Similarities and differences between Likert and PIRADS v2.1 scores of prostate multiparametric MRI: a pictorial review of histology-validated cases

Active Surveillance for Prostate Cancer: Expanding the Role of MR Imaging and the Use of PRECISE Criteria

Multiparametric magnetic resonance (MR) imaging has had an expanding role in active surveillance (AS) for prostate cancer. It can improve the accuracy of prostate biopsies, assist in patient selection, and help monitor cancer progression. The PRECISE recommendations standardize reporting of serial MR imaging scans during AS. We summarize the evidence on MR imaging-led AS and provide a clinical primer to help report using the PRECISE criteria. Some limitations to both serial imaging and the PRECISE recommendations must be considered as we move toward a more individualized risk-stratified approach to AS.

Dynamic Contrast-Enhanced Study in the mpMRI of the Prostate-Unnecessary or Underutilised? A Narrative Review

The aim of this review is to summarise recent scientific literature regarding the clinical use of DCE-MRI as a component of multiparametric resonance imaging of the prostate. This review presents the principles of DCE-MRI acquisition and analysis, the current role of DCE-MRI in clinical practice with special regard to its role in presently available categorisation systems, and an overview of the advantages and disadvantages of DCE-MRI described in the current literature. DCE-MRI is an important functional sequence that requires intravenous administration of a gadolinium-based contrast agent and gives information regarding the vascularity and capillary permeability of the lesion. Although numerous studies have confirmed that DCE-MRI has great potential in the diagnosis and monitoring of prostate cancer, its role is still inadequate in the PI-RADS categorisation. Moreover, there have been numerous scientific discussions about abandoning the intravenous application of gadolinium-based contrast as a routine part of MRI examination of the prostate. In this review, we summarised the recent literature on the advantages and disadvantages of DCE-MRI, focusing on an overview of currently available data on bpMRI and mpMRI, as well as on studies providing information on the potential better usability of DCE-MRI in improving the sensitivity and specificity of mpMRI examinations of the prostate.

The Predictive Value of Prostate-Specific Antigen Density: A Retrospective Analysis of Likert 3 Multiparametric MRI of the Prostate

Background Many international studies have covered the predictors of prostate cancer, but there is limited information pertaining to Likert 3 MRI scores and the diagnosis of clinically significant prostate cancer (cs-PCa). Therefore, this study aimed to assess the detection rate of significant prostate cancer in men with a Likert 3 score multiparametric MRI (mp-MRI) and the predictive value of prostate-specific antigen (PSA) density in detecting significant prostate cancer. Methods This is a retrospective analysis of patients referred for suspected confined prostate cancer. Inclusion criteria were patients with prostate mp-MRI score of Likert 3 and a prostate biopsy performed. Exclusion criteria included grossly abnormal feeling prostate, no biopsy performed, and an mp-MRI score (Prostate Imaging-Reporting and Data System/Likert) of 1, 2, 4, and 5. cs-PCa was defined as ≥ Gleason 3+4 prostate cancer. PSA density (PSAD) was calculated from MRI estimation of prostate volume. PSAD and histology results were subjected to receiver operating characteristic (ROC) curve analysis with the intention to assess the detection rate of significant prostate cancer in men with Likert 3 mp-MRI and the predictive value of PSAD in detecting significant prostate cancer. Results A total of 819 eligible men had a pre-biopsy mp-MRI scan taken between October 2019 and March 2022. A total of 177 men (21.6%, n = 819) were Likert 3 positive, and 31 did not proceed to take prostate biopsies. A total of 146 patients were included in the study. The median PSAD was 0.19 in men with cs-PCa. Prostate cancer was detected in 42 men (28.8% of the total included set), of which 27 (18.5%) had a Gleason 3+3 prostate cancer and 15 (10.3%) had Gleason ≥ 3+4 prostate cancer. Therefore, 35.7% (n = 42) of biopsy-positive men with Likert 3 mp-MRI had cs-PCa. The ROC curve analysis confirms that PSAD is a predictor of cs-PCa. The optimal PSAD threshold was 0.16 (95% CI: 0.14-0.19), which gives an accuracy of 0.7371, a sensitivity of 0.7333, and a specificity of 0.7375. Conclusion The specificity of PSAD is arguably insufficient for it to stand alone as a decision-making tool when counseling men with equivocal mp-MRI on whether or not to undergo prostate biopsy. A predictive model will need to incorporate other independent risk factors. These may include lesion size, multiplicity, location of lesion(s), and age.

Magnetic Resonance Imaging Follow-up of Targeted Biopsy-negative Prostate Lesions

BACKGROUND

The optimal radiological follow-up of prostate lesions negative on magnetic resonance imaging (MRI)-targeted biopsy (MRI-TB) is yet to be optimised.

OBJECTIVE

To present medium-term radiological and clinical follow-up of biopsy-negative lesions.

