Session: MP59: Benign Prostatic Hyperplasia: Surgical Therapy & New Technology III
MP59-16: Magnetic Resonance Imaging Transition Zone Volume is Highly Concordant with Enucleated Volume after Holmium Laser Enucleation of the Prostate due to Variation in the Transition Zone Index
Introduction: Holmium laser enucleation of the prostate (HoLEP) aims to remove the entire prostate transition zone. Whole prostate gland volume (WGV) is often used to predict HoLEP enucleated volume. However, WGV and enucleated volume are sometimes discordant implying variability in the ratio of transition zone volume (TZV) to WGV (transition zone index, TZI). We aim to determine the relationship between TZI and WGV and assess the concordance between HoLEP enucleated volume and MRI estimated WGV and TZV. Methods: A prospective HoLEP database was queried to identify patients with MRI within one year of HoLEP. TZI was calculated by dividing TZV by WGV. Patients were categorically stratified based on ellipsoid WGV, as measured by a radiologist. The ratio between TZI and WGV was assessed using stratified analysis and regression. Concordance was defined as the ratio of enucleated volume to WGV and TZV with mean values compared using ANOVA. Results: We analyzed 218 patients with mean WGV of 101g (range 16.7 - 388) and TZV of 63.6g (range 6.06 - 346). TZV was more concordant with enucleated volume compared to WGV (mean 0.984, SD 0.297) vs 0.56 (SD 0.187, p<0.001). Mean TZI and enucleated specimen concordance all varied significantly when stratified by prostate volume (Table). Regression analysis revealed a significant, positive, non-linear relationship between WGV and TZI, but with high variability between individual patients (r=0.62) (Figure). Conclusions: MRI transition zone volume measurements are highly concordant with HoLEP enucleated volumes, especially when compared with whole gland volume measurements. On average, larger prostates have a higher TZI, but TZI is highly variable in individual patients and may not be accurately predicted from WGV alone. Therefore, preoperative transition zone measurement with MRI provides a valuable, accurate, and non-invasive tool for estimating enucleated volume prior to HoLEP. SOURCE OF Funding: None
