The role of multi-parametric MRI in loco-regional staging of men diagnosed with early prostate cancer

Performance of an ultra-fast deep-learning accelerated MRI screening protocol for prostate cancer compared to a standard multiparametric protocol

OBJECTIVES

To establish and evaluate an ultra-fast MRI screening protocol for prostate cancer (PCa) in comparison to the standard multiparametric (mp) protocol, reducing scan time and maintaining adequate diagnostic performance.

MATERIALS AND METHODS

This prospective single-center study included consecutive biopsy-naïve patients with suspected PCa between December 2022 and March 2023. A PI-RADSv2.1 conform mpMRI protocol was acquired in a 3 T scanner (scan time: 25 min 45 sec). In addition, two deep-learning (DL) accelerated sequences (T2- and diffusion-weighted) were acquired, serving as a screening protocol (scan time: 3 min 28 sec). Two readers evaluated image quality and the probability of PCa regarding PI-RADSv2.1 scores in two sessions. The diagnostic performance of the screening protocol with mpMRI serving as the reference standard was derived. Inter- and intra-reader agreements were evaluated using weighted kappa statistics.

RESULTS

We included 77 patients with 97 lesions (mean age: 66 years; SD: 7.7). Diagnostic performance of the screening protocol was excellent with a sensitivity and specificity of 100%/100% and 89%/98% (cut-off ≥ PI-RADS 4) for reader 1 (R1) and reader 2 (R2), respectively. Mean image quality was 3.96 (R1) and 4.35 (R2) for the standard protocol vs. 4.74 and 4.57 for the screening protocol (p < 0.05). Inter-reader agreement was moderate (κ: 0.55) for the screening protocol and substantial (κ: 0.61) for the multiparametric protocol.

CONCLUSION

The ultra-fast screening protocol showed similar diagnostic performance and better imaging quality compared to the mpMRI in under 15% of scan time, improving efficacy and enabling the implementation of screening protocols in clinical routine.

CLINICAL RELEVANCE STATEMENT

The ultra-fast protocol enables examinations without contrast administration, drastically reducing scan time to 3.5 min with similar diagnostic performance and better imaging quality. This facilitates patient-friendly, efficient examinations and addresses the conflict of increasing demand for examinations at currently exhausted capacities.

KEY POINTS

Time-consuming MRI protocols are in conflict with an expected increase in examinations required for prostate cancer screening. An ultra-fast MRI protocol shows similar performance and better image quality compared to the standard protocol. Deep-learning acceleration facilitates efficient and patient-friendly examinations, thus improving prostate cancer screening capacity.

Evaluation of image-based prognostic parameters of post-prostatectomy urinary incontinence: A literature review

Prostate cancer is the second most common male cancer, and radical prostatectomy is a highly effective treatment for intermediate and high-risk disease. However, post-prostatectomy urinary incontinence remains a major functional side-effect in patients undergoing radical prostatectomy. Despite recent improvements in preoperative imaging quality and surgical techniques, it remains challenging to predict or prevent occurrence of this complication. The aim of this research was to review the current published literature on pre- and postoperative imaging evaluation of the prostate and pelvic structures, to identify added value in the prediction of post-prostatectomy urinary incontinence. A computerized bibliographic search of the PubMed library was carried out to identify imaging-based articles evaluating the pelvic floor and surrounding structures pre- and/or postradical prostatectomy to predict post-prostatectomy urinary incontinence. A total of 32 articles were included. Of these, 29 papers assessed the importance of magnetic resonance imaging evaluation, with a total of 16 parameters evaluated. The most common parameters were intravesical protrusion, the membranous urethral length, prostatic volume and periurethral fibrosis. Preoperative membranous urethral length and its preservation after surgery showed the strongest correlation with urinary incontinence. Three studies evaluated ultrasound, with all carried out postoperatively. This technique benefits from a dynamic evaluation, and the results are promising for proximal urethral hypermobility and the degree of bladder neck funneling on the Valsalva maneuver. Several imaging studies evaluated the predictors of post-prostatectomy urinary incontinence, with preoperative membranous urethral length offering the most promise. However, the current literature is limited by the single-center nature of studies, and the heterogeneity in patient populations and methodologies used.

