The role of magnetic resonance imaging (MRI) in focal therapy for prostate cancer: recommendations from a consensus panel

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

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

Multifocality of Prostate Cancer and Candidacy for Focal Therapy Based on Magnetic Resonance Imaging

OBJECTIVES

To determine the prevalence of multiparametric magnetic resonance imaging (mpMRI)-detected and targeted biopsy-confirmed multifocal and unifocal prostate cancer (PCa) among patients with Prostate Imaging Reporting and Data System (PI-RADS) ≥3 lesions. Focal therapy (FT) options for PCa are tied to accurate spatial identification on mpMRI.

METHODS

Men without prior diagnosis of PCa receiving mpMRI, targeted and systematic prostate biopsy in the Prospective Loyola Urology mpMRI (PLUM) Prostate Biopsy Cohort from 2015-2021 were included. Patients with PI-RADS ≥3 lesions were classified by mpMRI lesion location, targeted biopsy, and systematic biopsy. Patients with single biopsy-confirmed grade group (GG) 2 lesions and concordant systematic biopsy were defined as FT candidates. Multivariable logistic regression evaluated predictors of mpMRI-undetected contralateral PCa.

RESULTS

Of 897 patients, 450 (50.2%) had a single, 141 (15.7%) had multiple unilateral, and 306 (34.1%) had bilateral mpMRI lesions. 28.7% had a single targeted biopsy-confirmed lesion while 10.4% were multifocal. Among single targeted biopsy-confirmed patients, 92/257 (35.8%) had contralateral PCa missed by mpMRI with DRE, PSA, and biopsy history identified as independent predictors. Systematic biopsy findings dropped the rate of single confirmed lesions from 28.7% to 18.4% and multifocal PCa increased from 10.4% to 20.6%. After GG restrictions, 61/897 (6.8%) remained potential FT candidates.

CONCLUSIONS

Among men with clinical suspicion of prostate cancer receiving mpMRI, 28.7% had a single targeted biopsy-confirmed lesion and 10.4% had multifocality on mpMRI, but many mpMRI-undetected contralateral PCa were identified. Only 6.0% of biopsy-naïve men remained with a single GG2 mpMRI lesion potentially amenable to FT.

MR Imaging in Real Time Guiding of Therapies in Prostate Cancer

Magnetic resonance imaging (MRI)-guided therapy for prostate cancer (PCa) aims to reduce the treatment-associated comorbidity of existing radical treatment, including radical prostatectomy and radiotherapy. Although active surveillance has been used as a conservative method to reduce overtreatment, there is a growing demand for less morbidity and personalized (focal) treatment. The development of multiparametric MRI was of real importance in improving the detection, localization and staging of PCa. Moreover, MRI has been useful for lesion targeting within the prostate, as it is used in the guidance of prostate biopsies, by means of cognitive registration, MRI-ultrasound fusion guidance or direct in-bore MRI-guidance. With regard to PCa therapies, MRI is used for precise probe placement into the lesion and to accurately monitor the treatment in real-time. Moreover, advances in MR-compatible thermal ablation allow for noninvasive real-time temperature mapping during treatment. In this review, we present an overview of the current status of MRI-guided therapies in PCa, focusing on cryoablation, focal laser ablation, high intensity focused ultrasound and transurethral ultrasound ablation. We explain the important role of MRI in the evaluation of the completeness of the ablation and during follow-up. Finally, we will discuss the challenges and future development inherent to these new technologies.

Automatic Segmentation of Pelvic Cancers Using Deep Learning: State-of-the-Art Approaches and Challenges

The recent rise of deep learning (DL) and its promising capabilities in capturing non-explicit detail from large datasets have attracted substantial research attention in the field of medical image processing. DL provides grounds for technological development of computer-aided diagnosis and segmentation in radiology and radiation oncology. Amongst the anatomical locations where recent auto-segmentation algorithms have been employed, the pelvis remains one of the most challenging due to large intra- and inter-patient soft-tissue variabilities. This review provides a comprehensive, non-systematic and clinically-oriented overview of 74 DL-based segmentation studies, published between January 2016 and December 2020, for bladder, prostate, cervical and rectal cancers on computed tomography (CT) and magnetic resonance imaging (MRI), highlighting the key findings, challenges and limitations.

Developments in Vascular-Targeted Photodynamic Therapy for Urologic Malignancies

With improved understanding of cancer biology and technical advancements in non-invasive management of urological malignancies, there is renewed interest in photodynamic therapy (PDT) as a means of focal cancer treatment. The application of PDT has also broadened as a result of development of better-tolerated and more effective photosensitizers. Vascular-targeted PDT (VTP) using padeliporfin, which is a water-soluble chlorophyll derivative, allows for tumor-specific cytotoxicity and has demonstrated efficacy in the management of urologic malignancies. Herein, we describe the evolution of photodynamic therapy in urologic oncology and the role of VTP in emerging treatment paradigms.

Role of multiparametric prostate MRI in the management of prostate cancer

INTRODUCTION

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

MATERIALS AND METHODS

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

CONCLUSION

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

Elevated Tumor Lactate and Efflux in High-grade Prostate Cancer demonstrated by Hyperpolarized 13C Magnetic Resonance Spectroscopy of Prostate Tissue Slice Cultures

Non-invasive assessment of the biological aggressiveness of prostate cancer (PCa) is needed for men with localized disease. Hyperpolarized (HP) ¹³C magnetic resonance (MR) spectroscopy is a powerful approach to image metabolism, specifically the conversion of HP [1-¹³C]pyruvate to [1-¹³C]lactate, catalyzed by lactate dehydrogenase (LDH). Significant increase in tumor lactate was measured in high-grade PCa relative to benign and low-grade cancer, suggesting that HP ¹³C MR could distinguish low-risk (Gleason score ≤3 + 4) from high-risk (Gleason score ≥4 + 3) PCa. To test this and the ability of HP ¹³C MR to detect these metabolic changes, we cultured prostate tissues in an MR-compatible bioreactor under continuous perfusion. ³¹P spectra demonstrated good viability and dynamic HP ¹³C-pyruvate MR demonstrated that high-grade PCa had significantly increased lactate efflux compared to low-grade PCa and benign prostate tissue. These metabolic differences are attributed to significantly increased LDHA expression and LDH activity, as well as significantly increased monocarboxylate transporter 4 (MCT4) expression in high- versus low- grade PCa. Moreover, lactate efflux, LDH activity, and MCT4 expression were not different between low-grade PCa and benign prostate tissues, indicating that these metabolic alterations are specific for high-grade disease. These distinctive metabolic alterations can be used to differentiate high-grade PCa from low-grade PCa and benign prostate tissues using clinically translatable HP [1-¹³C]pyruvate MR.

