Prostate Imaging after Focal Ablation (PI-FAB): A Proposal for a Scoring System for Multiparametric MRI of the Prostate After Focal Therapy

Combining Percentage Prostate-Specific Antigen Reduction and Multiparametric Magnetic Resonance Imaging to Reduce Unnecessary Biopsy After Focal Therapy With High-Intensity Focused Ultrasound for Prostate Cancer

OBJECTIVES

To test the feasibility of combining percentage prostate-specific antigen (PSA) reduction and multiparametric magnetic resonance imaging (mpMRI) to determine the clinical scenario in which follow-up biopsy could be avoided after focal therapy (FT) with high-intensity focused ultrasound (HIFU) for prostate cancer.

METHODS

We reviewed 90 men treated with FT. Percentage PSA reduction was calculated by PSA nadir within postoperative 6 months. mpMRI was arranged at postoperative 6 months, followed by routine biopsy. Logistic regression analyses were performed to identify predictors for clinically significant prostate cancer (csPC) on follow-up biopsy. Receiver operating characteristic curve analysis was done to assess the area under the curve (AUC). The diagnostic performance of percentage PSA reduction and mpMRI to predict csPC was also calculated.

RESULTS

Eight patients had csPC recurrence. Percentage PSA reduction and Prostate Imaging-Reporting and Data System (PI-RADS) ≥ 3 at postoperative 6 months were predictors for csPC (p = 0.033 and p = 0.02, respectively). The AUC of mpMRI, percentage PSA reduction, and their combination were 0.95, 0.816, and 0.982, respectively. The sensitivity, specificity, positive predictive value, and negative predictive value of PSA reduction < 70% and PI-RADS ≥ 3 to predict csPC were 87.5%, 69.5%, 21.9%, 98.3%, and 87.5%, 96.3%, 70%, 98.8%, respectively. Using the criteria of PSA reduction < 70% or PI-RADS ≥ 3 to determine biopsy candidates could avoid 60% of biopsies, without missing csPC.

CONCLUSION

For patients whose PSA reduction > 70% and PI-RADS < 3, we suggested avoiding routine biopsy at 6 months after FT with HIFU.

Diagnostic Performance of Multiparametric MRI for Detection of Prostate Cancer After Focal Therapy

BACKGROUND

Minimally invasive focal therapy of low- to intermediate-risk prostate cancer is becoming more common and has demonstrated lower morbidity compared to other treatments. Multiparametric prostate magnetic resonance imaging (mpMRI) has the potential to be an effective posttreatment evaluation method for residual/recurrent neoplasm.

OBJECTIVE

This study aimed to evaluate the ability of mpMRI to detect residual/recurrent neoplasm after focal therapy treatment of prostate cancer using a 3-point Likert scale.

METHODS

This retrospective study included patients who underwent focal therapy utilizing cryoablation, high-frequency ultrasound, and radiofrequency ablation for low- to intermediate-risk prostate cancer with baseline mpMRI and biopsy and a 6- to 12-month follow-up mpMRI and biopsy. Three abdominal fellowship-trained readers were asked to evaluate the follow-up mpMRI utilizing a 3-point Likert scale based on the level of suspicion as "nonviable," "equivocal," or "viable." Diagnostic statistics and Light's κ for interreader variability were calculated.

RESULTS

A total of 142 patients were included (mean age, 65 ± 7 years). When considering "equivocal" or "viable" as positive, the overall sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the receiver operating characteristic curve (AUC) for detecting recurrent grade group (GG) 2 or greater disease for Reader 1 were 0.47, 0.83, 0.24, 0.93, and 0.65; for Reader 2, 0.73, 0.75, 0.26, 0.96, and 0.74; and for Reader 3, 0.73, 0.57, 0.17, 0.95, and 0.65. When considering "viable" as positive, the overall sensitivity, specificity, PPV, NPV, and AUC for Reader 1 were 0.47, 0.92, 0.41, 0.94, and 0.69; for Reader 2, 0.33, 0.97, 0.56, 0.93, and 0.65; and for Reader 3, 0.53, 0.84, 0.29, 0.94, and 0.69. κ was 0.39.

CONCLUSIONS

This study suggests that DCE and DWI are the most important sequences in mpMRI and demonstrates the efficacy of utilizing a 3-point grading system in detecting and diagnosing prostate cancer after focal therapy.

CLINICAL IMPACT

mpMRI can be used to monitor for residual/recurrent disease after focal therapy.

MRI after focal therapy for prostate cancer: what radiologists must know?

Focal therapy (FT) is a rapidly growing field aiming to minimize the side effects of whole gland treatments in patients with localized prostate cancer and multiparametric MRI plays an important role in patient selection, treatment planning, and post-treatment monitoring. This article reviews the currently available prostate cancer FT techniques, discusses the key imaging findings that affect patient selection and treatment planning, and illustrates the spectrum of expected and abnormal post-treatment MRI findings.

The prognostic role of prostate MRI in prostate cancer patients

PURPOSE OF REVIEW

Multiparametric MRI (mpMRI) has been included in the diagnostic pathway of prostate cancer (PCa). However, the role of this imaging modality in predicting clinical outcomes after diagnosis has been poorly addressed so far. This review aims to summarize the most relevant updates on the prognostic role of mpMRI.

RECENT FINDINGS

Baseline mpMRI features help to predict adverse pathology at radical prostatectomy (RP) and grade reclassification during active surveillance. Parameters derived at prostate mpMRI such as PI-RADS score 4-5, the maximum diameter of the index lesion and the presence of extracapsular invasion/seminal vesicle invasion are among the strongest predictors of biochemical recurrence (BCR) for men treated with RP. mpMRI-based predictive models can achieve similar accuracy for BCR prediction when compared with validated models that relied on final pathology. Moreover, the use of mpMRI findings to predict disease recurrence after radiotherapy or focal therapy seems to optimize patient's risk stratification after treatment, ruling out disease recurrence.

