Performance characteristics of MR imaging in the evaluation of clinically low-risk prostate cancer: a prospective study

Comparison of model-based versus deep learning-based image reconstruction for thin-slice T2-weighted spin-echo prostate MRI

PURPOSE

To compare a previous model-based image reconstruction (MBIR) with a newly developed deep learning (DL)-based image reconstruction for providing improved signal-to-noise ratio (SNR) in high through-plane resolution (1 mm) T2-weighted spin-echo (T2SE) prostate MRI.

METHODS

Large-area contrast and high-contrast spatial resolution of the reconstruction methods were assessed quantitatively in experimental phantom studies. The methods were next evaluated radiologically in 17 subjects at 3.0 Tesla for whom prostate MRI was clinically indicated. For each subject, the axial T2SE raw data were directed to MBIR and to the DL reconstruction at three vendor-provided levels: (L)ow, (M)edium, and (H)igh. Thin-slice images from the four reconstructions were compared using evaluation criteria related to SNR, sharpness, contrast fidelity, and reviewer preference. Results were compared using the Wilcoxon signed-rank test using Bonferroni correction, and inter-reader comparisons were done using the Cohen and Krippendorf tests.

RESULTS

Baseline contrast and resolution in phantom studies were equivalent for all four reconstruction pathways as desired. In vivo, all three DL levels (L, M, H) provided improved SNR versus MBIR. For virtually, all other evaluation criteria DL L and M were superior to MBIR. DL L and M were evaluated as superior to DL H in fidelity of contrast. For 44 of the 51 evaluations, the DL M reconstruction was preferred.

CONCLUSION

The deep learning reconstruction method provides significant SNR improvement in thin-slice (1 mm) T2SE images of the prostate while retaining image contrast. However, if taken to too high a level (DL High), both radiological sharpness and fidelity of contrast diminish.

Advanced strain elastography is a reliable approach for prostate cancer detection in patients with elevated PSA levels

This study aimed to examine the validity and reproducibility of strain elastography (SE) for detecting prostate cancer (PCa) in patients with elevated prostate-specific antigen (PSA) levels. The study included 107 patients with elevated PSA levels. All eligible patients underwent transrectal ultrasound (TRUS) with real-time elastography (RTE) to detect suspicious lesions. Two readers independently evaluated the lesions and assigned a strain ratio and elastography score to each lesion. Histopathology was used as a reference standard to estimate the validity of RTE in predicting malignant lesions. An intraclass correlation (ICC) was performed to detect reliability of the strain ratios and elastography scores. TRUS-guided biopsy detected malignancies in 64 (59.8%) patients. TRUS with RTE revealed 122 lesions. The strain ratio index (SRI) cut-off values to diagnose malignancy were 4.05 and 4.35, with sensitivity, specificity, and accuracy of 94.7%, 91.3%, and 93.4%, respectively. An elastography score > 3 was the best cut-off value for detecting malignancy. According to readers, the sensitivity, specificity, and accuracy were 91.3-94.7%, 89.5-93.4%, and 91.3-90.9%, respectively. Excellent inter-reader agreement was recorded for SRI and elastography scores, with ICC of 0.937 and 0.800, respectively. SE proves to be an efficient tool for detecting PCa with high accuracy in patients with elevated PSA levels.

The cribriform morphology impairs Gleason 7 prostate cancer lesion detection on multiparametric magnetic resonance imaging

BACKGROUND

Prostate multiparametric magnetic resonance imaging (mpMRI) is a useful tool for the detection of tumor lesions however, some clinically significant lesions are still missed. We determined whether the cribriform pattern has an effect on lesion detection in mpMRI.

METHODS

We reviewed the single-institution database of the patients who underwent mpMRI before radical prostatectomy. We included the patients only with the Gleason 7 final pathology of open radical prostatectomy with curative intent between 2016 and 2021. Prostatectomy mappings according to the 16-sector map and cribriform patterns were re-evaluated by two genitourinary pathologists. Prostate mpMRIs were read by two genitourinary radiologists. If the index and nonindex lesions in pathology mapping were matched with mpMRI as Prostate Imaging Reporting and Data System-3 or higher, it was defined as detectable. We compared the detection rates of lesions with and without cribriform morphology. In regression analysis, we also assessed the factors affecting the detectability of prostate cancer lesions.

RESULTS

A total of 120 patients and 157 lesions were included in our study. While 52 of 83 cribriform pattern positive lesions could be detected in mpMRI, 59 of 74 cribriform pattern negative lesions could be detected (62.7% vs. 79.7%, respectively, p = 0.019). The lesions were also distributed homogeneously according to diameters and analyzed separately. All lesions between 21 and 30 mm with the negative cribriform pattern were detected on mpMRI. However, only 77.8% of cribriform pattern positive lesions between 21 and 30 mm could be detected (p = 0.034). The Higher D'Amico risk group and the absence of cribriform morphology were independent predictors for the lesion detection on mpMRI.

CONCLUSION

The presence of cribriform pattern in Gleason 7 prostate cancer lesions decreases the lesion detection rate of mpMRI.

Paradigm Shift in Prostate Cancer Diagnosis: Pre-Biopsy Prostate Magnetic Resonance Imaging and Targeted Biopsy

With regard to the indolent clinical characteristics of prostate cancer (PCa), the more selective detection of clinically significant PCa (CSC) has been emphasized in its diagnosis and management. Magnetic resonance imaging (MRI) has advanced technically, and recent international cooperation has provided a standardized imaging and reporting system for prostate MRI. Accordingly, prostate MRI has recently been investigated and utilized as a triage tool before biopsy to guide tissue sampling to increase the detection rate of CSC beyond the staging tool for patients in whom PCa was already confirmed on conventional systematic biopsy. Radiologists must understand the current paradigm shift for better PCa diagnosis and management. This article reviewed the recent literature, demonstrating the diagnostic value of pre-biopsy prostate MRI with targeted biopsy and discussed unsolved issues regarding the paradigm shift in the diagnosis of PCa.

Defining Diagnostic Criteria for Prostatic Ductal Adenocarcinoma at Multiparametric MRI

Background Prostatic ductal adenocarcinoma (DAC) is an aggressive histologic variant of prostate cancer that often warrants multimodal therapy and poses a significant diagnostic challenge clinically and at imaging. Purpose To develop multiparametric MRI criteria to define DAC and to assess their diagnostic performance in differentiating DAC from prostatic acinar adenocarcinoma (PAC). Materials and Methods Men with histologically proven DAC who had multiparametric MRI before radical prostatectomy were retrospectively identified from January 2011 through November 2018. MRI features were predefined using a subset of nine DACs and then compared for men with peripheral-zone DACs 1 cm or greater in size and men with matched biopsy-confirmed International Society of Urological Pathology grade group 4-5 PAC, by four independent radiologists blinded to the pathologic diagnosis. Diagnostic performance was determined by consensus read. Patient and tumor characteristics were compared by using the Fisher test, t-tests, and Mann-Whitney U test. Agreement (Cohen κ) and sensitivity analyses were also performed. Results There were 59 men with DAC (median age, 63 years [interquartile range, 56, 67 years]) and 59 men with PAC (median age, 64 years [interquartile range, 59, 69 years]). Predefined MRI features, including intermediate T2 signal, well-defined margin, lobulation, and hypointense rim, were detected in a higher proportion of DACs than PACs (76% [45 of 59] vs 5% [three of 59]; P < .001). On consensus reading, the presence of three or more features demonstrated 76% sensitivity, 94% specificity, 94% positive predictive value [PPV], and 80% negative predictive value [NPV] for all DACs and 100% sensitivity, 95% specificity, 81% PPV, and 100% NPV for pure DACs. The DACs and PACs showed no difference in contrast enhancement (100% vs 100%; P >.99, median T2 signal intensity (254 vs 230; P = .99), or apparent diffusion coefficient (median, 677 10^-6 mm²/sec vs 685 10^-6 mm²/sec; P = .73). Conclusion The presence of intermediate T2 signal, well-defined margin, lobulation, and/or hypointense rim, together with restricted diffusion and contrast enhancement at multiparametric MRI of the prostate, suggests prostatic ductal adenocarcinoma rather than prostatic acinar adenocarcinoma. © RSNA, 2022 Online supplemental material is available for this article.

