Reassessment of nonplanimetric transrectal ultrasound prostate volume estimates

Comparison of Transabdominal and Transrectal Ultrasound for Sizing of the Prostate

OBJECTIVE

To compare the accuracy of prostate sizing between pelvic abdominal (PUS) and transrectal (TRUS) ultrasound in a large, diverse cohort of men at our institution. Prostate volume plays a vital role in all types of prostate disease. American Urological Association guidelines (2018) for surgical management of benign prostatic hyperplasia now include consideration of prostate volume measurement prior to surgical intervention. Ultrasound is a quick and radiation-free imaging modality.

METHODS

We performed a single-center, retrospective study of 299 patients with prostate sizing between January 1, 2012 and August 31, 2017. Prostate volume was derived from ellipsoid volume calculation using dimensions measured on ultrasound. PUS and TRUS were compared by calculating the Pearson correlation coefficient and intraclass correlation coefficient, and agreement between modalities assessed using the Bland Altman analysis. This analysis was done for the whole sample population as well as for specific groupings according to body mass index, prostate size, and time between exams.

RESULTS

A total of 236 patients had PUS followed by TRUS and met study inclusion criteria. Median age was 63, median prostate specific antigen value prior to PUS was 7.6 ng/mL, and only 20% were white. Mean volume differences between the two modalities for the data (vol_PUS - vol_TRUS) were (-0.3 ± 1.1) cm³. Bland-Altman analysis showed agreement between PUS and TRUS only for prostates ≤ 30 cm³.

CONCLUSION

For prostates less than 30 cc, we found that PUS is interchangeable with TRUS in estimating prostate volume. However, for larger prostates where size may alter surgical management, we would recommend TRUS or cross-sectional imaging.

Deep Learning for Real-time, Automatic, and Scanner-adapted Prostate (Zone) Segmentation of Transrectal Ultrasound, for Example, Magnetic Resonance Imaging-transrectal Ultrasound Fusion Prostate Biopsy

BACKGROUND

Although recent advances in multiparametric magnetic resonance imaging (MRI) led to an increase in MRI-transrectal ultrasound (TRUS) fusion prostate biopsies, these are time consuming, laborious, and costly. Introduction of deep-learning approach would improve prostate segmentation.

OBJECTIVE

To exploit deep learning to perform automatic, real-time prostate (zone) segmentation on TRUS images from different scanners.

DESIGN, SETTING, AND PARTICIPANTS

Three datasets with TRUS images were collected at different institutions, using an iU22 (Philips Healthcare, Bothell, WA, USA), a Pro Focus 2202a (BK Medical), and an Aixplorer (SuperSonic Imagine, Aix-en-Provence, France) ultrasound scanner. The datasets contained 436 images from 181 men.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Manual delineations from an expert panel were used as ground truth. The (zonal) segmentation performance was evaluated in terms of the pixel-wise accuracy, Jaccard index, and Hausdorff distance.

RESULTS AND LIMITATIONS

The developed deep-learning approach was demonstrated to significantly improve prostate segmentation compared with a conventional automated technique, reaching median accuracy of 98% (95% confidence interval 95-99%), a Jaccard index of 0.93 (0.80-0.96), and a Hausdorff distance of 3.0 (1.3-8.7) mm. Zonal segmentation yielded pixel-wise accuracy of 97% (95-99%) and 98% (96-99%) for the peripheral and transition zones, respectively. Supervised domain adaptation resulted in retainment of high performance when applied to images from different ultrasound scanners (p > 0.05). Moreover, the algorithm's assessment of its own segmentation performance showed a strong correlation with the actual segmentation performance (Pearson's correlation 0.72, p < 0.001), indicating that possible incorrect segmentations can be identified swiftly.

CONCLUSIONS

Fusion-guided prostate biopsies, targeting suspicious lesions on MRI using TRUS are increasingly performed. The requirement for (semi)manual prostate delineation places a substantial burden on clinicians. Deep learning provides a means for fast and accurate (zonal) prostate segmentation of TRUS images that translates to different scanners.

PATIENT SUMMARY

Artificial intelligence for automatic delineation of the prostate on ultrasound was shown to be reliable and applicable to different scanners. This method can, for example, be applied to speed up, and possibly improve, guided prostate biopsies using magnetic resonance imaging-transrectal ultrasound fusion.