SUMMARY

Clinicians should account for prostate mpMRI findings when predicting clinical outcomes in patients diagnosed with PCa.

Surveillance After Focal Therapy for Prostate Cancer: A Comprehensive Review

Focal Therapy (FT) is an emerging treatment modality for prostate cancer (PCa). Due to its novelty, the research exploring how patients should be followed-up after treatment is limited. There is currently no established role for non-prostate-specific-antigen (PSA) biomarkers and PSMA PET. However, a combination of PSA testing, multiparametric magnetic resonance imaging (mpMRI), and systematic and targeted biopsies should routinely be used for surveillance after FT. PSA values that rise 1.0 ng/mL over the nadir after twelve months or rise 1.5 ng/mL over nadir after twenty-four to thirty-six months should raise suspicion for recurrence. The standard imaging technique is mpMRI, but it can often be difficult to interpret after FT, so using a scoring system such as prostate imaging after focal ablation (PI-FAB) or the transatlantic recommendations for prostate gland evaluation with magnetic resonance imaging after focal therapy (TARGET) allows for greater consistency between readers. This review seeks to summarize the current literature regarding surveillance after FT as it relates to biomarkers, imaging, biopsies, and consensus statements.

The Use of PI-FAB Score in Evaluating mpMRI After Focal Ablation of Prostate Cancer: Is It Reliable? Inter-Reader Agreement in a Tertiary Care Referral University Hospital

BACKGROUND/PURPOSE

to assess the inter-reader agreement of the PIFAB (Prostate Imaging after Focal Ablation) score, a new MRI-based standardized system for evaluating post-focal therapy prostate mpMRI, among radiologists in a single large cohort of patients treated with focal therapy (HIFU) in a tertiary care referral University Hospital.

METHODS

In total, 68 consecutive patients who underwent HIFU were included in this single-center retrospective observational study. A total of 109 post-HIFU follow-up mpMRIs were evaluated by three radiologists with varying levels of experience (12, 8, and 3 years, respectively). All patients underwent their first follow-up mpMRI at 6 months post-treatment, with 30 patients receiving additional evaluations at 18 months and 11 at 30 months.

RESULTS

The patients had a mean age of 70.6 ± 8.31 years, a mean pre-treatment PSA (prostate-specific antigen) of 7.85 ± 1.21 ng/mL, and a mean post-treatment PSA of 4.64 ± 4.2 ng/mL. The inter-reader agreement for PI-FAB among the three radiologists showed a Gwet's AC2 value of 0.941 (95% confidence interval: 0.904-0.978, p < 0.0001). For the most experienced radiologist, at the 6-month follow-up 64 (94.14%) patients were scored as PI-FAB 1, 1 (1.47%) as PI-FAB 2, and 3 (4.41%) as PI-FAB 3. At the 18-month and 30-month follow-ups all patients were scored as PI-FAB 1 (no suspicion of recurrence).

CONCLUSIONS

Our study demonstrates excellent inter-reader agreement among radiologists with varying levels of experience, confirming that the PI-FAB score is highly reproducible when evaluating post-treatment mpMRI scans. The low rate of PI-FAB 2 and PI-FAB 3 lesions observed at the first follow-up, coupled with the absence of significant recurrence in subsequent evaluations, suggests that HIFU is a reliable technique for prostate cancer treatment in selected patients.

Use of biochemical and imaging criteria for selecting patients for prostate biopsy in recurrence risk assessment post-HIFU therapy

PURPOSE

Despite the growing adoption of HIFU treatment for localized prostate cancer (PC), standardized criteria for evaluating success and predicting recurrence remain undefined. Herein, we analyze the predictive value of noninvasive tools such as PSA dynamics and MRI to determine recurrence.

METHODS

We identified from our HIFU therapy prospective registry patients who developed biopsy-proven recurrence, between 2016 and 2023. Clinically significant recurrence (CS-R) was defined as the presence of GG 2 or greater on control biopsy. Different modalities of PSA kinetics were analyzed and determinants for recurrence were based on either PSA or MRI criteria (PIRADS > 3). Sensitivity, specificity, PPV, and NPV were estimated based on single or combined criteria.

RESULTS

92 patients were included in the study. A total of 17(18%) patients had CS-R. Those patients presented higher PSA velocity (p < 0.001) and a higher proportion of PSA above nadir + 1 at 12 months (p = 0.001). Static PSA measurement and % of PSA drop were not associated with recurrence. Follow-up based on a combination of PSA parameters (PSA below nadir + 1) and MRI criteria had higher sensitivity (88%) and negative predictive value (96%) in detecting post-treatment recurrence. Limitation of the study included limited number of patients and a relatively short follow up period.

CONCLUSIONS

Post-HIFU recurrence surveillance through dynamic PSA monitoring shows better predictive value. Implementing 'for cause' surveillance biopsies guided by dynamic PSA changes along with mpMRI appears to enhance the detection of recurrences without missing a significant number of cases.

