Presentation Authors: Wesley R Pate*, Liz B Wang, Nishant Garg, Philip V Barbosa, Shaun E Wason, Boston, MA
Introduction: Prostate size is an important metric utilized in the management of many urologic diseases. Imaging to estimate prostate volume includes ultrasound (US), Computed Tomography (CT), and Magnetic Resonance Imagining (MRI); however, US stands apart as a fast, radiation-free, and cost-effective modality. Two methods of ultrasound used are transabdominal pelvic (PUS) and transrectal (TRUS) ultrasound, with the latter considered to be more accurate, but more invasive. This study aims to compare the accuracy of PUS to TRUS sizing and is the largest study to date to do so.
Methods: We performed a single-center, retrospective study of 199 patients with PUS and TRUS prostate sizing between January 1, 2012 and August 31, 2017. Prostate volume was derived from ellipsoid volume calculation (length x width x height x Ï€/6) using dimensions measured on US. Sizes obtained by PUS and TRUS were compared by calculating the Pearson correlation coefficient. We utilized the two sample z test to analyze for differences in prostate size between the US modalities. This univariate analysis was done for the whole sample population as well as for specific groupings of variables.
Results: A total of 199 patients had both PUS and TRUS prostate sizing. Median age was 63, median BMI was 27, 32 (16%) were white, 112 (56%) were black, and 35 (18%) were Hispanic. Median PSA value prior to PUS was 8.0 ng/mL. Average time between each US modality was 29 days, with 98 (49%) patients having TRUS within 31 days. Median size by PUS was and TRUS were both 52 cm3. Correlation between modalities was r=0.91 (p < 0.0001). No statistically significant difference in volume was found between PUS and TRUS (p = 0.43), including when analyzed by groups according to prostate size, time between US exams, and BMI. The mean of the volume differences, (volPUS - volTRUS), was (2.5 Â± 4.7) cm3, with 149 (75%) patients having a â‰¤ 25% difference between PUS and TRUS estimations.
Conclusions: There were no statistically significant differences between prostate size estimated by PUS versus TRUS. Additionally, there were no statistically significant differences in size when grouped by prostate volume, time between US exams, and BMI. As PUS is non-invasive, it should be the preferred modality for estimating prostate size.