Accuracy of ultrasound in estimation of prostate weight: Comparison of urologists and radiologists

Department of Urology, Mayo Clinic, Phoenix, Arizona, USA.
The Canadian Journal of Urology (Impact Factor: 0.98). 02/2010; 17(1):4985-8.
Source: PubMed


Measurements of prostate size are obtained to contribute in the diagnosis and follow up of patients with a variety of diseases. Since its introduction, transrectal ultrasonography (TRUS) of the prostate has become the most common method for assessment of prostate volumes. Ultrasonography, in general, has been associated with concerns of operator dependent variability. Herein, we analyze the accuracy of urologists and radiologists performing TRUS.
The accuracy of preoperative TRUS prostate volume estimation was evaluated by comparing it to gross specimen prostate weight following robot-assisted radical prostatectomy (RARP) performed from August 2004 to March 2008 in Mayo Clinic Arizona. A total of 800 RARPs were evaluated retrospectively with 302 patients having a prostate volume measurement with TRUS at our institution followed by RARP being performed within 30 days. The TRUS measurements were divided into two groups: those TRUS measurements performed by urologists (group 1), and those performed by radiologists (group 2). The accuracy of the two groups were compared using a Pearson correlation analysis.
The estimated weight by TRUS in the total cohort of patients correlated with the pathological specimen weight at 0.802 with a standard error of 0.90. Group 1 performed a total of 114 ultrasounds with a correlation of 0.835 and a standard error of 1.27. Group 2 performed a total of 188 with a correlation of 0.786 and a standard error of 0.88.
Urologists and radiologists are both consistently within 17%-22% of the estimated prostate specimen weight. Urologists appeared to have a slightly higher accuracy in estimation but a higher range of error for the whole group when compared to radiologists. Transrectal ultrasonography is a reliable technique to estimate prostate weight and accuracy to within 20% of the pathological weight. Urologists and radiologists are essentially equally proficient in estimating prostate weight with TRUS. These findings are particularly important with respect to specialty certification and competency/proficiency evaluation, as health care increasingly moves towards outcomes based reimbursement.