Navigating Focal Therapy for Prostate Cancer: Contemporary Perspectives and Future Trajectories in the Canadian Context

Objective: This article equips Canadian urologists with the latest advancements in focal therapy (FT) principles and outcomes while providing an overview of its current landscape in Canada, including challenges and future directions. Methods: We conducted a nonsystematic review of the literature on FT in urology and prostate cancer (PCa), focusing on Canadian-led studies. Articles were identified using PubMed, MEDLINE, and Google Scholar and selected based on relevance and originality. The final search was completed in April 2024. A survey was also conducted among Canadian urologists and radiologists practicing FT. It covered their experiences, access to technology, implementation challenges, and reimbursement policies. Data were collected via video calls, phone calls, or email, and responses were reported anonymously. Results: Fourteen Canadian urologists and radiologists performing FT were contacted, and 12 participated in this study. Despite the increasing adoption of FT by Canadian urologists, nationwide implementation remains limited due to financial constraints and resource shortages. This has restricted the availability of FT for Canadian men with PCa compared with their American and European counterparts. Only two provinces-Saskatchewan and Alberta-currently have billing codes for FT, forcing patients elsewhere to either join clinical trials or pay out of pocket. To close this care gap, equitable health care coverage and integration of FT into standard treatment options are essential. Conclusion: The quality of research in FT is showing promising improvements, with several clinical trials currently underway that may pave the way for broader acceptance within clinical guidelines by multiple urological societies. Although Canada has been slower to adopt FT compared with other parts of the world, Canadian urologists continue to advocate for provincial health care coverage to ensure that this innovative technology becomes accessible to Canadian patients.

Multiparametric MRI before and after Focal Therapy for Prostate Cancer: Pearls and Pitfalls for the Reporting Radiologist

In this era of personalized precision medicine, the accuracy of multiparametric MRI (mpMRI) and targeted biopsy in helping detect low-volume clinically significant prostate cancer has rekindled interest in focal therapy for primary prostate cancer. Such therapy may reduce the debilitating morbidity of radical whole-gland treatment. Post-focal therapy mpMRI surveillance is critical for assessing oncologic efficacy. Radiologists interpreting post-focal therapy mpMRI must be familiar with expected posttreatment changes and pitfalls in assessing posttreatment recurrence. In this review, the authors present their experience with mpMRI before and after focal therapy. While cryotherapy and irreversible electroporation are the primary modalities of focal therapy offered in their institution, the authors aim to provide a comprehensive overview of the more common focal therapy modalities in use. Pertinent considerations of mpMRI in pretreatment patient selection and treatment planning are discussed. The recently proposed standardized post-focal therapy assessment systems, Prostate Imaging after Focal Ablation (ie, PI-FAB) and Transatlantic Recommendations for Prostate Gland Evaluation with MRI after Focal Therapy (ie, TARGET), as well as pearls and pitfalls in the detection of tumor recurrence and medium- and long-term mpMRI surveillance of the post-focal therapy prostate, are also discussed. This review aims to provide a valuable reference for radiologists involved in the care of patients in the evolving field of prostate cancer focal therapy. Keywords: MR Imaging, Urinary, Prostate, Neoplasms-Primary, Focal Therapy, Prostate Cancer, MRI, Surveillance, Tumor Recurrence Published under a CC BY 4.0 license.

Is there a role of PSMA-PET in focal therapy planning and follow-up?

INTRODUCTION

Focal therapy (FT) is a promising alternative to radical treatments for localized Prostate Cancer (PCa) in selected patients. However, it is not yet considered a standard treatment option, and there is currently no consensus on managing patients after FT. In this context, Prostate-Specific Membrane Antigen Positron Emission Tomography (PSMA-PET) may support multiparametric MRI (mpMRI) for both pre-operative planning and follow-up. The aim of this systematic review was to provide a comprehensive overview of the current applications of PSMA-PET in the field of FT and to analyze its future perspectives.

EVIDENCE ACQUISITION

A literature search was performed using PubMed and Scopus databases, following the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) statement recommendations. All studies reporting data on PSMA-PET performed before and/or after FT for PCa were included. A narrative synthesis was employed to summarize the review findings. No quantitative synthesis was performed due to the heterogeneity and limitations of the studies.

EVIDENCE SYNTHESIS

Seven studies (2 case reports, 1 retrospective, and 4 prospective single-center studies) were included in this review. A moderate-severe risk of bias was assessed for the included studies. In the field of FT, PSMA-PET showed promising but yet not validated results with several possible applications: (1) pre-operative planning and staging, aiming to improve patient selection trough the identification of intraprostatic suspected lesions and more accurate local and systemic staging; (2) guidance for biopsy and Region of Interest (ROI) definition; (3) follow-up imaging tool, aiming to decrease the number of unnecessary surveillance biopsies.

CONCLUSIONS

Limited evidence exists regarding the use of PSMA-PET in the field of FT, considering pre-operative setting, treatment guidance and its use as a non-invasive tool to evaluate treatment success or failure and for follow-up. In this scenario, even if the current evidence is still limited and inconclusive, PSMA-PET showed promising results with several possible applications.

Applying Focal Therapy to Lesions Detected via Magnetic Resonance Imaging: Delivering Cancer Ablation Beyond the Visibility Phenomenon

The inclusion of imaging as a triage test in diagnostic guidelines for prostate cancer (PC) has introduced a visible target for guiding treatment allocation and disease management. Focal therapy (FT) is a promising approach with a low side-effect profile for treating magnetic resonance imaging (MRI)-visible PC within a limited framework of guideline recommendations or clinical trials. On the basis of accumulated clinical and research experience, we present a systematic approach to FT indications for ablation of visible targets that includes imaging findings, margin delineation, and energy selection. Confirmation of eligibility for FT is associated with the choice of energy source. We propose a 10-step framework that incorporates the contribution of all MRI sequences, the cancer growth pattern within the zonal anatomy to establish a margin around the MRI-visible lesion, safeguards for critical anatomic structures, and guidance for energy selection on the basis of specific properties. We discuss the key principles underlying this process. The aim of this methodology is to standardise FT interventions for MRI-visible PC and contribute to the development of a reproducible, stable treatment protocol. Quality control of the ablation procedure is crucial for broadening access to this technique beyond the confines of current regulatory pathways.