Detection of Extraprostatic Extension of Cancer on Biparametric MRI Combining Texture Analysis and Machine Learning: Preliminary Results

RATIONALE AND OBJECTIVES

Extraprostatic extension of disease (EPE) has a major role in risk stratification of prostate cancer patients. Currently, pretreatment local staging is performed with MRI, while the gold standard is represented by histopathological analysis after radical prostatectomy. Texture analysis (TA) is a quantitative postprocessing method for data extraction, while machine learning (ML) employs artificial intelligence algorithms for data classification. Purpose of this study was to assess whether ML algorithms could predict histopathological EPE using TA features extracted from unenhanced MR images.

MATERIALS AND METHODS

Index lesions from biparametric MRI examinations of 39 patients with prostate cancer who underwent radical prostatectomy were manually segmented on both T2-weighted images and ADC maps for TA data extraction. Combinations of different feature selection methods and ML classifiers were tested, and their performance was compared to a baseline accuracy reference.

RESULTS

The classifier showing the best performance was the Bayesian Network, using the dataset obtained by the Subset Evaluator feature selection method. It showed a percentage of correctly classified instances of 82%, an area under the curve of 0.88, a weighted true positive rate of 0.82 and a weighted true negative rate of 0.80.

CONCLUSION

A combined ML and TA approach appears as a feasible tool to predict histopathological EPE on biparametric MR images.

Implementation of a 5-Minute Magnetic Resonance Imaging Screening Protocol for Prostate Cancer in Men With Elevated Prostate-Specific Antigen Before Biopsy

PURPOSE

The aims of this study were to establish a 5-minute magnetic resonance (MR) screening protocol for prostate cancer in men before biopsy and to evaluate effects on Prostate Imaging Reporting and Data System (PI-RADS) V2 scoring in comparison to a conventional, fully diagnostic multiparametric MR imaging (mpMRI) approach.

MATERIALS AND METHODS

Fifty-two patients with elevated prostate-specific antigen levels and without prior biopsy were prospectively included in this institutional review board-approved study. In all patients, an mpMRI protocol according to the PI-RADS recommendations was acquired on a 3 T MRI system. In addition, an accelerated diffusion-weighted imaging sequence was acquired using simultaneous multislice technique (DW-EPISMS). Two readers independently evaluated the images for the presence/absence of prostate cancer according to the PI-RADS criteria and for additional findings. In a first reading session, only the screening protocol consisting of axial T2-weighted and DW-EPISMS images was made available. In a subsequent reading session, the mpMRI protocol was assessed blinded to the results of the first reading, serving as reference standard.

RESULTS

Both readers successfully established a final diagnosis according to the PI-RADS criteria in the screening and mpMRI protocol. Mean lesion size was 1.2 cm in the screening and 1.4 cm in the mpMRI protocol (P = 0.4) with 35% (18/52) of PI-RADS IV/V lesions. Diagnostic performance of the screening protocol was excellent with a sensitivity and specificity of 100% for both readers with no significant differences in comparison to the mpMRI standard (P = 1.0). In 3 patients, suspicious lymph nodes were reported as additional finding, which were equally detectable in the screening and mpMRI protocol.

CONCLUSIONS

A 5-minute MR screening protocol for prostate cancer in men with elevated prostate-specific antigen levels before biopsy is applicable for clinical routine with similar diagnostic performance as the full diagnostic mpMRI approach.

New prostate cancer prognostic grade group (PGG): Can multiparametric MRI (mpMRI) accurately separate patients with low-, intermediate-, and high-grade cancer?

PURPOSE

Our objective is to determine the accuracy of multiparametric MRI (mpMRI) in predicting pathologic grade of prostate cancer (PCa) after radical prostatectomy (RP) using simple apparent diffusion coefficient metrics and, specifically, whether mpMRI can accurately separate disease into one of two risk categories (low vs. higher grade) or one of three risk categories (low, intermediate, or high grade) corresponding to the new prognostic grade group (PGG) criteria.