DESIGN, SETTING, AND PARTICIPANTS

The records for men who underwent multiparametric MRI at the UCLH one-stop clinic for suspected prostate cancer between September 2017 and March 2020 were reviewed (n = 1199). Patients with Likert 4 or 5 lesions were considered (n = 495), and those with a subsequent negative MRI-TB comprised the final study population (n = 91).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Baseline and follow-up MRI and biopsy data (including prostate-specific antigen [PSA], prostate volume, radiological scores, and presence of any noncancerous pathology) were extracted from reports. The last follow-up date was the date of the last test or review in clinic.

RESULTS AND LIMITATIONS

Median follow-up was 1.8 yr (656 d, interquartile range [IQR] 359-1008). At baseline, the median age was 65.4 yr (IQR 60.7-70.0), median PSA was 7.1 ng/ml (IQR 4.7-10.0), median prostate volume was 54 ml (IQR 39.5-75.0), and median PSA density (PSAD) was 0.13 ng/ml2 (IQR 0.09-0.18). Eighty-six men (95%) had Likert 4 lesions, while the remaining five (5%) had Likert 5 lesions. Only 21 men (23%) had a single lesion; most had at least two. Atrophy was the most prevalent pathology on MRI-TB, present in 64 men (74%), and followed by acute inflammation in 42 (46%), prostatic intraepithelial neoplasia in 33 (36%), chronic inflammation in 18 (20%), atypia in 13 (14%), and granulomatous inflammation in three (3%). Fifty-eight men had a second MRI study (median 376 d, IQR 361-412). At the second MRI, median PSAD decreased to 0.11 ng/ml2 (IQR 0.08-0.18). A Likert 4 or 5 score persisted only in five men (9%); 40 men (69%) were scored Likert 3, while the remaining 13 (22%) were scored Likert 2 (no lesion). Of 45 men with a Likert ≥3 score, most only had one lesion at the second MRI (28 men; 62%). Of six men with repeat MRI-TB during the study period, two were subsequently diagnosed with prostate cancer and both had persistent Likert 4 scores (at baseline and at least one follow-up MRI).

CONCLUSIONS

Most biopsy-negative MRI lesions in the prostate resolve over time, but any persistent lesions should be closely monitored.

PATIENT SUMMARY

Lesions in the prostate detected via magnetic resonance imaging (MRI) scans that are negative for cancer on biopsy usually resolve. Repeat MRI can indicate persistent lesions that might need a second biopsy.

Does including histological outcomes in a multiparametric MRI report improve prostate biopsy decision making?

OBJECTIVES

To see if inserting audited histological outcome data for each Likert score into prostate mpMRI reports was helpful for clinicians counselling patients and influenced prostate biopsy uptake.

METHODS

A single radiologist reported 791 mpMRI scans for query prostate cancer between 2017 and 2019. A structured template which included histological outcome data from this cohort was devised and included in 207 mpMRI reports between January and June 2021. The outcomes of the new cohort were compared with the historical cohort, and with 160 contemporaneous reports without histological outcome data from the four other radiologists in the department. The opinion of this template was sought from referring clinicians who counselled patients.

RESULTS

The proportion of patients biopsied fell from 58.0 to 32.9% overall between the n = 791 cohort and the n = 207 cohort. This was most noticeable in those scoring Likert 3, where the proportion biopsied fell from 78.4 to 42.9%. This reduction was also seen when comparing the biopsy rates of patients scored Likert 3 by other reporters in a contemporaneous n = 160 cohort without the audit information (65.2%) with the n = 207 cohort (42.9%). 100% of counselling clinicians were in favour and 66.7% said it gave them greater confidence to advise the patient when they did not need a biopsy.

CONCLUSION

Fewer low-risk patients choose unnecessary biopsies when audited histological outcomes for the radiologist's Likert scores are included in mpMRI reports.

ADVANCES IN KNOWLEDGE

Clinicians welcome reporter-specific audit information in mpMRI reports which could result in fewer biopsies.

Making an art into a science: a mathematical "Likert tool" can change PI-RADS (v2) scores into Likert scores when reporting multiparametric MRI for prostate cancer

BACKGROUND

When reporting multiparametric magnetic resonance imaging (mpMRI) for prostate cancer, UK national guidelines recommend allocating both Likert and PI-RAD scores. Likert scores have been shown to better predict clinically significant cancer (csPCa) but are subjective and lack standardization.

PURPOSE

To compare differences in outcomes between the scoring systems and create a mathematical tool that can help to objectively allocate Likert scores.

MATERIAL AND METHODS

A total of 791 patients referred with query prostate cancer between 2017 and 2019 were prospectively allocated PI-RADS and Likert scores by a single experienced reporter. Histology results were used to compare the predictive accuracy of both scoring systems. A "Likert tool" was created based on a logistic regression of features found to be predictors of csPCa in a cohort of 2018-2019 patients (n = 411). Its performance was evaluated.