Clinical significance of multiparametric MRI and PSA density as predictors of residual tumor (pT0) following radical prostatectomy for T1a-T1b (incidental) prostate cancer

Purpose

The aim of this study was to evaluate predictors of residual tumor and clinical prognosis in T1a-T1b (incidental) prostate cancer by analysis of specimens from men undergoing surgery for benign prostatic hyperplasia.

Materials and methods

We retrospectively reviewed medical records of incidental prostate cancer patients who had undergone radical prostatectomy. Patients whose tumor statuses were further confirmed by prostate biopsy, or who had used androgen deprivation therapy before radical prostatectomy, were excluded. Clinical and pathological parameters were analyzed to evaluate residual tumor and clinical prognosis. We used univariate and multivariate logistic regression analyses, as well as receiver operator characteristics, to predict residual tumor (pT0).

Results

The final analysis included 95 patients. Among these patients, 67 (70.53%) exhibited residual tumor, whereas 28 (29.47%) did not (pT0). Pathology findings showed that 44 (65.67%), 16 (23.88%), and 7 patients (10.45%) exhibited Gleason scores of G6, G7, and ≥G8, respectively. Fifty-seven and 10 patients exhibited pathologic T stages T2 and T3, respectively. Mean follow-up duration was 70.26 (±34.67) months. Biochemical recurrence was observed in 11 patients; none were pT0 patients. Multivariate logistic regression showed that low prostate-specific antigen density after benign prostatic hyperplasia surgery and invisible lesion on multiparametric magnetic resonance imaging were significantly associated with pT0. Additionally, a combination of these factors showed an increase in the diagnostic accuracy of pT0, compared with mpMRI alone (AUC 0.805, 0.767, respectively); this combination showed sensitivity, specificity, and positive predictive values of 71.6%, 89.3%, and 94.1%, respectively.

Conclusion

Our results suggest that patients with incidental prostate cancer who have both prostate-specific antigen density ≤0.08 after benign prostatic hyperplasia surgery as well as invisible cancer lesion on multiparametric magnetic resonance imaging should be considered for active surveillance.

Comparison of prostate volume measured by endorectal coil MRI to prostate specimen volume and mass after radical prostatectomy

RATIONALE AND OBJECTIVES

To compare prostate volume measurements from 3-Tesla endorectal coil magnetic resonance imaging (ERC MRI) obtained with the prolate ellipsoid volume formula (EVF) and volumetry to pathology-based volume measurements.

METHODS

The institutional review board waived informed consent for this retrospective, health insurance portability and accountability act (HIPAA) compliant study, which included 195 patients who underwent 3-T ERC MRI between January 2008 and October 2011 and had pathologic prostate measurements available. Two readers in consensus measured the prostate length, height, and width on each MRI. They estimated prostate volumes using the prolate EVF (length × height × width × [π/6]) and also by performing three-dimensional volumetry. Pathologic specimen mass and dimensions were used to calculate prostate volume. Agreement was measured with Lin's concordance correlation coefficient (CCC). Volume differences were assessed using the Wilcoxon signed-rank test. Correct prostate-specific antigen (PSA) density classification rates were compared between EVF-based and volumetry-based PSA density levels using the exact McNemar test, with pathology-based PSA density as the reference standard.

RESULTS

Concordance was high between EVF and volumetry measurements (CCC, 0.950 [95% confidence interval, 0.935-0.962]) and between both kinds of MRI measurements and pathology (both CCC > 0.80). Based on a cut-off of ≤0.15 ng/mL/cm(3), use of EVF-based volume produced correct classification of 46 of 48 PSA density levels >15 ng/mL/cm(3) and 113 of 147 PSA density levels ≤15 ng/mL/cm(3); use of volumetry-based volume produced correct classification of 47 of 48 PSA density levels >15 ng/mL/cm(3) and 121 of 147 PSA density levels ≤15 ng/mL/cm(3). Rates of underclassification (P > .95) and overclassification (P = .10) did not differ significantly between EVF and volumetry.

CONCLUSIONS

EVF appears to be suitable for measuring prostate volume from ERC-MRI.

Is determination of transition zone volume by transrectal ultrasound in patients with clinically benign prostatic enlargement sufficiently reliable in the clinical setting?