Correlation of Stiffness of Prostate Cancer Measured by Shear Wave Elastography with Grade Group: A Preliminary Study

The aim of study was to explore the correlation between shear wave elastography (SWE) and grade group (GG) of prostate cancer (PCa). This retrospective study involved prostate-specific antigen elevated patients with elevated prostate-specific antigen levels who underwent SWE before transrectal ultrasound-guided needle biopsy. A total of 49 PCa lesions were reviewed after radical prostatectomy; 3-7 regions of interest were placed within the cancerous area on axial view compared with the tumor foci outlined on the slides by pathologist. The maximum SWE value was measured, quantitative SWE parameters (E_max, E_mean, E_min and standard deviation [SD]) were recorded and correlated with GG and then parameters were compared between indolent (≤2) and aggressive (≥3) GGs. The diagnostic value of each parameter was compared with the receiver operating characteristic curve. Forty-nine PCa foci were divided into two groups on the basis of their GGs. All SWE parameters exhibited a significant linear trend with GG. The area under the receiver operating characteristic curve (AUC) was 0.816 for E_max; with a cutoff point of 84 kPa, sensitivity and specificity were 81.3% and 82.4% to differentiate low and high GGs in PCa. The AUC was 0.776 for E_mean; with a cutoff point of 71 kPa, sensitivity and specificity were 78.1% and 76.5%. For E_min, the AUC was 0.739; with a cutoff point of 60 kPa, sensitivity and specificity were 68.8% and 70.6%. For SD, the AUC was 0.681; with a cutoff point of 8.3 kPa, sensitivity and specificity were 46.9% and 94.1%. There were no significant differences between the four SWE parameters (p < 0.05 for all). SWE features were correlated with GGs, and this correlation may have excellent diagnostic performance in predicting high GG in PCa.

Risk Factors for Pathologically Confirmed Lymph Nodes Metastasis in Patients With Clinical T2N0M0 Stage Prostate Cancer

Objective

To explore the risk factors for postoperatively pathological lymph node metastasis in patients with clinical T2N0M0 stage prostate cancer (PCa).

Methods

We retrospectively analyzed clinicopathological data of 316 patients with clinical T2 stage PCa and preoperative negative lymph nodes [LN(−)] indicated by imaging (cT2N0M0) between January 2014 and May 2019. Multivariate logistic regression analysis was performed to determine risk factors for postoperatively pathological pLN(+) in patients with cT2N0M0 stage PCa. Spearman correlation analysis was used to explore the relationship between tumor burden and Prostate Imaging Reporting and Data System version 2 (PI-RADS v2) score.

Results

A total of 45 patients (14.2%) were confirmed by postoperative pathology to have LN metastasis. Univariate analysis indicated that total prostate-specific antigen (tPSA), PI-RADS v2 score, postoperative Gleason grade group (GGG), intraductal carcinoma of the prostate (IDC-P), clinical T2 substaging, and postoperative pathological tumor burden were risk factors for pLN(+) in all patients. Multivariate analysis showed that tPSA and postoperative GGG were risk factors for pLN(+) in all patients. Univariate analysis revealed that tPSA, PIRADS v2 score, clinical T2 substaging, IDC-P, postoperative pathological tumor burden, and postoperative GGG were risk factors for pLN(+) in patients with GGG ≥ 3. Multivariate analysis suggested that tPSA, PI-RADS v2 score, clinical T2 substaging, postoperative pathological tumor burden, and GGG were risk factors for pLN (+) in patients with GGG ≥ 3. Spearman correlation analysis showed that PI-RADS v2 score was positively correlated with clinical T2 substaging and postoperative pathological tumor burden.

Conclusion

There was a high risk of LN metastasis in patients with cT2 PCa if they had high preoperative tPSA or high postoperative GGG. Patients with cT2 PCa and GGG ≥ 3 had a high risk of LN metastasis if they had high PI-RADS v2 score, high preoperative clinical stage or high postoperative pathological tumor burden. PI-RADS v2 score predicted tumor burden well in patients with GGG ≥ 3.

Advanced ultrasound in the diagnosis of prostate cancer

The diagnosis of prostate cancer (PCa) can be challenging due to the limited performance of current diagnostic tests, including PSA, digital rectal examination and transrectal conventional US. Multiparametric MRI has improved PCa diagnosis and is recommended prior to biopsy; however, mp-MRI does miss a substantial number of PCa. Advanced US modalities include transrectal prostate elastography and contrast-enhanced US, as well as improved B-mode, micro-US and micro-Doppler techniques. These techniques can be combined to define a novel US approach, multiparametric US (mp-US). Mp-US improves PCa diagnosis but is not sufficiently accurate to obviate the utility of mp-MRI. Mp-US using advanced techniques and mp-MRI provide complementary information which will become even more important in the era of focal therapy, where precise identification of PCa location is needed.

Role of Changes in Magnetic Resonance Imaging or Clinical Stage in Evaluation of Disease Progression for Men with Prostate Cancer on Active Surveillance

BACKGROUND

Active surveillance (AS) protocols rely on rectal examination, prostate-specific antigen, imaging, and biopsy to identify disease progression.

OBJECTIVE

To evaluate whether an AS regimen based on magnetic resonance imaging (MRI) or clinical stage changes can detect reclassification to grade group (GG) ≥2 disease compared with scheduled systematic biopsies.

DESIGN, SETTING, AND PARTICIPANTS

We identified a cohort of men initiated on AS between January 2013 and April 2016 at a single tertiary-care center. Patients completed confirmatory testing and prostate MRI prior to enrollment, then underwent laboratory and physical evaluation every 6 mo, MRI every 18 mo, and biopsy every 3yr.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

MRI results were evaluated using composite Likert/Prostate Imaging Reporting and Data System v2 scoring. MRI and clinical changes were assessed for association with disease progression. Univariable and multivariable regression models were used to predict upgrading on 3-yr biopsy.

RESULTS AND LIMITATIONS

At 3yr, of 207 men, 66 (32%) had≥GG2 at biopsy: 55 (83%) with GG2, 10 (15%) with GG3, and one (1.5%) with GG4. Among patients with a 3-yr MRI score of ≥3, 41% had≥GG2 disease, compared with 15% with an MRI score of <3 (p=0.0002). The MRI score increased in 48 men (23%), decreased in 27 (13%), and was unchanged in 132 (64%) men. Increases in MRI score were not associated with reclassification after adjusting for the 3-yr MRI score (p=0.9). Biopsying only for an increased MRI score or clinical stage would avoid 681 biopsies per 1000 men, at the cost of missing ≥GG2 disease in 169 patients.

CONCLUSIONS

An AS strategy that uses MRI or clinical changes to trigger prostate biopsy avoids many biopsies but misses an unacceptable amount of clinically significant disease. Prostate biopsy for men on AS should be performed at scheduled intervals, regardless of stable imaging or examination findings.

PATIENT SUMMARY

An active surveillance strategy for biopsy based only on increases in magnetic resonance imaging score or clinical stage will avoid many biopsies; however, it will miss many patients with clinically significant prostate cancer.

Extensive disease among potential candidates for hemi-ablative focal therapy for prostate cancer

OBJECTIVE

To examine a set of proposed eligibility factors for hemi-ablative focal therapy in prostate cancer and to determine the likelihood of residual extensive disease.

METHODS

We retrospectively analyzed data from 98 patients with unilateral prostate cancer on biopsy with detailed tumor maps from whole-mount slides and preoperative magnetic resonance imaging data. These patients met the focal therapy consensus meeting inclusion criteria (prostate-specific antigen <15 ng/mL, clinical stage T1c-T2a and Gleason score 3 + 3 or 3 + 4 on needle biopsy), and underwent radical prostatectomy between 2000 and 2014. Extensive disease was defined as having Gleason pattern 4/5 in bilateral lobes, any extraprostatic extension, seminal vesicle invasion or lymph node invasion. Both lobes of the prostate were scored on magnetic resonance imaging. Preoperative characteristics including biopsy and magnetic resonance imaging data were used to predict extensive disease.

