Prostate Magnetic Resonance Imaging for Local Recurrence Reporting (PI-RR): International Consensus -based Guidelines on Multiparametric Magnetic Resonance Imaging for Prostate Cancer Recurrence after Radiation Therapy and Radical Prostatectomy

Post-Prostatectomy Magnetic Resonance-Guided Radiotherapy on a 1.5 Tesla Magnetic Resonance Integrated Linear Accelerator: Feasibility, Toxicity, and Preliminary Clinical Outcomes

INTRODUCTION

This study aimed to prospectively investigate magnetic resonance (MR)-guided radiotherapy (MRgRT) for post-prostatectomy prostate cancer and report preliminary clinical outcomes.

METHODS

All included patients underwent salvage or adjuvant adaptive MRgRT on a 1.5T MR integrated linear accelerator (MR-LINAC). Gastrointestinal and genitourinary toxicities were assessed. The primary endpoint was the progression-free survival (PFS) rate estimated by Kaplan-Meier (KM) survival analysis. A progression event was defined as the first occurrence of biochemical failure, radiological progression, or death. Secondary endpoints were biochemical failure-free survival (bFFS) rate, radiological PFS (rPFS) rate, and ≥G2 adverse events.

RESULTS

Thirty post-prostatectomy patients were enrolled and followed (median follow-up: 32.0 months; 3.0-48.1 months). Three patients had biochemical failure during follow-up. One patient developed pelvic node metastases. All patients were alive. The estimated PFS rates were 96.4% (95% confidence interval [95%CI]: 89.8%-100.0%) at 2 years and 78.8% (95%CI: 61.3%-100%) at 3 years. The estimated bFFS rates were 96.4% (95%CI: 89.8%-100%) /86.6%(95%CI: 73.4%-100%) at 2/3 years, respectively. The corresponding rPFS rates were 100% at 2 years and 92.3% (95%CI: 78.9%-100%) at 3 years, respectively. There was only one acute G2 GI adverse event (1/30, 3.33%) of abdominal pain occurred. Two late G2 events (one rectal bleeding and one urinary frequency) were scored (2/30, 6.67%). No ≥G3 events were observed.

CONCLUSION

Our findings suggest the feasibility, excellent patient tolerance, and encouraging efficacy of post-prostatectomy MRgRT, extending our knowledge of the clinical outcomes of MRgRT and serving as a benchmark for future investigation.

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.

The diagnostic performance and reader agreement of the Prostate Imaging for Recurrence Reporting system in the evaluation of local recurrence in patients with biochemically recurrent prostate cancer

BackgroundThe multiparametric magnetic resonance imaging (mpMRI)-based Prostate Imaging for Recurrence Reporting (PI-RR) system has been proposed to evaluate local recurrence in patients with prostate cancer (PCa) who have been treated with radiation therapy (RT) or radical prostatectomy (RP).PurposeTo evaluate the diagnostic performance and interreader agreement of the PI-RR system in the diagnosis of locally recurrent PCa remains.Material and MethodsA total of 110 patients who have biochemically recurrent PCa after RT (n = 35) or RP (n = 75) were included in this retrospective study. All patients underwent mpMRI, PSMA-PET/CT, and biopsy. Four radiologists with varying levels of expertise independently assessed the local recurrence of PCa using PI-RR. The reference standard was the biopsy pathology. The receiver operating characteristic (ROC) curve was used to evaluate the performance of PI-RR and PSMA-PET/CT, and areas under the ROC curve (AUC) were calculated. Interreader agreement across four readers was evaluated using the intraclass correlation coefficient (ICC).ResultsAmong 110 patients with biochemically recurrent PCa, 28 had local recurrence and 82 had no local recurrence. Using a cutoff of 4, the AUCs of PI-RR in the diagnosis of local recurrence were in the range of 0.61-0.84 in patients treated with RT and 0.71-0.89 in patients treated with RP. The ICC was 0.86 (95% confidence interval = 0.81-0.91).ConclusionPI-RR using a cutoff of 4 has a favorable diagnostic performance and interreader agreement, which might be alternatively used for detecting local recurrence in patients with biochemically recurrent PCa treated with RT or RP.

The Role of Dynamic Contrast Enhanced Magnetic Resonance Imaging in Evaluating Prostate Adenocarcinoma: A Partially-Blinded Retrospective Study of a Prostatectomy Patient Cohort With Whole Gland Histopathology Correlation and Application of PI-RADS or TNM Staging

BACKGROUND

Dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) in the current Prostate Imaging-Reporting and Data System version 2.1 (PI-RADS v2.1) is considered optional, with primary scoring based on T2-weighted imaging (T2WI) and diffusion weighted imaging (DWI). Our study is designed to assess the relative contribution of DCE MRI in a patient-cohort with whole mount prostate histopathology and spatially-mapped prostate adenocarcinoma (PCa) for reference.

METHODS

We performed a partially-blinded retrospective review of 47 prostatectomy patients with recent multi-parametric MRI (mpMRI). Scans included T2WI, DWI with apparent diffusion coefficient (ADC) mapping, and DCE imaging. Lesion conspicuity was scored on a 10-point scale with ≥ 6 considered "positive," and image quality was assessed on a 4-point scale for each sequence. The diagnostic contribution of DCE images was evaluated on a 4-point scale. The mpMRI studies were assigned PI-RADS scores and tumor, node, metastasis (TNM) T-stage with blinded comparison to spatially-mapped whole-mount pathology. Results were compared to the prospective clinical reports, which used standardized PI-RADS templates that emphasize T2WI, DWI and ADC.

RESULTS

Per lesion sensitivity for PCa was 93.5%, 82.6%, 63.0%, and 58.7% on T2WI, DCE, ADC and DWI, respectively. Mean lesion conspicuity was 8.5, 7.9, 6.2, and 6.1, on T2W, DCE, ADC and DWI, respectively. The higher values on T2WI and DCE imaging were not significantly different from each other but were both significantly different from DWI and ADC (p < 0.001). DCE scans were determined to have a marked diagnostic contribution in 83% of patients, with the most common diagnostic yield being detection of contralateral peripheral zone tumor or delineating presence/absence of extra-prostatic extension (EPE), contributing to more accurate PCa staging by PI-RADS or TNM, as compared to histopathology.

CONCLUSION

We demonstrate that DCE may contribute to lesion detection and local staging as compared to T2WI plus DWI-ADC alone and that lesion conspicuity using DCE is markedly improved as compared to DWI-ADC. These findings support modification of PI-RADS v2.1 to include use of DCE acquisitions and that a TNM staging is feasible on mpMRI as compared to surgical pathology.

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.

F18-DCFPyL PSMA-PET/CT Versus MRI: Identifying the Prostate Cancer Region Most at Risk of Radiation Therapy Recurrence for Tumor Dose Escalation

PURPOSE

Local recurrence of prostate cancer (PCa) after radiation therapy (RT) typically occurs at the site of dominant tumor burden, and recent evidence confirms that magnetic resonance imaging (MRI) guided tumor dose escalation improves outcomes. With the emergence of prostate-specific membrane antigen (PSMA) positron emission tomography (PET), we hypothesize that PSMA-PET and MRI may not equally depict the region most at risk of recurrence after RT.

METHODS AND MATERIALS

Patients with intermediate- to high-risk PCa and MRI plus PSMA-PET performed before RT were identified. The sextant most at risk of recurrence was defined as the pathologically dominant region with peak biopsy percentage core length involvement and any sextant with ≥ 40% percentage core length involvement (pathologic gross tumor volume [pGTV], per prior work). Imaging methods were reviewed independently to compare GTVs with pGTVs most at risk of recurrence. A paired chi-square test was employed for analysis.