Introduction

Controversies exist regarding the accuracy of transrectal ultrasound (TRUS) determination of transition zone volume (TZV) when compared with enucleated adenoma weight.

Aim

To determine the accuracy and reliability of measurements of the TZV by TRUS, by comparing preoperative radiological findings with the enucleated prostate adenoma volume, measured by fluid displacement volumetry (FDV), after retropubic prostatectomy performed by the Millin method, and, moreover, to evaluate changes in the surgical capsule size in the intermediate postoperative period.

Material and methods

We measured TZV preoperatively using TRUS and postoperatively with FDV in 112 patients who underwent retroperitoneal prostatectomy for benign prostatic hyperplasia (BPH).

Results

The TRUS volume correlated well with specimen volumes (r = 0.945, p < 0.0001). The median (quartile 1, quartile 3) absolute error was 7.35 ml (4.15 ml, 9.28 ml) and the median percent error was 9.12% (4.75%, 14.98%). Percent error, but not absolute error, was significantly related to TRUS TZV (p < 0.001 and 0.217, respectively). Adenomas > 80 cc were associated with lower percent error. The median volume of the residual prostate tissue measured 3.5 years after prostatectomy was 92.65 cc (65.75 cc, 109.58 cc), whereas the median volume of the surgical capsule, depending on the equation used for its calculation, was 24.80 cc (16.25 cc, 37.37 cc) and 31.43 cc (23.14 cc, 43.32 cc).

Conclusions

The TRUS TZV correlated well with values determined by FDV. It can be reliably used in clinical management of BPH.

Impact of bent distortion on accuracy of measurement during transrectal ultrasonography for prostatic imaging: a preliminary study

OBJECTIVE

To evaluate the effect of bent distortion of the image of the prostate on the accuracy of 3-dimensional measurements during transrectal ultrasonography (TRUS).

METHODS

TRUS images were obtained prospectively from 60 patients with prostate cancer. The degree of rectal compression on the probe was varied in each case to obtain a typical bent distortion image (BDI) and a minimally bent image (MBI). Magnetic resonance imaging (MRI) served as the reference. Axial and midsagittal BDI, MDI, and MRI were selected. Three-dimensional prostate diameters (height, width, and length) and volume were obtained from all images by 2 independent observers. The data were analyzed by using a paired t test, intraclass correlation coefficients (ICCs), and Bland-Altman plots.

RESULTS

The MBI and BDI diameters differed significantly (P <.001). All ICCs for the MBI diameters and volume and the ICCs for BDI length and volume exceeded 0.9, which indicates high measurement reliability. However, the ICCs for BDI height and width were below 0.9. When the difference in MBI or BDI relative to MRI was calculated for each variable, the MBI differences were all significantly smaller than the BDI differences (P <.001).

CONCLUSION

Bent distortion during TRUS affects the accuracy of measurements. MBI is also morphologically more realistic than BDI. Therefore, to minimize prostatic image distortion, the rectal probe should be placed so that the posterior wall of the prostate is as flat as possible.

Automated computer-derived prostate volumes from MR imaging data: comparison with radiologist-derived MR imaging and pathologic specimen volumes

PURPOSE

To compare prostate gland volume (PV) estimation of automated computer-generated multifeature active shape models (MFAs) performed with 3-T magnetic resonance (MR) imaging with that of other methods of PV assessment, with pathologic specimens as the reference standard.

MATERIALS AND METHODS

All subjects provided written informed consent for this HIPAA-compliant and institutional review board-approved study. Freshly weighed prostatectomy specimens from 91 patients (mean age, 59 years; range, 42-84 years) served as the reference standard. PVs were manually calculated by two independent readers from MR images by using the standard ellipsoid formula. Planimetry PV was calculated from gland areas generated by two independent investigators by using manually drawn regions of interest. Computer-automated assessment of PV with an MFA was determined by the aggregate computer-calculated prostate area over the range of axial T2-weighted prostate MR images. Linear regression, linear mixed-effects models, concordance correlation coefficients, and Bland-Altman limits of agreement were used to compare volume estimation methods.

RESULTS

MFA-derived PVs had the best correlation with pathologic specimen PVs (slope, 0.888). Planimetry derived volumes produced slopes of 0.864 and 0.804 for two independent readers when compared with specimen PVs. Ellipsoid formula-derived PVs had slopes closest to one when compared with planimetry PVs. Manual MR imaging and MFA PV estimates had high concordance correlation coefficients with pathologic specimens.

