Can 3D Multiparametric Ultrasound Imaging Predict Prostate Biopsy Outcome?

OBJECTIVES: To assess the value of 3D multiparametric ultrasound imaging, combining hemodynamic and tissue stiffness quantifications by machine learning, for the prediction of prostate biopsy outcomes. METHODS: After signing informed consent, 54 biopsy-naïve patients underwent a 3D dynamic contrast-enhanced ultrasound (DCE-US) recording, a multi-plane 2D shear-wave elastography (SWE) scan with manual sweeping from base to apex of the prostate, and received 12-core systematic biopsies (SBx). 3D maps of 18 hemodynamic parameters were extracted from the 3D DCE-US quantification and a 3D SWE elasticity map was reconstructed based on the multi-plane 2D SWE acquisitions. Subsequently, all the 3D maps were segmented and subdivided into 12 regions corresponding to the SBx locations. Per region, the set of 19 computed parameters was further extended by derivation of eight radiomic features per parameter. Based on this feature set, a multiparametric ultrasound approach was implemented using five different classifiers together with a sequential floating forward selection method and hyperparameter tuning. The classification accuracy with respect to the biopsy reference was assessed by a group-k-fold cross-validation procedure, and the performance was evaluated by the Area Under the Receiver Operating Characteristics Curve (AUC). RESULTS: Of the 54 patients, 20 were found with clinically significant prostate cancer (csPCa) based on SBx. The 18 hemodynamic parameters showed mean AUC values varying from 0.63 to 0.75, and SWE elasticity showed an AUC of 0.66. The multiparametric approach using radiomic features derived from hemodynamic parameters only produced an AUC of 0.81, while the combination of hemodynamic and tissue-stiffness quantifications yielded a significantly improved AUC of 0.85 for csPCa detection (p-value < 0.05) using the Gradient Boosting classifier. CONCLUSIONS: Our results suggest 3D multiparametric ultrasound imaging combining hemodynamic and tissue-stiffness features to represent a promising diagnostic tool for biopsy outcome prediction, aiding in csPCa localization.

The Impact of Omitting Contralateral Systematic Biopsy on the Surgical Planning of Patients with a Unilateral Suspicious Lesion on Magnetic Resonance Imaging Undergoing Robot-assisted Radical Prostatectomy for Prostate Cancer.

Background and objective: A combined approach of magnetic resonance imaging (MRI)-targeted biopsy (TBx) and bilateral systematic biopsy (SBx) is advised in patients who have an increased risk of prostate cancer (PCa). The diagnostic gain of SBx in detecting PCa for treatment planning of patients undergoing robot-assisted radical prostatectomy (RARP) is unknown. This study aims to determine the impact of omitting contralateral SBx on the surgical planning of patients undergoing RARP in terms of nerve-sparing surgery (NSS) and extended pelvic lymph node dissection (ePLND). Methods: Case files from 80 men with biopsy-proven PCa were studied. All men had a unilateral suspicious lesion on MRI, and underwent TBx and bilateral SBx. Case files were presented to five urologists for the surgical planning of RARP. Each case file was presented randomly using two different sets of information: (1) results of TBx + bilateral SBx, and (2) results of TBx + ipsilateral SBx. The urologists assessed whether they would perform NSS and/or ePLND. Key findings and limitations: A change in the surgical plan concerning NSS on the contralateral side was observed in 9.0% (95% confidence interval [CI] 6.4-12.2) of cases. Additionally, the indication for ePLND changed in 5.3% (95% CI 3.3-7.9) of cases. Interobserver agreement based on Fleiss' kappa changed from 0.44 to 0.15 for the indication of NSS and from 0.84 to 0.83 for the indication of ePLND. Conclusions and clinical implications: In our series, the diagnostic information obtained from contralateral SBx has limited impact on the surgical planning of patients with a unilateral suspicious lesion on MRI scheduled to undergo RARP. Patient summary: In patients with one-sided prostate cancer on magnetic resonance imaging, omitting biopsies on the other side rarely changed the surgical plan with respect to nerve-sparing surgery and the indication to perform extended lymph node dissection.

The association between patient and disease characteristics, and the risk of disease progression in patients with prostate cancer on active surveillance.

