Magnetic resonance imaging-transrectal ultrasound fusion focal cryotherapy of the prostate: A prospective development study

Abstract

Objectives: The use of software-based magnetic resonance-transrectal ultrasound fusion to deliver focal therapy may increase the precision of treatment. This is a prospective development study assessing the feasibility of Magnetic resonance imaging-transrectal ultrasound (MRI-TRUS) fusion focal cryotherapy.

Methods and materials: Consecutive patients undergoing focal cryotherapy were included in an academic registry (December 2013-June 2014). MRI-TRUS fusion focal cryotherapy was offered to men with visible clinically significant prostate cancer (Galil SeedNet system). Eligibility was determined by multiparametric MRI (mpMRI), and transperineal template mapping or targeted biopsies. A rigid fusion platform (Biojet) was used with the operator ensuring the ice ball covered at least the lesion. Adverse events were scored using the NCICTC V4. Genitourinary toxicity was assessed using patient-reported outcome measures (IPSS, IIEF-15, and UCLA-EPIC). Early contrast-enhanced MRI and mpMRI at 6 to 12 months were used to assess extent of lesion ablation.

Results: Of 23 patients scheduled, 5 did not have image fusion owing to surgeon preference. Overall, 18 patients undergoing image-fusion cryotherapy had median age of 68 (interquartile range [IQR]: 65-73) years and median preoperative prostate-specific antigen = 9.54 (5.65-16)ng/ml. In all, 13 (72.2%) and 5 (27.8%) patients had intermediate and high-risk cancer, respectively. In total, 10 adverse events were reported with one of these as serious (grade 3) because of admission for hematuria requiring wash out only. There was no difference in the IIEF-15 between baseline and study end (P = 0.24). The IPSS remained stable (P = 0.12), whereas the UCLA-EPIC tended to improve (P = 0.065). The prostate-specific antigen level significantly decreased at 1.8 (1.04-2.93) ng/ml (P<0.001). Both early and late mpMRI showed no residual disease in the treated area. In 2 men, radiological progression of known contralateral disease was observed; both underwent focal high intensity focused ultrasound.

Conclusion: MRI-TRUS fusion focal cryotherapy is feasible in most patients and seems to accurately guide ablation demonstrated by posttreatment imaging. Additional studies are needed to determine efficacy using postcryotherapy biopsy.

Keywords: Cryotherapy; Focal therapy; Image fusion; Prostate neoplasms.