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    • "If any error was made in measuring the height, width or length of the prostate by TRUS, the accuracy of prostate volume and PSAD would be reduced. However, TRUS is widely used to calculate prostate volume and is considered a reliable technique to estimate prostate size, with accuracy within 20% of the pathological weight.28 Moreover, a significant intra-observer variation in TRUS-guided prostate volume measurement could also exist even among highly experience radiologists. "
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    ABSTRACT: Purpose To investigate the relationship between prostate volume and the increased risk for being diagnosed with prostate cancer (PCa) in men with slowly increasing prostate specific antigen (PSA). Materials and Methods A cohort of 1035 men who visited our hospital's health promotion center and were checked for serum PSA levels more than two times between January 2001 and November 2011 were included. Among them, 116 patients had a change in PSA levels from less than 4 ng/mL to more than 4 ng/mL and underwent transrectal ultrasound guided prostate biopsy. Median age was 55.9 years and 26 (22.4%) had PCa. We compared the initial PSA level, the last PSA level, age, prostate volume, PSA density (PSAD), PSA velocity, and follow-up period between men with and without PCa. The mean follow-up period was 83.7 months. Results Significant predictive factors for the detection of prostate cancer identified by univariate analysis were prostate volume, follow-up period and PSAD. In the multivariate analysis, prostate volume (p<0.001, odds ratio: 0.890) was the most significant factor for the detection of prostate cancer. In the receiver operator characteristic curve of prostate volume, area under curve was 0.724. At the cut-off value of 28.8 mL for prostate volume, the sensitivity and specificity were 61.1% and 73.1% respectively. Conclusion In men with PSA values more than 4 ng/mL during the follow-up period, a small prostate volume was the most important factor in early detection of prostate cancer.
    Yonsei medical journal 09/2013; 54(5):1202-6. DOI:10.3349/ymj.2013.54.5.1202 · 1.29 Impact Factor
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    • "However, using TRUS to take measurements is known to result in 10-12% variability in the calculated volume upon repeated tests [2]. It is also known that there is an error of approximately 17-22% when volumes calculated using TRUS measurements are compared with direct volume measurements taken before and after prostate resection by robot-assisted radical prostatectomy [3]. These direct measurement methods have less variation than methods utilizing TRUS, primarily due to user-dependent variation. "
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    ABSTRACT: Transrectal ultrasonography (TRUS) is a non-invasive modality widely used in urology on an outpatient basis to measure the volume and anatomical structure of the prostate. However, the prostate volume measured by TRUS often varies from test to test. The aim of this study was to determine the clinical significance of the different shapes of the prostate, as shown by TRUS before and after transurethral resection of the prostate (TURP). We evaluated 103 patients who underwent TURP. TRUS was performed preoperatively, and the International Prostatic Symptom Score (IPSS) and quality of life (QoL) were assessed preoperatively and at 6 months postoperatively. Patients were classified into two groups: patients with a bilaterally enlarged transitional zone were assigned to group A, and those with a protruding retrourethral zone were assigned to group B. There were no statistically significant differences between the two groups in preoperative variables. However, postoperative IPSS scores were lower in group A than group B (9.87+/-6.15 vs. 13.18+/-8.07, p=0.02). With regard to postoperative IPSS scores relative to preoperative IPSS scores, both groups showed a significant decrease, but group A experienced a significantly greater decrease than group B (13.43+/-7.47 vs. 8.67+/-8.33, p=0.005). Patients with a prostate protruding into the bladder have less of a decrease in their IPSS scores after TURP, compared to patients that do not have prostate protrusion, meaning that patients with protrusion experience less symptomatic relief.
    Korean journal of urology 07/2010; 51(7):483-7. DOI:10.4111/kju.2010.51.7.483
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    ABSTRACT: What's known on the subject? and What does the study add? The Epstein criteria, which utilize prostate specific antigen density (PSAD) benchmarks, are recognized to be a reasonable method of selecting men for active surveillance of prostate cancer. Transrectal ultrasonography, however, may not be a sufficiently precise method of measuring prostate volume for the determination of PSAD. This study shows that despite impressive intra-observer variability in transrectal ultrasonography guided prostate volume measurements, this variability typically does not affect the PSAD to an extent by which qualification for active surveillance would be altered. • To determine intra-observer variability in transrectal ultrasonography (TRUS) guided prostate volume measurements in the Johns Hopkins active surveillance group and to establish whether or not this variability could affect prostate-specific antigen density (PSAD) estimates in this cohort. • In all, 253 patients with a combined total of 1111 prostate biopsies underwent TRUS-guided prostate volume measurements performed by the same physician at least three times over the course of their care. • Coefficients of variation (CV) were calculated for each set of measurements performed on each patient by the same physician, and average CVs were determined for each physician and for physicians overall. The CVs were correlated with the average of each patient's measured prostate volumes to look for any trend. • Finally, measured prostate volumes were used with each patient's initial prostate-specific antigen (PSA) value to calculate PSAD to reveal whether or not the degree of variability found in these measurements would have led to PSADs that would have otherwise precluded qualification for active surveillance. • The average CV for all sets of prostate volume data was 0.168. Average CVs for each physician ranged from 0.136 to 0.234. • However, actual CVs ranged anywhere from 0.013 to 0.549. The CVs were found to have no correlation with prostate volumes (Pearson correlation coefficient: 0.04). • In 95% of cases, variability in TRUS-guided prostate volume measurement did not affect PSAD sufficiently to elicit a value greater than 0.15. • Even among individuals who are highly experienced in TRUS-guided prostate volume measurement, significant intra-observer variation exists. However, this variability is not enough to affect one's eligibility for prostate cancer active surveillance when PSAD criteria are used. • The TRUS-guided prostate volume measurements remain a reliable method of assessing PSAD in patients with prostate cancer.
    BJU International 07/2011; 108(11):1739-42. DOI:10.1111/j.1464-410X.2011.10223.x · 3.53 Impact Factor
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