CONCLUSION

MFAs with axial T2-weighted MR imaging provided an automated and efficient tool with which to assess PV. Both MFAs and MR imaging planimetry require adjustments for optimized PV accuracy when compared with prostatectomy specimens.

[Parameters to improve the specificity of the prostate-specific antigen. Early detection of prostate cancer]

PURPOSE

The aim of the study was to improve the case detection rate of prostate cancer for patients who had unremarkable palpation findings and a PSA value in the range of 4 to 10 ng/ml by combination of the parameters total PSA (tPSA), f/tPSA ratio, prostate volume, PSA density, patient's age and transrectal ultrasound findings.

METHODS

Sextant biopsy of the prostate was performed for 619 patients aged 45-75 years who had unremarkable palpation findings and PSA values in the range of 4 to 10 ng/ml. The f/tPSA ratio was determined, transrectal ultrasound examination was performed, the prostate volume was measured and the PSA density calculated. The relationship between the various test variables - and their combination - and the histology results was investigated using logistic regression.

RESULTS

Prostate cancer was detected in 131 of 619 patients. Analysis of the aforementioned test variables by means of logistic regression revealed that the combination of the parameters f/tPSA ratio, PSA density and patient's age can significantly increase the sensitivity and specificity of PSA in predicting prostate cancer compared with the use of these parameters on an individual basis. With an assumed limit value of 5% for performance of punch biopsy, 31% of biopsies could be avoided in practice. In such a case, only 3% of instances of prostate cancer would have gone undetected.

CONCLUSION

The combined use of f/tPSA ratio, PSA density and patient's age can significantly enhance the case detection sensitivity for the PSA range of 4 to 10 ng/ml.

Evaluation of prostate volume by transabdominal ultrasonography with modified ellipsoid formula at different stages of benign prostatic hyperplasia

The aim of the study was to propose an eccentricity parameter (EP)-based correction to the ellipsoid formula to improve the evaluation of the prostate volume defined by transabdominal ultrasonography (TAUS) at different stages of benign prostatic hyperplasia (BPH). All 202 adult male volunteers underwent the prostate volume evaluations with TAUS and computerized tomography (CT). Based on the EP index, three clearly different stages of BPH were also deduced by analytical analysis. By applying the correction formula, the mean prostate volume differences of TAUS with CT were improved from 28.1%, -25.4% and -0.6% to 7.6%, -3.5% and -0.6% for EP < 0.055, 0.055 < EP < 0.14 and EP > 0.14, respectively. Hence, for EP > 0.14, representing the advanced stage of BPH, TAUS with the ellipsoid formula can be regarded as an effective tool for computing volume, whereas for EP < 0.14, the correction formula is recommended to improve the volume estimation based on TAUS.

Interobserver variability of transrectal ultrasound for prostate volume measurement according to volume and observer experience. AJR Am J Roentgenol. 2009;192:444-449. [PMID: 19155408 DOI: 10.2214/ajr.07.3617]

OBJECTIVE

The purpose of our study was to evaluate the interobserver variability of transrectal ultrasound for prostate volume measurement according to the prostate volume and the level of observer experience.

SUBJECTS AND METHODS

Endorectal sonography was performed independently by two experienced observers in 101 patients and by one experienced and one less experienced observer in 110 patients; the prostate volume was then measured using the prolate ellipsoid formula. The volume difference between observers was analyzed according to the mean measured prostate volume determined by the observers and according to the level of observer experience.

RESULTS

The volume difference was greater in prostates with a mean measured volume >or= 30 mL than in prostates with a mean measured volume < 30 mL (6.00 vs 1.51 mL in the experienced observers and 6.84 vs 3.99 mL in the experienced and less experienced observers) (p < 0.05). The frequency of volume differences > 5 mL was greater in prostates with a mean measured volume >or= 30 mL than in prostates with a mean measured volume < 30 mL (between the experienced observers, 18% vs 1%; between the experienced and less experienced observers, 54% vs 25%) (p < 0.01 in both comparisons). The volume difference was greater between the experienced and less experienced observers (5.00 mL) than between the experienced observers (2.96 mL) (p = 0.01). The frequency of volume difference > 5 mL was greater between the experienced and less experienced observers (35%) than between the experienced observers (7%) (p < 0.01).