Focal therapy for localized prostate cancer in the era of routine multi-parametric MRI

BACKGROUND

Prostate cancer focal therapy aims to minimize the side-effects of whole gland treatments, such as radical prostatectomy and radiotherapy without compromising oncological efficacy. However, concerns exist regarding the multifocal nature of prostate cancer and the lack of long-term oncological data for this form of treatment. In recent years, the routine adoption of multi-parametric magnetic resonance imaging (mpMRI) of the prostate has improved our ability to select candidates for focal therapy and to accurately deliver this form of prostate cancer treatment.

METHODS

We performed a review of the literature to provide a summary of the oncological and functional outcomes of men receiving primary prostate focal therapy. Furthermore, we discuss the impact of the routine implementation of mpMRI as part of the initial prostate cancer diagnostic pathway on the selection of candidates and delivery of focal therapy. Finally, we summarize knowledge gaps in the field and highlight active clinical trials in this arena.

RESULTS

Primary focal therapy involves the application of one of a number of energies that ablate tissue, such as cryotherapy and high intensity focused ultrasound (HIFU). Success is principally dependent on highly accurate patient selection and disease localization underpinned in large part by the routine integration of pre-biopsy mpMRI. Prospective medium-term follow-up data for primary HIFU and cryotherapy for men with intermediate-risk disease have shown acceptable cancer control with low risk of side effects and complications. Additional research is needed to clearly define an appropriate follow-up approach and to guide the management of in- and out-of-field recurrences. Multiple comparative trials with randomization against standard care are currently underway in men with intermediate- and high-risk prostate cancer.

CONCLUSION

The widespread adoption of prostate mpMRI has led to improved disease localization, enabling the performance of focal therapy as a viable treatment strategy for men with low volume intermediate-risk prostate cancer.

Magnetic Resonance Imaging Assessment After Therapy in Prostate Cancer

Prostate cancer is the fifth leading cause of death worldwide. A variety of treatment options is available for localized prostate cancer and may range from active surveillance to focal therapy or whole gland treatment, that is, surgery or radiotherapy. Serum prostate-specific antigen levels are an important tool to monitor treatment success after whole gland treatment, unfortunately prostate-specific antigen is unreliable after focal therapy. Multiparametric magnetic resonance imaging of the prostate is rapidly gaining field in the management of prostate cancer and may play a crucial role in the evaluation of recurrent prostate cancer. This article will focus on postprocedural magnetic resonance imaging after different forms of local therapy in patients with prostate cancer.

Magnetic Resonance-Guided Prostate Ablation

In 2019, the American Cancer Society (ACS) estimates that 174,650 new cases of prostate cancer will be diagnosed and 31,620 will die due to the prostate cancer in the United States. Prostate cancer is often managed with aggressive curative intent standard therapies including radiotherapy or surgery. Regardless of how expertly done, these standard therapies often bring significant risk and morbidity to the patient's quality of life with potential impact on sexual, urinary, and bowel functions. Additionally, improved screening programs, using prostatic-specific antigen and transrectal ultrasound-guided systematic biopsy, have identified increasing numbers of low-risk, low-grade "localized" prostate cancer. The potential, localized, and indolent nature of many prostate cancers presents a difficult decision of when to intervene, especially within the context of the possible comorbidities of aggressive standard treatments. Active surveillance has been increasingly instituted to balance cancer control versus treatment side effects; however, many patients are not comfortable with this option. Although active debate continues on the suitability of either focal or regional therapy for the low- or intermediate-risk prostate cancer patients, no large consensus has been achieved on the adequate management approach. Some of the largest unresolved issues are prostate cancer multifocality, limitations of current biopsy strategies, suboptimal staging by accepted imaging modalities, less than robust prediction models for indolent prostate cancers, and safety and efficiency of the established curative therapies following focal therapy for prostate cancer. In spite of these restrictions, focal therapy continues to confront the current paradigm of therapy for low- and even intermediate-risk disease. It has been proposed that early detection and proper characterization may play a role in preventing the development of metastatic disease. There is level-1 evidence supporting detection and subsequent aggressive treatment of intermediate- and high-risk prostate cancer. Therefore, accurate assessment of cancer risk (i.e., grade and stage) using imaging and targeted biopsy is critical. Advances in prostate imaging with MRI and PET are changing the workup for these patients, and advances in MR-guided biopsy and therapy are propelling prostate treatment solutions forward faster than ever.

Hyperpolarized in vivo pH imaging reveals grade-dependent acidification in prostate cancer

There is an unmet clinical need for new and robust imaging biomarkers to distinguish indolent from aggressive prostate cancer. Hallmarks of aggressive tumors such as a decrease in extracellular pH (pH_e) can potentially be used to identify aggressive phenotypes. In this study, we employ an optimized, high signal-to-noise ratio hyperpolarized (HP) ¹³C pH_e imaging method to discriminate between indolent and aggressive disease in a murine model of prostate cancer. Transgenic adenocarcinoma of the mouse prostate (TRAMP) mice underwent a multiparametric MR imaging exam, including HP [¹³C] bicarbonate MRI for pH_e, with ¹H apparent diffusion coefficient (ADC) mapping and HP [1-¹³C] pyruvate MRI to study lactate metabolism. Tumor tissue was excised for histological staining and qRT-PCR to quantify mRNA expression for relevant glycolytic enzymes and transporters. We observed good separation in pH_e between low- and high-grade tumor regions, with high-grade tumors demonstrating a lower pH_e. The pH_e also correlated strongly with monocarboxylate transporter Mct4 gene expression across all tumors, suggesting that lactate export via MCT4 is associated with acidification in this model. Our results implicate extracellular acidification as an indicator of indolent-to-aggressive transition in prostate cancer and suggest feasibility of HP pH_e imaging to detect high-grade, clinically significant disease in men as part of a multiparametric MRI examination.

Comparison of outcomes of salvage robot-assisted laparoscopic prostatectomy for post-primary radiation vs focal therapy

OBJECTIVES

To compare salvage robot-assisted laparoscopic prostatectomy (RALP) outcomes in patients who underwent radiation and those who underwent focal ablation as primary therapies.

PATIENTS AND METHODS

We evaluated 126 patients who underwent salvage RALPbetween 2008 and 2018. Of these, 94 (74.6%) received radiation and 32 focal ablation (25.4%) as primary therapy. These groups were compared with regard to clinical, oncological and functional outcomes. Kaplan-Meier curves and regression models were used to identify survival estimations and their predictors.