METHODS

This retrospective, HIPAA-compliant, IRB-approved study included 140 patients with PCa who underwent 3 T mpMRI with endorectal coil and transrectal ultrasound-guided (TRUS-G) biopsy before RP. MpMRI was used to classify lesions using a two-tier (low-grade/PGG 1 vs. high-grade/PGG 2-5) or a three-tier system (low-grade/PGG 1 vs. intermediate-grade/PGG 2 vs. high-grade/PGG 3-5). Accuracy of mpMRI was compared against RP for each system.

RESULTS

The predictive accuracy of mpMRI using the two-tier system is higher than when using three-tier system (0.77 and 0.45, respectively). There were similar rates of undergrading between mpMRI and TRUS-G biopsy compared to RP (16% & 21%; respectively); rate of overgrading was higher for mpMRI vs. TRUS-G biopsy compared to RP (42% & 17%, respectively). When mpMRI and TRUS-G biopsy are combined, rate of undergrading is 1.4% and overgrading is 11%.

CONCLUSIONS

MpMRI predictive accuracy is higher when using a two-tier vs. a three-tier system, suggesting that advanced metrics may be necessary to delineate intermediate- from high-grade disease. Rates of under- and overgrading decreased when mpMRI and TRUS-G biopsy are combined, suggesting that these techniques may be complementary in predicting tumor grade.

Magnetic resonance imaging in the early detection of prostate cancer and review of the literature on magnetic resonance imaging-stratified clinical pathways

INTRODUCTION

With level 1 evidence now available on the diagnostic accuracy of multiparametric magnetic resonance imaging (MRI) we must now utilise this data in developing an MRI-stratified diagnostic pathway for the early detection of prostate cancer. Areas covered: A literature review was conducted and identified seven randomised control trials (RCT's) assessing the diagnostic accuracy of such a pathway against the previously accepted systematic/random trans-rectal ultrasound guided (TRUS) biopsy pathway. The studies were heterogeneous in their design. Five studies assessed the addition of MRI-targeted biopsies to a standard care systematic TRUS biopsy pathway. Three of these studies showed either an increase in their diagnostic accuracy or the potential to remove systematic biopsies. Two studies looked specifically at a targeted biopsy only pathway and although the results were again mixed, there was no decrease in the diagnostic rate and overall significantly fewer biopsy cores were taken in the MRI group. Expert commentary: Results from these RCT's together with multiple retrospective and prospective studies point towards either an improved diagnostic rate for clinically significant cancer and/or a reduction in the need for systematic biopsies with a MRI-stratified pathway. The challenge for the urological community will be to implement pre-biopsy MRI into a routine clinical pathway with likely independent monitoring of standards.

Petersen P, Vogelius IR, Aznar MC. A modeling study of functional magnetic resonance imaging to individualize target definition of seminal vesicles for external beam radiotherapy

BACKGROUND

Pre-treatment magnetic resonance imaging (MRI) can give patient-specific evaluation of suspected pathologically involved volumes in the seminal vesicles (SV) in prostate cancer patients. By targeting this suspicious volume we hypothesize that radiotherapy is more efficient without introducing more toxicity. In this study we evaluate the concept of using MRI-defined target volumes in terms of tumor control probability (TCP) and rectal normal tissue complication probability (NTCP).

MATERIAL AND METHODS

Twenty-one high-risk prostate cancer patients were included. Pre-treatment CT images, T2 weighted (T2w) MRI and two multi-parametric MRI were acquired. Overlap between a suspicious volume in the SV observed on T2w images and a suspicious volume observed on either multi-parametric MRI was assumed to reflect a true malignant region (named 'MRI positive'). In addition the entire SV on the CT-scan was delineated. Three treatment plans of 2 Gy ×39 fractions were generated per patient: one covering the MRI positive volume in SV and prostate with margin of 11 mm to the MRI positive in the SV and two plans covering prostate and SV using 11 and 7 mm SV margin, respectively. All plans were prescribed the same PTV mean dose. Rectal NTCP grade ≥2 was evaluated with the Lyman-Kutcher-Burman model and TCP was estimated by a logistic model using the combined MRI positive volume in SV and prostate as region-of-interest.