CONCLUSION

Prostate volume measurement by transrectal ultrasound may vary when patients have large prostates or observers have varying levels of experience.

Radical prostatectomy for incidental (stage T1a-T1b) prostate cancer: analysis of predictors for residual disease and biochemical recurrence

BACKGROUND

Controversies exist about the most appropriate management for patients with incidental prostate cancer after surgery for benign prostatic hyperplasia (BPH).

OBJECTIVES

To test the accuracy of preoperative clinical variables in predicting the presence of residual disease and biochemical recurrence in patients with incidental prostate cancer treated with radical retropubic prostatectomy.

DESIGN, SETTING, AND PARTICIPANTS

We analyzed 126 T1a-T1b prostate cancers diagnosed at surgery for BPH between 1995 and 2007.

INTERVENTION

All patients underwent radical retropubic prostatectomy within 6 mo of surgery for BPH.

MEASUREMENTS

Univariate and multivariate logistic regression models addressed the association between the predictors (age, prostate-specific antigen [PSA] before and after surgery for BPH, T1a-T1b stage, prostate volume, and Gleason score at surgery for BPH) and the presence of residual cancer at radical retropubic prostatectomy. Cox proportional hazards regression analyses tested the relationship between the same predictors and the rate of biochemical recurrence after radical retropubic prostatectomy.

RESULTS AND LIMITATIONS

Seventy-five (59.5%) patients were stage T1a and 51 (40.5%) were stage T1b. At radical retropubic prostatectomy, 21 (16.7%) patients were pT0 and seven (5.6%) patients had extraprostatic disease (pT3). PSA before and after surgery for BPH and Gleason score at surgery for BPH were the only independent predictors of residual cancer at radical retropubic prostatectomy (all p<0.04). Stage (T1a vs T1b) did not predict residual cancer or the rate of biochemical recurrence. With a mean follow-up of 57 mo, the 5- and 10-yr biochemical recurrence-free survival rates were 92% and 87%, respectively. PSA after surgery for BPH and Gleason score at surgery for BPH were the only significant multivariate predictors of biochemical recurrence (all p<0.04). The main limitation of this study is the requirement of an external validation before implementation of the clinical recommendations.

CONCLUSION

PSA measured before and after surgery for BPH and Gleason score at surgery for BPH were the only significant predictors of the presence of residual cancer at radical retropubic prostatectomy. PSA measured after surgery for BPH and Gleason score at surgery for BPH were the only independent predictors of biochemical recurrence after radical retropubic prostatectomy.

Validation of the contemporary epstein criteria for insignificant prostate cancer in European men

OBJECTIVES

The Epstein criteria represent the most widely used scheme for prediction of clinically insignificant prostate cancer (PCa). However, they were never validated in European men. We assessed the rate of unfavorable prostate cancer (Gleason 7-10 or non-organ-confined disease) in a cohort of 366 men who fulfilled the Epstein clinically insignificant PCa criteria.

METHODS

Between 1996 and 2006, 2580 men underwent radical prostatectomy at a single academic European institution. Of those, 366 fulfilled the contemporary Epstein clinically insignificant PCa criteria. Analyses targeted the rate of pathologically unfavorable prostate cancer, defined as either Gleason sum 7-10 or non-organ-confined disease, or a combination of these characteristics in patients with clinically insignificant PCa.

RESULTS

Gleason 7-10 prostate cancer at radical prostatectomy was found in 88 patients (24%) with clinically insignificant PCa. In addition, 30 (34.1%) of the 88 patients harboured non-organ-confined disease. Consequently, the contemporary Epstein criteria for clinically insignificant PCa were inaccurate in 24% of patients.

CONCLUSIONS

The Epstein clinical insignificant PCa criteria may underestimate the true nature of prostate cancer in as many as 24% of European patients. Therefore, caution is advised when treatment decisions are based solely on these criteria.