RESULTS

Eighty-eight patients (n = 88) were identified. Overall, there were no differences in the sensitivity of MRI and PSMA-PET for identifying the pGTV most at risk of recurrence. However, PSMA-PET demonstrated a trend of improved sensitivity for high-risk PCa compared with MRI (n = 46, 96% vs 87%, P = .06), while MRI outperformed PSMA-PET for the intermediate-risk group (n = 42, 93% vs 81%, P = .03). PSMA-PET showed lower specificity, misidentifying GTV in uninvolved pathologic sextants for 12% of intermediate-risk patients, whereas MRI was faultless (12% vs 0%, P = .03). MRI and PSMA-PET each misidentified uninvolved sextants for 9% of patients in the high-risk group.

CONCLUSIONS

MRI demonstrates superior sensitivity in identifying the region most at risk of RT recurrence for intermediate-risk PCa, whereas PSMA-PET may add value for some high-risk patients. Informed by sextant biopsy information and MRI, clinicians should consider integrating PSMA-PET for patients with high-risk diseases when delineating GTVs.

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.

Imaging assessment of prostate cancer recurrence: advances in detection of local and systemic relapse

Prostate cancer (PCa) relapse, defined either by persistent PSA levels (after RP) or biochemical recurrence (BCR), is a common occurrence. The imaging evaluation of patients experiencing PCa relapse has undergone significant advancements in the past decade, notably with the introduction of new Positron Emission Tomography (PET) tracers such as Prostate-specific membrane antigen (PSMA), and the progress in functional Magnetic Resonance Imaging (MRI). This article will explore the role of traditional imaging, the evolution of MRI towards the development of the Prostate Magnetic Resonance Imaging for Local Recurrence Reporting (PI-RR) scoring system, and how next-generation imaging is enhancing diagnostic accuracy in the setting of PCa relapse, which is essential for adopting personalized strategies that may ultimately impact outcomes.

Interpreting Prostate Multiparametric MRI: Beyond Adenocarcinoma - Anatomical Variations, Mimickers, and Post-Intervention Changes

Prostate magnetic resonance imaging (MRI) is an essential tool in the diagnostic pathway for prostate cancer. However, its accuracy can be confounded by a spectrum of noncancerous entities with similar radiological features, posing a challenge for definitive diagnosis. This review synthesizes current knowledge on the MRI phenotypes of both common and rare benign prostate conditions that may be mistaken for malignancy. The narrative encompasses anatomical variants, other neoplastic processes, inflammatory conditions, and alterations secondary to medical interventions. Furthermore, this review underscores the critical role of MRI quality in diagnostic accuracy and explores the emerging contributions of artificial intelligence in enhancing image interpretation.

Prostate Imaging for Recurrence Reporting System Made Easy: A Case-Based Review of Prostate Cancer Local Recurrence on Magnetic Resonance Imaging

Prostate cancer (PCa) is one of the most prevalent cancers worldwide. Even following appropriate initial treatments, a subset of the patients develops tumor recurrence. Magnetic resonance imaging (MRI) is pivotal in investigating local recurrence, but its performance is limited in detecting recurrence at other sites (especially in subcentimeter lymph nodes). Recently, an expert consensus proposed a scoring system for MRI-based assessment of local recurrence, called prostate imaging for recurrence reporting system (PI-RR). This case-based review describes the expected post-treatment changes and MRI findings of local PCa recurrence after RP and RT.

The Role of Prostate-Specific Membrane Antigen-Radioligand and Magnetic Resonance Imaging in Patients with Prostate Cancer Biochemical Recurrence

A significant proportion of men with prostate cancer will experience biochemical recurrence (BCR), which is characterized by an elevation in prostate-specific antigen (PSA) levels after receiving treatment with curative intent. Imaging plays an important role in the management of patients with BCR. It can help identify sites of recurrence to determine the most appropriate management strategies, ranging from salvage treatment for local recurrences to systemic treatments for those with advanced, distant disease. PET/CT with prostate-specific membrane antigen (PSMA)-radioligands is the most sensitive method for the detection of prostate cancer recurrence, with significantly higher cancer detection rates compared to conventional imaging techniques such as bone scan and computed tomography, even at lower PSA levels. Nevertheless, interpretation of PSMA PET/CT images can be challenging, particularly for the evaluation of local recurrence due to urinary activity that can mimic or mask the presence of cancer. Furthermore, some prostate cancers may not express PSMA and have false negative results. Multiparametric prostate MRI is an excellent method for the evaluation of local recurrence and can overcome some of the limitations of PSMA PET/CT. In this review, we discuss the role of imaging in managing patients with prostate cancer BCR and describe the potential benefits of MRI in the PSMA-radioligand imaging era, emphasizing the assessment of local recurrence.

New Prostate MRI Scoring Systems (PI-QUAL, PRECISE, PI-RR, and PI-FAB): AJR Expert Panel Narrative Review

Multiparametric MRI (mpMRI), interpreted using PI-RADS, improves the initial detection of clinically significant prostate cancer. Prostate MR image quality has increasingly recognized relevance to the use of mpMRI for prostate cancer diagnosis. Additionally, mpMRI is increasingly used in scenarios beyond initial detection, including active surveillance and assessment for local recurrence after prostatectomy, radiation therapy, or focal therapy. In acknowledgment of these evolving demands, specialized prostate MRI scoring systems beyond PI-RADS have emerged to address distinct scenarios and unmet needs. Examples include Prostate Imaging Quality (PIQUAL) for assessment of image quality of mpMRI, Prostate Cancer Radiological Estimation of Change in Sequential Evaluation (PRECISE) recommendations for evaluation of serial mpMRI examinations during active surveillance, Prostate Imaging for Recurrence Reporting (PI-RR) system for assessment for local recurrence after prostatectomy or radiation therapy, and Prostate Imaging after Focal Ablation (PI-FAB) for assessment for local recurrence after focal therapy. These systems' development and early uptake signal a compelling shift toward prostate MRI standardization in different scenarios, and ongoing research will help refine their roles in practice. This AJR Expert Panel Narrative Review critically examines these new prostate MRI scoring systems (PI-QUAL, PRECISE, PI-RR, and PI-FAB), analyzing the available evidence, delineating current limitations, and proposing solutions for improvement.

Salvage Magnetic Resonance Imaging-guided Transurethral Ultrasound Ablation for Localized Radiorecurrent Prostate Cancer

Background and objective

Toxicity from local salvage therapy for radiorecurrent prostate cancer (PCa) remains a concern. This phase 2 study evaluates the outcomes of salvage magnetic resonance imaging (MRI)-guided transurethral ultrasound ablation (sTULSA).

Methods

Men with biochemically relapsed, biopsy-proven PCa following definitive radiotherapy underwent whole- or partial-gland sTULSA (NCT03350529). Prostate-confined recurrence was confirmed by MRI and prostate-specific membrane antigen (PSMA) positron emission tomography (PET) computed tomography (CT). The primary endpoints were safety (Clavien-Dindo classification) and efficacy (prostate-specific antigen [PSA], PSMA PET-CT, and MRI-targeted biopsy at 12 mo). The secondary endpoints included functional and survival outcomes.

Key findings and limitations

Thirty-nine patients underwent sTULSA (64% whole gland), with a median age of 73 yr (interquartile range [IQR]: 69-77) and PSA of 3.3 ng/ml (IQR: 2-6.2). Three patients had undergone prior salvage therapy, 16 were receiving hormonal therapy at enrollment, and 12 had a history of transurethral interventions. Eighteen patients had incidental urethral strictures on baseline cystoscopy. Over a median follow-up of 40 mo (IQR: 24-55), 56% experienced adverse events. Severe genitourinary toxicity (Clavien-Dindo ≥3 or hospitalization) occurred in 28%, including three patients with puboprostatic fistulas and two patients requiring cystectomy. Leak-free continence was maintained in 53%. At 12 mo, 89% showed no cancer in the targeted area, with a median PSA reduction of 95% (p < 0.001). Five-year metastasis-free, failure-free, and biochemical recurrence-free survival probabilities (95% confidence interval) were 97% (0.93-1.00), 70% (0.54-0.91), and 54% (0.31-0.93), respectively. Limitations included single-arm design and moderate sample size.