RESULTS

Before surgery, more patients were potent in the focal ablation group compared to the radiation group (46.9% vs 22.6%; P = 0.013). Peri-operative characteristics and complication rates were not significantly different between the two groups. Postoperative catheterization duration was shorter in the focal ablation group (mean 10 vs 16 days; P = 0.018). At final pathology, the focal ablation group had higher non-organ-confined disease (71% vs 50%; P = 0.042) and positive surgical margin (PSM) rates (43.8% vs 17%; P = 0.004) as compared to the radiation group; however, 5-year biochemical recurrence (BCR)-free survival rates were similar (59% vs 56%; P = 0.761). Postoperative 1-year full (no pads/day) and social (0-1 pad/day) continence rates were significantly higher in the focal ablation as compared to the radiation group (77.3% vs 39.2%, P = 0.002, and 87.5% vs 51.3%, P = 0.002, respectively). Multivariate analyses showed primary focal ablation and nerve-sparing to be predictors of postoperative continence. Erectile function was preserved in 13% and 27% of preoperatively potent patients in the radiation and focal ablation groups, respectively (P = 0.435). No predictors were identified for postoperative potency.

CONCLUSIONS

Radiation was associated with inferior functional outcomes after salvage RALP. Focal therapies were associated with higher non-organ-confined disease and PSMrates, with no significant difference in short-term BCR-free survival.

Two-centre comparative experimental study of biparametric MRI at 3.0 T with and without endorectal coil using kiwifruit (Actinidia deliciosa) as a phantom for human prostate

BACKGROUND

Application of an endorectal coil (ERC) for 3.0-T prostate magnetic resonance imaging (MRI) is contentious. We hypothesised that a multicoil phased-array protocol provides T2-weighted images (T2WI) and diffusion-weighted images (DWI) with reduced field-of-view (DWI_reduced) and monoexponential apparent diffusion coefficient (ADC) maps that are technically equivalent with ERC or without ERC (noERC).

METHODS

Axial T2WI (repetition time [TR] 7500 ms, echo time [TE] 98-101 ms) and DWI_reduced (field-of-view 149-179 × 71-73 mm², TR/TE 4500-5500/61-74 ms, b values, 50/800 s/mm²) ERC and noERC images were obtained on identical clinical 3.0-T scanners at two centres and compared for signal-to-noise ratio (SNR) in anterior and posterior outer pericarp (OP) and peripheral placenta (PP) in five green Hayward kiwifruit (Actinidia deliciosa, European Union regulation 543/2011 class 2). Corroboration in 21 patients with benign prostate hyperplasia (negative biopsy, prostate imaging reporting and data system version 2 ≤ 2) involved identical MRI protocols: 10 at site 1, noERC, and 11 at site 2, with ERC. Two-tailed Student's t test was used.

RESULTS

With few exceptions, signal-to-noise ratio (SNR) was similar in kiwifruits and prostates for ERC and noERC. In T2WI, SNR was higher posteriorly in noERC MRI for peripheral zone (PZ) (p < 0.001). In DWI_reduced, SNR was higher posteriorly in ERC-OP (p = 0.013) and ERC-PZ (p = 0.026) for b = 50 s/mm²; noERC-OP (p = 0.044) and ERC-PZ (p = 0.001) for b = 800 s/mm²; and ERC-OP (p = 0.001), noERC-OP (p = 0.001), and ERC-PZ (p = 0.001) for ADC, respectively. Volumes of kiwifruits and prostates were similar (89.2 ± 11.2 versus 90.8 ± 48.5 cm³, p = 0.638-0.920).

CONCLUSIONS

Findings imply that multicoil phased-array 3.0-T prostate MRI with T2WI and DWI_reduced with ADC maps provides equivalent results with and without ERC.

Positron Emission Tomography/Computed Tomography with Gallium-68-labeled Prostate-specific Membrane Antigen Detects Relapse After Vascular-targeted Photodynamic Therapy in a Prostate Cancer Model

BACKGROUND

Evaluating the efficacy of focal therapy for prostate cancer is limited by current approaches and may be improved with biological imaging techniques.

OBJECTIVE

We assessed whether positron emission tomography/computed tomography with gallium-68-labeled prostate-specific membrane antigen (⁶⁸Ga-PSMA PET/CT) can be used to predict relapse after vascular-targeted photodynamic therapy (VTP).

DESIGN, SETTING, AND PARTICIPANTS

A total of 1×10⁶ LNCaP cells were grafted subcutaneously in the flanks of 6-8-wk-old SCID mice. Of 24 mice with measurable tumors 6 wk after tumor implantation, 20 were treated with VTP (150mW/cm²) to ablate the tumors. Blood prostate-specific antigen (PSA) levels were assessed, and ⁶⁸Ga-PSMA PET/CT images were performed 1 d before VTP and 1 and 4 wk after.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Local tumor relapse was evaluated by histology, and tumors were analyzed by prostate-specific membrane antigen (PSMA) and PSA immunohistochemistry. T tests and Kruskal-Wallis tests were used to determine significance.

RESULTS AND LIMITATIONS

Four weeks after VTP, 11 (65%) mice had complete responses and six (35%) had tumor relapses confirmed by histology (hematoxylin and eosin, and PSMA immunohistochemistry). All mice with local relapse had positive ⁶⁸Ga-PSMA PET/CT findings 4 wk after VTP; all complete responders did not. One week after VTP, the relapse detection sensitivity of ⁶⁸Ga-PSMA PET/CT was 75%, whereas the sensitivity of PSA was only 33%. Compared with controls, relapsed tumors had a three-fold reduction in the number of cells with strong PSA staining by immunohistochemistry (1.5% vs 4.5%; p=0.01).

CONCLUSIONS

In a preclinical prostate cancer model, we show that ⁶⁸Ga-PSMA PET/CT can identify and predict relapse earlier than blood PSA level. These findings support further testing in clinical trials.

PATIENT SUMMARY

Positron emission tomography/computed tomography with gallium-68-labeled prostate-specific membrane antigen may be used to follow and evaluate treatment outcomes in men who receive focal therapy for prostate cancer.

Percutaneous MR-guided prostate cancer cryoablation technical updates and literature review

Prostate cancer (PCa) is the most common malignant tumor in males. The benefits in terms of overall reduction in specific mortality due to the widespread use of Prostate Specific Antigen (PSA) screening and the advancements in the curative treatments (radical prostatectomy or radiotherapy) appear to have reached a plateau. There remains, however, the questions of overdiagnosis and overtreatment of such patients. Currently, the main challenge in the treatment of patients with clinically organ-confined PCa is to offer an oncologically efficient treatment with as little morbidity as possible. Amongst the arising novel curative techniques for PCa, cryoablation (CA) is the most established one, which is also included in the NICE and AUA guidelines. CA is commonly performed under ultrasound guidance with the inherent limitations associated with this technique. The recent advancements in MRI have significantly improved the accuracy of detecting and characterizing a clinically significant PCa. This, alongside the development of wide bore interventional MR scanners, has opened the pathway for in bore PCa treatment. Under MRI guidance, PCa CA can be used either as a standard whole gland treatment or as a tumor targeted one. With MR-fluoroscopy, needle guidance capability, multiplanar and real-time visualization of the iceball, MRI eliminates the inherent limitations of ultrasound guidance and can potentially lead to a lower rate of local complications. The aim of this review article is to provide an overview about PCa CA with a more specific insight on MR guided PCa CA; the limitations, challenges and applications of this novel technique will be discussed.