RESULTS

Among our cohort of 98 patients, 40% (95% CI 30-50%) had extensive disease. A total of 33% (95% CI 24-43%) had Gleason pattern 4/5 in both lobes with a median Gleason pattern 4/5 tumor volume in the biopsy negative lobe of 0.06 cm³ , 17 patients had pathological tumor stage ≥3 and one patient had lymph node invasion.

CONCLUSIONS

An important number of patients meeting the focal therapy consensus meeting inclusion criteria can present extensive disease. Further studies using targeted biopsies might provide more accurate information about the selection of focal therapy candidates.

Biologic Significance of Magnetic Resonance Imaging Invisibility in Localized Prostate Cancer

PURPOSE

Multiparametric magnetic resonance imaging (mpMRI) is used widely for prostate cancer (PCa) evaluation. Approximately 35% of aggressive tumors, however, are not visible on mpMRI. We sought to identify the molecular alterations associated with mpMRI-invisible tumors and determine whether mpMRI visibility is associated with PCa prognosis.

METHODS

Discovery and validation cohorts included patients who underwent mpMRI before radical prostatectomy and were found to harbor both mpMRI-visible (Prostate Imaging and Reporting Data System 3 to 5) and -invisible (Prostate Imaging and Reporting Data System 1 or 2) foci on surgical pathology. Next-generation sequencing was performed to determine differential gene expression between mpMRI-visible and -invisible foci. A genetic signature for tumor mpMRI visibility was derived in the discovery cohort and assessed in an independent validation cohort. Its association with long-term oncologic outcomes was evaluated in a separate testing cohort.

RESULTS

The discovery cohort included 10 patients with 26 distinct PCa foci on surgical pathology, of which 12 (46%) were visible and 14 (54%) were invisible on preoperative mpMRI. Next-generation sequencing detected prioritized genetic mutations in 14 (54%) tumor foci (n = 8 mpMRI visible, n = 6 mpMRI invisible). A nine-gene signature (composed largely of cell organization/structure genes) associated with mpMRI visibility was derived (area under the curve = 0.89), and the signature predicted MRI visibility with 75% sensitivity and 100% specificity (area under the curve = 0.88) in the validation cohort. In the testing cohort (n = 375, median follow-up 8 years) there was no significant difference in biochemical recurrence, distant metastasis, or cancer-specific mortality in patients with predicted mpMRI-visible versus -invisible tumors (all P > .05).

CONCLUSION

Compared with mpMRI-invisible disease, mpMRI-visible tumors are associated with underexpression of cellular organization genes. mpMRI visibility does not seem to be predictive of long-term cancer outcomes, highlighting the need for biopsy strategies that detect mpMRI-invisible tumors.

Can We Improve the Preoperative Prediction of Prostate Cancer Recurrence With Multiparametric MRI?

INTRODUCTION

The use of multiparametric magnetic resonance imaging (mpMRI) to assess prostate cancer (PCa) has increased over the past decade. We aimed to assess if preoperative mpMRI lesion score, a variable routinely available for men undergoing pre-biopsy MRI, improves the performance of commonly used preoperative predictive models for PCa recurrence.

PATIENTS AND METHODS

We analyzed data from 372 patients with PCa treated with radical prostatectomy in 2012 to 2017 and assessed with pre-biopsy mpMRI within 6 months prior to surgery. Suspicious areas for cancer were scored on a standardized 5-point scale. Cox regression was used to assess the association between mpMRI score and the risk of postoperative biochemical recurrence. Two different models were tested accounting for factors included in the Kattan nomogram and in the D'Amico risk-classification.

RESULTS

Overall, 53% and 30% of patients were found with a lesion scored 4 or 5 at pre-biopsy mpMRI, respectively. Risk varied widely by mpMRI (29% 2-year risk of biochemical recurrence for a score of 5 vs. 5% for a score of 1-2), and mpMRI score was associated with large hazard ratios after adjusting for stage, grade, and prostate-specific antigen: 1.66, 1.96, and 2.71 for scores 3, 4, and 5, respectively. However, 95% confidence intervals were very wide (0.19-14.20, 0.26-14.65, and 0.36-20.55, respectively) and included 1.

CONCLUSIONS

Our data did not show that preoperative models, commonly used to assess PCa risk, were improved after including the pre-biopsy mpMRI score. However, the value of pre-biopsy mpMRI to improve preoperative risk models should be investigated in larger data sets.

PSA screening - for whom and when?

Reasons for and against screening of prostate cancer have been discussed widely over the last decade. In 2014, the European Randomized Trial for Screening of Prostate Cancer (ERSPC) has reported a relative reduction of the cancer-specific survival of 27% in participants who definitely followed the screening protocol. This relative advantage has proven to be stable from year 7 to year 13 after the beginning of screening. Still, the disadvantages of overdiagnosis and overtreatment are the downsides of a population-based screening approach. But given the overall advantage of screening, a risk-adapted prostate-specific antigen (PSA) screening using a baseline PSA value at ages 45-50 may significantly reduce the number needed to diagnose maintaining the benefits of screening. PROBASE is a randomized risk-adapted screening trial currently ongoing in Germany to answer this important question.

Prostate Cancer Detection with Multiparametric MRI: A Comparison of 1 M-Concentration Gadobutrol with 0.5 M-Concentration Gadolinium-Based Contrast Agents

INTRODUCTION

Gadobutrol (Gd-DO3A-butrol) (Gadovist®) is a macrocyclic gadolinium-based contrast agent for magnetic resonance imaging (MRI) formulated at 1.0 mmol Gd/ml. Gadobutrol's higher concentration compared to other contrast agents (0.5 mmol Gd/ml) is associated with higher T1 relaxivity. We examined whether gadobutrol increases the accuracy of prostate cancer detection using dynamic contrast-enhanced MRI.

MATERIALS AND METHODS

Multiparametric MRI was performed in 379 patients: 94 patients received 1 M gadobutrol while 285 randomly received equivalent doses of 0.5 M gadoterate meglumine or gadopentetate dimeglumine. MRI images were retrospectively and blindly assessed for the presence of cancer by comparing them with prostate biopsy findings.

RESULTS

The specificity and accuracy were significantly higher with 1 M gadobutrol than 0.5 M of the other contrast agents. There were no significant differences in the sensitivity, or positive and negative predictive values.

CONCLUSION

Multiparametric MRI using 1 M gadobutrol may improve the accuracy of prostate cancer detection.

Prostate Imaging-Reporting and Data System Version 2: Beyond Prostate Cancer Detection

The main purpose of Prostate Imaging-Reporting and Data System Version 2 (PI-RADSv2) is to effectively detect clinically significant prostate cancers (csPCa) using multiparametric magnetic resonance imaging. Since the first introduction of PI-RADSv2, researchers have validated its diagnostic performance in identifying csPCa, and these promising data have influenced biopsy and treatment schemes. However, in this article, we focused on the potential of PI-RADSv2 in relation to various aspects of PCa such as Gleason score, tumor volume, extraprostatic extension, lymph node metastasis, and postoperative biochemical recurrence, beyond prostate cancer detection.

