We present a quantitative model to analyze the detrimental effects of for edema on the quality of prostate brachytherapy implants We account for both tissue expansion, implant migration by mapping intra-operative ultrasound, post-implant CT We pre-process the ultrasound with a phase congruency filter, and map it to the volume CT using a B-spline deformable mutual information similarity metric To test the method, we implanted a standard training phantom with 48 seeds, imaged the phantom with ultrasound, CT, registered the two for ground truth Edema was simulated by distorting the CT volume by known transformations The objective was to match the distorted implant to the intra-operative ultrasound Performance was measured relative to ground truth We successfully mapped 100% of deformed seeds to ground truth under edematic expansion up to 40% of volume growth Seed matching performance was 98% with random seed migration of 3mm superimposed on 10% edematic volume growth This method promises to be clinically applicable as the first quantitative analysis tool to measure edematic implant deformations occurring between the operating room, post-operative CT imaging