Role of novel imaging in the management of prostate cancer

This review summarizes novel imaging in the management of prostate cancer including multiparametric MRI, PET-CT scans with different radiotracers including ¹¹C-acetate, ¹¹C-choline, ¹⁸F-choline, ¹⁸F sodium fluoride, prostate-specific membrane antigen, and anti-1-amino-3-[18F] fluorocyclobutane-1-carboxylic acid (fluciclovine).

The SmartTarget Biopsy Trial: A Prospective, Within-person Randomised, Blinded Trial Comparing the Accuracy of Visual-registration and Magnetic Resonance Imaging/Ultrasound Image-fusion Targeted Biopsies for Prostate Cancer Risk Stratification

BACKGROUND

Multiparametric magnetic resonance imaging (mpMRI)-targeted prostate biopsies can improve detection of clinically significant prostate cancer and decrease the overdetection of insignificant cancers. It is unknown whether visual-registration targeting is sufficient or augmentation with image-fusion software is needed.

OBJECTIVE

To assess concordance between the two methods.

DESIGN, SETTING, AND PARTICIPANTS

We conducted a blinded, within-person randomised, paired validating clinical trial. From 2014 to 2016, 141 men who had undergone a prior (positive or negative) transrectal ultrasound biopsy and had a discrete lesion on mpMRI (score 3-5) requiring targeted transperineal biopsy were enrolled at a UK academic hospital; 129 underwent both biopsy strategies and completed the study.

INTERVENTION

The order of performing biopsies using visual registration and a computer-assisted MRI/ultrasound image-fusion system (SmartTarget) on each patient was randomised. The equipment was reset between biopsy strategies to mitigate incorporation bias.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The proportion of clinically significant prostate cancer (primary outcome: Gleason pattern ≥3+4=7, maximum cancer core length ≥4mm; secondary outcome: Gleason pattern ≥4+3=7, maximum cancer core length ≥6mm) detected by each method was compared using McNemar's test of paired proportions.

RESULTS AND LIMITATIONS

The two strategies combined detected 93 clinically significant prostate cancers (72% of the cohort). Each strategy detected 80/93 (86%) of these cancers; each strategy identified 13 cases missed by the other. Three patients experienced adverse events related to biopsy (urinary retention, urinary tract infection, nausea, and vomiting). No difference in urinary symptoms, erectile function, or quality of life between baseline and follow-up (median 10.5 wk) was observed. The key limitations were lack of parallel-group randomisation and a limit on the number of targeted cores.

CONCLUSIONS

Visual-registration and image-fusion targeting strategies combined had the highest detection rate for clinically significant cancers. Targeted prostate biopsy should be performed using both strategies together.

PATIENT SUMMARY

We compared two prostate cancer biopsy strategies: visual registration and image fusion. A combination of the two strategies found the most clinically important cancers and should be used together whenever targeted biopsy is being performed.

Deep dense multi-path neural network for prostate segmentation in magnetic resonance imaging

PURPOSE

We propose an approach of 3D convolutional neural network to segment the prostate in MR images.

METHODS

A 3D deep dense multi-path convolutional neural network that follows the framework of the encoder-decoder design is proposed. The encoder is built based upon densely connected layers that learn the high-level feature representation of the prostate. The decoder interprets the features and predicts the whole prostate volume by utilizing a residual layout and grouped convolution. A set of sub-volumes of MR images, centered at the prostate, is generated and fed into the proposed network for training purpose. The performance of the proposed network is compared to previously reported approaches.

RESULTS

Two independent datasets were employed to assess the proposed network. In quantitative evaluations, the proposed network achieved 95.11 and 89.01 Dice coefficients for the two datasets. The segmentation results were robust to variations in MR images. In comparison experiments, the segmentation performance of the proposed network was comparable to the previously reported approaches. In qualitative evaluations, the segmentation results by the proposed network were well matched to the ground truth provided by human experts.

CONCLUSIONS

The proposed network is capable of segmenting the prostate in an accurate and robust manner. This approach can be applied to other types of medical images.

MR-Guided Prostate Interventions

Prostate cancer is the most commonly diagnosed noncutaneous cancer and second leading cause of death in men. Many patients with clinically organ-confined prostate cancer undergo definitive treatment of the whole gland, including radical prostatectomy, radiation therapy, and cryosurgery. Active surveillance is a growing alternative option for patients with documented low-volume and low-grade prostate cancer. However, many patients are wanting a less morbid focal treatment alternative. With recent advances in software and hardware of magnetic resonance imaging (MRI), multiparametric MRI of the prostate has been shown to improve the accuracy in detecting and characterizing clinically significant prostate cancer. Targeted biopsy is increasingly utilized to improve the yield of MR detected, clinically significant prostate cancer and to decrease in detection of indolent prostate cancer. MR-guided targeted biopsy techniques include cognitive MR fusion transrectal ultrasound (TRUS) biopsy, in-bore transrectal targeted biopsy using robotic transrectal device, and in-bore direct MR-guided transperineal biopsy with a software based transperineal grid template. In addition, advances in MR-compatible thermal ablation technology allow accurate focal or regional delivery of thermal ablative energy to the biopsy-proved, MRI-detected tumor. MR-guided ablative treatment options include cryoablation, laser ablation, and high-intensity focused ultrasound with real-time or near simultaneous monitoring of the ablation zone. We present a contemporary review of MR-guided techniques for prostatic interventions.

3D Registration of mpMRI for Assessment of Prostate Cancer Focal Therapy

RATIONALE AND OBJECTIVES

This study aimed to assess a novel method of three-dimensional (3D) co-registration of prostate magnetic resonance imaging (MRI) examinations performed before and after prostate cancer focal therapy.

MATERIALS AND METHODS

We developed a software platform for automatic 3D deformable co-registration of prostate MRI at different time points and applied this method to 10 patients who underwent focal ablative therapy. MRI examinations were performed preoperatively, as well as 1 week and 6 months post treatment. Rigid registration served as reference for assessing co-registration accuracy and precision.

RESULTS

Segmentation of preoperative and postoperative prostate revealed a significant postoperative volume decrease of the gland that averaged 6.49 cc (P = .017). Applying deformable transformation based on mutual information from 120 pairs of MRI slices, we refined by 2.9 mm (max. 6.25 mm) the alignment of the ablation zone, segmented from contrast-enhanced images on the 1-week postoperative examination, to the 6-month postoperative T2-weighted images. This represented a 500% improvement over the rigid approach (P = .001), corrected by volume. The dissimilarity by Dice index of the mapped ablation zone using deformable transformation vs rigid control was significantly (P = .04) higher at the ablation site than in the whole gland.