Genes involved in prostate cancer progression determine MRI visibility

MRI is used to image prostate cancer and target tumors for biopsy or therapeutic ablation. The objective was to understand the biology of tumors not visible on MRI that may go undiagnosed and untreated. Methods: Prostate cancers visible or invisible on multiparametric MRI were macrodissected and examined by RNAseq. Differentially expressed genes (DEGs) based on MRI visibility status were cross-referenced with publicly available gene expression databases to identify genes associated with disease progression. Genes with potential roles in determining MRI visibility and disease progression were knocked down in murine prostate cancer xenografts, and imaged by MRI. Results: RNAseq identified 1,654 DEGs based on MRI visibility status. Comparison of DEGs based on MRI visibility and tumor characteristics revealed that Gleason score (dissimilarity test, p<0.0001) and tumor size (dissimilarity test, p<0.039) did not completely determine MRI visibility. Genes in previously reported prognostic signatures significantly correlated with MRI visibility suggesting that MRI visibility was prognostic. Cross-referencing DEGs with external datasets identified four genes (PHYHD1, CENPF, ALDH2, GDF15) that predict MRI visibility, progression free survival and metastatic deposits. Genetic modification of a human prostate cancer cell line to induce miR-101 and suppress CENPF decreased cell migration and invasion. As prostate cancer xenografts in mice, these cells had decreased visibility on diffusion weighted MRI and decreased perfusion, which correlated with immunostaining showing decreased cell density and proliferation. Conclusions: Genes involved in prostate cancer prognosis and metastasis determine MRI visibility, indicating that MRI visibility has prognostic significance. MRI visibility was associated with genetic features linked to poor prognosis.

Predictive role of Trimprob associated with multiparametric MRI in the diagnosis of prostate cancer

Objectives

To evaluate the predictive value of TRIMprob test to detect prostate cancer (PCa) in patients referred to prostate biopsy (PB).

Material and Methods

Patients with PSA <10ng/mL and rectal exam without findings suggestive of prostate cancer were selected for TRIMprob evaluation. Exam was performed by a single operator through transperineal approach. Patients admitted for the study were submitted to TRIMprob and multiparametric magnetic resonance (mpMRI) and posteriorly to PB.

Results

In total, 77 patients were included. TRIMprob showed evidences of PCa in 25 (32.5%) and was negative in 52 patients (67.5%). The rate of detection of prostate cancer at biopsy was higher in patients with positive TRIMprob (16/25; 64.0%) than in patients with negative TRIMprob (11/52; 21.1%; p<0.001). Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of TRIMprob were respectively 61.5%, 82.0%, 64.0%, 80.3% and 74.0%. ROC curve showed the following areas under the curve values for TRIMprob, mpMRI and combination of TRIMprob + mpMRI: 0.706; 0.662 and 0.741 respectively. At combined analysis, when both TRIMprob and mpMRI were negative for prostate cancer, accuracy was 96.3% or only 1 in 27 PB was positive (3.7%).

Conclusions

Trimprob had similar predictive value for PCa in patients submitted to PB as mpMRI. Combined TRIMprob and mpMRI showed higher accuracy than when performed singly.

The performance of PI-RADSv2 and quantitative apparent diffusion coefficient for predicting confirmatory prostate biopsy findings in patients considered for active surveillance of prostate cancer

PURPOSE

To assess the performance of the updated Prostate Imaging Reporting and Data System (PI-RADSv2) and the apparent diffusion coefficient (ADC) for predicting confirmatory biopsy results in patients considered for active surveillance of prostate cancer (PCA).

METHODS

IRB-approved, retrospective study of 371 consecutive men with clinically low-risk PCA (initial biopsy Gleason score ≤6, prostate-specific antigen <10 ng/ml, clinical stage ≤T2a) who underwent 3T-prostate MRI before confirmatory biopsy. Two independent radiologists recorded the PI-RADSv2 scores and measured the corresponding ADC values in each patient. A composite score was generated to assess the performance of combining PI-RADSv2 + ADC.

RESULTS

PCA was upgraded on confirmatory biopsy in 107/371 (29%) patients. Inter-reader agreement was substantial (PI-RADSv2: k = 0.73; 95% CI [0.66-0.80]; ADC: r = 0.74; 95% CI [0.69-0.79]). Accuracies, sensitivities, specificities, positive predicted value and negative predicted value of PI-RADSv2 were 85, 89, 83, 68, 95 and 78, 82, 76, 58, 91% for ADC. PI-RADSv2 accuracy was significantly higher than that of ADC for predicting biopsy upgrade (p = 0.014). The combined PI-RADSv2 + ADC composite score did not perform better than PI-RADSv2 alone. Obviating biopsy in patients with PI-RADSv2 score ≤3 would have missed Gleason Score upgrade in 12/232 (5%) of patients.

CONCLUSION

PI-RADSv2 was superior to ADC measurements for predicting PCA upgrading on confirmatory biopsy.

Diagnostic value and relative weight of sequence-specific magnetic resonance features in characterizing clinically significant prostate cancers

Purpose

To assess the diagnostic weight of sequence-specific magnetic resonance features in characterizing clinically significant prostate cancers (csPCa).

Materials and methods

We used a prospective database of 262 patients who underwent T2-weighted, diffusion-weighted, and dynamic contrast-enhanced (DCE) imaging before prostatectomy. For each lesion, two independent readers (R1, R2) prospectively defined nine features: shape, volume (V_Max), signal abnormality on each pulse sequence, number of pulse sequences with a marked (S_Max) and non-visible (S_Min) abnormality, likelihood of extracapsular extension (ECE) and PSA density (dPSA). Overall likelihood of malignancy was assessed using a 5-level Likert score. Features were evaluated using the area under the receiver operating characteristic curve (AUC). csPCa was defined as Gleason ≥7 cancer (csPCa-A), Gleason ≥7(4+3) cancer (csPCa-B) or Gleason ≥7 cancer with histological extraprostatic extension (csPCa-C),

Results

For csPCa-A, the Signal1 model (S_Max+S_Min) provided the best combination of signal-related variables, for both readers. The performance was improved by adding V_Max, ECE and/or dPSA, but not shape. All models performed better with DCE findings than without.

When moving from csPCa-A to csPCa-B and csPCa-C definitions, the added value of V_Max, dPSA and ECE increased as compared to signal-related variables, and the added value of DCE decreased.

For R1, the best models were Signal1+ECE+dPSA (AUC = 0,805 [95%CI:0,757–0,866]), Signal1+V_Max+dPSA (AUC = 0.823 [95%CI:0.760–0.893]) and Signal1+ECE+dPSA [AUC = 0.840 (95%CI:0.774–0.907)] for csPCa-A, csPCA-B and csPCA-C respectively. The AUCs of the corresponding Likert scores were 0.844 [95%CI:0.806–0.877, p = 0.11], 0.841 [95%CI:0.799–0.876, p = 0.52]) and 0.849 [95%CI:0.811–0.884, p = 0.49], respectively.

For R2, the best models were Signal1+V_Max+dPSA (AUC = 0,790 [95%CI:0,731–0,857]), Signal1+V_Max (AUC = 0.813 [95%CI:0.746–0.882]) and Signal1+ECE+V_Max (AUC = 0.843 [95%CI: 0.781–0.907]) for csPCa-A, csPCA-B and csPCA-C respectively. The AUCs of the corresponding Likert scores were 0. 829 [95%CI:0.791–0.868, p = 0.13], 0.790 [95%CI:0.742–0.841, p = 0.12]) and 0.808 [95%CI:0.764–0.845, p = 0.006]), respectively.

Conclusion

Combination of simple variables can match the Likert score’s results. The optimal combination depends on the definition of csPCa.

Is contrast enhancement needed for diagnostic prostate MRI?

Prostate Imaging Reporting and Data System version 2 (PI-RADS v2) provides clinical guidelines for multiparametric magnetic resonance imaging (mpMRI) [T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI)] of prostate. However, DCE-MRI seems to show a limited contribution in prostate cancer (PCa) detection and management. In our experience, DCE-MRI, did not show significant change in diagnostic performance in addition to DWI and T2WI [biparametric MRI (bpMRI)] which represent the predominant sequences to detect suspected lesions in peripheral and transitional zone (TZ). In this article we reviewed the role of DCE-MRI also indicating the potential contribute of bpMRI approach (T2WI and DWI) and lesion volume evaluation in the diagnosis and management of suspected PCa.

[MRI of the prostate]

New clinical and technological advances in the field of magnetic resonance imaging (MRI) and targeted image-guided biopsy techniques have significantly improved the detection, localization and staging as well as active surveillance of prostate cancer in recent years. Multiparametric MRI (mpMRI) is currently the main imaging technique for the detection, characterization and diagnostics of metastasizing prostate cancer and is of high diagnostic importance for local staging within the framework of the detection of prostate cancer.