PURPOSE: The objective of this study was to identify and assess patient and disease characteristics associated with an increased risk of disease progression in men with prostate cancer on active surveillance. METHODS: We studied patients with low-risk (ISUP GG1) or favorable intermediate-risk (ISUP GG2) PCa. All patients had at least one repeat biopsy. Disease progression was the primary outcome of this study, based on pathological upgrading. Univariate and multivariate Cox proportional hazard analyses were used to evaluate the association between covariates and disease progression. RESULTS: In total, 240 men were included, of whom 198 (82.5%) were diagnosed with low-risk PCa and 42 (17.5%) with favorable intermediate-risk PCa. Disease progression was observed in 42.9% (103/240) of men. Index lesion > 10 mm (HR = 2.85; 95% CI 1.74-4.68; p < 0.001), MRI (m)T-stage 2b/2c (HR = 2.52; 95% CI 1.16-5.50; p = 0.02), highest PI-RADS score of 5 (HR 3.05; 95% CI 1.48-6.28; p = 0.002) and a higher PSA level (HR 1.06; 95% CI 1.01-1.11; p = 0.014) at baseline were associated with disease progression on univariate analysis. Multivariate analysis showed no significant baseline predictors of disease progression. CONCLUSION: In AS patients with low-risk or favorable intermediate-risk PCa, diameter of index lesion, MRI (m)T-stage, height of the PI-RADS score and the PSA level at baseline are significant predictors of disease progression to first repeat biopsy.

Reliable Visualization of the Treatment Effect of Transperineal Focal Laser Ablation in Prostate Cancer Patients by Magnetic Resonance Imaging and Contrast-enhanced Ultrasound Imaging.

Background: Transperineal focal laser ablation (TPLA) treatment for prostate cancer (PCa) is an experimental focal ablative therapy modality with low morbidity. However, a dosimetry model for TPLA is lacking. Objective: To determine (1) the three-dimensional (3D) histologically defined ablation zone of single- and multifiber TPLA treatment for PCa correlated with magnetic resonance imaging (MRI) and contrast-enhanced ultrasound (CEUS) and (2) a reliable imaging modality of ablation zone volumetry. Design setting and participants: This was a prospective, multicenter, and interventional phase I/II pilot study with an ablate-and-resect design. TPLA was performed in 12 patients with localized prostate cancer divided over four treatment regimens to evaluate potential variation in outcomes. Intervention: TPLA was performed approximately 4 wk prior to robot-assisted radical prostatectomy (RARP) in a daycare setting using local anesthesia. Outcome measurements and statistical analysis: Four weeks after TPLA, ablation zone volumetry was determined on prostate MRI and CEUS by delineation and segmentation into 3D models and correlated with whole-mount RARP histology using the Pearson correlation index. Results and limitations: Twelve office-based TPLA procedures were performed successfully under continuous transrectal ultrasound guidance using local perineal anesthesia. No serious adverse events occurred. A qualitative analysis showed a clear demarcation of the ablation zone on T2-weighted MRI, dynamic contrast-enhanced MRI, and CEUS. On pathological evaluation, no remnant cancer was observed within the ablation zone. Ablation zone volumetry on CEUS and T2-weighted MRI compared with histology had a Pearson correlation index of r = 0.94 (95% confidence interval [CI] 0.74-0.99, p < 0.001) and r = 0.93 (95% CI 0.73-0.98, p < 0.001), respectively. Conclusions: CEUS and prostate MRI could reliably visualize TPLA ablative effects after minimally invasive PCa treatment with a high concordance with histopathological findings and showed no remnant cancer. Patient summary: The treatment effects of a novel minimally invasive ablation therapy device can reliably be visualized with radiological examinations. These results will improve planning and performance of future procedures.

Corrigendum to "Clinical Trial Protocol: Developing an Image Classification Algorithm for Prostate Cancer Diagnosis on Three-dimensional Multiparametric Transrectal Ultrasound" [Eur. Urol. Open Sci. 49 (2023) 32-43].

[This corrects the article DOI: 10.1016/j.euros.2022.12.018.].

Reliability of whole mount radical prostatectomy histopathology as the ground truth for artificial intelligence assisted prostate imaging.