CONCLUSIONS

Our findings illustrate our method's ability to correct for deformation at the ablation site. The preliminary analysis suggests that deformable transformation computed from mutual information of preoperative and follow-up MRI is accurate in co-registration of MRI examinations performed before and after focal therapy. The ability to localize the previously ablated tissue in 3D space may improve targeting for image-guided follow-up biopsy within focal therapy protocols.

[Prostate cancer diagnostic by saturation randomized biopsy versus rigid targeted biopsy]

INTRODUCTION

Optimal diagram teaming up randomized biopsy (BR) to targeted biopsy (BC) is still missing for the diagnostic of prostate cancer (CP). This study compares diagram of 6, 12 or 18 BR with or without BC rigid.

METHODS

Between January 2014 and May 2016, 120 patients had prostate biopsy BR and BC. Each patient had 18 BR and BC. Results compared sextant (6 BR), standard (12 BR) and saturation (18 BR) protocol with or without the adding of BC for the detection of CP.

RESULTS

Rectal examination was normal, mean PSA at 8.99ng/mL and mean volume at 54cm³. It was first round for 48% of patients. Forty-four cancers were found by the group 18 BR+BC (control). The detection rate was respectively, for 6, 12 and 18 BR of 61%, 82% and 91%. The add of BC increased this detection of +27% for 6 BR+BC, +13% for 12 BR+BC and +9% for 18 BR+BC. BC found 70% of all CP. Nine percent of CP were missed by BR only. Significant CP (Gleason≥7) diagnostic was the same for 12 BR+BC and 18 BR+BC.

CONCLUSION

The add of BC to BR increase the detection of CP by 10%. Twelve BR+BC is the optimal diagram for the diagnostic of CP finding 95% of CP and 97% of significant CP.

LEVEL OF EVIDENCE

4.

Focal Ablation of Early-Stage Prostate Cancer: Candidate Selection, Treatment Guidance, and Assessment of Outcome

Prostate cancer lesions smaller than 0.5 m³, or Gleason pattern 3, are likely clinically insignificant. Clinically significant disease is often limited to a single index lesion. Focal ablation targets this index lesion, maintains oncological control, and minimizes complications by preserving healthy prostate tissue. Template mapping biopsy or multiparametric MRI-targeted biopsies are used to identify appropriate index lesions. Multiple energy modalities have been tested, including high-intensity frequency ultrasound, cryoablation, laser ablation, photodynamic therapy, focal brachytherapy, radiofrequency ablation, irreversible electroporation. Outcome is assessed by biopsy of the target area, triggered by prostate-specific antigen measurements or MRI imaging, or performed per protocol at 12 months.

[Evaluation and results of ablative therapies in prostate cancer]

OBJECTIVE

To perform a state of the art about methods of evaluation and present results in ablative therapies for localized prostate cancer.

METHODS

A review of the scientific literature was performed in Medline database (http://www.ncbi.nlm.nih.gov) and Embase (http://www.embase.com) using different associations of keywords. Publications obtained were selected based on methodology, language and relevance. After selection, 102 articles were analysed.

RESULTS

Analyse the results of ablative therapies is presently difficult considering the heterogeneity of indications, techniques and follow-up. However, results from the most recent and homogeneous studies are encouraging. Oncologically, postoperative biopsies (the most important criteria) are negative (without any tumor cells in the treated area) in 75 to 95%. Functionally, urinary and sexual pre-operative status is spared (or recovered early) in more than 90% of the patients treated. More and more studies underline also the correlation between the results and the technique used considering the volume of the gland and, moreover, the "index lesion" localization.

CONCLUSION

The post-treatment pathological evaluation by biopsies (targeted with MRI or, perhaps in a near future, with innovative ultrasonography) is the corner stone of oncological evaluation of ablative therapies. Ongoing trials will allow to standardize the follow-up and determine the best indication and the best techniques in order to optimize oncological and functional results for each patient treated.

[Indications and limits of ablative therapies in prostate cancer]

OBJECTIVE

To perform a state of the art about indications and limits of ablative therapies for localized prostate cancer.

METHODS

A review of the scientific literature was performed in Medline database (http://www.ncbi.nlm.nih.gov) and Embase (http://www.embase.com) using different associations of keywords. Publications obtained were selected based on methodology, language and relevance. After selection, 107 articles were analysed.

RESULTS

The objective to combine reduction of side effects and oncological control has induced recent development of several ablative therapies. Beyond this heterogeneity, some preferential indications appear: unilateral cancer of low risk (but with significant volume, excluding active surveillance) or intermediate risk (excluding majority of grade 4); treatment targeted the index lesion, by quarter or hemi-ablation, based on biopsy and mpMRI. In addition, indications must considered specific limits of each energy, such as gland volume and tumor localization.

CONCLUSION

Based on new imaging and biopsy, ablative therapies will probably increased its role in the future in management of localize prostate cancer. The multiple ongoing trials will certainly be helpful to better define their indications and limits.

The 3DBiopsy Prostate Biopsy System: Preclinical Investigation of a Needle, Actuator, and Specimen Collection Device Allowing Sampling of Individualized Prostate Lengths Between 20 and 60 mm

OBJECTIVE

To increase the likelihood of detecting anterior cancers within the prostate and provide a specimen that spans the length of the gland. Newly designed 17- and 15-gauge (G) biopsy needles, a variable actuator, and an integrated pathology system intended for the longer cores were developed and tested for this purpose.

MATERIALS AND METHODS

Testing was performed comparing 2 common cannula tip grinds, a Vet-point (sharp tip) and a Menghini-point (atraumatic tip), and were tested against 18-G Bard Monopty in porcine kidney. A variable actuator was developed to fire the needle 20-60 mm and tested in cadaver prostates.

RESULTS

The aggregate firings for 3 different shot lengths comparing the Vet- with the Menghini-tip cannulas demonstrated 91% vs 85.2% fill (length of specimen/length of core bed, P = .007). A 15-G trocar needle with the Vet-tip cannula also had the best performance, with an aggregate standard deviation of 6.4% across 3 firing ranges and a minimum to maximum specimen length of 81%-105% of potential fill. Cadaver testing with the Vet-tip needles in the actuator for the transrectal (17-G) and transperineal (15-G) biopsies demonstrated mean fills of 93.3% and 76.5%, respectively. The new transrectal ultrasound needle obtained a 2-fold increase in specimen length over the standard Bard device (P <.001).

CONCLUSION

Longer and consistent cores were obtained using the new biopsy needles. Combined with an adjustable actuator, the physician can obtain specimens that include peripheral and anterior zone tissue in 1 core. Determination of cancer location on the longer specimens could enhance focal therapy planning.