PI-RADS version 2: Preoperative role in the detection of normal-sized pelvic lymph node metastasis in prostate cancer

OBJECTIVES

To analyze whether Prostate Imaging Reporting and Data System (PI-RADSv2) scores are associated with a risk of normal-sized pelvic lymph node metastasis (PLNM) in prostate cancer (PCa).

MATERIALS AND METHODS

A consecutive series of 221 patients who underwent magnetic resonance imaging and radical prostatectomy with pelvic lymph node dissection (PLND) for PCa were retrospectively analyzed under the approval of institutional review board in our institution. No patients had enlarged (≥0.8cm in short-axis diameter) lymph nodes. Clinical parameters [prostate-specific antigen (PSA), greatest percentage of biopsy core, and percentage of positive cores], and PI-RADSv2 score from two independent readers were analyzed with multivariate logistic regression and receiver operating-characteristic curve for PLNM. Diagnostic performance of PI-RADSv2 and Briganti nomogram was compared. Weighted kappa was investigated regarding PI-RADSv2 scoring.

RESULTS

Normal-sized PLNM was found in 9.5% (21/221) of patients. In multivariate analysis, PI-RADSv2 (reader 1, p=0.009; reader 2, p=0.026) and PSA (reader 1, p=0.008; reader 2, p=0.037) were predictive of normal-sized PLNM. Threshold of PI-RADSv2 was a score of 5, where PI-RADSv2 was associated with high sensitivity (reader 1, 95.2% [20/21]; reader 2, 90.5% [19/21]) and negative predictive value (reader 1, 99.2% [124/125]; reader 2, 98.6% [136/138]). However, diagnostic performance of PI-RADSv2 (AUC=0.786-0.788) was significantly lower than that of Briganti nomogram (AUC=0.890) for normal-sized PLNM (p<0.05). The inter-reader agreement was excellent for PI-RADSv2 of 5 or not (weighted kappa=0.804).

CONCLUSION

PI-RADSv2 scores may be associated with the risk of normal-sized PLNM in PCa.

Review of Prostate Imaging Reporting and Data System version 2

Prostate MRI has been a hot topic in recent years in large part due to the high incidence of prostate cancer worldwide. Advances in technology have allowed multiparametric MRI to improve lesion detection and characterization in prostate imaging. Additionally, prostate MRI has shown great promise in the detection of clinically significant cancer. In 2012, the European Society of Urogenital Radiology established clinical guidelines for multiparametric MRI of the prostate to facilitate a greater level of standardization and consistency, which became known as the Prostate Imaging Reporting and Data System (PI-RADS). Subsequently, the American College of Radiology, European Society of Urogenital Radiology and the AdMeTech Foundation jointly created PI-RADS version 2. This article focuses on summarizing the key points of PI-RADS version 2.

Are magnetic resonance imaging undetectable prostate tumours clinically significant? Results of histopathological analyses

OBJECTIVE

To investigate whether tumours at threshold values for detection on magnetic resonance imaging (MRI) represent clinically significant tumours or not, and therefore the utility of MRI in active surveillance (AS) protocols.

PATIENTS AND METHODS

A retrospective analysis of a single institution database was performed after Institutional Review Board approval. Between 2010 and 2013, 1633 patients underwent robot-assisted laparoscopic prostatectomy (RALP) at a single institution by a single surgeon. Of these, 1361 had complete clinical data and were included in analysis. Multivariate logistic regression was used to assess histopathological grade compared to tumour size whilst controlling for biopsy Gleason score, prostate-specific antigen level, body mass index, race, and age.

RESULTS

Of 120 tumours <5 mm in size, four were Gleason score 4 + 3. Of 276 tumours of 5-10 mm, 22 (8.1%) were Gleason score 4 + 3 and one (0.2%) was Gleason score 8. On multivariate regression analyses, tumours of <5 mm were much less likely to be high grade (Gleason score >3 + 4) at RALP compared to larger tumours (3.3% vs 25.1%, P < 0.001), or Gleason score ⩾8 (0.0% vs 7.6%, P < 0.001). Size was further shown to significantly correlate with grade on multivariate regression (P < 0.001).

CONCLUSIONS

Prostate tumours below the detection threshold for MRI (5 mm) most probably represent clinically insignificant tumours, which alone would not necessitate leaving AS in favour of more aggressive therapy. These findings point to a possible role of MRI in modern AS protocols.

Dynamic contrast-enhanced imaging has limited added value over T2-weighted imaging and diffusion-weighted imaging when using PI-RADSv2 for diagnosis of clinically significant prostate cancer in patients with elevated PSA

AIM

To determine the added value of dynamic contrast-enhanced imaging (DCE) over T2-weighted imaging (T2-WI) and diffusion-weighted imaging (DWI) for detection of clinically significant prostate cancer (csPC) in patients with elevated prostate-specific antigen (PSA).

METHODS AND MATERIALS

Two hundred and forty-five patients with elevated PSA underwent multiparametric (mp) magnetic resonance imaging (MRI) of the prostate before biopsy. mpMRI was performed using a 3 T MRI system without an endorectal coil. Patients underwent transrectal ultrasound-guided systematic 12 core biopsy followed by radical prostatectomy (n=68), radiation therapy (n=91), or clinical follow-up for at least 2 years (n=86). csPC was defined as Gleason score ≥3+4 and/or tumour volume of ≥0.5 ml, and/or tumour stage ≥T3a. The MRI findings were scored according to the Prostate Imaging Reporting and Data System version 2 (PI-RADSv2) and an alternative overall assessment category (PI-RADSv2Alt) based on only T2-WI and DWI.

RESULTS

In 144 patients (58.8%), csPC was found within 2 years after MRI. With scoring according to the PI-RADSv2 guidelines, DCE was not needed for determination of the overall assessment category in 80.8% (198/245) of patients. Receiver operating characteristic (ROC) analysis showed an area under the curve of 0.79 (95% confidence interval [CI]: 0.74-0.85) for PI-RADSv2 and 0.79 (95% CI: 0.73-0.85) for PI-RADSv2Alt.

CONCLUSION

The added value of DCE over T2-WI and DWI is limited when using PI-RADSv2 for diagnosis of csPC in patients with elevated PSA before biopsy. An alternative overall assessment score using only T2-WI and DWI yielded similar performance to PI-RADSv2.

Prospective Pilot Trial to Evaluate a High Resolution Diffusion-Weighted MRI in Prostate Cancer Patients

OBJECTIVES

High-resolution prostate imaging may allow for detection of subtle changes in tumor size, decrease the reliance on biopsies, and help define tumor boundaries during ablation. This pilot clinical trial evaluates a novel high-resolution prostate MRI for detection of small, biopsy-proven prostate tumors.

METHODS

Our team developed a software that can be loaded on any modern MRI to generate high resolution diffusion-weighted imaging sequences (HR-DWI), which were compared to standard diffusion-weighted imaging sequence (S-DWI) in a prospective pilot trial in active surveillance patients. HR-DWI captures the entire volume of the prostate rather than sections, reducing streaking artifacts and geometric distortions. Multiple shots, rather than single shots, are used to differentiate signal and noise, enhancing resolution. All images were read by two radiologists. The primary outcome was the percent of biopsy-proven zones seen in 17 patients. The trial was powered to detect discordant proportions of 0.04 and 0.40 at one-sided alpha=0.05.

RESULTS

The resolution was defined using standard phantoms. HR-DWI produced a 5-fold improvement in spatial resolution when compared to S-DWI. Multiparametric (MP)-MRI incorporating S-DWI was useful for predicting biopsy results (AUC 0.72, Fisher's exact p<0.001); however, using HR-DWI allowed MP-MRI to be more highly predictive of biopsy results (AUC 0.88, Fisher's exact p<0.001). AUC for MP-MRI incorporating HR-DWI was significantly larger than MP-MRI incorporating S-DWI (p=0.002). MP-MRI with HR-DWI had a sensitivity of 95.7% and identified tumor in 22 of 23 zones proven to have cancer on biopsy. In contrast, MP-MRI with S-DWI had a sensitivity of 60.9% and only identified 14 of 23 biopsy-positive zones (p=0.004).