The impact of targeted training, a dedicated protocol and on-site training material in reducing observer variability of prostate and transition zone dimensions measured by transrectal ultrasonography, in multicentre multinational clinical trials of men with symptomatic benign prostatic enlargement

OBJECTIVE

To assess the variability of a standardized protocol of transrectal ultrasonography (TRUS), with targeted training, and compare it to the variability in other multicentre clinical trials, as TRUS-estimated total prostate volume (TPV) and transition zone volume (TZV) are considered important efficacy endpoints in assessing new drug therapies for benign prostatic enlargement (BPE), but standardizing TRUS remains a challenge in such studies.

PATIENTS AND METHODS

In all, 174 patients with BPE in the placebo arm of a 30-centre clinical trial were analysed at baseline, 13 and 26 weeks with TRUS, to extract TPV and TZV values. All TRUS operators received training in the standardized methods, which was supplemented at the outset by a compact disc-based video.

RESULTS

The mean (sd) changes from baseline in TPV at 13 and 26 weeks were - 2.9 (8.9) and -1.9 (8.5) mL, respectively; the respective mean changes from baseline in TZV were -1.2 (6.4) and + 0.7 (7.8) mL. For TPV, 80% of the measurements had differences of + 5.2 to -13.4 mL at 13 weeks, and + 8.0 to - 10.9 mL at 26 weeks. For TZV, 80% of the differences were + 5.8 to - 7.4 at 13 weeks, and + 9.3 to -6.5 mL at 26 weeks.

CONCLUSION

The performance of TRUS compared favourably with similar published multicentre studies, which we suggest relates in part to the careful implementation of the protocol. We showed that diligent implementation of a detailed protocol, supplemented by targeted training of investigators and provision of on-site training material, promoted consistent acquisition and successful derivation of key clinical trial endpoints. Quantifying the variability of such endpoints will enable us to track deployment quality for future clinical trials, and will ensure that trials are sufficiently powered to define small changes in prostate size.

Interpretation of pre- versus postimplant TRUS images

In order to summarize the inter-observer variability of pre- and postimplant TRUS image interpretation. Ten patients treated with Pd-103 brachytherapy were studied. Preimplant prostatevolumes ranged from 21 to 51 cm3. The number of sources implanted ranged from 74 to 155, and the number of sources per cm3 prostate volume ranged from 3.0 to 4.3. A set of transverse images (6 MHz) were taken immediately prior to and following source placement. Original printer images were sent to four investigators and the prostate outlined independently on a cellophane overlay. The overlays were digitized into a Varian MMS 7.0 treatment planning system (Charlottesville, VA) for volume determinations. There was moderate interobserver variability in TRUS volume determination, accentuated for the postimplant images. The standard deviations varied from 2% to 13% of the mean (median: 7%) for preimplant volumes, versus 7% to 32% (median: 13%) for postimplant volumes. Interobserver prostatic edge (border) localization variability was greatest at the base and apex, with closer agreement along the posterior border. For preimplant images, the majority of edge points were within 1.0 mm of the mean. At each coordinate, with the exception of the anterior base, the majority of points were within 2.0 mm of the mean. In general, border identification variability was greater in the post implant images. While all prostate imaging modalities suffer from interobserver variability, preimplant and postimplant TRUS appears capable of consistently determining prostatic volume and borders. It appears that intraoperative TRUS-based dosimetry is a practical goal, provided that seed location coordinates can be added to the prostatic edge information derived from TRUS images.

Likelihood of prostate cancer based on prostate-specific antigen density by MRI: retrospective analysis

OBJECTIVE

As a screening test for prostate cancer (PCA), prostate-specific antigen (PSA) may induce unnecessary prostate biopsy in patients with PSA 4.1-10.0 ng/ml. PCA detection may be delayed in patients with PSA < or =4.0 ng/ml. MRI-based PSA density of the prostate (PSAD) and of the prostatic transitional zone (PSAT) could improve differentiation of PCA and benign prostatic hyperplasia.

MATERIAL AND METHODS

Total prostate and transitional zone volumes were planimetrically determined in axial, T2-weighted fast spin echo MR images of the prostate. Serum PSA concentration was measured with an automated standardized microparticle enzyme immune assay. PSAD and PSAT were calculated in 17 patients with clinically significant PCA and 42 patients with benign prostatic hypertrophy (BPH) (66 +/- 6 versus 64 +/- 8 years, p = 0.2410, t test) who had PSA levels < or =10.0 ng/ml.