Multi-parametric MRI imaging of the prostate-implications for focal therapy

The primary goal of a focal therapy treatment paradigm is to achieve cancer control through targeted tissue destruction while simultaneously limiting deleterious effects on peri-prostatic structures. Focal therapy approaches are employed in several oncologic treatment protocols, and have been shown to provide equivalent cancer control for malignancies such as breast cancer and renal cell carcinoma. Efforts to develop a focal therapy approach for prostate cancer have been challenged by several concepts including the multifocal nature of the disease and limited capability of prostate ultrasound and systematic biopsy to reliably localize the site(s) and aggressiveness of disease. Multi-parametric MRI (mpMRI) of the prostate has significantly improved disease localization, spatial demarcation and risk stratification of cancer detected within the prostate. The accuracy of this imaging modality has further enabled the urologist to improve biopsy approaches using targeted biopsy via MRI-ultrasound fusion. From this foundation, an improved delineation of the location of disease has become possible, providing a critical foundation to the development of a focal therapy strategy. This chapter reviews the accuracy of mpMRI for detection of “aggressive“ disease, the accuracy of mpMRI in determining the tumor volume, and the ability of mpMRI to accurately identify the index lesion. While mpMRI provides a critical, first step in developing a strategy for focal therapy, considerable questions remain regarding the relationship between MR identified tumor volume and pathologic tumor volume, the accuracy and utility of mpMRI for treatment surveillance and the optimal role and timing of follow-up mpMRI.

Natural Orifice Transluminal Endoscopic Partial Prostatectomy: A Real-time Image-guided Focal Extirpative Feasibility Study

OBJECTIVE

To assess the feasibility of focal endoscopic excision of prostate cancer (PCa) under guidance of real-time magnetic resonance imaging (MRI) or magnetic ultrasound fusion (MUF).

MATERIALS AND METHODS

Using a cadaveric model, multifocal PCa was simulated using 2 MRI-compatible fiducial markers. These were inserted transrectally and used to generate regions of interests (ROIs) on a 1.5-T surface-coil MRI. The first marker was placed in the right mid-peripheral zone (ROI 1), and the second marker was placed in the left seminal vesicle as a referent lesion for subsequent imaging. MRI of the specimen was then obtained. The radiologist created ROIs using fusion biopsy system at each marker. Two additional incidental ROIs were identified in the left transitional zone (ROI 2-suspicious for benign prostatic hyperplasia nodule) and in the right anterior peripheral zone (ROI 3-suspicious for PCa). Holmium laser enucleation of the transitional zone of the prostate was performed to gain access to the peripheral zone lesions. MUF was used during endoscopic laser excision to convey targeting accuracy. The cadaver was then reimaged to determine the adequacy of resection and examined for histopathologic correlation.

RESULTS

Real-time MUF imaging identified the target lesions consistently at the locations designated as ROIs. Complete endoscopic resection of ROIs was possible. Repeated MUF imaging and the postprocedure MRI confirmed the completeness of resection. Pathologic examination demonstrated complete excision, intact neurovascular bundles, and posterior prostatic capsule.

CONCLUSION

This approach may represent a new minimally invasive frontier for focal surgical resection of PCa, making histopathologic margin status determination possible.

Assessing Prostate Cancer Aggressiveness with Hyperpolarized Dual-Agent 3D Dynamic Imaging of Metabolism and Perfusion

New magnetic resonance (MR) molecular imaging techniques offer the potential for noninvasive, simultaneous quantification of metabolic and perfusion parameters in tumors. This study applied a three-dimensional dynamic dual-agent hyperpolarized ¹³C magnetic resonance spectroscopic imaging approach with ¹³C-pyruvate and ¹³C-urea to investigate differences in perfusion and metabolism between low- and high-grade tumors in the transgenic adenocarcinoma of mouse prostate (TRAMP) transgenic mouse model of prostate cancer. Dynamic MR data were corrected for T1 relaxation and RF excitation and modeled to provide quantitative measures of pyruvate to lactate flux (k_PL ) and urea perfusion (urea AUC) that correlated with TRAMP tumor histologic grade. k_PL values were relatively higher for high-grade TRAMP tumors. The increase in k_PL flux correlated significantly with higher lactate dehydrogenase activity and mRNA expression of Ldha, Mct1, and Mct4 as well as with more proliferative disease. There was a significant reduction in perfusion in high-grade tumors that associated with increased hypoxia and mRNA expression of Hif1α and Vegf and increased k_trans , attributed to increased blood vessel permeability. In 90% of the high-grade TRAMP tumors, a mismatch in perfusion and metabolism measurements was observed, with low perfusion being associated with increased k_PL This perfusion-metabolism mismatch was also associated with metastasis. The molecular imaging approach we developed could be translated to investigate these imaging biomarkers for their diagnostic and prognostic power in future prostate cancer clinical trials. Cancer Res; 77(12); 3207-16. ©2017 AACR.

MRI-guided focal therapy of prostate cancer

With the advent of focal therapy as a recognized treatment option for men with prostate cancer, there are a host of emerging interventions that take advantage of MRI for image guidance. Focal therapy affords a middleground option for patients with low- to intermediate-grade prostate cancer by providing a means of keeping their cancer at bay while avoiding the negative consequences of radical therapies. However, the practice of focal treatment is far from straightforward, with some believing focal treatment errs on the side of overtreatment among patients with low-grade cancer; others worry it is undertreatment in potentially significant multifocal disease. Further research is necessary, both relating to focal therapy in general and to the utility of each MRI-guided focal treatment discussed.

Focal Therapy for Prostate Cancer: Pending Questions

Focal therapy (FT) represents a potential shift in clinical practice by featuring a tissue-sparing approach for prostate cancer (PCa) treatment. It stands midway between active surveillance (AS) and more aggressive options like radical prostatectomy (RP) or radiotherapy. The field has enormously evolved in the last few years but there are still pending questions to answer in the future. The manuscript overlooks FT in terms of indications, available energies, situation of tumor microenvironment, follow-up, re-interventions, and the future of this approach for PCa.

Utilization of multiparametric prostate magnetic resonance imaging in clinical practice and focal therapy: report from a Delphi consensus project

Purpose

To codify the use of multiparametric magnetic resonance imaging (mpMRI) for the interrogation of prostate neoplasia (PCa) in clinical practice and focal therapy (FT).

Methods

An international collaborative consensus project was undertaken using the Delphi method among experts in the field of PCa. An online questionnaire was presented in three consecutive rounds and modified each round based on the comments provided by the experts. Subsequently, a face-to-face meeting was held to discuss and finalize the consensus results.

Results

mpMRI should be performed in patients with prior negative biopsies if clinical suspicion remains, but not instead of the PSA test, nor as a stand-alone diagnostic tool or mpMRI-targeted biopsies only. It is not recommended to use a 1.5 Tesla MRI scanner without an endorectal or pelvic phased-array coil. mpMRI should be performed following standard biopsy-based PCa diagnosis in both the planning and follow-up of FT. If a lesion is seen, MRI-TRUS fusion biopsies should be performed for FT planning. Systematic biopsies are still required for FT planning in biopsy-naïve patients and for patients with residual PCa after FT. Standard repeat biopsies should be taken during the follow-up of FT. The final decision to perform FT should be based on histopathology. However, these consensus statements may differ for expert centers versus non-expert centers.