CONCLUSION

We developed a novel DWI and evaluated its improved resolution in a clinical setting. This technology has many potential applications and should be evaluated in future clinical trials as a patient management tool.

Restriction spectrum imaging improves MRI-based prostate cancer detection

PURPOSE

To compare the diagnostic performance of restriction spectrum imaging (RSI), with that of conventional multi-parametric (MP) magnetic resonance imaging (MRI) for prostate cancer (PCa) detection in a blinded reader-based format.

METHODS

Three readers independently evaluated 100 patients (67 with proven PCa) who underwent MP-MRI and RSI within 6 months of systematic biopsy (N = 67; 23 with targeting performed) or prostatectomy (N = 33). Imaging was performed at 3 Tesla using a phased-array coil. Readers used a five-point scale estimating the likelihood of PCa present in each prostate sextant. Evaluation was performed in two separate sessions, first using conventional MP-MRI alone then immediately with MP-MRI and RSI in the same session. Four weeks later, another scoring session used RSI and T2-weighted imaging (T2WI) without conventional diffusion-weighted or dynamic contrast-enhanced imaging. Reader interpretations were then compared to prostatectomy data or biopsy results. Receiver operating characteristic curves were performed, with area under the curve (AUC) used to compare across groups.

RESULTS

MP-MRI with RSI achieved higher AUCs compared to MP-MRI alone for identifying high-grade (Gleason score greater than or equal to 4 + 3=7) PCa (0.78 vs. 0.70 at the sextant level; P < 0.001 and 0.85 vs. 0.79 at the hemigland level; P = 0.04). RSI and T2WI alone achieved AUCs similar to MP-MRI for high-grade PCa (0.71 vs. 0.70 at the sextant level). With hemigland analysis, high-grade disease results were similar when comparing RSI + T2WI with MP-MRI, although with greater AUCs compared to the sextant analysis (0.80 vs. 0.79).

CONCLUSION

Including RSI with MP-MRI improves PCa detection compared to MP-MRI alone, and RSI with T2WI achieves similar PCa detection as MP-MRI.

The Efficacy of Multiparametric Magnetic Resonance Imaging and Magnetic Resonance Imaging Targeted Biopsy in Risk Classification for Patients with Prostate Cancer on Active Surveillance

PURPOSE

We determined whether multiparametric magnetic resonance imaging targeted biopsies may replace systematic biopsies to detect higher grade prostate cancer (Gleason score 7 or greater) and whether biopsy may be avoided based on multiparametric magnetic resonance imaging among men with Gleason 3+3 prostate cancer on active surveillance.

MATERIALS AND METHODS

We identified men with previously diagnosed Gleason score 3+3 prostate cancer on active surveillance who underwent multiparametric magnetic resonance imaging and a followup prostate biopsy. Suspicion for higher grade cancer was scored on a standardized 5-point scale. All patients underwent a systematic biopsy. Patients with multiparametric magnetic resonance imaging regions of interest also underwent magnetic resonance imaging targeted biopsy. The detection rate of higher grade cancer was estimated for different multiparametric magnetic resonance imaging scores with the 3 biopsy strategies of systematic, magnetic resonance imaging targeted and combined.

RESULTS

Of 206 consecutive men on active surveillance 135 (66%) had a multiparametric magnetic resonance imaging region of interest. Overall, higher grade cancer was detected in 72 (35%) men. A higher multiparametric magnetic resonance imaging score was associated with an increased probability of detecting higher grade cancer (Wilcoxon-type trend test p <0.0001). Magnetic resonance imaging targeted biopsy detected higher grade cancer in 23% of men. Magnetic resonance imaging targeted biopsy alone missed higher grade cancers in 17%, 12% and 10% of patients with multiparametric magnetic resonance imaging scores of 3, 4 and 5, respectively.

CONCLUSIONS

Magnetic resonance imaging targeted biopsies increased the detection of higher grade cancer among men on active surveillance compared to systematic biopsy alone. However, a clinically relevant proportion of higher grade cancer was detected using only systematic biopsy. Despite the improved detection of disease progression using magnetic resonance imaging targeted biopsy, systematic biopsy cannot be excluded as part of surveillance for men with low risk prostate cancer.

Prostate MRSI predicts outcome in radical prostatectomy patients

BACKGROUND

New non-invasive methods are needed for sub-stratifying high-risk prostate cancer patients. Magnetic resonance spectroscopic imaging (MRSI) maps metabolites in prostate cancer, providing information on tumor aggressiveness and volume.

PURPOSE

To investigate the correlation between MRSI and treatment failure (TF) after radical prostatectomy (RP).

METHODS

Two-hundred sixty-two patients who underwent endorectal MRI/MRSI followed by RP at our institution from 2003 to 2007 were studied. MRI stage, number of voxels in the MRSI index lesion (NILV), number of high-grade voxels (NHGV), and number of voxels containing undetectable polyamines (NUPV) were derived. Clinical outcome was followed until August, 2014. Treatment failure was defined as 1) biochemical recurrence (BCR), 2) persistently detectable PSA after RP, or 3) adjuvant therapy initiated in the absence of BCR. MRI/MRSI features and clinical parameters were compared to TF by univariate Cox Proportional Hazards Regression. After backward selection, each MRSI parameter was included in a separate regression model adjusted for NCCN-based clinical risk score (CRS), number of biopsy cores positive (NPC), and MRI stage.

RESULTS

In univariate analysis, all clinical variables were associated with TF in addition to MRI stage, NILV, NHGV, and NUPV. In multivariate analysis, NILV, NHGV, and NUPV were also significant risk factors for TF (p=0.016, p=0.002, p=0.006, respectively). The association between the number of tumor voxels with undetectable polyamines and the probability of treatment failure has not been previously reported. The number of MRSI cancer voxels correlated with extracapsular extension (ECE) (p<0.0001).

CONCLUSIONS

MRSI was associated with post-radical prostatectomy treatment failure in models adjusted for the number of positive biopsy cores and clinical risk score. This is the first report that in radical prostatectomy patients MRSI has an association with treatment failure independent of the number of positive biopsy cores. MRSI may help the clinician determine whether patients with high risk disease who undergo RP are candidates for specialized additional treatment.

Exponential apparent diffusion coefficient in evaluating prostate cancer at 3 T: preliminary experience

OBJECTIVE

To investigate the feasibility of exponential apparent diffusion coefficient (eADC) derived from diffusion-weighted imaging (DWI) in evaluating prostate cancers at 3 T.

METHODS

74 consecutive patients with surgically confirmed single peripheral zone (PZ) prostate cancer ≥0.5 cm(3) who underwent pre-operative DWI at 3 T were retrospectively selected. Based on radiological-pathological correlation, eADC and apparent diffusion coefficient (ADC) (×10(-3) mm(2) s(-1)) for the cancers and benign PZ were measured by two independent readers. Tumour eADC or ADC was correlated with Gleason score. Receiver operating characteristic curve analysis was performed to differentiate between Gleason score 6 and 7 or higher, by eADC and ADC. Lesion-to-background contrast ratio was compared between eADC and ADC.

RESULTS

Mean tumour eADC (0.48-0.50) and ADC (0.72-0.75) were significantly different from those of benign PZ (eADC, 0.20-0.27; ADC, 1.34-1.66), respectively (p < 0.001). A moderate correlation between tumour eADC or ADC and Gleason score was seen. For differentiating between Gleason score 6 and 7 or higher, eADC (0.818-0.883) showed a similar area under the curve with ADC (0.840-0.889) (p > 0.05). Lesion-to-background contrast ratio of eADC (Reader 1, 2.43; Reader 2, 2.23) was significantly greater than that of ADC (Reader 1, 2.21; Reader 2, 2.12) (p < 0.001).