The development of artificial intelligence-based imaging techniques for prostate cancer (PCa) detection and diagnosis requires a reliable ground truth, which is generally based on histopathology from radical prostatectomy specimens. This study proposes a comprehensive protocol for the annotation of prostatectomy pathology slides. To evaluate the reliability of the protocol, interobserver variability was assessed between five pathologists, who annotated ten radical prostatectomy specimens consisting of 74 whole mount pathology slides. Interobserver variability was assessed for both the localization and grading of PCa. The results indicate excellent overall agreement on the localization of PCa (Gleason pattern ≥ 3) and clinically significant PCa (Gleason pattern ≥ 4), with Dice similarity coefficients (DSC) of 0.91 and 0.88, respectively. On a per-slide level, agreement for primary and secondary Gleason pattern was almost perfect and substantial, with Fleiss Kappa of .819 (95% CI .659-.980) and .726 (95% CI .573-.878), respectively. Agreement on International Society of Urological Pathology Grade Group was evaluated for the index lesions and showed agreement in 70% of cases, with a mean DSC of 0.92 for all index lesions. These findings show that a standardized protocol for prostatectomy pathology annotation provides reliable data on PCa localization and grading, with relatively high levels of interobserver agreement. More complicated tissue characterization, such as the presence of cribriform growth and intraductal carcinoma, remains a source of interobserver variability and should be treated with care when used in ground truth datasets.

The Diagnostic Value of PSMA PET/CT in Men with Newly Diagnosed Unfavorable Intermediate-Risk Prostate Cancer.

Our objective was to determine the diagnostic value of prostate-specific membrane antigen (PSMA) PET/CT in staging men with newly diagnosed unfavorable intermediate-risk prostate cancer (PCa). Methods: Patients with newly diagnosed unfavorable intermediate-risk PCa, in whom PSMA PET/CT was performed as a primary staging modality, were retrospectively studied. PSMA PET/CT was performed at several diagnostic centers and reported by expert nuclear medicine physicians within 2 high-volume PCa centers. A multivariate logistic regression analysis, taking into account clinical, biochemical, pathologic, and radiologic variables, was performed to identify potential independent predictors for metastatic disease on PSMA PET/CT. Results: In total, 396 men with newly diagnosed unfavorable intermediate-risk PCa were studied. Metastatic disease was observed in 37 (9.3%) men, of whom 29 (7.3%) had molecular imaging locoregional lymph node metastases (miN1) and 16 (4.0%) had distant metastases (miM1). A radiologic tumor stage of at least T3 on MRI (odds ratio, 2.72 [95% CI, 1.27-5.83]; P = 0.01) and more than 50% positive prostate biopsies (odds ratio, 3.87 [95% CI, 1.74-8.62]; P = 0.001) were found to be independently associated with metastatic disease on PSMA PET/CT. Conclusion: Given that metastatic disease was observed in nearly 1 in 10 men with newly diagnosed unfavorable intermediate-risk PCa, PSMA PET/CT is considered to be of diagnostic value within this population. Further stratification using the radiologic tumor stage and the percentage of positive prostate biopsies could aid in identifying those patients at risk of having metastatic disease on PSMA PET/CT.

Clinical Trial Protocol: Developing an Image Classification Algorithm for Prostate Cancer Diagnosis on Three-dimensional Multiparametric Transrectal Ultrasound.

Introduction and hypothesis: The tendency toward population-based screening programs for prostate cancer (PCa) is expected to increase demand for prebiopsy imaging. This study hypothesizes that a machine learning image classification algorithm for three-dimensional multiparametric transrectal prostate ultrasound (3D mpUS) can detect PCa accurately. Design: This is a phase 2 prospective multicenter diagnostic accuracy study. A total of 715 patients will be included in a period of approximately 2 yr. Patients are eligible in case of suspected PCa for which prostate biopsy is indicated or in case of biopsy-proven PCa for which radical prostatectomy (RP) will be performed. Exclusion criteria are prior treatment for PCa or contraindications for ultrasound contrast agents (UCAs). Protocol overview: Study participants will undergo 3D mpUS, consisting of 3D grayscale, 4D contrast-enhanced ultrasound, and 3D shear wave elastography (SWE). Whole-mount RP histopathology will provide the ground truth to train the image classification algorithm. Patients included prior to prostate biopsy will be used for subsequent preliminary validation. There is a small, anticipated risk for participants associated with the administration of a UCA. Informed consent has to be given prior to study participation, and (serious) adverse events will be reported. Statistical analysis: The primary outcome will be the diagnostic performance of the algorithm for detecting clinically significant PCa (csPCa) on a per-voxel and a per-microregion level. Diagnostic performance will be reported as the area under the receiver operating characteristic curve. Clinically significant PCa is defined as the International Society of Urological grade group ≥2. Full-mount RP histopathology will be used as the reference standard. Secondary outcomes will be sensitivity, specificity, negative predictive value, and positive predictive value for csPCa on a per-patient level, evaluated in patients included prior to prostate biopsy, using biopsy results as the reference standard. A further analysis will be performed on the ability of the algorithm to differentiate between low-, intermediate-, and high-risk tumors. Discussion and summary: This study aims to develop an ultrasound-based imaging modality for PCa detection. Subsequent head-to-head validation trials with magnetic resonance imaging have to be performed in order to determine its role in clinical practice for risk stratification in patients suspected for PCa.