RESULTS

Fourteen of twenty-one patients were classified as MRI positive, six of which had suspicious volumes in all three MRI modalities. On average TCP for the plan covering prostate and the MRI positive volume was 3% higher (up to 11%) than the two other plans which was statistically significant. The increased TCP was obtained without increasing rectal NTCP grade ≥2.

CONCLUSIONS

Using functional MRI for individualized target delineation in the SV may improve the treatment outcome in radiotherapy of prostate cancer without increasing the rectal toxicity.

Dramatic increase in the utilization of multiparametric magnetic resonance imaging for detection and management of prostate cancer

PURPOSE

Multiparametric MRI (mpMRI) of the prostate is an evolving technology that provides functional information of the prostate that helps distinguish benign from malignant lesions. We hypothesized that mpMRI is rapidly adopted in the US to fill the unmet need for a non-invasive, accurate screening tool. The aim of this study is to assess the increasing utilization of mpMRI for the diagnosis and management of prostate cancer.

METHODS

We conducted a retrospective review of an institutional clinical data repository of four million patients. Clinical information from all men undergoing mpMRI from October 2013 to December 2015 was collected in a prospectively designed database. Individual chart reviews were performed for each patient.

RESULTS

1521 mpMRI of the prostate were performed with an increase in the use of 486% over 26 months. The most common indication for mpMRI was abnormal screening (64%) and 47% of these men went on to prostate biopsy, either by cognitive mapping (65%) or MRI-US fusion targeting (35%). 261 men elected to defer prostate needle biopsy after informative decision-making with their urologist. 12.7% of mpMRI were performed for active surveillance, 7.5% for clinical staging, and 3.2% by radiation oncologists planning radiotherapy. 7% of mpMRI were performed to evaluate the pelvis for biochemical recurrence, a third of which identified a region of suspicion for targeted.

CONCLUSION

Prostate mpMRI is increasingly performed for both the diagnosis and management of prostate cancer. As clinical utilization increases along with the diffusion of technology and radiologic expertise, MpMRI has the potential to influence clinical decision-making and fulfill the need for a non-invasive, accurate tool for the diagnosis and management of prostate cancer.

The very-high-risk prostate cancer: a contemporary update

BACKGROUND

Treatment of high-risk prostate cancer has evolved considerably over the past two decades, yet patients with very-high-risk features may still experience poor outcome despite aggressive therapy. We review the contemporary literature focusing on current definitions, role of modern imaging and treatment alternatives in very-high-risk prostate cancer.

METHODS

We searched the MEDLINE database for all clinical trials or practice guidelines published in English between 2000 and 2016, with the following search terms: 'prostatic neoplasms' (MeSH Terms) AND ('high risk' (keyword) OR 'locally advanced' (keyword) OR 'node positive' (keyword)). Abstracts pertaining to very-high-risk prostate cancer were evaluated and 40 pertinent studies served as the basis for this review.

RESULTS

The term 'very'-high-risk prostate cancer remains ill defined. The European Association of Urology and National Comprehensive Cancer Network guidelines provide the only available definitions, categorizing those with clinical stage T3-4 or minimal nodal involvement as very high risk irrespective of PSA level or biopsy Gleason score. Modern imaging with multiparametric magnetic resonance imaging and positron emission tomography-prostate-specific membrane antigen scans has a role in pre-treatment assessment. Local definitive therapy by external beam radiation combined with androgen deprivation is supported by several randomized clinical trials, whereas the role of surgery in the very-high-risk setting combined with adjuvant radiation/androgen deprivation therapy is emerging. Growing evidence suggest neoadjuvant taxane-based chemotherapy in the context of a multimodal approach may be beneficial.

CONCLUSIONS

Men with very-high-risk tumors may benefit from local definitive treatment in the setting of a multimodal regimen, offering local control and possibly cure in well selected patients. Further studies are necessary to better characterize the 'very'-high-risk category and determine the optimal therapy for the individual patient.