CONCLUSION

The eADC may offer similar diagnostic utility with ADC in the differentiation of the cancer from benign prostate tissue. Moreover, the eADC appears to allow improved tissue contrast.

ADVANCES IN KNOWLEDGE

The eADC may be a comparable alternative to ADC for evaluating prostate cancer, with removing T2 shine-through effects from DWI.

Molecular Profiles of Prostate Cancer: To Treat or Not to Treat

A major dilemma in the selection of treatment for men with prostate cancer is the difficulty in accurately characterizing the risk posed by the cancer. This uncertainty has led physicians to recommend aggressive therapy for most men diagnosed with prostate cancer and has led to concerns about the benefits of screening and the adverse consequences of excessive treatment. Genomic analyses of prostate cancer reveal distinct patterns of alterations in the genomic landscape of the disease that show promise for improved prediction of prognosis and better medical decision making. Several molecular profiles are now commercially available and are being used to inform medical decisions. This article describes the clinical tests available for distinguishing aggressive from nonaggressive prostate cancer, reviews the new genomic tests, and discusses their advantages and limitations and the evidence for their utility in various clinical settings.

PI-RADS Prostate Imaging - Reporting and Data System: 2015, Version 2

The Prostate Imaging - Reporting and Data System Version 2 (PI-RADS™ v2) is the product of an international collaboration of the American College of Radiology (ACR), European Society of Uroradiology (ESUR), and AdMetech Foundation. It is designed to promote global standardization and diminish variation in the acquisition, interpretation, and reporting of prostate multiparametric magnetic resonance imaging (mpMRI) examination, and it is based on the best available evidence and expert consensus opinion. It establishes minimum acceptable technical parameters for prostate mpMRI, simplifies and standardizes terminology and content of reports, and provides assessment categories that summarize levels of suspicion or risk of clinically significant prostate cancer that can be used to assist selection of patients for biopsies and management. It is intended to be used in routine clinical practice and also to facilitate data collection and outcome monitoring for research.

Updated prostate imaging reporting and data system (PIRADS v2) recommendations for the detection of clinically significant prostate cancer using multiparametric MRI: critical evaluation using whole-mount pathology as standard of reference

OBJECTIVES

To evaluate the recommendations for multiparametric prostate MRI (mp-MRI) interpretation introduced in the recently updated Prostate Imaging Reporting and Data System version 2 (PI-RADSv2), and investigate the impact of pathologic tumour volume on prostate cancer (PCa) detectability on mpMRI.

METHODS

This was an institutional review board (IRB)-approved, retrospective study of 150 PCa patients who underwent mp-MRI before prostatectomy; 169 tumours ≥0.5-mL (any Gleason Score [GS]) and 37 tumours <0.5-mL (GS ≥4+3) identified on whole-mount pathology maps were located on mp-MRI consisting of T2-weighted imaging (T2WI), diffusion-weighted (DW)-MRI, and dynamic contrast-enhanced (DCE)-MRI. Corresponding PI-RADSv2 scores were assigned on each sequence and combined as recommended by PI-RADSv2. We calculated the proportion of PCa foci on whole-mount pathology correctly identified with PI-RADSv2 (dichotomized scores 1-3 vs. 4-5), stratified by pathologic tumour volume.

RESULTS

PI-RADSv2 allowed correct identification of 118/125 (94 %; 95 %CI: 90-99 %) peripheral zone (PZ) and 42/44 (95 %; 95 %CI: 89-100 %) transition zone (TZ) tumours ≥0.5 mL, but only 7/27 (26 %; 95 %CI: 10-42 %) PZ and 2/10 (20 %; 95 %CI: 0-52 %) TZ tumours with a GS ≥4+3, but <0.5 mL. DCE-MRI aided detection of 4/125 PZ tumours ≥0.5 mL and 0/27 PZ tumours <0.5 mL.

CONCLUSIONS

PI-RADSv2 correctly identified 94-95 % of PCa foci ≥0.5 mL, but was limited for the assessment of GS ≥4+3 tumours ≤0.5 mL. DCE-MRI offered limited added value to T2WI+DW-MRI.

KEY POINTS

• PI-RADSv2 correctly identified 95 % of PCa foci ≥0.5 mL • PI-RADSv2 was limited for the assessment of GS ≥4+3 tumours ≤0.5 mL • DCE-MRI offered limited added value to T2WI+DW-MRI.

Prostate-specific antigen-based prostate cancer screening: Past and future

Prostate-specific antigen-based prostate cancer screening remains a controversial topic. Up to now, there is worldwide consensus on the statement that the harms of population-based screening, mainly as a result of overdiagnosis (the detection of clinically insignificant tumors that would have never caused any symptoms), outweigh the benefits. However, worldwide opportunistic screening takes place on a wide scale. The European Randomized Study of Screening for Prostate Cancer showed a reduction in prostate cancer mortality through prostate-specific antigen based-screening. These population-based data need to be individualized in order to avoid screening in those who cannot benefit and start screening in those who will. For now, lacking a more optimal screening approach, screening should only be started after the process of shared decision-making. The focus of future research is the reduction of unnecessary testing and overdiagnosis by further research to better biomarkers and the value of the multiparametric magnetic resonance imaging, potentially combined in already existing prostate-specific antigen-based multivariate risk prediction models.

Information of prostate biopsy positive core: does it affect MR detection of prostate cancer on using 3T-MRI?

OBJECTIVE

We assessed which information from a prostate biopsy had the strongest relationship with prostate cancer detection by 3T-MRI.

MATERIALS AND METHODS

Sixty-one consecutive patients with biopsy-proven prostate cancer who underwent 3T-MRI before biopsy were enrolled in this retrospective study. Two radiologists independently reviewed T2-weighted and diffusion-weighted images. When the cancer lesions were revealed by biopsy and MRI depicted them at corresponding sites, we classified these lesions as MRI-detectable cancer. If the cancer lesions were revealed by biopsy, but any cancers had not been detected, we classified these lesions as MRI-undetectable cancer. We compared the Gleason score (GS), cancer ratio (CaR) and cancer length (CaL) from core biopsies between the two groups.

THE RESULTS

GS, CaR and CaL differed significantly between the MRI-detectable group (N = 70), and the MRI-undetectable group (N = 73). 3T-MRI could detect cancer cores with a sensitivity of 90.5% in cores with CaR ≥ 60%, and with a sensitivity of 81.8% in those with CaL ≥ 5 mm. Receiver operating characteristic analysis showed that CaR (P = 0.006) and CaL (P = 0.010) significantly associated with the prostate cancer detection using MRI rather than GS.

CONCLUSION

CaR and CaL from the core biopsies showed a stronger relationship to detection of the prostate cancer on 3T-MRI than the GS did.

[Prostate cancer]

For many clinical issues regarding prostate cancer magnetic resonance imaging (MRI) is gaining increasing importance for prostate diagnostics. The high morphological resolution of T2-weighted sequences is unsurpassed compared to other imaging modalities. It enables not only the detection and localization of prostate cancer but also allows the evaluation of extracapsular extensions. Functional MRI methods, such as diffusion-weighted imaging (DWI), dynamic contrast-enhanced (DCE) MRI and proton magnetic resonance spectroscopy ((1)H-MRS) increase the specificity and to a lesser extent, the sensitivity of diagnostics. In accordance with the interdisciplinary S3 guidelines, prostate MRI is recommended for patients with at least one negative biopsy for cancer detection. According to the guidelines areas suspected of being cancerous should be selectively biopsied in addition to the systematic biopsy. The transmission of findings about the suspected tumor areas according to the structured PI-RADS classification system has proven its worth. The localization and staging of prostate carcinoma is best achieved with the help of MRI and is recommended in the S3 guidelines especially for tumors with a clinical stage cT3/4 or with a Gleason grading system score ≥8. In addition to these applications MRI is mainly used under study conditions for local recurrence or active surveillance.

How accurate is multiparametric MR imaging in evaluation of prostate cancer volume?