Conclusions and clinical implications

It has been observed that sTULSA is effective for radiorecurrent PCa, although genitourinary toxicity remains a concern. Further studies should refine patient selection and treatment parameters to improve safety and tolerability.

Patient summary

In this study, we examined a new treatment called magnetic resonance imaging-guided transurethral ultrasound ablation for prostate cancer that has returned after radiation therapy. We found that the treatment provided effective and lasting cancer control for most patients. However, a notable number of patients experienced significant genitourinary toxicity, including severe adverse effects affecting urinary function. Careful patient selection is crucial to minimize these adverse effects and ensure the best results.

Magnetic Resonance Imaging Techniques for Post-Treatment Evaluation After External Beam Radiation Therapy of Prostate Cancer: Narrative Review

Background/Objectives: This study aimed to investigate the prognostic value of advanced techniques of magnetic resonance imaging (MRI) biochemical recurrence (BCR) after radiotherapy in patients with prostate cancer (PCa). Methods: A comprehensive literature review was conducted to evaluate the role of MRI in detecting BCR of PCa patients after external beam radiation therapy. Results: National guidelines do not recommend imaging techniques in clinical follow-up PCa. However, in 2021, the European Association of Urogenital Radiology (ESUR), the European Association of Urological Imaging (ESUI), and the PI-RADS Steering Committee introduced the Prostate Imaging for Recurrence Reporting (PI-RR) system. PI-RR incorporates the MRI biomarkers in the post-treatment process. In the last decade, a growing number of clinical researchers have investigated the role of various MRI techniques in BCR. Conclusions: The integration of advanced MRI technologies into clinical routine marks the beginning of a new era of BCR with accuracy.

Comparison of tracer kinetic models in differentiating malignant from normal prostate tissue using dynamic contrast-enhanced MRI

Purpose

The aim of this study was to evaluate the diagnostic value of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) derived kinetic parameters with high spatiotemporal resolution in discriminating malignant from normal prostate tissues.

Methods

Fifty patients with suspicious of malignant diseases in prostate were included in this study. Regions of interest (ROI) were manually delineated by experienced radiologists. Voxel-wise kinetic parameters were produced with the following tracer kinetic models (TKMs): Tofts model, extended Tofts model (ETM), Brix's conventional two-compartment model (Brix), adiabatic tissue homogeneity model (ATH), and distributed parameter model (DP). The initial area under the signal-time curve (IAUC) with an uptake integral approach was also included. Mann-Whitney U test and receiver operating characteristic (ROC) curves were used to evaluate the capability of distinguishing tumor lesions from normal tissues. A p-value of 0.05 or less is considered statistically significant. ROI based parameters correlation analysis between DP and ETM were performed.

Results

624 lesions and 269 normal tissue ROIs were obtained. Thirty parameters were derived from the six kinetic models. Except for PS from Brix, statistically significant differences between lesions and normal tissues (P<0.05) were observed in other parameters.Ve from DP, ATH and Brix and PS from ATH have AUC values less than 0.6 in the ROC analysis. MTT, Vp and PS from DP, Ktrans from ETM and Tofts, E and PS from ATH, IAUC parameters and F from Brix have AUC values larger than 0.8. Ve and Vp from DP and ETM are correlated (r> 0.65). The correlation coefficient between Ktrans from ETM and PS from DP is 0.751.

Conclusion

MTT, Vp and PS from DP, Ktrans from ETM and Tofts, E and PS from ATH, F from Brix and IAUC parameters can be used to differentiate malignant lesions from normal tissues in the prostate.

Prostate Magnetic Resonance Imaging Using the Prostate Imaging for Recurrence Reporting (PI-RR) Scoring System to Detect Recurrent Prostate Cancer: A Systematic Review and Meta-analysis

BACKGROUND AND OBJECTIVE

Prostate Imaging for Recurrence Reporting (PI-RR) was introduced in 2021 to standardize the interpretation and reporting of multiparametric magnetic resonance imaging (MRI) for prostate cancer following whole-gland treatment. The system scores image on a scale from 1 to 5 and has shown promising results in single-center studies. The aim of our systematic review and meta-analysis was to assess the diagnostic performance of the PI-RR system in predicting the likelihood of local recurrence after whole-gland treatment.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for diagnostic test accuracy were followed. Relevant databases were searched up to December 2023. Primary studies met the eligibility criteria if they reported MRI diagnostic performance in prostate cancer recurrence using PI-RR. Diagnostic performance for MRI was assessed using two different cutoff points (≥3 or ≥4 for positivity according to the PI-RR system). A meta-analysis with a random-effects model was used to estimate pooled sensitivity and specificity values.

KEY FINDINGS AND LIMITATIONS

Sixteen articles were identified for full-text reading, of which six were considered eligible, involving a total of 467 patients. Using a cutoff of PI-RR ≥3 (4 studies) for recurrent disease, the sensitivity was 77.8% (95% confidence interval [CI] 69.9-84.1%) and the specificity was 80.2% (95% CI 58.2-92.2%). Using a cutoff of PI-RR ≥4 (4 studies), the sensitivity was 61.9% (95% CI 35.6-82.7%) and the specificity was 86.6% (95% CI 75.1-93.3%). Overall, the inter-rater agreement varied from fair to excellent.

CONCLUSIONS AND CLINICAL IMPLICATIONS

PI-RR is accurate in detecting local recurrence after whole-gland treatment for prostate cancer and shows fair-to-good to excellent inter-reader agreement. Overall, a PI-RR cutoff of ≥3 showed high sensitivity and specificity.

PATIENT SUMMARY

We reviewed studies that reported on how good MRI scans using a scoring system called PI-RR were in detecting recurrence of prostate cancer. We found that this system shows good performance, with fair to excellent agreement between different radiologists.

French AFU Cancer Committee Guidelines - Update 2024-2026: Prostate cancer - Management of metastatic disease and castration resistance

PURPOSE OF THIS DOCUMENT

The Oncology Committee of the French Urology Association is proposing updated recommendations for the management of recurrent and/or metastatic prostate cancer (PCa).

METHODS

A systematic review of the literature from 2022 to 2024 was conducted by the CCAFU on the therapeutic management of recurrent PCa following local or metastatic treatment, assessing the references based on their level of evidence.

RESULTS

Molecular imaging is the standard approach for assessing recurrence after local treatment and should not delay early salvage treatment. Androgen deprivation therapy (ADT) is the primary treatment option for metastatic PCa. Intensification of ADT, now cononsidered standard care for metastatic PCa, involves incorporating at least one new-generation hormone therapy (ARPI). For patients with high-volume metastatic disease at diagnosis, adding docetaxel to ADT+ARPI may be considered for eligible patients. In castration-resistant PCa (CRPC) patients, poly(ADP) ribose polymerase (PARP) inhibitors and PSMA radioligand therapy are new treatment options. The combination and sequencing of treatmentsare influenced by several factors, including patient and disease characteristics, prior therapies, genomic status, and molecular imaging findings.

CONCLUSION

This update of French recommendations should help to improve the management recurrent or metastatic PCa patients.

Reirradiation - still navigating uncharted waters?

With the emergence of high-precision radiotherapy technologies such as stereotactic ablative radiotherapy (SABR), MR guided brachytherapy, image guided intensity modulated photon and proton radiotherapy and most recently daily adaptive radiotherapy, reirradiation is increasingly recognized as a viable treatment option for many patients. This includes those with recurrent, metastatic or new malignancies post initial radiotherapy. The primary challenge in reirradiation lies in balancing tumor control against the risk of severe toxicity from cumulative radiation doses to previously irradiated normal tissue. Although technology for precise delivery has advanced at a fast pace, clinical practice of reirradiation still mostly relies on individual expertise, as prospective evidence is scarce, the level of reporting in clinical studies is not standardized and of low quality - especially with respect to cumulative doses received by organs at risk. A recent ESTRO/EORTC initiative proposed a standardized definition of reirradiation and formulated general requirements for minimal reporting in clinical studies [1]. As a consequence we found it timely to convene for an international and interdisciplinary meeting with experts in the field to summarize the current evidence, identify knowledge gaps and explore which best practices can be derived for safe reirradiation. The meeting was held on 15.06.2023 in Zurich and was endorsed by the scientific societies SASRO, DEGRO and ESTRO. Here, we report on available evidence and research priorities in the field of reirradiation, as discussed during the meeting.

