  Gynecologic malignancies are a leading cause of death in women worldwide.
Standard treatment for many primary and recurrent gynecologic cancer cases
includes a combination of external beam radiation, followed by brachytherapy.
Magnetic Resonance Imaging (MRI) is benefitial in diagnostic evaluation, in
mapping the tumor location to tailor radiation dose, and in monitoring the
tumor response to treatment. Initial studies of MR-guidance in gynecologic
brachtherapy demonstrate the ability to optimize tumor coverage and reduce
radiation dose to normal tissues, resulting in improved outcomes for patients.
In this article we describe a methodology to aid applicator placement and
treatment planning for 3 Tesla (3T) MR-guided brachytherapy that was developed
specifically for gynecologic cancers. This has been used in 18 cases to date in
the Advanced Multimodality Image Guided Operating suite at Brigham and Women's
Hospital. It is comprised of state of the art methods for MR imaging, image
analysis, and treatment planning. An MR sequence using 3D-balanced steady state
free precession in a 3T MR scan was identified as the best sequence for
catheter identification with ballooning artifact at the tip. 3D treatment
planning was performed using MR images. Item in development include a software
module designed to support virtual needle trajectory planning that includes
probabilistic bias correction, graph based segmentation, and image registration
algorithms. The results demonstrate that 3T MR has a role in gynecologic
brachytherapy. These novel developments improve targeted treatment to the tumor
while sparing the normal tissues.