PURPOSE

To assess the factors influencing multiparametric (MP) magnetic resonance (MR) imaging accuracy in estimating prostate cancer histologic volume (Vh).

MATERIALS AND METHODS

A prospective database of 202 patients who underwent MP MR imaging before radical prostatectomy was retrospectively used. Institutional review board approval and informed consent were obtained. Two independent radiologists delineated areas suspicious for cancer on images (T2-weighted, diffusion-weighted, dynamic contrast material-enhanced [DCE] pulse sequences) and scored their degree of suspicion of malignancy by using a five-level Likert score. One pathologist delineated cancers on whole-mount prostatectomy sections and calculated their volume by using digitized planimetry. Volumes of MR true-positive lesions were measured on T2-weighted images (VT2), on ADC maps (VADC), and on DCE images [VDCE]). VT2, VADC, VDCE and the greatest volume determined on images from any of the individual MR pulse sequences (Vmax) were compared with Vh (Bland-Altman analysis). Factors influencing MP MR imaging accuracy, or A, calculated as A = Vmax/Vh, were evaluated using generalized linear mixed models.

RESULTS

For both readers, Vh was significantly underestimated with VT2 (P < .0001, both), VADC (P < .0001, both), and VDCE (P = .02 and P = .003, readers 1 and 2, respectively), but not with Vmax (P = .13 and P = .21, readers 1 and 2, respectively). Mean, 25th percentile, and 75th percentile, respectively, for Vmax accuracy were 0.92, 0.54, and 1.85 for reader 1 and 0.95, 0.57, and 1.77 for reader 2. At generalized linear mixed (multivariate) analysis, tumor Likert score (P < .0001), Gleason score (P = .009), and Vh (P < .0001) significantly influenced Vmax accuracy (both readers). This accuracy was good in tumors with a Gleason score of 7 or higher or a Likert score of 5, with a tendency toward underestimation of Vh; accuracy was poor in small (<0.5 cc) or low-grade (Gleason score ≤6) tumors, with a tendency toward overestimation of Vh.

CONCLUSION

Vh can be estimated by using Vmax in aggressive tumors or in tumors with high Likert scores.

Prostate cancer: diagnostic performance of real-time shear-wave elastography

PURPOSE

To prospectively evaluate the performance of real-time ultrasonographic (US) shear-wave elastography (SWE) in the diagnosis of peripheral zone prostate cancer in patients with high and/or increasing prostate-specific antigen levels and/or abnormal digital rectal examination results.

MATERIALS AND METHODS

After signing an informed consent form, men referred for transrectal prostate biopsy were enrolled in this prospective HIPAA-compliant two-center study, which was conducted with institutional review board approval. Transrectal US SWE of the prostate was performed after a conventional transrectal US examination and immediately before US-guided 12-core sextant biopsy. For each sextant, the maximum SWE value was measured and matched to the pathologic results of that sextant biopsy. The diagnostic performance of SWE was assessed at both patient and sextant levels. The elasticity value maximizing the Youden index was used to derive sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV).

RESULTS

The elasticity values were matched to pathologic results for a total of 1040 peripheral zone sextants in 184 men. One hundred twenty-nine positive biopsy findings (size, ≥3 mm; Gleason score, ≥6) were identified in 68 patients. The sextant-level sensitivity, specificity, PPV, NPV, and area under the receiver operating characteristic curve for SWE with a cutoff of 35 kPa for differentiating benign from malignant lesions were 96% (95% confidence interval [CI]: 95%, 97%), 85% (95% CI: 83%, 87%), 48% (95% CI: 46%, 50%), 99% (95% CI: 98%, 100%), and 95% (95% CI: 93%, 97%), respectively.

CONCLUSION

Use of a 35-kPa threshold at SWE may provide additional information for the detection and biopsy guidance of prostate cancer, enabling a substantial reduction in the number of biopsies while ensuring that few peripheral zone adenocarcinomas are missed.

Clinical role of pathological downgrading after radical prostatectomy in patients with biopsy confirmed Gleason score 3 + 4 prostate cancer

OBJECTIVE

To identify preoperative factors predicting Gleason score downgrading after radical prostatectomy (RP) in patients with biopsy Gleason score 3+4 prostate cancer and to determine if prediction of downgrading can identify potential candidates for active surveillance (AS).

PATIENTS AND METHODS

We identified 1317 patients with biopsy Gleason score 3+4 prostate cancers who underwent RP at the Memorial Sloan-Kettering Cancer Center between 2005 and 2013. Several preoperative and biopsy characteristics were evaluated by forward selection regression, and selected predictors of downgrading were analysed by multivariable logistic regression. Decision curve analysis was used to evaluate the clinical utility of the multivariate model.

RESULTS

Gleason score was downgraded after RP in 115 patients (9%). We developed a multivariable model using age, prostate-specific antigen density, percentage of positive cores with Gleason pattern 4 cancer out of all cores taken, and maximum percentage of cancer involvement within a positive core with Gleason pattern 4 cancer. The area under the curve for this model was 0.75 after 10-fold cross validation. However, decision curve analysis revealed that the model was not clinically helpful in identifying patients who will downgrade at RP for the purpose of reassigning them to AS.

CONCLUSION

While patients with pathological Gleason score 3 + 3 with tertiary Gleason pattern ≤4 at RP in patients with biopsy Gleason score 3 + 4 prostate cancer may be potential candidates for AS, decision curve analysis showed limited utility of our model to identify such men. Future study is needed to identify new predictors to help identify potential candidates for AS among patients with biopsy confirmed Gleason score 3 + 4 prostate cancer.

Multiparametric 3T MRI for the prediction of pathological downgrading after radical prostatectomy in patients with biopsy-proven Gleason score 3 + 4 prostate cancer

OBJECTIVES

The aim of this study was to assess the diagnostic performance of pre-treatment 3-Tesla (3T) multiparametric magnetic resonance imaging (mpMRI) for predicting Gleason score (GS) downgrading after radical prostatectomy (RP) in patients with GS 3 + 4 prostate cancer (PCa) on biopsy.

METHODS

We retrospectively reviewed 304 patients with biopsy-proven GS 3 + 4 PCa who underwent mpMRI before RP. On T2-weighted imaging and three mpMRI combinations (T2-weighted imaging + diffusion-weighted imaging [DWI], T2-weighted imaging + dynamic contrast-enhanced-MRI [DCE-MRI], and T2-weighted imaging + DWI + DCE-MRI), two radiologists (R1/R2) scored the presence of a dominant tumour using a 5-point Likert scale (1 = definitely absent to 5 = definitely present). Diagnostic performance in identifying downgrading was evaluated via areas under the curves (AUCs). Predictive accuracies of multivariate models were calculated.

RESULTS

In predicting downgrading, T2-weighted imaging + DWI (AUC = 0.89/0.85 for R1/R2) performed significantly better than T2-weighted imaging alone (AUC = 0.72/0.73; p < 0.001/p = 0.02 for R1/R2), while T2-weighted imaging + DWI + DCE-MRI (AUC = 0.89/0.84 for R1/R2) performed no better than T2-weighted imaging + DWI (p = 0.48/p > 0.99 for R1/R2). On multivariate analysis, the clinical + mpMRI model incorporating T2-weighted imaging + DWI (AUC = 0.92/0.88 for R1/R2) predicted downgrading significantly better than the clinical model (AUC = 0.73; p < 0.001 for R1/R2).

CONCLUSION

mpMRI improves the ability to identify a subgroup of patients with Gleason 3 + 4 PCa on biopsy who are candidates for active surveillance. DCE-MRI (compared to T2 + DWI) offered no additional benefit to the prediction of downgrading.

KEY POINTS

Diagnostic performance of T2-weighted-imaging + DWI was better than T2-weighted-imaging alone. Diagnostic performance of T2-weighted-imaging + DWI was similar to T2-weighted-imaging + DWI + DCE-MRI. Combining clinical and T2-weighted-imaging + DWI features best predicted GS downgrading. mpMRI might prevent overtreatment by increasing eligibility for PCa active surveillance.