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.

Quantitative Prostate MRI, From the AJR Special Series on Quantitative Imaging

Prostate MRI has traditionally relied on qualitative interpretation. However, quantitative components hold the potential to markedly improve performance. The ADC from DWI is probably the most widely recognized quantitative MRI biomarker and has shown strong discriminatory value for clinically significant prostate cancer (csPCa) as well as for recurrent cancer after treatment. Advanced diffusion techniques, including intravoxel incoherent motion, diffusion kurtosis, diffusion tensor imaging, and specific implementations such as restriction spectrum imaging, purport even better discrimination, but are more technically challenging. The inherent T1 and T2 of tissue also provide diagnostic value, with more advanced techniques deriving luminal water imaging and hybrid-multidimensional MRI. Dynamic contrast-enhanced imaging, primarily using a modified Tofts model, also shows independent discriminatory value. Finally, quantitative size and shape features can be combined with the aforementioned techniques and be further refined using radiomics, texture analysis, and artificial intelligence. Which technique will ultimately find widespread clinical use will depend on validation across a myriad of platforms use-cases.

Extracellular gadolinium-based contrast agents

Extracellular gadolinium-based contrast agents (GBCA) are commonly used in magnetic resonance imaging (MRI) because they increase the detection of alterations, improve tissue characterisation and enable a more precise differential diagnosis. GBCAs are considered to be safe but they are not risk-free. When using GBCAs, it is important to be aware of the risks and to know how to react in different situations (pregnancy, breastfeeding, kidney failure) including if complications occur (extravasations, adverse, allergic or anaphylactic reactions). The article describes the characteristics of the gadolinium molecule, the differences in the biochemical structure of these GBCA, their biodistribution and the effect on the MRI signal. It also reviews safety aspects and the most common clinical applications.

Integrated framework for quantitative T2-weighted MRI analysis following prostate cancer radiotherapy

Purpose

The aim of this study is to develop a framework for quantitative analysis of longitudinal T2-weighted MRIs (T2w) following radiotherapy (RT) for prostate cancer.

Materials and methods

The developed methodology includes: (i) deformable image registration of longitudinal series to pre-RT T2w for automated detection of prostate, peripheral zone (PZ), and gross tumor volume (GTV); and (ii) T2w signal-intensity harmonization based on three reference tissues. The REgistration and HARMonization (REHARM) framework was applied on T2w acquired in a clinical trial consisting of two pre-RT and three post-RT MRI exams. Image registration was assessed by the DICE coefficient between automatic and manual contours, and intensity normalization via inter-patient histogram intersection. Longitudinal consistency was evaluated by the repeatability coefficient and Pearson correlation (r) between the two T2w exams before RT.

Results

T2w from 107 MRI exams (23 patients) were utilized. Following REHARM, the histogram intersections for prostate, PZ and GTV increased from median = 0.43/0.16/0.13 to 0.66/0.44/0.46. The repeatability in T2w intensity estimation was better for the automatic than the manual contours for all three regions of interest (r = 0.9, p < 0.0001, for GTV). The changes in the tissues' T2w values pre- and post-RT became significant, indicating the measurable quantitative signal related to radiation.

Conclusions

The developed methodology allows to automate longitudinal analysis reducing data acquisition-related variation and improving consistency. The quantitative characterization of RT-induced changes in T2w will lead to new understanding of radiation effects enabling prediction modeling of RT response.

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.

What the urologist needs to know before radical prostatectomy: MRI effective support to pre-surgery planning

BACKGROUND

Radical prostatectomy (RP) is recommended in case of localized or locally advanced prostate cancer (PCa), but it can lead to side effects, including urinary incontinence (UI) and erectile dysfunction (ED). Magnetic resonance imaging (MRI) is recommended for PCa diagnosis and staging, but it can also improve preoperative risk-stratification.

PURPOSE

This nonsystematic review aims to provide an overview on factors involved in RP side effects, highlighting anatomical and pathological aspects that could be included in a structured report.

EVIDENCE SYNTHESIS

Considering UI evaluation, MR can investigate membranous urethra length (MUL), prostate volume, the urethral sphincter complex, and the presence of prostate median lobe. Longer MUL measurement based on MRI is linked to a higher likelihood of achieving continence restoration. For ED assessment, MRI and diffusion tensor imaging identify the neurovascular bundle and they can aid in surgery planning. Finally, MRI can precisely describe extra-prostatic extension, prostate apex characteristics and lymph-node involvement, providing valuable preoperative information for PCa treatment.

CONCLUSIONS

Anatomical principals structures involved in RP side effects can be assessed with MR. A standardized MR report detailing these structures could assist urologists in planning optimal and tailored surgical techniques, reducing complications, and improving patients' care.

Determining the optimal pharmacokinetic modelling and simplified quantification method of [18F]AlF-P16-093 for patients with primary prostate cancer (PPCa)

PURPOSE

This paper discusses the optimization of pharmacokinetic modelling and alternate simplified quantification method for [18F]AlF-P16-093, a novel tracer for in vivo imaging of prostate cancer.

METHODS

Dynamic PET/CT scans were conducted on eight primary prostate cancer patients, followed by a whole-body scan at 60 min post-injection. Time-activity curves (TACs) were obtained by drawing volumes of interest for primary prostatic and metastatic lesions. Optimal kinetic modelling involved evaluating three compartmental models (1T2K, 2T3K, and 2T4K) accounting for fractional blood volume (Vb). The simplified quantification method was then determined based on the correlation between the static uptake measure and total distribution volume (Vt) obtained from the optimal pharmacokinetic analysis.

RESULTS

In total, 17 intraprostatic lesions, 10 lymph nodes, and 36 osseous metastases were evaluated. Visually, the contrast of the tumor increased and showed the steepest incline within the first few minutes, whereas background activity decreased over time. Full pharmacokinetic analysis revealed that a reversible two-compartmental (2T4K) model is the preferred kinetic model for the given tracer. The kinetic parameters K1, k3, Vb, and Vt were all significantly higher in lesions when compared with normal tissue (P < 0.01). Several simplified protocols were tested for approximating comprehensive dynamic quantification in tumors, with image-based SURmean (the ratio of tumor SUVmean to blood SUVmean) within the 28-34 min window found to be sufficient for approximating the total distribution Vt values (R2 = 0.949, P < 0.01). Both Vt and SURmean correlated significantly with the total serum prostate-specific antigen (tPSA) levels (P < 0.01).

CONCLUSIONS

This study introduced an optimized pharmacokinetic modelling approach and a simplified acquisition method for [18F]AlF-P16-093, a novel PSMA-targeted radioligand, highlighting the feasibility of utilizing one static PET imaging (between 30 and 60 min) for the diagnosis of prostate cancer. Note that the image-derived input function in this study may not reflect the true corrected plasma input function, therefore the interpretation of the associated kinetic parameter estimates should be done with caution.

Application of next-generation imaging in biochemically recurrent prostate cancer

BACKGROUND

Biochemical recurrence (BCR) following primary interventional treatment occurs in approximately one-third of patients with prostate cancer (PCa). Next-generation imaging (NGI) can identify local and metastatic recurrence with greater sensitivity than conventional imaging, potentially allowing for more effective interventions. This narrative review examines the current clinical evidence on the utility of NGI for patients with BCR.

METHODS

A search of PubMed was conducted to identify relevant publications on NGI applied to BCR. Given other relevant recent reviews on the topic, this review focused on papers published between January 2018 to May 2023.

