Prostatectomy and radiation therapy have been the cornerstone of the treatment of prostate cancer (PCa) for several decades. While being effective treatment methods, the downside is the burden of substantial adverse effects.

Evolution of magnetic resonance imaging (MRI) of prostate has improved the PCa detection, localization and characterization, paving the way for less invasive ablative treatments. MRI-guided transurethral ultrasound ablation (TULSA) is a novel method in the field of prostate ablation. With TULSA, prostatic tissue is destroyed by thermal energy generated by high-intensity ultrasound. TULSA can be used for the treatment of both malignant (primary, salvage or palliative) and benign (hyperplasia) prostate conditions.

The purpose of this doctoral research was to investigate acute and subacute MRI findings related to TULSA treatment, and the evolution of post-treatment necrotic tissue up to one year. The results showed that the extent of tissue necrosis, measured by contrast-enhanced MRI as non-perfused volume (NPV), enlarged within the first few weeks after the procedure. With longer follow-up NPV gradually decreased, and after one year most of the necrotic tissue had disappered. The resolution of necrotic tissue after ablation was markedly slower for irradiated than treatment-naïve prostate tissue.

Fiducial markers implanted in prostate are widely used in the radiation therapy. Safety and efficacy of ultrasound ablation for radiorecurrent PCa in the presence of gold fiducial markers had not been previously studied. There was a reasonable doubt, that intraprostatic fiducial markers could hinder ablation-based salvage treatments by mechanically obstructing the ablative energy, and by causing MRI artifacts. Our results showed that patients with intraprostatic gold fiducial markers can successfully be treated with TULSA.

Overall, this work offers knowlegde on clinical routine, assessment of post-TULSA condition, and optimization of follow-up protocols.