RESULTS

Assuming a policy whereby patients with a PI-RADS/Likert score of ≥3 are biopsied, Likert scoring (sensitivity 0.92, specificity 0.77) would have resulted in 107 fewer biopsies and 20.3% higher cancer yields than the PI-RADS score (sensitivity 0.99, specificity 0.43). Thirteen patients would have avoided over-diagnosis of clinically insignificant prostate cancer (iPCa). Similar outcomes (111 fewer biopsies, 22.3% increase in cancer yield, iPCa diagnosis avoided in 16 patients) could be seen when the "Likert tool" was applied to the same patient cohort (sensitivity 0.93, specificity 0.79) and to a separate cohort (n = 380).

CONCLUSION

PI-RADS and Likert scores are different. A "Likert tool" could reduce inter-reporter variability, decrease the number of patients unnecessarily biopsied, increase csPCa yield, and decrease over-diagnosis of iPCa.

Natural History of Patients with Prostate MRI Likert 1-3 and Development of RosCaP: a Multivariate Risk Score for Clinically Significant Cancer

INTRODUCTION

Clinically significant prostate cancer (csCaP) with Gleason ≥3 + 4 is found in 10% negative prebiopsy multiparametric (mp) MRI cases and varies widely for equivocal mpMRI cases. The objective of this study was to investigate long-term outcomes of patients with negative and equivocal mpMRIs and to develop a predictive score for csCaP risk stratification in this group.

PATIENTS AND METHODS

Patients who underwent an upfront mpMRI between May 2015 and March 2018 with an MRI score Likert 1 to 3 were included in the study. Patients had either a CaP diagnosis at MRI-targeted biopsy or were not diagnosed and attended follow-up in the community. Outcomes were analysed through the Kaplan-Meier estimator and Cox Model. Regression coefficients of significant variables were used to develop a Risk of significant Cancer of the Prostate score (RosCaP).

RESULTS

At first assessment 281/469 patients had mpMRI only and 188/469 mpMRI and biopsy, 26 csCaP were found at biopsy, including 10/26 in Likert 3 patients. 12/371 patients discharged without CaP after first assessment were diagnosed with csCaP during a median of 34.2 months' follow-up, 11/12 diagnosis occurred in patients omitting initial biopsy. csCaP diagnosis-free survival was 95.7% in the MRI group and 99.1% in the biopsy group. From these outcomes, a continuous RosCaP score was developed: RosCaP = 0.083 x Age - 0.202 x (1/PSA Density) + 0.786 (if Likert 3), and 4 risk classes were proposed. Limitations include retrospective design and absence of external validation.

CONCLUSION

Age, PSA Density and MRI Likert score were significantly associated to the risk of csCaP and utilised to devise the novel RosCap predictive score focused to support risk assessment in patients with negative or equivocal mpMRI results.

Landmarks in the evolution of prostate biopsy

Approaches and techniques used for diagnostic prostate biopsy have undergone considerable evolution over the past few decades: from the original finger-guided techniques to the latest MRI-directed strategies, from aspiration cytology to tissue core sampling, and from transrectal to transperineal approaches. In particular, increased adoption of transperineal biopsy approaches have led to reduced infectious complications and improved antibiotic stewardship. Furthermore, as image fusion has become integral, these novel techniques could be incorporated into prostate biopsy methods in the future, enabling 3D-ultrasonography fusion reconstruction, molecular targeting based on PET imaging and autonomous robotic-assisted biopsy.

Quality checkpoints in the MRI-directed prostate cancer diagnostic pathway

Multiparametric MRI of the prostate is now recommended as the initial diagnostic test for men presenting with suspected prostate cancer, with a negative MRI enabling safe avoidance of biopsy and a positive result enabling MRI-directed sampling of lesions. The diagnostic pathway consists of several steps, from initial patient presentation and preparation to performing and interpreting MRI, communicating the imaging findings, outlining the prostate and intra-prostatic target lesions, performing the biopsy and assessing the cores. Each component of this pathway requires experienced clinicians, optimized equipment, good inter-disciplinary communication between specialists, and standardized workflows in order to achieve the expected outcomes. Assessment of quality and mitigation measures are essential for the success of the MRI-directed prostate cancer diagnostic pathway. Quality assurance processes including Prostate Imaging-Reporting and Data System, template biopsy, and pathology guidelines help to minimize variation and ensure optimization of the diagnostic pathway. Quality control systems including the Prostate Imaging Quality scoring system, patient-level outcomes (such as Prostate Imaging-Reporting and Data System MRI score assignment and cancer detection rates), multidisciplinary meeting review and audits might also be used to provide consistency of outcomes and ensure that all the benefits of the MRI-directed pathway are achieved.

Diagnostic Performance of a Magnetic Resonance Imaging-directed Targeted plus Regional Biopsy Approach in Prostate Cancer Diagnosis: A Systematic Review and Meta-analysis

Context

Systematic biopsies are additionally recommended to maximize the diagnostic performance of the magnetic resonance imaging (MRI) diagnostic pathway for men with suspected prostate cancer (PCa) and positive scans. To reduce unnecessary systematic biopsies (SBx), MRI-directed approaches comprising targeted plus regional biopsy (TBx + RBx) are being investigated.