RESULTS

NGI technologies, including positron emission tomography (PET) radiotracers and multiparametric magnetic resonance imaging, have demonstrated increased sensitivity and selectivity for diagnosing BCR at prostate-specific antigen (PSA) concentrations <2.0 ng/ml. Detection rates range between 46% and 50%, with decreasing PSA levels for choline (1-3 ng/ml), fluciclovine (0.5-1 ng/ml), and prostate-specific membrane antigen (0.2-0.49 ng/ml) PET radiotracers. Expert working groups and European and US medical societies recommend NGI for patients with BCR.

CONCLUSIONS

Available data support the improved detection performance and selectivity of NGI modalities versus conventional imaging techniques; however, limited clinical evidence exists demonstrating the application of NGI to treatment decision-making and its impact on patient outcomes. The emergence of NGI and displacement of conventional imaging may require a reexamination of the current definitions of BCR, altering our understanding of early recurrence. Redefining the BCR disease state by formalizing the role of NGI in patient management decisions will facilitate greater alignment across research efforts and better reflect the published literature.

First-in-human study of PSMA-targeting agent, [18F]AlF-P16-093: dosimetry and initial evaluation in prostate cancer patients

PURPOSE

This is a first-in-human study to evaluate the radiation dosimetry of a new prostate-specific membrane antigen (PSMA)-targeted radiopharmaceutical, [18F]AlF-P16-093, and also initial investigation of its ability to detect PSMA-positive tumors using PET scans in a cohort of prostate cancer (PCa) patients.

METHODS

The [18F]AlF-P16-093 was automatically synthesized with a GE TRACERlab. A total of 23 patients with histopathologically proven PCa were prospectively enrolled. Dosimetry and biodistribution study investigations were carried out on a subset of six (6) PCa patients, involving multiple time-point scanning. The mean absorbed doses were estimated with PMOD and OLINDA software.

RESULTS

[18F]AlF-P16-093 was successfully synthesized, and radiochemical purity was > 95%, and average labeling yield was 36.5 ± 8.3% (decay correction, n = 12). The highest tracer uptake was observed in the kidneys, spleen, and liver, contributing to an effective dose of 16.8 ± 1.3 μSv/MBq, which was ~ 30% lower than that of [68Ga]Ga-P16-093. All subjects tolerated the PET examination well, and no reportable side-effects were observed. The PSMA-positive tumors displayed rapid uptake, and they were all detectable within 10 min, and no additional lesions were observed in the following multi-time points scanning. Each patient had at least one detectable tumor lesion, and a total of 356 tumor lesions were observed, including intraprostatic, lymph node metastases, bone metastases, and other soft tissue metastases.

CONCLUSIONS

We report herein a streamlined method for high yield synthesis of [18F]AlF-P16-093. Preliminary study in PCa patients has demonstrated its safety and acceptable radiation dosimetry. The initial diagnostic study indicated that [18F]AlF-P16-093 PET/CT is efficacious and potentially useful for a widespread application in the diagnosis of PCa patients.

The Transatlantic Recommendations for Prostate Gland Evaluation with Magnetic Resonance Imaging After Focal Therapy (TARGET): A Systematic Review and International Consensus Recommendations

BACKGROUND AND OBJECTIVE

Magnetic resonance imaging (MRI) can detect recurrences after focal therapy for prostate cancer but there is no robust guidance regarding its use. Our objective was to produce consensus recommendations on MRI acquisition, interpretation, and reporting after focal therapy.

METHODS

A systematic review was performed in July 2022 to develop consensus statements. A two-round consensus exercise was then performed, with a consensus meeting in January 2023, during which 329 statements were scored by 23 panellists from Europe and North America spanning urology, radiology, and pathology with experience across eight focal therapy modalities. Using RAND Corporation/University of California-Los Angeles methodology, the Transatlantic Recommendations for Prostate Gland Evaluation with MRI after Focal Therapy (TARGET) were based on consensus for statements scored with agreement or disagreement.

KEY FINDINGS AND LIMITATIONS

In total, 73 studies were included in the review. All 20 studies (100%) reporting suspicious imaging features cited focal contrast enhancement as suspicious for cancer recurrence. Of 31 studies reporting MRI assessment criteria, the Prostate Imaging-Reporting and Data System (PI-RADS) score was the scheme used most often (20 studies; 65%), followed by a 5-point Likert score (six studies; 19%). For the consensus exercise, consensus for statements scored with agreement or disagreement increased from 227 of 295 statements (76.9%) in round one to 270 of 329 statements (82.1%) in round two. Key recommendations include performing routine MRI at 12 mo using a multiparametric protocol compliant with PI-RADS version 2.1 standards. PI-RADS category scores for assessing recurrence within the ablation zone should be avoided. An alternative 5-point scoring system is presented that includes a major dynamic contrast enhancement (DCE) sequence and joint minor diffusion-weighted imaging and T2-weighted sequences. For the DCE sequence, focal nodular strong early enhancement was the most suspicious imaging finding. A structured minimum reporting data set and minimum reporting standards for studies detailing MRI data after focal therapy are presented.

CONCLUSIONS AND CLINICAL IMPLICATIONS

The TARGET consensus recommendations may improve MRI acquisition, interpretation, and reporting after focal therapy for prostate cancer and provide minimum standards for study reporting.

PATIENT SUMMARY

Magnetic resonance imaging (MRI) scans can detect recurrent of prostate cancer after focal treatments, but there is a lack of guidance on MRI use for this purpose. We report new expert recommendations that may improve practice.

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.

68Ga-RM2 PET-MRI versus MRI alone for evaluation of patients with biochemical recurrence of prostate cancer: a single-centre, single-arm, phase 2/3 imaging trial

BACKGROUND

National Comprehensive Cancer Network guidelines include prostate-specific membrane antigen (PSMA)-targeted PET for detection of biochemical recurrence of prostate cancer. However, targeting a single tumour characteristic might not be sufficient to reflect the full extent of disease. Gastrin releasing peptide receptors (GRPR) have been shown to be overexpressed in prostate cancer. In this study, we aimed to evaluate the diagnostic performance of the GRPR-targeting radiopharmaceutical 68Ga-RM2 in patients with biochemical recurrence of prostate cancer.

METHODS

This single-centre, single-arm, phase 2/3 trial was done at Stanford University (USA). Adult patients (aged ≥18 years) with biochemical recurrence of prostate cancer, a Karnofsky performance status of 50 or higher, increasing prostate-specific antigen concentration 0·2 ng/mL or more after prostatectomy or 2 ng/mL or more above nadir after radiotherapy, and non-contributory conventional imaging (negative CT or MRI, and bone scan) were eligible. All participants underwent 68Ga-RM2 PET-MRI. The primary outcome was the proportion of patients with PET-positive findings on 68Ga-RM2 PET-MRI compared with MRI alone after initial therapy, at a per-patient and per-lesion level. The primary outcome would be considered met if at least 30% of patients had one or more lesions detected by 68Ga-RM2 PET-MRI and the detection by 68Ga-RM2 PET-MRI was significantly greater than for MRI. Each PET scan was interpreted by three independent masked readers using a standardised evaluation criteria. This study is registered with ClinicalTrials.gov, NCT02624518, and is complete.

FINDINGS

Between Dec 12, 2015, and July 27, 2021, 209 men were screened for eligibility, of whom 100 were included in analyses. Median follow-up was 49·3 months (IQR 36·7-59·2). The primary endpoint was met; 68Ga-RM2 PET-MRI was positive in 69 (69%) patients and MRI alone was positive in 40 (40%) patients (p<0·0001). In the per-lesion analysis 68Ga-RM2 PET-MRI showed significantly higher detection rates than MRI alone (143 vs 96 lesions; p<0·0001). No grade 1 or worse events were reported.

INTERPRETATION

68Ga-RM2 PET-MRI showed better diagnostic performance than MRI alone in patients with biochemical recurrence of prostate cancer. Further prospective comparative studies with PSMA-targeted PET are needed to gain a better understanding of GRPR and PSMA expression patterns in these patients.

FUNDING

The US Department of Defense.

