. Magnetic resonance imaging (MRI) plays a crucial role in directing appropriate management through accurate diagnosis, detection of complications and anatomic extent. MRI aids in the selection of optimal surgical approach such as anterior, posterior, or combined-based on the lesion extent and relationship to adjacent structures. This article reviews the anatomy of the retrorectal-presacral space and the related tumors, optimal MRI protocol, MRI-based approach to differential diagnosis, and finally pertinent reporting pointers and implications of MR imaging findings for surgical management.