Integration of multiparametric MRI into active surveillance of prostate cancer

Prostate cancer is the most common noncutaneous cancer in men though many men will not die of this disease and may not require definitive treatment. Active surveillance (AS) is an increasingly utilized potential solution to the issue of overtreatment of prostate cancer. Traditionally, prostate cancer patients have been stratified into risk groups based on clinical stage on digital rectal examination, prostate-specific antigen and biopsy Gleason score, though each of these variables has significant limitations. This review will discuss the potential role for prostate multiparametric MRI and targeted biopsy techniques incorporating MRI in the selection of candidates for AS, monitoring patients on AS and as triggers for definitive treatment.

Integrating MRI for the diagnosis of prostate cancer

PURPOSE OF REVIEW

We review recent developments in prostate MRI for prostate cancer diagnosis.

RECENT FINDINGS

Large series have strengthened the case for the use of MRI prior to subsequent biopsy to maximize the detection of clinically significant disease, and reduce the detection of clinically insignificant disease. This has effectively moved the discussion on from whether MRI is useful in prostate cancer detection to how best to use it, and at which time point. The Prostate Imaging- Reporting And Data System (PIRADS) group have published a second version of the PIRADS criteria for prostate MRI, covering acquisition, interpretation, and reporting both for clinical practice and data collection for research.There is debate about the commonly used and more prescriptive PIRADS system versus the less prescriptive systems based on overall clinical impression of clinically significant disease (e.g. Likert or simplified quantum scoring). Studies suggest that the Likert or simplified quantum scoring approach may outperform PIRADSv2. Published data are conflicting on whether software-assisted fusion of MRI lesions to ultrasound used at biopsy is more effective than visual registration by a trained operator.

SUMMARY

The use of prostate MRI is increasing worldwide, and the debate now focuses on how best to use it to optimize the detection of clinically significant disease.

Diagnostic Value of Guided Biopsies: Fusion and Cognitive-registration Magnetic Resonance Imaging Versus Conventional Ultrasound Biopsy of the Prostate

OBJECTIVE

To better assess the increased utilization of multiparametric magnetic resonance imaging (mpMRI) and fusion biopsy of the prostate, we compared prostate cancer detection rates among (a) men undergoing MR-ultrasound (US) fusion biopsy, (b) mpMRI cognitive-registration biopsy, and (c) conventional transrectal US-guided biopsy for the detection of prostate cancer.

MATERIALS AND METHODS

We present a retrospective review of consecutive patients undergoing mpMRI of the prostate with subsequent prostate biopsy from October 2013 to September 2015. Lesions concerning for prostate cancer visualized on mpMRI were targeted with cognitive-registration or MR-US fusion biopsies. A cohort of men undergoing conventional prostate biopsy was utilized for comparison. Rates of cancer detection were compared among the 3 cohorts.

RESULTS

A total of 231 patients underwent mpMRI-targeted biopsy (81 fusion, 150 cognitive). There was no difference in prostate specific antigen, mpMRI-defined Prostate Imaging Reporting and Data System score or number of lesions, or history of prostate cancer among the cohorts. The overall detection rate of cancer was significantly higher in the fusion cohort (48.1%) compared with both the cognitive (34.6% P = .04) and conventional (32.0%, P = .03) cohorts. Cancer detection rates were comparable in the MRI-cognitive and transrectal prostate US biopsy groups (34.6% vs 32%). MR fusion detected significantly more Gleason ≥7 cancer (61.5 vs 37.5%, P = .04) and significantly less Gleason 6 cancer (38.5 vs 62.5%, P = .04) compared with conventional biopsy.

CONCLUSION

Targeted biopsy of the prostate using MR-US fusion increased the cancer detection rate compared with both cognitive registration and conventional biopsy and was associated with detection of higher-grade cancer compared with conventional biopsy.

Evaluating the Role of mpMRI in Prostate Cancer Assessment

Prostate cancer is the most common malignancy among American men. The role of multi-parametric MRI has recently gained more importance in detection of prostate cancer, its targeted biopsy, and focal therapy guidance. In this review, uses of multi-parametric MRI in prostate cancer assessment and treatment are discussed.