Conclusions

The mpMRI is an important tool for characterizing and targeting PCa in clinical practice and FT. Standardization of acquisition and reading should be the main priority to guarantee consistent mpMRI quality throughout the urological community.

Electronic supplementary material

The online version of this article (doi:10.1007/s00345-016-1932-1) contains supplementary material, which is available to authorized users.

MRI-Guided Prostate Biopsy of Native and Recurrent Prostate Cancer

Prostate cancer is the most commonly diagnosed noncutaneous cancer and second-leading cause of death in men. Many patients with clinically organ-confined prostate cancer undergo definitive, curative treatment of the whole gland with either radical prostatectomy or radiation therapy. However, many men are reluctant to take the definitive step due to potential morbidity associated with either therapy. A growing interest in active surveillance or focal therapy has emerged as realistic alternatives for many patients. With each of these management strategies, it is critical to accurately quantify and stage the cancer with improved biopsy targeting and more precise imaging with magnetic resonance imaging (MRI). Furthermore, having dependable prostate imaging allows for targeted biopsies to improve the yield of clinically significant prostate cancer and decrease detection of indolent prostate cancer. MRI-guided targeted biopsy techniques include cognitive MRI/transrectal ultrasound fusion biopsy, in-bore transrectal targeted biopsy using a calibrated guidance device, and in-bore direct MR-guided transperineal biopsy with a software-based transperineal grid template. Herein we present a contemporary review of MRI-guided targeted biopsy techniques for new and recurrent cancerous foci of the prostate.

How are we going to train a generation of radiologists (and urologists) to read prostate MRI?

PURPOSE OF REVIEW

Multiparametric MRI has gained tremendous importance in the daily practice for patients at risk or diagnosed with prostate cancer. Interpretation of multiparametric-MRI is a complex task, supposedly restricted to experienced radiologists. The purpose of this review is to analyze fundamentals of multiparametric-MRI interpretation and to describe how multiparametric-MRI training could be organized.

RECENT FINDINGS

Recently, professional guidelines have been published to provide technical and interpretation frameworks and harmonize multiparametric-MRI practice, but the question of physicians training in prostate multiparametric-MRI reading is still pending. What kind of education, practice, and training makes a radiologist able to reliably interpret a prostate multiparametric-MRI? How can findings be reported to be easily understood? How much experience is needed? How can we train urologists and other physicians to review the examinations they request? Is double-reading necessary?

SUMMARY

An institutional-based competency certification process for prostate multiparametric-MRI interpretation may encourage nonspecialized radiologists to qualify for prostate imaging in a standardized and reproducible way, exactly as urologists need it.

Trends in targeted prostate brachytherapy: from multiparametric MRI to nanomolecular radiosensitizers

The treatment of localized prostate cancer is expected to become a significant problem in the next decade as an increasingly aging population becomes prone to developing the disease. Recent research into the biological nature of prostate cancer has shown that large localized doses of radiation to the cancer offer excellent long-term disease control. Brachytherapy, a form of localized radiation therapy, has been shown to be one of the most effective methods for delivering high radiation doses to the cancer; however, recent evidence suggests that increasing the localized radiation dose without bound may cause unacceptable increases in long-term side effects. This review focuses on methods that have been proposed, or are already in clinical use, to safely escalate the dose of radiation within the prostate. The advent of multiparametric magnetic resonance imaging (mpMRI) to better identify and localize intraprostatic tumors, and nanomolecular radiosensitizers such as gold nanoparticles (GNPs), may be used synergistically to increase doses to cancerous tissue without the requisite hazard of increased side effects.

Questions and answers on prostate multiparameter magnetic resonance imaging: Everything a urologist should know

CONTEXT

For many years, the detection of prostate cancer (PC) and the management of its therapy have been based primarily on prostate-specific antigen, rectal examination and prostate biopsy. However, these parameters have known limitations. Multiparametric magnetic resonance imaging (mpMRI) for prostate cancer has undergone extensive development in recent years, providing morphological and functional information. The aim of this study is to present an updated review of the scope and limitations of prostatic mpMRI for PC, in the framework of a multidisciplinary vision.

ACQUISITION OF EVIDENCE

We conducted a literature review (in PubMed) of articles referencing "mpMRI/staging/ PC/detection/active surveillance/therapy planning/post-therapy". We included 4 systematic reviews and other articles published in high impact-factor journals within the field of radiology and urology.

SUMMARY OF THE EVIDENCE

MpMRI provides morphological and functional information concerning PC. This information is integrated into the Prostate Imaging Report and Date System, classifying the probability of clinically significant carcinoma on a scale from 1 to 5. The usefulness of mpMRI is currently being established for patients with high prostate-specific antigen levels and prior negative prostate biopsy; tumour staging in selected cases; assessment of patients who are candidates for active surveillance; the planning of focal treatments; and the assessment of tumour persistence and recurrence.

CONCLUSIONS

MpMRI currently fills a relevant role in the diagnosis and therapeutic decision-making of PC. More widespread use of the technique requires a cost/benefit analysis.

Mathematical Models of Contrast Transport Kinetics for Cancer Diagnostic Imaging: A Review

Angiogenesis plays a fundamental role in cancer growth and the formation of metastasis. Novel cancer therapies aimed at inhibiting angiogenic processes and/or disrupting angiogenic tumor vasculature are currently being developed and clinically tested. The need for earlier and improved cancer diagnosis, and for early evaluation and monitoring of therapeutic response to angiogenic treatment, have led to the development of several imaging methods for in vivo noninvasive assessment of angiogenesis. The combination of dynamic contrast-enhanced imaging with mathematical modeling of the contrast agent kinetics enables quantitative assessment of the structural and functional changes in the microvasculature that are associated with tumor angiogenesis. In this paper, we review quantitative imaging of angiogenesis with dynamic contrast-enhanced magnetic resonance imaging, computed tomography, and ultrasound.

Hemiablative Focal Low Dose Rate Brachytherapy: A Phase II Trial Protocol

BACKGROUND

The objective of focal brachytherapy (BT) is to provide effective prostate cancer control for low-risk disease but with reduced genitourinary, gastrointestinal and sexual side effects in a cost-effective way.

OBJECTIVE

The aim of this study is to describe a phase II study examining technical and dosimetric feasibility and toxicity, quality of life changes, and local control with post-treatment biopsy outcomes in men with early stage low volume prostate cancer treated with focal iodine-125 seed BT.