RESULTS

For differentiation of BPH and PCA, PSA alone above the optimal cutoff level of 4.2 ng/ml showed an odds ratio for PCA of 6.7 (95% confidence interval [CI], 1.9-23.2). PSAD showed an odds ratio for PCA of 71.3 (95% CI, 11.8-430.9) above the optimal cutoff level of 0.07 ng/ml/cc. PSAT demonstrated an odds ratio for PCA of 320.0 (95% CI, 27.1-3781.4) above the optimal cutoff level of 0.15 ng/ml/cc.

CONCLUSIONS

In patients with PSA < or =10.0 ng/ml, MRI-based PSAD and PSAT appear to improve differentiation of prostate cancer and BPH and are feasible to reduce the frequency of unnecessary prostate biopsy.

The role of serial transrectal ultrasonography in a ‘watchful waiting’ protocol for men with localized prostate cancer

OBJECTIVE

To determine the value of serial 6-monthly transrectal ultrasonography (TRUS) in a cohort of men with localized prostate cancer who consented to a programme of watchful waiting with selective delayed intervention.

PATIENTS AND METHODS

Since November 1995, 180 men were accrued into an ongoing prospective study of watchful waiting with selective delayed intervention; 174 patients enrolled before 31 December 1999 comprised the cohort for the present study. The prospectively collected clinical data, including the TRUS reports, were reviewed systematically. Twenty-eight men met the arbitrarily predefined criteria of disease progression and required definitive treatment. The TRUS findings were scored as being consistent with the clinical scenario (i.e. clinical, biochemical or histological progression) if they reported a new or enlarging hypoechoic peripheral zone lesion, or a > or = 30% increase in overall prostate volume at the time of progression. In 136 men who had undergone two or more serial TRUS examinations the relationships between the rate of change of prostate-specific antigen (PSA) and changes in both gland volume and the number of hypoechoic lesions were also examined.

RESULTS

The group of 28 men who progressed to require radical intervention underwent 83 TRUS examinations (median number per patient, three). Two men underwent TRUS only once at baseline because of progression within 6 months. Of these 28 men, only seven had changes on TRUS that were regarded as being consistent with progression; all seven consisted of the growth of an existing nodule or the appearance of a new nodule. In only one case was this accompanied by an increase of > or = 30% in gland volume. In the 136 men who underwent two or more serial TRUS examinations (median three, maximum nine), there was no correlation between the rate of change of PSA and changes in either gland volume or the number of peripheral zone hypoechoic lesions.

CONCLUSION

The use of serial TRUS in men with known but untreated prostate cancer is of limited value as a determinant of disease progression.

Evaluation of prostate volume by transrectal ultrasonography for use in a brachytherapy program

OBJECTIVES

To evaluate two methods of measuring the prostate volume using transrectal ultrasonography. The measurements were performed in vivo at preplanning and again preoperatively in connection with brachytherapy. The accurate measurement of the prostate volume is important in a brachytherapy program for treatment planning.

METHODS

A total of 43 patients with biopsy-proven prostate cancer underwent prospective determination of the prostate volume, by one physician, using transrectal ultrasonography. Volume calculations were made at the preplanning and preoperative settings, both by a hand-held rectal probe using the prolate ellipsoid formula and by a mounted probe in a stepping device using the planimetric method.

RESULTS

The coefficient of variation between the preplanning and preoperative prostate volumes with the probe holder was less than 3% compared with the hand-held probe, which was greater than 10%. The difference between the median values at the preplanning and preoperative settings by serial planimetry was 2.5 cm(3) (range 0.2 to 9.4). The difference in the median volumes between the preplanning and preoperative ellipsoid calculations was 6.7 cm(3) (range 0.3 to 38.7). The difference between the median values with the ellipsoid volume was significant (P <0.001). The Pearson correlation coefficient for all values using the planimetric method was 0.92 versus 0.58 for the ellipsoid method. The correlation coefficient was significantly greater for the planimetric method (P <0.001).

CONCLUSIONS

On the basis of these data, planimetric prostate volume determination, by a single ultrasonographer, is an accurate and reproducible method with applicability to a brachytherapy program.

Prospective evaluation of prostate cancer detection by prostate-specific antigen-related parameters

BACKGROUND

The diagnostic value of prostate-specific antigen (PSA) for differentiating prostate cancer from benign prostatic conditions is limited by its lack of specificity. Several PSA-related parameters have been suggested as enhancing the discriminatory power of total PSA values, but their clinical utility should be considered preliminary until established in a prospectively evaluated cohort.

