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The Good, the Bad, and the Useful of CT, MRI, and TRUS in Assessing Prostate Volume
Daniel Givner, MD1, Caroline Sha, BS2, Wyatt L. Penske, BS3, Kimberly A. Maciolek, MD4, Lori Lerner, MD3.
1Boston Medical Center, Boston, MA, USA, 2Boston University Chobanian and Avedisian School of Medicine, Boston, MA, USA, 3VA Boston Healthcare System, Boston, MA, USA, 4University of Virginia, Charlottesville, VA, USA.
BACKGROUND: Precise evaluation of prostate volume (PV) is critical in determining appropriate management for patients. A myriad of imaging modalities can delineate prostate anatomy to varying degrees. Computed Tomography (CT) is generally the most readily available in patient records. There is limited data regarding how well CT agrees with actual PV or other modalities. We compared the accuracy of CT relative to transrectal ultrasound (TRUS) and magnetic resonance imaging (MRI) in estimating PV determined by pathology gross specimens.
METHODS: A single-center retrospective chart review investigated 113 BPH patients who received TRUS, CT, and/or MRI and then underwent robot-assisted laparoscopic prostatectomy between January 2018 and June 2023. TRUS PV was determined by the surgeon at the time of biopsy using the ellipsoid equation (V=L×W×H×0.52). Therefore, for CT and MRI, ellipsoid PV was similarly used to ensure consistency across modalities. TRUS, CT, and MRI volumes were compared with the reference gross specimen volume, as determined by the pathologist.
RESULTS: CT (n=38) exhibited the lowest correlation with actual PV (⍴=0.69, p<0.05), modestly overestimating size with the second-highest mean bias (d̅=3.51±14.03 cm3). MRI (n=55) had the greatest correlation (⍴=0.83, p<0.05), overestimating size with the lowest mean bias (2.83±11.17 cm3). TRUS (n=103) showed moderate correlation (⍴=0.72, p<0.05), underestimating size with the greatest mean bias (d̅=-4.99±13.02 cm3).
CONCLUSIONS: CT appears less accurate or precise in assessing PV as compared to TRUS and MRI, with MRI showing the best agreement with gross specimen volumes. However, due to CT's widespread accessibility, understanding CT's tendency to overestimate PV can aid clinicians when determining appropriate management.
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