Determination of Prostate Volume by Transrectal Ultrasound

Abstract

Estimation of prostate gland volume with transrectal ultrasound may provide important information in the evaluation of benign and malignant prostatic diseases. To determine the most accurate means of volume estimation 150 patients underwent transrectal ultrasound with 15 separate methods of volume estimation. All patients underwent subsequent radical prostatectomy or cystoprostatectomy. Prostate specimen weights were compared with the results of each volume estimation method. Step-section planimetry, previously assumed to be the most accurate means of volume measurement, exhibited a Pearson correlation coefficient of 0.93. The elliptical volume, widely used as an alternative to planimetry, demonstrated a correlation coefficient of 0.90. The most accurate method to estimate prostate weight (r = 0.94) was a variation of the prolate spheroid formula, expressed as pi/6 (transverse dimension)2 (anteroposterior dimension). When different volume ranges were considered, this prolate spheroid formula provided the closest estimate of weight in glands of less than 40 gm. and those in the 40 to 80 gm. range. The most accurate method to estimate prostates weighing greater than 80 gm. was the formula pi/6 (transverse dimension)3.

Accuracy and repeatability of prostate volume measurements by transrectal ultrasound

“…However, this method does not necessarily determine the true in vivo prostate volume, due to shrinkage because of loss of blood supply, 5 and the volume might also be overestimated because of adjacent periprostatic tissue. 13 Several methodological studies, like measurement of water filled balloons, 14 and cadaver studies 13,15 have demonstrated that under ideal conditions, planimetry measures a volume very close to the true volume, and can be used as the gold standard of prostate volume measurement.…”

“…The prolate elipsoid formula, multiplying the largest anterioposterior (height), transverse (width) and cephalocaudal (length) prostate diameters by 0.524 (H6W6L6p/6) is probably the most commonly used method, 6,7 since it is rapid, reproducible, and has been shown to have high correlation with the actual prostate volume. 5 However, it has been questioned whether the prolate elipsoid formula gives accurate results in large prostates. 5,8 The prolate spheroid formula W6W6H6p/6 might be equally accurate, 5 and has the advantage of requiring measurements in the transversal plane only.…”

“…5 However, it has been questioned whether the prolate elipsoid formula gives accurate results in large prostates. 5,8 The prolate spheroid formula W6W6H6p/6 might be equally accurate, 5 and has the advantage of requiring measurements in the transversal plane only.…”

Three months’ treatment with the α1-blocker alfuzosin does not affect total or transition zone volume of the prostate

“…These investigators were all carefully trained in a standardized method of assessing prostate volume by TRUS. 7 Each took part in a 1-h lecture explaining the techniques of measurement of the prostate; the instruction included a teaching videotape as well as printed materials explaining the specific techniques to be utilized. The investigators were also given a copy of the videotape and asked to review it immediately prior to performing each examination.…”

“…7 Statistical analyses and graphing were performed using SigmaStat and SigmaPlot as well as SPSS vs 11.0. Baseline data distributions were described by mean and standard deviation.…”