Objective

To systematically evaluate the diagnostic performance of MRI-directed TBx + RBx approaches in comparison to MRI-directed TBx alone and TBx + SBx approaches.

Evidence acquisition

The MEDLINE and Embase databases were searched according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses process. Identified reports were critically appraised according to the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) criteria. Detection of grade group (GG) ≥2 PCa was the endpoint of interest. Fixed-effect meta-analyses were conducted to characterize summary effect sizes and quantify heterogeneity. Only MRI-positive men were included.

Evidence synthesis

A total of eight studies were included for analysis. Among a cumulative total of 2603 men with suspected PCa, the GG ≥2 PCa detection rate did not significantly differ between MRI-directed TBx + RBx and TBx + SBx approaches (risk ratio [RR] 0.95, 95% confidence interval [CI] 0.90-1.01; p = 0.09). The TBx + RBx results were obtained using significantly fewer biopsy cores and avoiding contralateral SBx altogether. By contrast, there was significant difference in GG ≥2 PCa detection between MRI-directed TBx + RBx and TBx approaches (RR 1.18, 95% CI 1.10-1.25; p < 0.001).

Conclusions

MRI-directed TBx + RBx approaches showed a nonsignificant difference in detection of GG ≥2 PCa compared to the recommended practice of MRI-directed TBx + SBx. However, owing to the extensive heterogeneity among the studies included, future prospective clinical studies are needed to further investigate, optimize, and standardize this promising biopsy approach.

Patient summary

We reviewed the scientific literature on prostate biopsy approaches using magnetic resonance imaging (MRI)-directed targeted biopsy plus regional biopsy of the prostate. The studies we identified found arguments to potentially embrace such a combined biopsy approach for future diagnostics in prostate cancer.

Current Opinion on the Use of Magnetic Resonance Imaging in Staging Prostate Cancer: A Narrative Review

Accurate staging is critical for treatment planning and prognosis in men with prostate Cancer. Prostate magnetic imaging resonance (MRI) may aid in the staging evaluation by verifying organ-confined status, assessing the status of the pelvic lymph nodes, and establishing the local extent of the tumor in patients being considered for therapy. MRI has a high specificity for diagnosing extracapsular extension, and therefore may impact the decision to perform nerve sparing prostatectomy, along with seminal vesicle invasion and lymph node metastases; however, its sensitivity remains limited. Current guidelines vary significantly regarding endorsing the use of MRI for staging locoregional disease. For high-risk prostate cancer, most guidelines recommend cross sectional imaging, including MRI, to evaluate for more extensive disease that may merit change in radiation field, extended androgen deprivation therapy, or guiding surgical planning. Although MRI offers reasonable performance characteristics to evaluate bone metastases, guidelines continue to support the use of bone scintigraphy. Emerging imaging technologies, including coupling positron emission tomography (PET) with MRI, have the potential to improve the accuracy of prostate cancer staging with the use of novel radiotracers.

Diagnostic Accuracy of Abbreviated Bi-Parametric MRI (a-bpMRI) for Prostate Cancer Detection and Screening: A Multi-Reader Study

(1) Background: There is currently limited evidence on the diagnostic accuracy of abbreviated biparametric MRI (a-bpMRI) protocols for prostate cancer (PCa) detection and screening. In the present study, we aim to investigate the performance of a-bpMRI among multiple readers and its potential application to an imaging-based screening setting. (2) Methods: A total of 151 men who underwent 3T multiparametric MRI (mpMRI) of the prostate and transperineal template prostate mapping biopsies were retrospectively selected. Corresponding bpMRI (multiplanar T2WI, DWI, ADC maps) and a-bpMRI (axial T2WI and b 2000 s/mm² DWI only) dataset were derived from mpMRI. Three experienced radiologists scored a-bpMRI, standard biparametric MRI (bpMRI) and mpMRI in separate sessions. Diagnostic accuracy and interreader agreement of a-bpMRI was tested for different positivity thresholds and compared to bpMRI and mpMRI. Predictive values of a-bpMRI were computed for lower levels of PCa prevalence to simulate a screening setting. The primary definition of clinically significant PCa (csPCa) was Gleason ≥ 4 + 3, or cancer core length ≥ 6 mm. (3) Results: The median age was 62 years, the median PSA was 6.8 ng/mL, and the csPCa prevalence was 40%. Using a cut off of MRI score ≥ 3, the sensitivity and specificity of a-bpMRI were 92% and 48%, respectively. There was no significant difference in sensitivity compared to bpMRI and mpMRI. Interreader agreement of a-bpMRI was moderate (AC1 0.58). For a low prevalence of csPCa (e.g., <10%), higher cut offs (MRI score ≥ 4) yield a more favourable balance between the predictive values and positivity rate of MRI. (4) Conclusion: Abbreviated bpMRI protocols could match the diagnostic accuracy of bpMRI and mpMRI for the detection of csPCa. If a-bpMRI is used in low-prevalence settings, higher cut-offs for MRI positivity should be prioritised.