METHODS

In a prospective cohort study, results of ultrasound-guided biopsy and/or transurethral resection of the prostate gland were assessed in 706 consecutive Japanese men. The clinical usefulness of total PSA, free PSA, percentage of free PSA, PSA density (PSAD), PSA density for transition zone (PSADT) and gland volume for predicting prostate cancer was investigated using receiver operating characteristic (ROC) curve analysis in 16 different patient subgroups.

RESULTS

Overall, 150 of the 706 patients (21.2%) had prostate carcinoma. The ROC curve analysis showed that PSAD and PSADT were more powerful predictors of prostate cancer than total PSA in most of the 16 patient subgroups tested. The improvement in performance was modest, however. No substantial difference was noted between PSAD and PSADT. Total gland volume did not significantly affect the performance of these parameters. The use of a PSAD threshold value of 0.11-10.15 ng/mL per cm3 (or a PSADT value of 0.23-0.27 ng/mL per cm3) would have avoided 24-48% (or, for PSADT, 34-40%) of unnecessary biopsies at the cost of missing 5-10% of detectable cancers in a patient subgroup with intermediate total PSA levels. The performance of free PSA and percentage of free PSA was worse than that of any other test in this study. This may be due to inappropriate handling of sera prior to measurement.

CONCLUSIONS

The discriminatory potential of total PSA for predicting prostate cancer was modestly improved by the use of PSAD and PSADT. No substantial advantage of PSADT over PSAD could be demonstrated. Stringent and standardized storage conditions should always be maintained when applying free PSA-related parameters.

Serum free prostate specific antigen and prostate specific antigen density measurements for predicting cancer in men with prior negative prostatic biopsies

PURPOSE

We examined the usefulness of measurements of free prostate specific antigen (PSA) and PSA density for predicting prostate cancer in men who had had a prior negative biopsy, a serum PSA level of 4.1 to 10.0 ng./ml. and benign findings on prostate examination.

MATERIALS AND METHODS

We measured percent free serum PSA and PSA density in 163 male volunteers age 50 years or older who were advised to have repeat prostatic biopsies for a serum PSA level of 4.1 to 10.0 ng./ml.

RESULTS

Of 99 men who had repeat biopsies 20 (20%) had prostate cancer detected. Prostate cancer was significantly associated with lower free PSA level and higher PSA density, with overlap in 83% of the cases. The use of percent free PSA cutoffs of 28 and 30% would have detected 90 and 95% of cancers, respectively, and avoided 13 and 12% of the biopsies, respectively. PSA density cutoffs of 0.10 and 0.08 would have detected 90 and 95% of cancers, respectively, and avoided 31 and 12% of biopsies, respectively.

CONCLUSIONS

Free PSA and PSA density predict prostate cancer in men who have had prior negative prostatic biopsies, serum PSA levels of 4.1 to 10.0 ng./ml. and a benign prostate examination. Both parameters may be used to avoid unnecessary biopsies with an acceptable decrease in sensitivity. Further studies are needed to determine cutoffs to be used in clinical practice.

Outcome of sextant biopsy according to gland volume

OBJECTIVES

To reassess positive rate of sextant biopsy according to gland size.

METHODS

We evaluated 1974 consecutive men with systematic sextant biopsy, among whom we examined biopsy yield according to gland-volume intervals of 10 cc.

RESULTS

Decreasing yield of sextant biopsy is strongly associated with increasing gland volume (P < 0.001). Highest biopsy rate (39.6%) was recorded among men with prostates smaller than 20 cc. The lowest biopsy rate (10.1%) was recorded among men with prostates between 80 and 89.9 cc. Among men with biopsy-proven cancer, age, serum prostate-specific antigen, and Gleason grade were comparable (P > 0.05) throughout the range of gland-volume intervals.

CONCLUSIONS

Our findings suggest that gland size represents an important determinant contributing to the yield of sextant biopsy in men at risk of harboring a nonpalpable, isoechoic cancer. Consequently, an individualized sector biopsy approach, based on prostate volume, may warrant consideration because it may ensure superior detection of clinically significant disease among all men at risk, regardless of prostate size.