Identification of cell differentiation trajectory-related gene signature to reveal the prognostic significance and immune landscape in prostate cancer based on multiomics analysis

Background

In the context of prostate cancer (PCa), the occurrence of biochemical recurrence (BCR) stands out as a pivotal factor significantly impacting prognosis, potentially leading to metastasis and mortality. However, the early detection of BCR poses a substantial challenge for PCa patients. There is an urgent need to pinpoint hub genes that can serve as predictive indicators for BCR in PCa patients.

Methods

Our primary goal was to identify cell differentiation trajectory-related gene signature in PCa patients by pseudo-time trajectory analysis. We further explored the functional enrichment of overlapped marker genes and probed clinically relevant modules and BCR-related genes using Weighted Gene Co-expression Network Analysis (WGCNA) in PCa patients. Key genes predicting recurrence-free survival were meticulously identified through univariate and multivariate Cox regression analyses. Subsequently, these genes were utilized to construct a prognostic gene signature, the expression, predictive efficacy, putative functions, and immunological landscape of which were thoroughly validated. Additionally, we employed immunohistochemistry (IHC) and a western blotting assay to quantify the expression of PYCR1 in clinical samples.

Results

Our single-cell RNA (scRNA) sequencing analysis unveiled three subgroups characterized by distinct differentiation trajectories, and the marker genes associated with these groups were extracted from PCa patients. These marker genes successfully classified the PCa sample into two molecular subtypes, demonstrating a robust correlation with clinical characteristics and recurrence-free survival. Through WGCNA and Lasso analysis, we identified four hub genes (KLK3, CD38, FASN, and PYCR1) to construct a risk profile of prognostic genes linked to BCR. Notably, the high-risk patient group exhibited elevated levels of B cell naive, Macrophage M0, and Macrophage M2 infiltration, while the low-risk group displayed higher levels of T cells CD4 memory activated and monocyte infiltration. Furthermore, IHC and western blotting assays confirmed the heightened expression of PYCR1 in PCa tissues.

Conclusion

This study leveraged the differentiation trajectory and genetic variability of the microenvironment to uncover crucial prognostic genes associated with BCR in PCa patients. These findings present novel perspectives for tailoring treatment strategies for PCa patients on an individualized basis.

An MRI assessment of prostate cancer local recurrence using the PI-RR system: diagnostic accuracy, inter-observer reliability among readers with variable experience, and correlation with PSA values

OBJECTIVES

The Prostate Imaging for Recurrence Reporting (PI-RR) system has been recently proposed to promote standardisation in the MR assessment of prostate cancer (PCa) local recurrence after radical prostatectomy (RP) and radiation therapy (RT). This study aims to evaluate PI-RR's diagnostic accuracy, assess the inter-observer reliability among readers with variable experience, and correlate imaging results with anatomopathological and laboratory parameters.

METHODS

Patients who underwent a pelvic MRI for suspicion of PCa local recurrence after RP or RT were retrospectively enrolled (October 2017-February 2020). PI-RR scores were independently assessed for each patient by five readers with variable experience in prostate MRI (two senior and three junior radiologists). Biochemical data and histopathological features were collected. The reference standard was determined through biochemical, imaging, or histopathological follow-up data. Reader's diagnostic performance was assessed using contingency tables. Cohen's kappa coefficient (κ) and intraclass correlation coefficient (ICC) were calculated to measure inter-observer reliability.

RESULTS

The final cohort included 120 patients (median age, 72 years [IQR, 62-82]). Recurrence was confirmed in 106 (88.3%) patients. Considering a PI-RR score ≥ 3 as positive for recurrence, minimum and maximum diagnostic values among the readers were as follows: sensitivity 79-86%; specificity 64-86%; positive predictive value 95-98%; negative predictive value 33-46%; accuracy 79-87%. Regardless of reader's level of experience, the inter-observer reliability resulted good or excellent (κ ranges across all readers: 0.52-0.77), and ICC was 0.8. Prostate-specific antigen (PSA) velocity, baseline-PSA, and trigger-PSA resulted predictive of local recurrence at imaging.

CONCLUSIONS

The PI-RR system is an effective tool for MRI evaluation of PCa local recurrence and facilitates uniformity among radiologists.

CLINICAL RELEVANCE STATEMENT

This study confirmed the PI-RR system's good diagnostic accuracy for the MRI evaluation of PCa local recurrences. It showed high reproducibility among readers with variable experience levels, validating it as a promising standardisation tool for assessing patients with biochemical recurrence.

KEY POINTS

• In this retrospective study, the PI-RR system revealed promising diagnostic performances among five readers with different experience (sensitivity 79-86%; specificity 64-86%; accuracy 79-87%). • The inter-observer reliability among the five readers resulted good or excellent (κ ranges: 0.52-0.77) with an intraclass correlation coefficient of 0.8. • The PI-RR assessment score may facilitate standardisation and generalizability in the evaluation of prostate cancer local recurrence among radiologists.

Diagnostic Performance of 68Ga-PSMA-11 PET/CT Versus Multiparametric MRI for Detection of Intraprostatic Radiorecurrent Prostate Cancer

For men with prostate cancer who develop biochemical failure after radiotherapy, European guidelines recommend reimaging with 68Ga-PSMA-11 PET/CT and multiparametric MRI (mpMRI). However, the accuracy of 68Ga-PSMA-11 PET/CT for detecting intraprostatic recurrences is unclear, both with and without mpMRI. Methods: A single-center retrospective study of a series of patients investigated for radiorecurrence between 2016 and 2022 is described. All patients underwent 68Ga-PSMA-11 PET/CT, mpMRI, and prostate biopsy. PET/CT images were interpreted independently by 2 expert readers masked to other imaging and clinical data. The primary outcome was the diagnostic accuracy of PET/CT versus mpMRI and of PET/CT with mpMRI together versus mpMRI alone. The secondary outcome was the proportion of cancers missed by mpMRI but detected by PET/CT. Diagnostic accuracy analysis was performed at the prostate hemigland level using cluster bootstrapping. Results: Thirty-five men (70 hemiglands) were included. Cancer was confirmed by biopsy in 43 of 70 hemiglands (61%). PET/CT sensitivity and negative predictive values (NPVs) were 0.89 (95% CI, 0.78-0.98) and 0.79 (95% CI, 0.62-0.95), respectively, which were not significantly different from results by MRI (sensitivity of 0.72; 95% CI, 0.61-0.83; P = 0.1) (NPV of 0.59; 95% CI, 0.41-0.75; P = 0.07). Specificity and positive predictive values were not significantly different. When PET/CT and MRI were used together, the sensitivity was 0.98 (95% CI, 0.92-1.00) and NPV was 0.93 (95% CI, 0.75-1.00), both significantly higher than MRI alone (P = 0.003 and P < 0.001, respectively). Specificity and positive predictive values remained not significantly different. MRI missed 12 of 43 cancers (28%; 95% CI, 17%-43%), of which 11 of 12 (92%; 95% CI, 62%-100%) were detected by PET/CT. Conclusion: For detecting intraprostatic radiorecurrence, 68Ga-PSMA-11 PET/CT has high sensitivity that is not significantly different from mpMRI. When 68Ga-PSMA-11 PET/CT and mpMRI were used together, the results conferred a significantly greater sensitivity and NPV than with mpMRI alone. 68Ga-PSMA-11 PET/CT may therefore be a useful tool in the diagnosis of localized radiorecurrence.

The practical clinical role of machine learning models with different algorithms in predicting prostate cancer local recurrence after radical prostatectomy

BACKGROUND

The detection of local recurrence for prostate cancer (PCa) patients following radical prostatectomy (RP) is challenging and can influence the treatment plan. Our aim was to construct and verify machine learning models with three different algorithms based on post-operative mpMRI for predicting local recurrence of PCa after RP and explore their potential clinical value compared with the Prostate Imaging for Recurrence Reporting (PI-RR) score of expert-level radiologists.

