Presentation Authors: Thomson Tai, Maywood, IL, Robert Blackwell, Springfield, IL, Spencer Hart*, Gopal Gupta, Maywood, IL
Introduction: Magnetic resonance imaging (MRI) of the prostate uses image segmentation to calculate prostate volume, which has the potential to yield more accurate volume estimation compared to traditional volume estimation by transrectal ultrasonography (TRUS).
Methods: We retrospectively identified 198 patients who had an MRI of the prostate followed by a MR-fused TRUS prostate biopsy. Paired t-tests were used to compare volume estimation techniques. Patients were then grouped by prostate volume on MRI (group 1 40cc). The difference in volume calculation techniques was compared between the two groups using Studentâ€™s t-test.
Results: For the 198 patients, the mean MR-estimated prostate volume was 58.6cc (SD: 33.5) was significantly higher than the TRUS-estimated prostate volume of 50.4cc (SD: 29.2) (p < 0.001). When MR-estimated prostate volumes were stratified at a gland size of 40cc, a difference was seen. Patients in the smaller prostate cohort had little difference in estimated size between techniques (n=64, mean difference 2.1cc (SD: 10.1)), compared to patients in the larger gland size cohort (n=134, mean difference 11.4cc (SD: 14.3), p < 0.001.
Conclusions: TRUS underestimates prostate volume compared to MRI, particularly in patient with gland sizes >40cc. This has implications in PSA density and surgical planning.