Rezūm System Water Vapor Treatment for Lower Urinary Tract Symptoms/Benign Prostatic Hyperplasia: Validation of Convective Thermal Energy Transfer and Characterization With Magnetic Resonance Imaging and 3-Dimensional Renderings

Two-year results after convective radiofrequency water vapor thermal therapy of symptomatic benign prostatic hyperplasia

“…Prostate volumes assessed by gadolinium-enhanced MRI at 1, 3, and 6 months after convective RF thermal therapy were significantly decreased at all time points, P <0.001 12. The volume was reduced by 24% at month 3 and 30% at month 6.…”

“…Transurethral convective thermal therapy utilizes RF to generate wet thermal energy in the form of water vapor (steam). As the vapor is convectively dispersed through the tissue interstices, it phase shifts from vapor back to liquid almost immediately upon injection into the tissue releasing and delivering ~208 cal of thermal energy in 9 s. The resultant tissue temperature of ~70°C results in irreversible and near instantaneous cell death, creating a roughly spherical ablative lesion of ~1.5–2 cm 12. This convective heat transfer, or vapor physically moving through the tissue, involves virtually no discernible thermal gradient as seen with conductive heat transfer technologies (e.g., TUNA, TUMT).…”

“…These modifications in dosimetry and technique were guided by serial gadolinium-enhanced magnetic resonance imaging (MRI) performed after the thermal therapy in 59 of the 65 patients in this study at each of the scheduled follow-up visits through 6 months 12. Early characterization of thermal ablation had been identified in a study involving histological examination of convective RF water vapor thermal therapy-treated prostates in patients previously scheduled for surgical removal of the prostate 10…”

“…Convective RF water vapor energy (Rezūm System; NxThera, Inc., Maple Grove, MN, USA) was introduced as a minimally invasive, radiofrequency thermal energy-based treatment, designed to convectively deliver sterile water vapor, or steam for targeted ablation limited to the transition and central zones in men with clinical BPH 10–12. The objective of this report was to assess the 2-year clinical outcomes in the first patients treated with this new technology.…”

<div>Perspective on the Rezūm^&reg; System: a minimally invasive treatment strategy for benign prostatic hyperplasia using convective radiofrequency water vapor thermal therapy</div>

“…MRI scans in these pilot studies were conducted at the three centers, and data were analyzed by an independent urologist (Biomedical Imaging Resource; Mayo Clinic, Rochester, MN, USA). Three-dimensional (3D) volume renderings allowed visualization of thermal lesions in relation to prostate zonal anatomy and lesion resolution after the water vapor thermal therapy 9,17. The pilot study thermal treatment procedure evolved with slight modifications to optimize water vapor delivery, dosimetry, and endoscopic technique based on characterization of the ablative lesions with MRI, time course to resolution, and changes in prostate volume.…”