Multiparametric MRI: An Opportunity for Focal Therapy of Prostate Cancer

Is imaging accurate enough to detect index lesion in prostate cancer? Analysis of the performance of MRI and other imaging modalities

Prostate imaging techniques have progressed across the years allowing for a better detection and characterization of prostate cancer (PCa) lesions. These advancements have led to the possibility to also improve and tailor the treatments on the most aggressive lesion, defined as Index Lesion (IL), to reduce morbidity. The IL is, indeed, considered as the entity which encompass the most aggressive features in prostate cancer disease. Multiparametric magnetic resonance imaging (mpMRI) has emerged as the suggested tool to detect the disease and plan treatments, including those under investigation such as focal therapy (FT). Our review aimed to query the literature on the ability of mpMRI in IL detection and to explore the future perspectives in PCa IL diagnosis. A review of the literature was performed from January 2010 to July 2023. All studies investigating the performance of mpMRI and other main imaging techniques able to detect the IL were assessed and evaluated. mpMRI performs well in the detection of IL with a sensitivity which reaches 71% to 94% among the different studies. However, mpMRI seems to have limited sensitivity in the detection of small tumours (<0.5 mL) and low-grade histology lesions. To overcome these limitations other diagnostic imaging techniques have been proposed. Multiparametric Ultrasound has shown results comparable to mpMRI while detecting 4.3% fewer clinically significant PCa (P=0.042). Positron emission tomography-based modalities using PSMA seems to have higher sensitivity than mpMRI, being able to yield from 13.5% to 18.2% additional cancers. MRI has emerged as the recommended tool since most of the IL can be easily identified, and is the imaging of choice while selecting patients for FT. Other imaging modalities has been proposed to improve PCa lesions detection, but results need to be confirmed by ongoing randomized controlled trial.

Real-Time and Delayed Imaging of Tissue and Effects of Prostate Tissue Ablation

PURPOSE OF REVIEW

Prostate ablation is increasingly being utilized for the management of localized prostate cancer. There are several energy modalities with varying mechanism of actions which are currently used for prostate ablation. Prostate ablations, whether focal or whole gland, are performed under ultrasound and/or MRI guidance for appropriate treatment plan execution and monitoring. A familiarity with different intraoperative imaging findings and expected tissue response to these ablative modalities is paramount. In this review, we discuss the intraoperative, early, and delayed imaging findings in prostate from the effects of prostate ablation.

RECENT FINDINGS

The monitoring of ablation both during and after the therapy became increasingly important due to the precise targeting of the target tissue. Recent findings suggest that real-time imaging techniques such as MRI or ultrasound can provide anatomical and functional information, allowing for precise ablation of the targeted tissue and increasing the effectiveness and precision of prostate cancer treatment. While intraprocedural imaging findings are variable, the follow-up imaging demonstrates similar findings across various energy modalities. MRI and ultrasound are two of the frequently used imaging techniques for intraoperative monitoring and temperature mapping of important surrounding structures. Follow-up imaging can provide valuable information about ablated tissue, including the success of the ablation, presence of residual cancer or recurrence after the ablation. It is critical and helpful to understand the imaging findings during the procedure and at different follow-up time periods to evaluate the procedure and its outcome.

Does the type of biopsy used for diagnosis impact subsequent treatment selection in prostate cancer patients?

PURPOSE

Multiparametric magnetic resonance imaging (mpMRI) targeted biopsy has emerged as an augmentation to systematic prostate biopsy (SBx) with improved diagnostic accuracy. The purpose of this study was to determine whether biopsy modality impacted management of prostate cancer (PCa).

METHODS

We performed a retrospective review of patients with newly diagnosed non-metastatic PCa at our institution (2014-2020). Either ultrasound-guided 12-core SBx or SBx plus ≥1targeted biopsy cores from identifiable lesions on mpMRI were performed. Patients were managed with active surveillance (AS), radiation therapy (RT), or radical prostatectomy (RP). Multivariate logistic and multinomial regression analyses were performed.

RESULTS

Of 578 patients, 221(38%) proceeded with AS, 121(21%) received RT, and 236(41%) underwent RP. Median age and prostate-specific antigen (PSA) were 65.4 years and 7.2 ng/mL, respectively. On multivariate analysis, biopsy type did not predict decision to pursue treatment (p=.951). On multinomial regression analysis, biopsy type did not predict selection of AS over RP (p=.973) or RT over RP (p=.813). Alternatively, age, grade group, and PSA were significant predictors of management selection.

CONCLUSIONS

Biopsy technique did not impact management for patients with new PCa diagnosis. Despite paradigm shifts in obtaining tissue diagnosis, age, PSA, and grade group remain valuable indices for shared decision-making and counseling patients with PCa.

PI-RADS: what is new and how to use it

The prostate imaging reporting and data system (PI-RADS) has revolutionized the use of magnetic resonance imaging (MRI) for the management of prostate cancer (PCa). The most recent version 2.1, PI-RADS v2.1, provides specific refinements in the performance, relaxing some recommendations which were not found to be helpful, while reinforcing and clarifying others. The interpretation of T2-weighted imaging (T2WI) in the transition zone (TZ), and the overall assessment of TZ nodules, now allows for a clearer distinction between those which are clearly benign and those which might warrant tissue sampling. Additional changes also resolve discrepancies in T2WI and diffusion-weighted imaging (DWI) of the peripheral zone (PZ). PI-RADS v2.1 is a simpler, more straightforward, and more reproducible method to better communicate between physicians regarding findings on prostate MRI.