An Magnetic Resonance Imaging-directed Targeted-plus-perilesional Biopsy Approach for Prostate Cancer Diagnosis: "Less Is More".

Background: Considering that most men benefit diagnostically from increased sampling of index lesions, limiting systematic biopsy (SBx) to the region around the index lesion could potentially minimize overdetection while maintaining the detection of clinically significant prostate cancer (csPCa). Objective: To evaluate the diagnostic performance of a hypothetical magnetic resonance imaging (MRI)-directed targeted-plus-perilesional biopsy approach. Design setting and participants: This single-center, retrospective analysis of prospectively generated data included all biopsy-naïve men with unilateral MRI-positive lesions (Prostate Imaging Reporting and Data System category ≥3), undergoing both MRI-directed targeted biopsies and SBx. Grade group 2-5 cancers were considered csPCa. Outcome measurements and statistical analysis: The diagnostic performance of a targeted-plus-perilesional biopsy approach was compared with that of a targeted-plus-systematic biopsy approach. The primary outcome was the detection of csPCa. Secondary outcomes included the detection of clinically insignificant prostate cancer (ciPCa) and the number of total biopsy cores. Results and limitations: A total of 235 men were included in the analysis; csPCa and ciPCa were detected, respectively, in 95 (40.4%) and 86 (36.6%) of these 235 men. A targeted-plus-perilesional biopsy approach would have detected 92/95 (96.8%; 95% confidence interval [CI] 91.0-99.3%) csPCa cases. At the same time, detection of systematically found ciPCa would be reduced by 11/86 (12.8%; 95% CI 6.6-21.7%). If a targeted-plus-perilesional biopsy approach would have been performed, the number of biopsy cores per patient would have been reduced significantly (a mean difference of 5.2; 95% CI 4.9-5.6, p < 0.001). Conclusions: An MRI-directed targeted-plus-perilesional biopsy approach detected almost all csPCa cases, while limiting overdiagnosis and reducing the number of biopsy cores. Prospective clinical trials are needed to substantiate the withholding of nonperilesional SBx in men with unilateral lesion(s) on MRI. Patient summary: Limiting systematic biopsies to the proximity of the suspicious area on magnetic resonance imaging helps detect an equivalent number of aggressive cancers and fewer indolent cancers. These findings may help patients and physicians choose the best biopsy approach.

An optimized prostate biopsy strategy in patients with a unilateral lesion on prostate magnetic resonance imaging avoids unnecessary biopsies.

Purpose: The introduction of magnetic resonance imaging (MRI)-targeted biopsy (TBx) besides systematic prostate biopsies has resulted in a discussion on what the optimal prostate biopsy strategy is. The ideal template has high sensitivity for clinically significant prostate cancer (csPCa), while reducing the detection rate of clinically insignificant prostate cancer (iPCa). This study evaluates different biopsy strategies in patients with a unilateral prostate MRI lesion. Methods: Retrospective subgroup analysis of a prospectively managed database consisting of patients undergoing prostate biopsy in two academic centres. Patients with a unilateral lesion (PI-RADS ⩾ 3) on MRI were included for analysis. The primary objective was to evaluate the diagnostic performance for different biopsy approaches compared with bilateral systematic prostate biopsy (SBx) and TBx. Detection rates for csPCa (ISUP ⩾ 2), adjusted csPCa (ISUP ⩾ 3) and iPCa (ISUP = 1) were determined for SBx alone, TBx alone, contralateral SBx combined with TBx and ipsilateral SBx combined with TBx. A subgroup analysis was performed for biopsy-naive patients. Results: A total of 228 patients were included from October 2015 to September 2021. Prostate cancer (PCa) detection rate of combined SBx and TBx was 63.5% for csPCa, 35.5% for adjusted csPCa, and 14% for iPCa. The best performing alternative biopsy strategy was TBx and ipsilateral SBx, which reached a sensitivity of 98.6% (95% CI: 95.1-99.6) for csPCa and 98.8% (95% CI: 96.3-99.9) for adjusted csPCa, missing only 1.4% of csPCa, while reducing iPCa detection by 15.6% compared with SBx and TBx. TBx or SBx alone missed a significant amount of csPCa, with sensitivities of 90.3% (95% CI: 84.4-94.2) and 86.8% (95% CI: 80.4-91.4) for csPCa. Subgroup analysis on biopsy-naive patients showed similar results as the overall group. Conclusion: This study shows that performing TBx with ipsilateral SBx and omitting contralateral SBx is the optimal biopsy strategy in patients with a unilateral MRI lesion. With this strategy, a very limited amount of csPCa is missed and iPCa detection is reduced.