METHODS

A total of 176 patients were retrospectively enrolled and randomly divided into training (n = 123) and testing (n = 53) sets. The PI-RR assessments were performed by two expert-level radiologists with access to the operative histopathological and pre-surgical clinical results. The radiomics models to predict local recurrence were built by utilizing three different algorithms (i.e., support vector machine [SVM], linear discriminant analysis [LDA], and logistic regression-least absolute shrinkage and selection operator [LR-LASSO]). The combined model integrating radiomics features and PI-RR score was developed using the most effective classifier. The classification performances of the proposed models were assessed by receiver operating characteristic (ROC) curve analysis.

RESULTS

There were no significant differences between the training and testing sets concerning age, prostate-specific antigen (PSA), Gleason score, T-stage, seminal vesicle invasion (SVI), perineural invasion (PNI), and positive surgical margins (PSM). The radiomics model based on LR-LASSO exhibited superior performance than other radiomics models, with an AUC of 0.858 in the testing set; the PI-RR yielded an AUC of 0.833, and there was no significant difference between the best radiomics model and the PI-RR score. The combined model achieved the best predictive performance with an AUC of 0.924, and a significant difference was observed between the combined model and PI-RR score.

CONCLUSIONS

Our radiomics model is an effective tool to predict PCa local recurrence after RP. By integrating radiomics features with the PI-RR score, our combined model exhibited significantly better predictive performance of local recurrence than expert-level radiologists' PI-RR assessment.

The Role of Multiparametric MRI and MRI-targeted Biopsy in the Diagnosis of Radiorecurrent Prostate Cancer: An Analysis from the FORECAST Trial

BACKGROUND

The role of multiparametric magnetic resonance imaging (MRI) for detecting recurrent prostate cancer after radiotherapy is unclear.

OBJECTIVE

To evaluate MRI and MRI-targeted biopsies for detecting intraprostatic cancer recurrence and planning for salvage focal ablation.

DESIGN, SETTING, AND PARTICIPANTS

FOcal RECurrent Assessment and Salvage Treatment (FORECAST; NCT01883128) was a prospective cohort diagnostic study that recruited 181 patients with suspected radiorecurrence at six UK centres (2014 to 2018); 144 were included here.

INTERVENTION

All patients underwent MRI with 5 mm transperineal template mapping biopsies; 84 had additional MRI-targeted biopsies. MRI scans with Likert scores of 3 to 5 were deemed suspicious.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

First, the diagnostic accuracy of MRI was calculated. Second, the pathological characteristics of MRI-detected and MRI-undetected tumours were compared using the Wilcoxon rank sum test and chi-square test for trend. Third, four biopsy strategies involving an MRI-targeted biopsy alone and with systematic biopsies of one to two other quadrants were studied. Fisher's exact test was used to compare MRI-targeted biopsy alone with the best other strategy for the number of patients with missed cancer and the number of patients with cancer harbouring additional tumours in unsampled quadrants. Analyses focused primarily on detecting cancer of any grade or length. Last, eligibility for focal therapy was evaluated for men with localised (≤T3bN0M0) radiorecurrent disease.

RESULTS AND LIMITATIONS

Of 144 patients, 111 (77%) had cancer detected on biopsy. MRI sensitivity and specificity at the patient level were 0.95 (95% confidence interval [CI] 0.92 to 0.99) and 0.21 (95% CI 0.07 to 0.35), respectively. At the prostate quadrant level, 258/576 (45%) quadrants had cancer detected on biopsy. Sensitivity and specificity were 0.66 (95% CI 0.59 to 0.73) and 0.54 (95% CI 0.46 to 0.62), respectively. At the quadrant level, compared with MRI-undetected tumours, MRI-detected tumours had longer maximum cancer core length (median difference 3 mm [7 vs 4 mm]; 95% CI 1 to 4 mm, p < 0.001) and a higher grade group (p = 0.002). Of the 84 men who also underwent an MRI-targeted biopsy, 73 (87%) had recurrent cancer diagnosed. Performing an MRI-targeted biopsy alone missed cancer in 5/73 patients (7%; 95% CI 3 to 15%); with additional systematic sampling of the other ipsilateral and contralateral posterior quadrants (strategy 4), 2/73 patients (3%; 95% CI 0 to 10%) would have had cancer missed (difference 4%; 95% CI -3 to 11%, p = 0.4). If an MRI-targeted biopsy alone was performed, 43/73 (59%; 95% CI 47 to 69%) patients with cancer would have harboured undetected additional tumours in unsampled quadrants. This reduced but only to 7/73 patients (10%; 95% CI 4 to 19%) with strategy 4 (difference 49%; 95% CI 36 to 62%, p < 0.0001). Of 73 patients, 43 (59%; 95% CI 47 to 69%) had localised radiorecurrent cancer suitable for a form of focal ablation.

CONCLUSIONS

For patients with recurrent prostate cancer after radiotherapy, MRI and MRI-targeted biopsy, with or without perilesional sampling, will diagnose cancer in the majority where present. MRI-undetected cancers, defined as Likert scores of 1 to 2, were found to be smaller and of lower grade. However, if salvage focal ablation is planned, an MRI-targeted biopsy alone is insufficient for prostate mapping; approximately three of five patients with recurrent cancer found on an MRI-targeted biopsy alone harboured further tumours in unsampled quadrants. Systematic sampling of the whole gland should be considered in addition to an MRI-targeted biopsy to capture both MRI-detected and MRI-undetected disease.

PATIENT SUMMARY

After radiotherapy, magnetic resonance imaging (MRI) is accurate for detecting recurrent prostate cancer, with missed cancer being smaller and of lower grade. Targeting a biopsy to suspicious areas on MRI results in a diagnosis of cancer in most patients. However, for every five men who have recurrent cancer, this targeted approach would miss cancers elsewhere in the prostate in three of these men. If further focal treatment of the prostate is planned, random biopsies covering the whole prostate in addition to targeted biopsies should be considered so that tumours are not missed.

Pitfalls in Prostate MR Imaging Interpretation

Multiparametric MR imaging of the prostate is an essential diagnostic study in the evaluation of prostate cancer. Several entities including normal anatomic structures, benign lesions, and posttreatment changes can mimic prostate cancer. An in depth understanding of the pitfalls is important for accurate interpretation of prostate MR imaging.

Evaluation of Prostate Cancer Recurrence with MR Imaging and Prostate Imaging for Recurrence Reporting Scoring System

Detection of prostate cancer recurrence after whole-gland treatment with curative intent is critical to identify patients who may benefit from local salvage therapy. Among the different imaging modalities used in clinical practice, MR imaging is the most accurate in identifying local prostate cancer recurrence; indeed, it is an excellent technique for local recurrence detection superior to PET/CT, even at low PSA, but provides no information about extra-pelvic lymph nodes or bone metastasis. In 2021, a group of experts developed the Prostate Imaging for local Recurrence Reporting scoring system to standardize acquisition, interpretation, and reporting of prostate cancer recurrence.

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

At present there is no standardised system for scoring the appearance of the prostate on multiparametric magnetic resonance imaging (MRI) after focal ablation for localised prostate cancer. We propose a novel scoring system, the Prostate Imaging after Focal Ablation (PI-FAB) score, to fill this gap. PI-FAB involves a 3-point scale for rating MRI sequences in sequential order: (1) dynamic contrast-enhanced sequences; (2) diffusion-weighted imaging, split into assessment of the high-b-value sequence first and then the apparent diffusion coefficient map; and (3) T2-weighted imaging. It is essential that the pretreatment scan is also available to help with this assessment. We designed PI-FAB using our experience of reading postablation scans over the past 15 years and include details for four representative patients initially treated with high-intensity focus ultrasound at our institution to demonstrate the scoring system. We propose PI-FAB as a standardised method for evaluating prostate MRI scans after treatment with focal ablation. The next step is to evaluate its performance across multiple experienced readers of MRI after focal therapy in a clinical data set. PATIENT SUMMARY: We propose a scoring system called PI-FAB for assessing the appearance of magnetic resonance imaging scans of the prostate after focal treatment for localised prostate cancer. This will help clinicians in deciding on further follow-up.

