Accuracy of prostatic volume calculation in transrectal ultrasonography

Area of Science:

• Medical Imaging
• Urology
• Prostate Cancer Diagnostics

Background:

• Transrectal ultrasonography is vital for estimating prostatic volume.
• Accurate prostatic volume is essential for evaluating conservative treatments and improving prostate-specific antigen (PSA) specificity.
• Prostatic volume is a key factor in calculating PSA density (PSA/prostatic volume ratio).

Purpose of the Study:

• To compare the accuracy of ellipsoid and prolate ellipse volume calculations.
• To assess the reliability of different methods for measuring prostatic length in prolate ellipse calculations.
• To determine the most accurate method for prostatic volume estimation via transrectal ultrasonography.

Main Methods:

• Constructed 3D prostatic models from transrectal ultrasonotomograms at 5 mm intervals in 20 cases.
• Examined accuracy of ellipsoid and prolate ellipse volume calculations.
• Measured prostatic length using two methods: Lv (vertical to transverse section) and Lp (parallel to urethra) for prolate ellipse calculations.

Main Results:

• Ellipsoid volume calculation demonstrated significant errors (approx. 20%) and fluctuations (up to 50%) with scanning angle changes.
• Prolate ellipse calculation using Lp showed increased errors (avg. 25%) as the angle deviated from perpendicular.
• Prolate ellipse calculation using Lv for length proved most reliable, with errors least dependent on the angle between the plane and axis.

Conclusions:

• Prolate ellipse volume calculation is more accurate than ellipsoid calculation.
• Accurate prolate ellipse volume calculation requires the three axes to intersect at right angles.
• The Lv measurement provides the most dependable prostatic length for accurate prolate ellipse volume calculation.