Multiparametric MRI-ultrasound fusion prostate biopsy in patients without prior diagnosis of prostate cancer: beyond centers of excellence

PURPOSE

Multiparametric magnetic resonance imaging (mpMRI)-ultrasound (US) fusion prostate biopsy (FBx) has demonstrated increased accuracy for prostate cancer detection at designated centers of excellence. There is a concern if their results can be reproduced in smaller centers. Here, we evaluate the outcomes of FBx from a smaller academic center.

METHODS

A retrospective review of patients without a prior diagnosis of prostate cancer undergoing FBx from January 2014 to November 2019 was performed. Histopathological results were grouped into low-risk disease (Grade Group 1), intermediate-risk disease (Grade Group 2 and 3), and high-risk disease (Grade Group 4 or 5). Clinically significant (CS) prostate cancer was defined as Grade Group ≥ 2.

RESULTS

Five hundred and six men were included. Median age (IQR) and PSA (IQR) were 65.2 (60.3-70.2) years and 6.9 (5.2-9.7) ng/ml, respectively. There was no difference in overall cancer detection between FBx and SBx (53.6% vs 56.4% p = .1507). CS cancer detection was significantly higher with FBx (39.6% vs 35.3, p = .0275). FBx also outperformed SBx in diagnosing CS disease in patients with prior history of negative prostate biopsy (36.9% vs 27.9%, p < .001).

CONCLUSION

FBx detects a higher proportion of clinically significant disease and a lower proportion of clinically insignificant disease compared to SBx, in line with outcomes demonstrated by centers of excellence.

Role of multiparametric prostate MRI in the management of prostate cancer

INTRODUCTION

Prostate cancer has traditionally been diagnosed by an elevation in PSA or abnormal exam leading to a systematic transrectal ultrasound (TRUS)-guided biopsy. This diagnostic pathway underdiagnoses clinically significant disease while over diagnosing clinically insignificant disease. In this review, we aim to provide an overview of the recent literature regarding the role of multiparametric MRI (mpMRI) in the management of prostate cancer.

MATERIALS AND METHODS

A thorough literature review was performed using PubMed to identify articles discussing use of mpMRI of the prostate in management of prostate cancer.

CONCLUSION

The incorporation of mpMRI of the prostate addresses the shortcomings of the prostate biopsy while providing several other advantages. mpMRI allows some men to avoid an immediate biopsy and permits visualization of areas likely to harbor clinically significant cancer prior to biopsy to facilitate use of MR-targeted prostate biopsies. This allows for reduction in diagnosis of clinically insignificant disease as well as improved detection and better characterization of higher risk cancers, as well as the improved selection of patients for active surveillance. In addition, mpMRI can be used for selection and monitoring of patients for active surveillance and treatment planning during surgery and focal therapy.

Analyzing the current practice patterns and views among urologists regarding focal therapy for prostate cancer

INTRODUCTION AND OBJECTIVE

Focal therapy (FT) for localized prostate cancer (CaP) has been shown to have encouraging short-term oncological outcomes, excellent preservation of functional outcomes and is increasing in popularity in urologic community. We aim to evaluate the preferences and practice trends among urologists regarding this treatment strategy.

METHODS

A 20 item online questionnaire was designed to collect information on urologists' views and use of FT. The survey was sent to the members of the Endourological Society and the American Urological Association. Multivariate logistic regression analysis was done to determine predictors for utilization of FT.

RESULTS

A total of 425 responses were received [American Urological Association: 319, Endourological Society: 106]. Mean age of respondents was 53(SD: 11.3) years. Although half of the respondents (50.8%) believed FT to be moderate to extremely beneficial in the treatment of CaP, only 24.2% (103) of the respondents currently utilize FT in their practice. Respondents who were fellowship trained in urologic oncology were more likely to consider FT to be at least moderately beneficial (P < 0.001). Surgeon's experience (greater than 15 years in urology practice) (P = 0.025) and seeing more than 10 patients with new CaP diagnosis per month (P = 0.002) were independent predictors of FT utilization for localized CaP. While the most common setting for utilization of FT was in patients with unilateral intermediate-risk (72.8%) CaP, a small percentage of respondents also used FT for patients with unilateral high-risk CaP and bilateral intermediate risk (21.4% and 10.7%, respectively). Most common reasons for not using FT were the lack of belief in 'index lesion theory' (63.2%), lack of experience (41.3%), lack of belief in FT's efficacy (41.1%), lack of infrastructure (35.8%), difficult salvage treatment in cases of recurrence (22.7%) and high cost (21.8%). About 57.6% would use FT more often in an office or outpatient setting if they had access to reliable and cost-effective options.

CONCLUSIONS

Only a quarter of our respondents utilize FT in their practice with surgeon's experience being the important independent predictor for using FT. Majority of respondents though consider FT to be beneficial in CaP management, would use it more often if provided more reliable and cost-effective options. Over time, experience and accessibility to reliable methods to perform FT may lead to further utilization of this novel treatment strategy.