Predictors of clinically significant prostate cancer in biopsy-naïve and prior negative biopsy men with a negative prostate MRI: improving MRI-based screening with a novel risk calculator.

Purpose: A pre-biopsy decision aid is needed to counsel men with a clinical suspicion for clinically significant prostate cancer (csPCa), despite normal prostate magnetic resonance imaging (MRI). Methods: A risk calculator (RC) for csPCa (International Society of Urological Pathology grade group (ISUP) ⩾ 2) presence in men with a negative-MRI (Prostate Imaging-Reporting and Data System (PI-RADS) ⩽ 2) was developed, and its performance was compared with RCs of the European Randomized Study of Screening for Prostate Cancer (ERSPC), Prostate Biopsy Collaborative Group (PBCG), and Prospective Loyola University mpMRI (PLUM). All biopsy-naïve and prior negative biopsy men with a negative-MRI followed by systematic prostate biopsy were included from October 2015 to September 2021. The RC was developed using multivariable logistic regression with the following parameters: age (years), family history of PCa (first- or second-degree family member), ancestry (African Caribbean/other), digital rectal exam (benign/malignant), MRI field strength (1.5/3.0 Tesla), prior negative biopsy status, and prostate-specific antigen (PSA) density (ng/ml/cc). Performance of RCs was compared using receiver operating characteristic (ROC) curve analysis. Results: A total of 232 men were included for analysis, of which 18.1% had csPCa. Parameters associated with csPCa were family history of PCa (p < 0.0001), African Caribbean ancestry (p = 0.005), PSA density (p = 0.002), prior negative biopsy (p = 0.06), and age at biopsy (p = 0.157). The area under the curve (AUC) of the developed RC was 0.76 (95% CI 0.68-0.85). This was significantly better than the RCs of the ERSPC (AUC: 0.59; p = 0.001) and PBCG (AUC: 0.60; p = 0.002), yet similar to PLUM (AUC: 0.69; p = 0.09). Conclusion: The developed RC (Prostate Biopsy Cohort Amsterdam ('PROBA' RC), integrated predictors for csPCa at prostate biopsy in negative-MRI men and outperformed other widely used RCs. These findings require external validation before introduction in daily practice.

The challenge of prostate biopsy guidance in the era of mpMRI detected lesion: ultrasound-guided versus in-bore biopsy.

The current recommendation in patients with a clinical suspicion for prostate cancer is to perform systematic biopsies extended with targeted biopsies, depending on mpMRI results. Following a positive mpMRI [i.e. Prostate Imaging Reporting and Data System (PI-RADS) ≥3], three targeted biopsy approaches can be performed: visual registration of the MRI images with real-time ultrasound imaging; software-assisted fusion of the MRI images and real-time ultrasound images, and in-bore biopsy within the MR scanner. This collaborative review discusses the advantages and disadvantages of each targeting approach and elaborates on future developments. Cancer detection rates seem to mostly depend on practitioner experience and selection criteria (biopsy naïve, previous negative biopsy, prostate-specific antigen (PSA) selection criteria, presence of a lesion on MRI), and to a lesser extent dependent on biopsy technique. There is no clear consensus on the optimal targeting approach. The choice of technique depends on local experience and availability of equipment, individual patient characteristics, and onsite cost-benefit analysis. Innovations in imaging techniques and software-based algorithms may lead to further improvements in this field.