MRI and PSMA PET/CT of Biochemical Recurrence of Prostate Cancer

Prostate cancer may recur several years after definitive treatment, such as prostatectomy or radiation therapy. A rise in serum prostate-specific antigen (PSA) level is the first sign of disease recurrence, and this is termed biochemical recurrence. Patients with biochemical recurrence have worse survival outcomes. Radiologic localization of recurrent disease helps in directing patient management, which may vary from active surveillance to salvage radiation therapy, androgen-deprivation therapy, or other forms of systemic and local therapy. The likelihood of detecting the site of recurrence increases with higher serum PSA level. MRI provides optimal diagnostic performance for evaluation of the prostatectomy bed. Prostate-specific membrane antigen (PSMA) PET radiotracers currently approved by the U.S. Food and Drug Administration demonstrate physiologic urinary excretion, which can obscure recurrence at the vesicourethral junction. However, MRI and PSMA PET/CT have comparable diagnostic performance for evaluation of local recurrence after external-beam radiation therapy or brachytherapy. PSMA PET/CT outperforms MRI in identifying recurrence involving the lymph nodes and bones. Caveats for use of both PSMA PET/CT and MRI do exist and may cause false-positive or false-negative results. Hence, these techniques have complementary roles and should be interpreted in conjunction with each other, taking the patient history and results of any additional prior imaging studies into account. Novel PSMA agents at various stages of investigation are being developed, and preliminary data show promising results; these agents may revolutionize the landscape of prostate cancer recurrence imaging in the future. ©RSNA, 2023 Quiz questions for this article are available through the Online Learning Center. See the invited commentary by Turkbey in this issue. The slide presentation from the RSNA Annual Meeting is available for this article.

MRI-guided Minimally Invasive Focal Therapies for Prostate Cancer

Two cases involving patients diagnosed with localized prostate cancer and treated with MRI-guided focal therapies are presented. Patient selection procedures, techniques, outcomes, challenges, and future directions of MRI-guided focal therapies, as well as their role in the treatment of low- to intermediate-risk localized prostate cancer, are summarized.

Surveillance one year post focal cryotherapy for clinically significant prostate cancer using mpMRI and PIRADS v2.1: An initial experience from a prospective phase II mandatory biopsy study

Objectives

Multiparametric magnetic resonance imaging (mpMRI) surveillance post focal cryotherapy (FT) of prostate cancer is challenging as post treatment artefacts alter mpMRI findings. In this initial experience, we assessed diagnostic performance of mpMRI in detecting clinically significant prostate cancer (csPCa) after FT.

Materials and methods

This single-centre phase II prospective clinical trial recruited 28 men with localized csPCa for FT between October 2019 and April 2021. 12-months post FT mpMRI were performed prior to biopsy and sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of all mpMRI positive subjects were analysed. Chi square goodness of fit test correlated biopsy positive PIRADS3 (P3) and PIRADS4/5 lesions with histology grade group. One way ANOVA test assessed performance of ADC values in differentiating csPCa, non csPCa and benign lesions.

Results

Sensitivity, specificity, PPV and NPV of mpMRI were 100%, 14.28%, 53.84% and 100% for subjects with histologically proven cancer. Correlation of PIRADS v2.1 scores with histologically proven prostate cancer was statistically significant (p < 0.5). Correlation of P3 lesions with non-csPCa was statistically significant (p < 0.02535). Higher ADC value was associated with benign histology (adjusted odds ratio OR 0.97, 95% confidence interval: 0.94, 0.99) (p = 0.008). Among the malignant lesions, higher ADC value was associated with non-csPCa (adjusted OR: 0.97; 95% CI: 0.95, 0.99) (p = 0.032).

Conclusion

mpMRI is highly sensitive in detecting residual cancer. ADC values and PIRADS scores may be of value in differentiating csPCa from non-csPCa with a potential for risk stratification of men requiring re-biopsy versus non-invasive surveillance of remnant prostate.

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

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

Evaluation of a Deep Learning-based Algorithm for Post-Radiotherapy Prostate Cancer Local Recurrence Detection Using Biparametric MRI

OBJECTIVE

To evaluate a biparametric MRI (bpMRI)-based artificial intelligence (AI) model for the detection of local prostate cancer (PCa) recurrence in patients with radiotherapy history.

MATERIALS AND METHODS

This study included post-radiotherapy patients undergoing multiparametric MRI and subsequent MRI/US fusion-guided and/or systematic biopsy. Histopathology results were used as ground truth. The recurrent cancer detection sensitivity of a bpMRI-based AI model, which was developed on a large dataset to primarily identify lesions in treatment-naïve patients, was compared to a prospective radiologist assessment using the Wald test. Subanalysis was conducted on patients stratified by the treatment modality (external beam radiation treatment [EBRT] and brachytherapy) and the prostate volume quartiles.

RESULTS

Of the 62 patients included (median age = 70 years; median PSA = 3.51 ng/ml; median prostate volume = 27.55 ml), 56 recurrent PCa foci were identified within 46 patients. The AI model detected 40 lesions in 35 patients. The AI model performance was lower than the prospective radiology interpretation (Rad) on a patient-(AI: 76.1% vs. Rad: 91.3%, p = 0.02) and lesion-level (AI: 71.4% vs. Rad: 87.5%, p = 0.01). The mean number of false positives per patient was 0.35 (range: 0-2). The AI model performance was higher in EBRT group both on patient-level (EBRT: 81.5% [22/27] vs. brachytherapy: 68.4% [13/19]) and lesion-level (EBRT: 79.4% [27/34] vs. brachytherapy: 59.1% [13/22]). In patients with gland volumes >34 ml (n = 25), detection sensitivities were 100% (11/11) and 94.1% (16/17) on patient- and lesion-level, respectively.

CONCLUSION

The reported bpMRI-based AI model detected the majority of locally recurrent prostate cancer after radiotherapy. Further testing including external validation of this model is warranted prior to clinical implementation.

ESTRO ACROP consensus recommendation on the target volume definition for radiation therapy of macroscopic prostate cancer recurrences after radical prostatectomy

Background

The European Society for Radiotherapy & Oncology (ESTRO) Advisory Committee for Radiation Oncology Practice (ACROP) panel on prostate bed delineation reflected on macroscopic local recurrences in patients referred for postoperative radiotherapy (PORT), a challenging situation without standardized approach, and decided to propose a consensus recommendation on target volume selection and definition.

Methods

An ESTRO ACROP contouring consensus panel consisting of 12 radiation oncologists and one radiologist, all with subspecialty expertise in prostate cancer, was established. Participants were asked to delineate the prostate bed clinical target volumes (CTVs) in two separate clinically relevant scenarios: a local recurrence at the seminal vesicle bed and one apically at the level of the anastomosis. Both recurrences were prostate-specific membrane antigen (PSMA)-avid and had an anatomical correlate on magnetic resonance imaging (MRI). Participants also answered case-specific questionnaires addressing detailed recommendations on target delineation. Discussions via electronic mails and videoconferences for final editing and consensus were performed.

Results

Contouring of the two cases confirmed considerable variation among the panelists. Finally, however, a consensus recommendation could be agreed upon. Firstly, it was proposed to always delineate the entire prostate bed as clinical target volume and not the local recurrence alone. The panel judged the risk of further microscopic disease outside of the visible recurrence too high to safely exclude the rest of the prostate bed from the CTV. A focused, "stereotactic" approach should be reserved for re-irradiation after previous PORT. Secondly, the option of a focal boost on the recurrence was discussed.

Conclusion

Radiation oncologists are increasingly confronted with macroscopic local recurrences visible on imaging in patients referred for postoperative radiotherapy. It was recommended to always delineate and irradiate the entire prostate bed, and not the local recurrence alone, whatever the exact location of that recurrence. Secondly, specific dose-escalation on the macroscopic recurrence should only be considered if an anatomic correlate is visible. Such a focal boost is probably feasible, provided that OAR constraints are prioritized. Possible dose is also dependent on the location of the recurrence. Its potential benefit should urgently be investigated in prospective clinical trials.