Importance of dynamic contrast enhanced magnetic resonance imaging for targeting biopsy and salvage treatments after prostate cancer recurrence

Purpose
Evaluate T2 weighted MRI (T2W), diffusion weighted imaging (DWI), and dynamic contrast enhanced MRI (DCE-MRI) for determining areas of prostate cancer recurrence to target biopsy or salvage treatment in patients previously treated with I-125 seed brachytherapy.

Material and methods
MRI data from 15 patients, whose primary treatment was I-125 seed brachytherapy and who were subsequently treated with partial gland salvage high-dose-rate brachytherapy were retrospectively analyzed. Two radiologists independently reviewed imaging on two occasions blinded to clinical and biopsy information. At first review, the T2W and DWI sequences were assessed for likely presence of tumor and at second review, the additional DCE-MRI sequence was assessed. Results were recorded and compared on a prostate diagram divided into 12 sectors (quadrants at each of base, mid-gland, and apex) plus seminal vesicles (SV).

Results
Number of patients for whom recurrence was visible was 7/15 for T2W, 6.5/15 for DWI, and 15/15 for DCE-MRI (average of results for the two radiologists). Approximately, half of the sectors identified as showing recurrence were at the anterior base of the prostate.

Conclusions
In prostate cancer patients previously treated with I-125 permanent seed implants, DCE-MRI is superior to T2W and DWI in defining areas of recurrence, and should be used to target biopsy and for treatment planning of focal salvage therapies.