Patient summary

We propose a method for using results from magnetic resonance imaging (MRI) scans to guide targeted treatment of visible prostate cancer lesions. This will help to ensure accurate coverage and eradication of all of the cancer while minimising side effects.

Comparison of Transatlantic Recommendations for Prostate Gland Evaluation with MRI after Focal Therapy (TARGET) and Prostate Imaging after Focal Ablation (PI-FAB) for Detecting Recurrent Prostate Cancer at Prostate MRI

RATIONALE AND OBJECTIVES

The increasing use of focal therapy (FT) in localized prostate cancer (PCa) management requires a standardized MRI interpretation system to detect recurrent clinically significant PCa (csPCa). This pilot study evaluates the novel Transatlantic Recommendations for Prostate Gland Evaluation with MRI after Focal Therapy (TARGET) and compares its performance to that of the Prostate Imaging after Focal Ablation (PI-FAB) system.

MATERIALS AND METHODS

This retrospective study included 38 patients who underwent primary FT for localized PCa, with follow-up multiparametric MRI (mpMRI) and biopsy. Two radiologists assessed the mpMRIs using both PI-FAB and TARGET independently. Diagnostic performance metrics and area under the receiver operating characteristic curve (AUC) were calculated. Inter-reader and intrareader agreement were assessed using Cohen's κ and Kendall's τ.

RESULTS

14 patients had recurrent csPCa. PI-FAB showed high sensitivity (92.9% for both readers) and NPV (reader 1: 93.8%, reader 2: 92.9%) but moderate specificity (reader 1: 62.5%, reader 2: 54.2%). TARGET demonstrated lower sensitivity for one reader (reader 1: 78.6%, reader 2: 92.9%) but higher specificity (reader 1: 79.2%, reader 2: 62.5%) for both readers. Both systems displayed moderate inter-reader agreement (κ = 0.56 for PI-FAB, 0.57 for TARGET).

CONCLUSION

PI-FAB and TARGET exhibit similar performances in post-FT MRI. While PI-FAB had consistently high sensitivity, TARGET offered higher specificity for one reader. Moderate agreement levels demonstrate the viability of these systems in clinical settings and a promise for improvement.

Focal therapy for prostate cancer

Traditional treatments for localized prostate cancer include radical prostatectomy or radiation therapy but pose challenges due to treatment related side effects, namely erectile dysfunction and urinary incontinence. In recent years, focal therapy has emerged as a viable treatment option for localized low-intermediate risk prostate cancer in carefully selected patients. Short and medium-term studies show acceptable cancer control outcomes and reduced morbidity when comparing focal therapy to whole gland treatment for prostate cancer, however there is paucity of long-term studies. Here we review focal ablative therapies commonly used, discuss the role of imaging in monitoring treatment, and summarize oncologic outcomes based on studies to date.

ESR Essentials: using the right scoring system in prostate MRI-practice recommendations by ESUR

MRI has gained prominence in the diagnostic workup of prostate cancer (PCa) patients, with the Prostate Imaging Reporting and Data System (PI-RADS) being widely used for cancer detection. Beyond PI-RADS, other MRI-based scoring tools have emerged to address broader aspects within the PCa domain. However, the multitude of available MRI-based grading systems has led to inconsistencies in their application within clinical workflows. The Prostate Cancer Radiological Estimation of Change in Sequential Evaluation (PRECISE) assesses the likelihood of clinically significant radiological changes of PCa during active surveillance, and the Prostate Imaging for Local Recurrence Reporting (PI-RR) scoring system evaluates the risk of local recurrence after whole-gland therapies with curative intent. Underlying any system is the requirement to assess image quality using the Prostate Imaging Quality Scoring System (PI-QUAL). This article offers practicing radiologists a comprehensive overview of currently available scoring systems with clinical evidence supporting their use for managing PCa patients to enhance consistency in interpretation and facilitate effective communication with referring clinicians. KEY POINTS: Assessing image quality is essential for all prostate MRI interpretations and the PI-QUAL score represents  the standardized tool for this purpose. Current urological clinical guidelines for prostate cancer diagnosis and localization recommend adhering to the PI-RADS recommendations. The PRECISE and PI-RR scoring systems can be used for assessing radiological changes of prostate cancer during active surveillance and the likelihood of local recurrence after radical treatments respectively.

Established focal therapy-HIFU, IRE, or cryotherapy-where are we now?-a systematic review and meta-analysis

INTRODUCTION

Focal Therapy (FT) is a treatment option for the treatment of limited volume clinically significant prostate cancer (csPCa). We aim to systematically review outcomes of established FT modalities to assess the contemporary baseline and identify gaps in evidence that will aid in further trial and study design.

METHODS

We conducted a systematic review and meta-analysis of all primary studies reporting outcomes of FT using cryotherapy, high-intensity focused ultrasound (HIFU), and irreversible electroporation (IRE). We described patient inclusion criteria, selection tools, treatment parameters, and surveillance protocols, and pooled overall survival (OS), cancer-specific survival (CSS), metastasis-free survival (MFS), biochemical progression (BP), biopsy, secondary treatment, sexual, and urinary function outcomes. Composite failure was defined as salvage whole gland ablation, radical treatment, hormonal therapy or transition to watchful waiting.

