A prospective trial of real-time magnetic resonance-guided catheter placement in interstitial gynecologic brachytherapy

Purpose: To present outcome and toxicity results of the first real-time intraoperative MRI-guided interstitial approach to gynecologic cancer. Methods and Materials: From February 2004 to December 2006, 25 patients with gynecologic malignancies were enrolled and treated in a prospective clinical trial of real-time MRI-guided interstitial brachytherapy. This was followed by a confirmatory CT imaging scan. Statistical analyses included Kaplan-Meier estimates for overall and relapse-free survival. Results: MRI visualization of needles during placement permitted accurate placement with no inadvertent insertions. This prevented unnecessary normal-tissue perforation as confirmed by CT simulation. With a mean followup of 3.8 years (range, 2-6.8), 1-, 2-, and 3-year overall survival rates were 80%, 60% and 43%, respectively; corresponding relapse-free survival rates were 79%, 65%, and 59%, respectively. Actuarial acute toxicity rates for any grade were 0% at 0-14 days and 80% (all grade 1) at 14-90 days. Long-term (>180 days) actuarial toxicity rates were 8% gastrointestinal, 4% bladder and 4% vaginal. Conclusions: Real-time MRI guidance during insertion of interstitial needles followed by 3D-planning maximized opportunities for tumor targeting and sparing of normal tissues. Although image guidance requires additional anesthesia time, clinical outcomes indicate potential for a successful reduction in toxicity using 3D image-guided in addition to 3D image-planned brachytherapy.