A single centre service evaluation of the pre-biopsy mpMRI pathway for prostate cancer diagnosis

Aim:

To study the efficacy and impact of the local pre-biopsy multiparametric magnetic resonance imaging (mpMRI) pathway for prostate cancer diagnosis.

Methods:

In this tertiary centre, 570 patients had prostate mpMRI across a 6-month period in 2019. A total of 511 patients met inclusion criteria for retrospective analysis. MRI reporting used the Prostate Imaging-Reporting and Data System (PI-RADS) v2.1. These were assessed alongside histological outcomes and diagnostic times. PI-RADS ⩾ 3 were recommended for biopsy consideration. Gleason scoring ⩾ 3 + 4 and 3 + 3 were used to define clinically and non-clinically significant prostate cancer (csPCa and nsPCa), respectively.

Results:

Overall prostate cancer prevalence was 40% (204/511, csPCa in 31.1%) with an overall biopsy avoidance of 32.1% (164/511). Around 69.7% (356/511) scored PI-RADS ⩾ 3 and 30.3% (155/511) scored PI-RADS 1–2. About 22.6% (35/155) of PI-RADS 1–2 patients proceeded to biopsy, demonstrating a negative predictive value of 91.43% for csPCa. For PI-RADS ⩾ 3 patients, 63.4% (197/312) of those biopsied had cancer (Gleason ⩾ 3 + 3), with 50% (156/312) demonstrating csPCa. Around 76.7% (102/133) of PI-RADS 5, 35.3% (48/136) of PI-RADS 4, 14.0% (6/43) of PI-RADS 3 and 8.6% (3/35) of PI-RADS 1–2 scores demonstrated csPCa. Overall median prostate-specific antigen (PSA) density was 0.15 ng/mL2 (IQR: 0.10–0.27/mL2). PSA density were significantly different across PI-RADS cohorts ( H = 118.8, p < 0.0001) and across all three biopsy outcomes ( H = 99.72, p < 0.0001). Only 34.3% (119/347) of biopsied patients met the NHS 28-day standard. MRI acquisition and reporting met the 14-day local standard in 96.1% (491/511). The biopsy was the most delayed component with a median of 20 days (IQR: 8–43).

Conclusion:

Pre-biopsy mpMRI with PI-RADS scoring safely avoided biopsy in almost one-third (32.1%) of patients. The use of PSA-density in risk stratifying PI-RADS 3 lesions has informed local practice in the period 2020–2021, with implementation of a PSA-density threshold of 0.12 ng/mL2. Biopsy scheduling issues and anaesthetic requirements need to be overcome to improve diagnostic waiting times.

Level of evidence:

2

Comparison of different thresholds of PSA density for risk stratification of PI-RADSv2.1 categories on prostate MRI

OBJECTIVES

To compare the effect of different PSA density (PSAD) thresholds on the accuracy for clinically significant prostate cancer (csPCa) of the Prostate Imaging Reporting And Data System v.2.1 (PI-RADSv2.1).

METHODS

We retrospectively included 123 biopsy-naïve men who underwent multiparametric magnetic resonance imaging (mpMRI) and transperineal mpMRI-targeted and systematic prostate biopsy between April 2019 and October 2020. mpMRI, obtained on a 3.0T magnet with a PI-RADSv2.1-compliant protocol, was read by two radiologists (>1500/>500 mpMRI examinations). csPCa was defined as International Society of Urogenital Pathology grading group ≥2. Receiver operating characteristic analysis was used to calculate per-index lesion sensitivity, specificity, and area under the curve (AUC) of PI-RADSv.2.1 categories after adjusting for PSAD ≥0.10,≥0.15, and ≥0.20 ng/mL ml^-1. Per-adjusted category cancer detection rate (CDR) was calculated, and decision analysis performed to compare PSAD-adjusted PI-RADSv.2.1 categories as a biopsy trigger.

RESULTS

csPCa prevalence was 43.9%. PSAD-adjustment increased the CDR of PI-RADSv2.1 category 4. Sensitivity/specificity/AUC were 92.6%/53.6%/0.82 for unadjusted PI-RADS, and 85.2%/72.4%/0.84, 62.9%/85.5%/0.83, and 92.4%/53.6%/0.82 when adjusting PI-RADS categories for a 0.10, 0.15, and 0.20 ng/ml ml^-1 PSAD threshold, respectively. Triggering biopsy for PI-RADS four lesions and PSAD ≥0.10 ng/mL ml^-1 was the strategy with greatest net benefit at 30 and 40% risk probability (0.307 and 0.271, respectively).