SYNTHESIS

We identified 49 unique cohorts of men undergoing FT between 2008 and 2024 (21 cryotherapy, 20 HIFU, and 8 IRE). Median follow-up ranged from 6 to 63 months. Pooled OS was 98.0%, CSS 99.3%, and MFS 98.5%. Pooled BP was 9.4%/year. Biopsy was mandated post-FT within 24 months in 36/49 (73.5%) cohorts, with pooled csPCa (GG ≥ 2) rates of 22.2% overall, 8.9% infield, and 12.3% outfield. The pooled rate of secondary FT was 5.0%, radical treatment 10.5%, and composite failure 14.1%. Of 35 studies reporting sexual function, 45.7% reported a low, 48.6% moderate, and 5.7% severe impact. For 34 cohorts reporting urinary function, 97.1% reported a low impact. No differences were noted between cryotherapy, HIFU, or IRE in any of the outcomes.

CONCLUSION

FT with cryotherapy, HIFU, and IRE is associated with good short-intermediate term oncological and functional outcomes. However, outcome reporting is heterogeneous and often incomplete. Long-term follow-up and standardized reporting are required to better define and report FT outcomes.

Surveillance after Focal Therapy - a Comprehensive Review

BACKGROUND

to date, no standardized, evidence-based follow-up schemes exist for the monitoring of patients who underwent focal therapy (FT) and expert centers rely mainly on their own experience and/or institutional protocols. We aimed to perform a comprehensive review of the most advantageous follow-up strategies and their rationale after FT for prostate cancer (PCa).

METHODS

a narrative review of the literature was conducted to investigate different follow-up protocols of FT for PCa. Outcomes of interest were post-ablation oncological and functional outcomes and complications.

RESULTS

Oncological success after FT was generally defined as the biopsy-confirmed absence of clinically significant PCa in the treated zone. De novo PCa in the untreated area usually reflects an inaccurate patient selection and should be treated as primary PCa. During follow-up, oncological outcomes should be evaluated with periodic PSA, multiparametric MRI and prostate biopsy. The use of PSA derivatives and new biomarkers is still controversial and therefore not recommended. The first MRI after FT should be performed between 6-12 months to avoid ablation-related artifacts and diagnostic delay in case of FT failure. Other imaging modalities, such as PSMA PET/CT scan, are promising but still need to be validated in the post-FT setting. A 12-month "for-protocol" prostate biopsy, including targeted and systematic biopsy, was generally considered the preferred biopsy method to rule out tumor persistence/recurrence. Subsequent mpMRIs and biopsies should follow a risk-adapted approach depending on the clinical scenario. Functional outcomes should be periodically assessed using validated questionnaires within the first year, when typically recover to a new baseline. Complications, despite uncommon, should be strictly monitored mainly in the first month.

CONCLUSIONS

FT follow-up is a multifaceted process involving clinical, radiological, and histological assessment. Studies evaluating the impact of different follow-up strategies and ideal timings are needed to produce standardized protocols following FT.

MRI accuracy for recurrence after partial gland ablation with HIFU for localized prostate cancer. A systematic review and meta-analysis

BACKGROUND

Prostate cancer remains the most frequently diagnosed cancer among men. High-Intensity Focused Ultrasound (HIFU) has emerged as a thermal ablative technique for partial-gland-ablation (PGA), aiming to minimize collateral damage while maximizing tumor control. Monitoring after HIFU PGA relies on serial PSA testing, multiparametric-MRI, and biopsies. The diagnostic accuracy of MRI for clinically-significant cancer(csPCa) recurrence is challenging.

OBJECTIVE

This systematic review and meta-analysis aim to evaluate the accuracy of MRI in detecting early recurrence of localized prostate cancer following HIFU PGA.

METHODS

Adhering to PRISMA guidelines, a comprehensive literature search was conducted until May 8th 2024 using MEDLINE and Scopus. The inclusion criteria encompassed randomized controlled trials and cohort studies involving men diagnosed with localized prostate cancer who had as primary treatment HIFU PGA. The primary outcome measures included the sensitivity, specificity, positive-predictive value (PPV), and negative-predictive value (NPV) of MRI for csPCa(ISUP ≥ 2) based on biopsy results. We pooled data from studies with sufficient csPCa and csPCa-free patients (≥5) post HIFU for statistical analysis.

RESULTS

Fifteen studies meet the inclusion criteria, encompassing 1093 patients and 12 studies were eligible for meta-analysis. MRI sensitivity in detecting clinically-significant prostate cancer (csPCa) recurrence post HIFU PGA varied widely (0-89%), with a pooled sensitivity of 0.52 (95% CI:0.36-0.68). Specificity ranged from 44% to 100%, with a pooled specificity of 0.81 (95% CI:0.68-0.91). The pooled NPV was 0.82 (95% CI:0.72-0.90), and the pooled PPV was 0.50 (95% CI:0.35-0.65). Three studies reported in-field diagnostic performance with sensitivities ranging from 0.42 to 0.80 and specificities from 0.45 to 0.97.

CONCLUSION

MRI accuracy for clinically-significant recurrence after partial gland ablation with HIFU for localized prostate cancer shows low diagnostic performance in the treated lobe with pooled sensitivity of 0.52 (95% CI:0.36-0.68) and specificity of 0.81 (95% CI:0.68-0.91). Limits of this review include the low number of studies reporting about site of recurrence in or out of the treated lobe.

PI-QUAL version 2: A Multi-Reader reproducibility study on multiparametric MRI from a tertiary referral center

PURPOSE

To assess the inter-reader and intra-reader agreement of the Prostate imaging quality version 2 (PI-QUAL v.2) for multiparametric magnetic resonance imaging (mpMRI) among radiologists with varying levels of expertise.