CONCLUSIONS

PI-RADSv2.1 category four with PSAD ≥0.10 ng/mL ml^-1 was the biopsy-triggering cut-off with the highest net benefit in the range of expected prevalence for csPCa.

ADVANCES IN KNOWLEDGE

0.10 ng/mL ml^-1 is the PSAD threshold with higher clinical utility in stratifying the risk for prostate cancer of PI-RADSv.2.1 categories.

Evaluation of PSA and PSA Density in a Multiparametric Magnetic Resonance Imaging-Directed Diagnostic Pathway for Suspected Prostate Cancer: The INNOVATE Trial

Objectives: To assess the clinical outcomes of mpMRI before biopsy and evaluate the space remaining for novel biomarkers. Methods: The INNOVATE study was set up to evaluate the validity of novel fluidic biomarkers in men with suspected prostate cancer who undergo pre-biopsy mpMRI. We report the characteristics of this clinical cohort, the distribution of clinical serum biomarkers, PSA and PSA density (PSAD), and compare the mpMRI Likert scoring system to the Prostate Imaging-Reporting and Data System v2.1 (PI-RADS) in men undergoing biopsy. Results: 340 men underwent mpMRI to evaluate suspected prostate cancer. 193/340 (57%) men had subsequent MRI-targeted prostate biopsy. Clinically significant prostate cancer (csigPCa), i.e., overall Gleason ≥ 3 + 4 of any length OR maximum cancer core length (MCCL) ≥4 mm of any grade including any 3 + 3, was found in 96/195 (49%) of biopsied patients. Median PSA (and PSAD) was 4.7 (0.20), 8.0 (0.17), and 9.7 (0.31) ng/mL (ng/mL/mL) in mpMRI scored Likert 3,4,5 respectively for men with csigPCa on biopsy. The space for novel biomarkers was shown to be within the group of men with mpMRI scored Likert3 (178/340) and 4 (70/350), in whom an additional of 40% (70/178) men with mpMRI-scored Likert3, and 37% (26/70) Likert4 could have been spared biopsy. PSAD is already considered clinically in this cohort to risk stratify patients for biopsy, despite this 67% (55/82) of men with mpMRI-scored Likert3, and 55% (36/65) Likert4, who underwent prostate biopsy had a PSAD below a clinical threshold of 0.15 (or 0.12 for men aged <50 years). Different thresholds of PSA and PSAD were assessed in mpMRI-scored Likert4 to predict csigPCa on biopsy, to achieve false negative levels of ≤5% the proportion of patients whom who test as above the threshold were unsuitably high at 86 and 92% of patients for PSAD and PSA respectively. When PSA was re tested in a sub cohort of men repeated PSAD showed its poor reproducibility with 43% (41/95) of patients being reclassified. After PI-RADS rescoring of the biopsied lesions, 66% (54/82) of the Likert3 lesions received a different PI-RADS score. Conclusions: The addition of simple biochemical and radiological markers (Likert and PSAD) facilitate the streamlining of the mpMRI-diagnostic pathway for suspected prostate cancer but there remains scope for improvement, in the introduction of novel biomarkers for risk assessment in Likert3 and 4 patients, future application of novel biomarkers tested in a Likert cohort would also require re-optimization around Likert3/PI-RADS2, as well as reproducibility testing.

Predictive role of T2WI and ADC-derived texture parameters in differentiating Gleason score 3 + 4 and 4 + 3 prostate cancer

BACKGROUND

Since Gleason score (GS) 4 + 3 prostate cancer (PCa) has a worse prognosis than GS 3 + 4 PCa, differentiating these two types of PCa is of clinical significance.

OBJECTIVE

To assess the predictive roles of using T2WI and ADC-derived image texture parameters in differentiating GS 3 + 4 from GS 4 + 3 PCa.

METHODS

Forty-eight PCa patients of GS 3 + 4 and 37 patients of GS 4 + 3 are retrieved and randomly divided into training (60%) and testing (40%) sets. Axial image showing the maximum tumor size is selected in the T2WI and ADC maps for further image texture feature analysis. Three hundred texture features are computed from each region of interest (ROI) using MaZda software. Feature reduction is implemented to obtain 30 optimal features, which are then used to generate the most discriminative features (MDF). Receiver operating characteristic (ROC) curve analysis is performed on MDF values in the training sets to achieve cutoff values for determining the correct rates of discrimination between two Gleason patterns in the testing sets.

RESULTS

ROC analysis on T2WI and ADC-derived MDF values in the training set (n = 51) results in a mean area under the curve (AUC) of 0.953±0.025 (with sensitivity 0.9274±0.0615 and specificity 0.897±0.069), and 0.985±0.013 (with sensitivity 0.9636±0.0446 and specificity 0.9726±0.0258), respectively. Using the corresponding MDF cutoffs, 95.3% (ranges from 76.5% to 100%) and 94.1% (ranged from 76.5% to 100%) of test cases (n = 34) are correctly discriminated using T2WI and ADC-derived MDF values, respectively.

CONCLUSIONS

The study demonstrates that using T2WI and ADC-derived image texture parameters has a potential predictive role in differentiating GS 3 + 4 and GS 4 + 3 PCa.

Advances in the diagnostic options for prostate cancer

Over the past decade, despite the controversies surrounding prostate cancer screening, significant refinements have improved its application. PSA screening, although it has been questioned, appears to confer a mortality benefit and remains the most effective way to identify the possible presence of prostate cancer. Methods to improve the specificity of PSA screening and limit overdiagnosis of indolent cancers, including risk-stratified screening regimens, are currently being utilized. Certain imaging modalities, such as multiparametric MRI, have proven to be excellent adjuncts providing improved risk stratification and the ability for targeted biopsies; however, concerns over variability in interpretation and generalizability persist. A number of novel biomarkers have become available with nearly all demonstrating the ability to improve upon the specificity of PSA screening; however, optimal timing, direct comparisons, and usefulness in conjunction with imaging modalities remain to be elucidated. With the improvement in testing options and recognition of the risk/benefit ratio for men undergoing screening for prostate cancer, the increasing role of shared decision making in the process is emphasized.

Combined Use of Prostate-specific Antigen Density and Magnetic Resonance Imaging for Prostate Biopsy Decision Planning: A Retrospective Multi-institutional Study Using the Prostate Magnetic Resonance Imaging Outcome Database (PROMOD)

BACKGROUND

Previous studies suggested that prostate-specific antigen (PSA) density (PSAd) combined with magnetic resonance imaging (MRI) may help avoid unnecessary prostate biopsy (PB) with a limited risk of missing clinically significant prostate cancer (csPCa; Gleason grade group [GGG] >1).

OBJECTIVE

To define optimal diagnostic strategies based on the combined use of PSAd and MRI in patients at risk of prostate cancer (PCa).

DESIGN, SETTING, AND PARTICIPANTS

A retrospective analysis of the international multicenter Prostate MRI Outcome Database (PROMOD), including 2512 men having undergone PSAd and prostate MRI before PB between 2013 and 2019, was performed.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Rates of avoided PB, missed GGG 1, and csPCa according to 10 strategies based on PSAd values and MRI reporting scores (Prostate Imaging Reporting and Data System [PI-RADS]/Likert/IMPROD biparametric prostate MRI Likert). Decision curve analysis (DCA) was used to statistically compare the net benefit of each strategy. Combined systematic and targeted biopsies were used for reference.

RESULTS AND LIMITATIONS

According to DCA, the best strategy in biopsy-naive patients was #7 (PI-RADS/Likert 4-5 or PI-RADS/Likert 3 if PSAd >0.2), which avoided 41.2% PBs while missed 44% of GGG 1 and 10.9% of csPCa cases. From a clinical standpoint, however, strategies with a lower risk of missing csPCa included #10 (PI-RADS/Likert 4-5 or PI-RADS 3 if PSAd >0.10 or PSAd >0.2), which avoided 27% PBs while missing 24.4% GGG 1 and 4% csPCa cases, or #5 (PI-RADS/Likert 3-5 or PSAd>0.15), which avoided 14.7% PBs while missing 9.3% GGG 1 and 1.7% csPCa cases. Similar results were found in patients with a previous negative biopsy. This study is limited by its retrospective nature, and no central review of MRI and histopathological findings.

CONCLUSIONS

Combined PSAd and MRI findings allows individualization of the decision to perform PB on the basis of the risk of missing PCa that both patients and clinicians are ready to accept to avoid this procedure.

PATIENT SUMMARY

We compared several biopsy strategies based on a combination of prostate magnetic resonance imaging findings and prostate-specific antigen density, providing a readily available tool for each center and practicing urologist to counsel patients about their individual risk of significant prostate cancer.

Comparison of Likert and PI-RADS version 2 MRI scoring systems for the detection of clinically significant prostate cancer

OBJECTIVE

To compare the performance of Likert and Prostate Imaging-Reporting and Data System (PI-RADS) multiparametric (mp) MRI scoring systems for detecting clinically significant prostate cancer (csPCa).

METHODS

199 biopsy-naïve males undergoing prostate mpMRI were prospectively scored with Likert and PI-RADS systems by four experienced radiologists. A binary cut-off (threshold score ≥3) was used to analyze histological results by three groups: negative, insignificant disease (Gleason 3 + 3; iPCa), and csPCa (Gleason ≥3 +4). Lesion-level results and prostate zonal location were also compared.