METHODS

Fifty men underwent 3 T mpMRI scans in a tertiary referral center. Images were anonymized and assessed by six readers of different expertise (2 expert, 2 basic and 2 beginners) in two sessions: first using PI-QUAL v.2, and then using both PI-QUAL v.2 and v.1 after a 2-week interval. PI-QUAL v.2 scores were considered overall and, for comparison with PI-QUAL v.1, dichotomized according to the threshold of acceptable image quality. Gwet AC1 index was used to calculate the inter-reader and intra-reader agreement of the scores.

RESULTS

The inter-reader agreement for PI-QUAL v.2 scores was overall moderate (Gwet's AC1 = 0.55), being higher for expert readers compared to the beginner and basic ones (Gwet's AC1 = 0.66 versus 0.45-0-58). Intra-reader agreement varied from moderate to perfect (Gwet's AC1 = 0.43-1.00) and improved with increasing levels of expertise. The ratings were more reproducible for DWI and DCE sequences (Gwet's AC1 = 0.62-1.00) compared to T2w (Gwet's AC1 = 0.24-0.70). The intra-reader agreement between PI-QUAL v.2 and v.1 scores across readings ranged from almost perfect to perfect (Gwet's AC1 = 0.96-1.00).

CONCLUSIONS

In a tertiary referral center context, PI-QUAL v.2 is a moderately reliable tool for standardizing prostate mpMRI quality evaluations among readers with varying expertise.

The importance and future of prostate MRI report templates: improving oncological care

The radiologist's report is crucial for guiding care post-imaging, with ongoing advancements in report construction. Recent studies across various modalities and organ systems demonstrate enhanced clarity and communication through structured reports. This article will explain the benefits of disease-state specific reporting templates using prostate MRI as the model system. We identify key reporting components for prostate cancer detection and staging as well as imaging in active surveillance and following therapy. We discuss relevant reporting systems including PI-QUAL, PI-RADS, PRECISE, PI-RR and PI-FAB systems. Additionally, we examine optimal reporting structure including disruptive technologies such as graphical reporting and using artificial intelligence to improve report clarity and applicability.

Prospective close monitoring of the effect of vascular-targeted photodynamic therapy and high intensity focused ultrasound of localized prostate cancer by multiparametric magnetic resonance imaging

PURPOSE

The aim of this study is to describe the anatomical and functional changes observed in multiparametric magnetic resonance imaging (mpMRI) during follow-up after focal therapy (FT) for localized prostate cancer (PCa).

MATERIALS AND METHODS

In this prospective study, we analyzed pre- and postoperatively acquired mpMRI of 10 patients after FT (7 days; 3, 6, 9, 12 months). 7/10 (70%) patients underwent vascular-targeted photodynamic therapy (VTP). 3/10 (30%) patients underwent high-intensity focused ultrasound (HIFU). MpMR image analysis was performed using a semi-automatic software for segmentation of the prostate gland (PG) and tumor zones. Signal intensities (SI) of T2-weighted (T2w), T1-weighted (T1w),diffusion-weighted (DWI) and dynamic contrast-enhanced (DCE) images as well as volumes of the prostate gland (PGV) and tumor volumes (TV) were evaluated at each time point.

RESULTS

The results showed a significant increase of PGV 7 days after FT (p = 0.042) and a significant reduction of PGV between 7 days and 6, 9 and 12 months after FT (p < 0.001). The TV increased significantly 7 days after FT (p < 0.001) and decreased significantly between 7 days and 12 months after FT (p < 0.001). There was a significant increase in SI of the ADC in the ablation zone after 6, 9 and 12 months after FT (p < 0.001). 1/9 patients (11%) had recurrent tumor on rebiopsy characterized as a a small focal lesion on mpMRI with strong diffusion restriction (low SI on ADC map and high SI on b-value DWI).

CONCLUSION

MpMRI is able to represent morphologic changes of the ablated zone after FT and might be helpful to detect recurrent tumor.

Prostate MRI for the detection of clinically significant prostate cancer: Update and future directions

PURPOSE OF REVIEW

In recent decades, there has been an increasing role for magnetic resonance imaging (MRI) in the detection of clinically significant prostate cancer (csPC). The purpose of this review is to provide an update and outline future directions for the role of MRI in the detection of csPC.

RECENT FINDINGS

In diagnosing clinically significant prostate cancer pre-biopsy, advances include our understanding of MRI-targeted biopsy, the role of biparametric MRI (non-contrast) and changing indications, for example the role of MRI in screening for prostate cancer. Furthermore, the role of MRI in identifying csPC is maturing, with emphasis on standardization of MRI reporting in active surveillance (PRECISE), clinical staging (EPE grading, MET-RADS-P) and recurrent disease (PI-RR, PI-FAB). Future directions of prostate MRI in detecting csPC include quality improvement, artificial intelligence and radiomics, positron emission tomography (PET)/MRI and MRI-directed therapy.

SUMMARY

The utility of MRI in detecting csPC has been demonstrated in many clinical scenarios, initially from simply diagnosing csPC pre-biopsy, now to screening, active surveillance, clinical staging, and detection of recurrent disease. Continued efforts should be undertaken not only to emphasize the reporting of prostate MRI quality, but to standardize reporting according to the appropriate clinical setting.

MRI-based monitoring of prostate cancer after HIFU: Inter-reader agreement and diagnostic performance of the PI-FAB score

PURPOSE

To investigate inter-reader agreement, and diagnostic performance of the Prostate Imaging after Focal Ablation (PI-FAB) score applied to multiparametric MRI (mpMRI) in patients who underwent focal high-intensity focused ultrasound (HIFU) therapy for localized prostate cancer.