RESULTS

129/199 (64.8%) males underwent biopsy, 96 with Likert or PI-RADS score ≥3, and 21 with negative MRI. A further 12 patients were biopsied during follow-up (mean 507 days). Prostate cancer was diagnosed in 87/199 (43.7%) patients, 65 with (33.6%) csPCa. 30/92 (32.6%) patients with negative MRI were biopsied, with an NPV of 83.3% for cancer and 86.7% for csPCa. Likert and PI-RADS score differences were observed in 92 patients (46.2%), but only for 16 patients (8%) at threshold score ≥3. Likert scoring had higher specificity than PI-RADS (0.77 vs 0.66), higher area under the curve (0.92 vs 0.87, p = 0.002) and higher PPV (0.66 vs 0.58); NPV and sensitivity were the same. Likert had more five score results (58%) compared to PI-RADS (36%), but with similar csCPa detection (81.0 and 80.6% respectively). Likert demonstrated lower proportion of false positive in the predominately AFMS-involving lesions.

CONCLUSION

Likert and PI-RADS systems both demonstrate high cancer detection rates. Likert scoring had a higher AUC with moderately higher specificity and lower positive call rate and could potentially help to reduce the number of unnecessary biopsies performed.

ADVANCES IN KNOWLEDGE

This paper illustrates that the Likert scoring system has potential to help urologists reduce the number of prostate biopsies performed.

Contrast Medium or No Contrast Medium for Prostate Cancer Diagnosis. That Is the Question

The benefits and drawbacks of the dynamic contrast-enhanced MRI sequence for prostate cancer diagnosis are increasingly being recognized, with many centers adopting the biparametric (bp) MRI approach as the default initial approach. The abandonment of the routine use of contrast medium requires an assessment of the loss of diagnostic power against the gains in operational logistics, costs, time, capacity, and side effects. It is the balance of these factors weighted against the clinical priorities of patients that determines which patient groups can safely avoid dynamic contrast enhancement. Although systematic reviews and individual studies are broadly supportive of the bpMRI approach, the pathway impacts for men with suspected cancer using the bpMRI approach are still not well documented for clinical practice. Robust prospectively acquired data for bpMRI regarding biopsy avoidance, detection of clinically significant and insignificant cancers, and for increasing the precision of tumor grade and volume are needed. There is a requirement for prospective, randomized, or blinded head-to-head, multicenter studies, addressing the noninferiority of biopsy yields prompted by bpMRI and multiparametric MRI approaches. These studies should more precisely define patient groups where the benefits and harms of contrast enhancement are aligned to their clinical priorities. Only then can we be confident in recommending bpMRI as an initial diagnostic approach for prostate cancer diagnosis. Level of Evidence 1 Technical Efficacy Stage 5.

Diagnostic accuracy of biparametric versus multiparametric prostate MRI: assessment of contrast benefit in clinical practice

PURPOSE

To assess the added value of dynamic contrast-enhanced (DCE) in prostate MR in clinical practice.

METHODS

Two hundred sixty-four patients underwent prostate MRI, with T2 and DWI sequences initially interpreted, prior to full multiparametric magnetic resonance imaging (mpMRI) interpretation using a Likert 1-5 scale. A prospective opinion was given on likely benefit of contrast prior to review of the DCE sequence, and retrospectively following full mpMRI review. The final histology result following targeted and/or systematic biopsy of the prostate was used for outcome purposes.

RESULTS

Biparametric magnetic resonance imaging (bpMRI) and mpMRI were assigned the same score in 86% of cases; when dichotomising to a negative or positive MRI (Likert score ≥ 3), concordance increased to 92.8%. At Likert score ≥ 3 bpMRI detected 89.9% of all cancers and 93.5% clinically significant prostate cancers (csPCa) and mpMRI 90.7% and 94.6%, respectively. mpMRI had fewer false positives than bpMRI (11.4% vs 18.9%) and a lower Likert 3 rate (8.3% vs 17%), conferring higher specificity (74% vs 67%), but similar sensitivity (95% versus 94%) and ROC-AUC (90% vs 89%). At a positive MRI threshold of Likert ≥ 4, mpMRI had a higher sensitivity than bpMRI (89% versus 80%) and detected more csPCa (89.2% versus 79.6%). DCE was prospectively considered of potential benefit in 27.3%, but readers would only recall 11% of patients for DCE sequences, mainly to assess score 3 peripheral zone lesions. Following full mpMRI review, DCE was considered helpful in 28.4% of cases; in 23/75 (30.6%) of these cases this only became apparent after reviewing the sequence, reasons included increased confidence, presence of "safety-net" lesions or inflammatory lesions.

CONCLUSION

BpMRI has equivalent cancer detection rates to mpMRI; however, mpMRI had fewer Likert 3 call rates and increased specificity and was subjectively considered of benefit by readers in 28.4% of cases.

KEY POINTS

• bpMRI has similar cancer detection rates to the full mpMRI protocol at a positive MRI threshold of Likert 3. • mpMRI had fewer intermediate category 3 calls (8.3%) than bpMRI (17%) and fewer false positives than bpMRI (11.4% vs 18.9%), conferring higher specificity (74% vs 67%). • Readers considered DCE beneficial in 28.4% of cases, but in a relatively high number (30.6%) this only became apparent after reviewing the sequence.