METHODS

In this retrospective, IRB-approved, single-center study, 73 men, who underwent focal HIFU treatment and received follow-up mpMRIs with subsequent prostate biopsies, were included. The PI-FAB score was applied to follow-up MRIs at 6, 12, and 36 months post-HIFU by two radiologists with different experience levels. Inter-reader agreement was assessed using Gwet's AC1, and the diagnostic performance of the PI-FAB score was assessed in relation to histopathologic results of subsequent prostate biopsies for each reader.

RESULTS

PI-FAB scores showed substantial to almost perfect inter-reader agreement (AC1: 0.80-0.95) and demonstrated high specificity (Reader 1: 90-98 %, Reader 2: 87-98 %) and NPVs (Reader 1: 91-100 %, Reader 2: 88-97 %) in ruling out residual or recurrent in-field prostate cancer post-HIFU. Sensitivity (Reader 1: ≥43 %, Reader 2: ≥14 %) and PPVs (Reader 1: ≥33 %, Reader 2: ≥14 %) were mostly relatively lower, with notable disparities between the two readers, indicating the potential influence of radiologist experience.

CONCLUSIONS

The PI-FAB score provides a consistent and reliable tool for post-HIFU monitoring of prostate cancer using mpMRI. It demonstrates substantial to almost perfect inter-reader agreement and is particularly effective in excluding in-field residual or recurrent prostate cancer post-HIFU treatment. Its application can potentially enhance post-treatment patient care, emphasizing its value as a non-invasive MRI-based monitoring approach after focal ablative therapy of the prostate.

Evaluating Diagnostic Accuracy and Inter-reader Agreement of the Prostate Imaging After Focal Ablation Scoring System

Background and objective

Focal therapy (FT) is increasingly recognized as a promising approach for managing localized prostate cancer (PCa), notably reducing treatment-related morbidities. However, post-treatment anatomical changes present significant challenges for surveillance using current imaging techniques. This study aimed to evaluate the inter-reader agreement and efficacy of the Prostate Imaging after Focal Ablation (PI-FAB) scoring system in detecting clinically significant prostate cancer (csPCa) on post-FT multiparametric magnetic resonance imaging (mpMRI).

Methods

A retrospective cohort study was conducted involving patients who underwent primary FT for localized csPCa between 2013 and 2023, followed by post-FT mpMRI and a prostate biopsy. Two expert genitourinary radiologists retrospectively evaluated post-FT mpMRI using PI-FAB. The key measures included inter-reader agreement of PI-FAB scores, assessed by quadratic weighted Cohen's kappa (κ), and the system's efficacy in predicting in-field recurrence of csPCa, with a PI-FAB score cutoff of 3. Additional diagnostic metrics including sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy were also evaluated.

Key findings and limitations

Scans from 38 patients were analyzed, revealing a moderate level of agreement in PI-FAB scoring (κ = 0.56). Both radiologists achieved sensitivity of 93% in detecting csPCa, although specificity, PPVs, NPVs, and accuracy varied.

Conclusions and clinical implications

The PI-FAB scoring system exhibited high sensitivity with moderate inter-reader agreement in detecting in-field recurrence of csPCa. Despite promising results, its low specificity and PPV necessitate further refinement. These findings underscore the need for larger studies to validate the clinical utility of PI-FAB, potentially aiding in standardizing post-treatment surveillance.

Patient summary

Focal therapy has emerged as a promising approach for managing localized prostate cancer, but limitations in current imaging techniques present significant challenges for post-treatment surveillance. The Prostate Imaging after Focal Ablation (PI-FAB) scoring system showed high sensitivity for detecting in-field recurrence of clinically significant prostate cancer. However, its low specificity and positive predictive value necessitate further refinement. Larger, more comprehensive studies are needed to fully validate its clinical utility.

Focal therapy with high-intensity focused ultrasound for prostate cancer: 3-year outcomes from a prospective trial

OBJECTIVE

To assess the oncological and functional outcomes of focal high-intensity focused ultrasound (HIFU) in treating localised prostate cancer (PCa), a 3-year prospective study was undertaken using periodic post-ablation saturation biopsies.

PATIENTS AND METHODS

Men with two or fewer lesions of grade group (GG) ≤3 PCa were eligible for participation. Additional criteria included a prostate-specific antigen (PSA) level of ≤15 ng/mL, clinical T1c-T2, and a life expectancy of ≥10 years. The primary endpoint was failure-free survival (FFS), defined as absence of clinically significant PCa (csPCa) in- or out-of-field on protocol-mandated saturation biopsy, no whole-gland or systemic salvage treatment, PCa metastasis, or PCa-related death. Results are reported using two distinct definitions of csPCa: (i) the presence of any GG ≥2 and (ii) any GG ≥3 or core involvement of ≥6 mm. Secondary endpoints were functional patient-reported outcome measures addressing urinary, sexual, and bowel function.

RESULTS

A total of 91 patients were included: six (7%) with GG1 and 85 (93%) with GG ≥2. In all, 83 (91%) underwent at least one follow-up biopsy. Biopsy attendance at 6, 12, and 36 months was 84%, 67%, and 51%, respectively. The FFS at these time points for any GG ≥2 PCa was 79% (95% confidence interval [CI] 80-88%), 57% (95% CI 48-69%) and 44% (95% CI 34-56%), respectively. Using the second definition, FFS were 88% (95% CI 81-95%), 70% (95% CI 61-81%) and 65% (95% CI 55-77%), respectively. The 3-year cancer-specific survival was 100%, and freedom from metastasis was 99%. Magnetic resonance imaging (MRI) (negative predictive value of up to 89%, 95% CI 84-93%) and relative decrease of PSA values (P = 0.4) performed poorly in detecting residual disease. Urinary and bowel assessment returned to baseline questionnaire scores within 3 months. In all, 17 (21%) patients reported meaningful worsening in erectile function. A significant decrease of PCa related anxiety was observed.

CONCLUSIONS

Focal HIFU treatment for localised PCa shows excellent functional outcomes with half of the patients remaining cancer-free after 3 years. Whole-gland treatment was avoided in 81%. Early follow-up biopsies are crucial to change or continue the treatment modality at the right time, while the use of MRI and PSA in detecting PCa recurrence is uncertain.

MRI-guided Focused Ultrasound Focal Therapy for Intermediate-Risk Prostate Cancer: Final Results from a 2-year Phase II Clinical Trial

Background MRI-guided focal therapy (FT) allows for accurate targeting of localized clinically significant prostate cancer (csPCa) while preserving healthy prostate tissue, but the long-term outcomes of this approach require more study. Purpose To assess the 2-year oncological and functional outcomes of men with intermediate-risk prostate cancer (PCa) treated with targeted FT. Materials and Methods In this single-center prospective phase II trial, men with localized unifocal intermediate-risk PCa underwent transrectal MRI-guided focused ultrasound between July 2016 and July 2019. Planned ablation volumes included 10-mm margins when possible. Data regarding adverse events were collected and quality-of-life questionnaires were completed by participants at 6 weeks and at 5, 12, 18, and 24 months after treatment. Multiparametric MRI and targeted and systematic biopsies were performed at 24 months. Ablation volumes were determined by manual contouring of nonperfused volumes on immediate contrast-enhanced images. Generalized estimating equations were used to model trends in quality-of-life measures. Results Treatment was successfully completed in the 44 participants (median age, 67 years; IQR, 62-70 years; 36 patients with grade group [GG] 2; eight patients with GG 3). No major adverse events from treatment were recorded. One participant refused biopsy at 24 months. After 2 years, 39 of 43 participants (91%) had no csPCa at the treatment site and 36 of 43 (84%) had no cancer in the entire gland. No changes in International Index of Erectile Function-15 score or International Prostate Symptom Score were observed during 2-year follow-up (P = .73 and .39, respectively). Conclusion The majority of men treated with MRI-guided focused ultrasound for intermediate risk PCa had negative results for csPCa at biopsy 2 years after treatment. Additionally, there was no significant decline in quality of life per the validated questionnaires. Clinical trial registration no. NCT02968784 © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Woodrum in this issue.

Follow-up of vascular-targeted photodynamic therapy in a real-world setting

PURPOSE

Vascular-targeted photodynamic therapy (VTP) is an approved treatment option for unilateral low-risk prostate cancer (PCa).

METHODS

Patients with unilateral low- or intermediate-risk PCa undergoing hemiablation by VTP were evaluated in a real-world setting. Oncological outcome after VTP was measured by MRI-based re-biopsy at 12 and 24 months. Functional outcome after 1 year was investigated by IIEF-5 and IPSS questionnaires. Progression was defined as the evidence3 of ISUP ≥ 2 PCa.

RESULTS

At any control biopsy (n = 46) after VTP, only 37% of patients showed no evidence of PCa. Recurrence-free survival was 20 months (95% CI 4.9-45.5) and progression-free survival was 38.5 months (95% CI 33.5-43.6 months). In-field and out-field recurrent PCa occurs in 37% (55% ISUP ≥ 2 PCa) and 35% (56% ISUP ≥ 2 PCa). Seventy-nine percent of patients preserved erectile function, respectively. Ten percent of patients presented long-term bladder outlet obstruction. None of the patients presented incontinence.

CONCLUSION

Due to the high-recurrence in- and out-field recurrence rate in a mainly low-risk prostate cancer cohort, VTP has to be regarded critically as a therapy option in these patients. Pre-interventional diagnostic evaluation is the main issue before focal therapy to reduce the risk of tumor recurrence and progression.

Taking PI-QUAL beyond the prostate: Towards a standardized radiological image quality score (RI-QUAL)

PURPOSE

To compare the interreader agreement of a novel quality score, called the Radiological Image Quality Score (RI-QUAL), to a slighly modified version of the existing Prostate Imaging Quality (mPI-QUAL) score for magnetic resonance imaging (MRI) of the prostate.

METHODS

A total of 43 consecutive scans were evaluated by two subspecialized radiologists who assigned scores using both the RI-QUAL and mPI-QUAL methods. The interreader agreement was analyzed using three statistical methods: concordance correlation coefficient (CCC), intraclass correlation coefficient (ICC), and Cohen's kappa. Time needed to arrive at a quality judgment was measured and compared using the Wilcoxon signed rank test.

RESULTS

The interreader agreement for RI-QUAL and mPI-QUAL scores was comparable, as evidenced by the high CCC (0.76 vs. 0.77, p = 0.93), ICC (0.86 vs. 0.87, p = 0.93), and moderate Cohen's kappa (0.61 vs. 0.64, p = 0.85) values. Moreover, RI-QUAL assessment was faster than mPI-QUAL (19 vs. 40 s, p = 0.001).

CONCLUSION

RI-QUAL is a new quality score that has comparable interreader agreement to the mPI-QUAL score, but with the potential to be applied to different MRI protocols and even different modalities. Like PI-QUAL, RI-QUAL may also facilitate communication about quality to referring physicians, as it provides a standardized and easily interpretable score. Further studies are warranted to validate the usefulness of RI-QUAL in larger patient cohorts and for other imaging modalities.