METHODS

The study design is a prospective, multicenter trial with a planned sample size of 20 patients including men with a minimum age of 60 years, a life expectancy estimated to be greater than 10 years, with low or low-tier intermediate risk prostate cancer, unilateral disease on the biopsy, and a Gleason score of ≤3+4 and <25% cores involved. The investigations specific for the study are multi-parametric magnetic resonance imaging (Mp-MRI) baseline, at 20 and 36 months to rule out high grade disease and a transperineal mapping biopsy (baseline and at 36 months) for more accurate patient selection. The hemigland region will receive 144 Gy. Standard normal tissue constraints will be considered as for a whole gland (WG) implant. Dosimetric parameters will be evaluated at day 30 after the implant. Toxicity and quality of life will be evaluated with international validated questionnaires focusing on urinary, rectal, sexual domain, and general health-related quality of life. The patients will complete this assessment at baseline and then approximately every 6 months after the implant up to 10 years.

RESULTS

To date, one patient is involved in the trial. He underwent the pre-implant investigations which found bilateral disease. Therefore, a standard seed implant was performed. If the results from this trial provide evidence that the treatment is safe, feasible, and improves toxicity, funding will be sought to conduct a large, multicenter, randomized controlled trial (RCT).

CONCLUSIONS

This protocol is designed to show feasibility in delivering hemigland focal therapy with seed BT. It may answer crucial questions and obtain data which will enable downstream decisions on focal low dose rate (LDR) prostate BT.

CLINICALTRIAL

Clinicaltrial.gov NCT02643511; https://www.clinicaltrials.gov/ct2/show/NCT02643511 (Archived by Webcite at http://www.webcitation.org/6ghLCzIhY).

Focal vs extended ablation in localized prostate cancer with irreversible electroporation; a multi-center randomized controlled trial

Background

Current surgical and ablative treatment options for prostate cancer (PCa) may result in a high incidence of (temporary) incontinence, erectile dysfunction and/or bowel damage. These side effects are due to procedure related effects on adjacent structures including blood vessels, bowel, urethra and/or neurovascular bundle. Ablation with irreversible electroporation (IRE) has shown to be effective and safe in destroying PCa cells and also has the potential advantage of sparing surrounding tissue and vital structures, resulting in less impaired functional outcomes and maintaining men’s quality of life.

Methods/Design

In this randomized controlled trial (RCT) on IRE in localized PCa, 200 patients with organ-confined, unilateral (T1c-T2b) low- to intermediate-risk PCa (Gleason sum score 6 and 7) on transperineal template-mapping biopsies (TTMB) will be included. Patients will be randomized into focal or extended ablation of cancer foci with IRE. Oncological efficacy will be determined by multiparametric Magnetic Resonance Imaging, Contrast-Enhanced Ultrasound imaging if available, TTMP and Prostate Specific Antigen (PSA) follow-up. Patients will be evaluated up to 5 years on functional outcomes and quality of life with the use of standardized questionnaires.

Discussion

There is critical need of larger, standardized RCTs evaluating long-term oncological and functional outcomes before introducing IRE and other focal therapy modalities as an accepted and safe therapeutic option for PCa. This RCT will provide important short- and long-term data and elucidates the differences between focal or extended ablation of localized, unilateral low- to intermediate-risk PCa with IRE.

Trial registration

Clinicaltrials.gov database registration number NCT01835977. The Dutch Central Committee on Research Involving Human Subjects registration number NL50791.018.14.

Targeted prostate biopsy and MR-guided therapy for prostate cancer

Prostate cancer is the most commonly diagnosed noncutaneous cancer and second-leading cause of death in men. Many patients with clinically organ-confined prostate cancer undergo definitive treatment of the whole gland including radical prostatectomy, radiation therapy, and cryosurgery. Active surveillance is a growing alternative option for patients with documented low-volume, low-grade prostate cancer. With recent advances in software and hardware of MRI, multiparametric MRI of the prostate has been shown to improve the accuracy in detecting and characterizing clinically significant prostate cancer. Targeted biopsy is increasingly utilized to improve the yield of MR-detected, clinically significant prostate cancer and to decrease in detection of indolent prostate cancer. MR-guided targeted biopsy techniques include cognitive MR fusion TRUS biopsy, in-bore transrectal targeted biopsy using robotic transrectal device, and in-bore direct MR-guided transperineal biopsy with a software-based transperineal grid template. In addition, advances in MR compatible thermal ablation technology allow accurate focal or regional delivery of optimal thermal energy to the biopsy-proved, MRI-detected tumor, utilizing cryoablation, laser ablation, high-intensity focused ultrasound ablation under MR guidance and real-time or near simultaneous monitoring of the ablation zone. Herein we present a contemporary review of MR-guided targeted biopsy techniques of MR-detected lesions as well as MR-guided focal or regional thermal ablative therapies for localized naïve and recurrent cancerous foci of the prostate.

Multiparametric Magnetic Resonance Imaging of Recurrent Prostate Cancer

Multiparametric magnetic resonance (MR) imaging of the prostate combines both morphological and functional MR techniques by utilizing small field of view T1-weighted, T2-weighted, diffusion-weighted imaging, dynamic contrast-enhanced imaging, and MR spectroscopy to accurately detect, localize, and stage primary and recurrent prostate cancer. Localizing the site of recurrence in patients with rising prostate-specific antigen following treatment affects decision making regarding treatment and can be accomplished with multiparametric prostate MR. Several different treatment options are available for prostate cancer including radical prostatectomy, external beam radiation therapy, brachytherapy, androgen deprivation therapy, or a number of focal therapy techniques. The findings of recurrent prostate cancer can be different depending on the treatment the patient has received, and the radiologist must be able to recognize the variety of imaging findings seen with this common disease. This review article will detail the findings of recurrent prostate cancer on multiparametric MR and describe common posttreatment changes which may create challenges to accurate interpretation.

Toward Prostate Cancer Contouring Guidelines on Magnetic Resonance Imaging: Dominant Lesion Gross and Clinical Target Volume Coverage Via Accurate Histology Fusion

PURPOSE

Defining prostate cancer (PCa) lesion clinical target volumes (CTVs) for multiparametric magnetic resonance imaging (mpMRI) could support focal boosting or treatment to improve outcomes or lower morbidity, necessitating appropriate CTV margins for mpMRI-defined gross tumor volumes (GTVs). This study aimed to identify CTV margins yielding 95% coverage of PCa tumors for prospective cases with high likelihood.

METHODS AND MATERIALS

Twenty-five men with biopsy-confirmed clinical stage T1 or T2 PCa underwent pre-prostatectomy mpMRI, yielding T2-weighted, dynamic contrast-enhanced, and apparent diffusion coefficient images. Digitized whole-mount histology was contoured and registered to mpMRI scans (error ≤2 mm). Four observers contoured lesion GTVs on each mpMRI scan. CTVs were defined by isotropic and anisotropic expansion from these GTVs and from multiparametric (unioned) GTVs from 2 to 3 scans. Histologic coverage (proportions of tumor area on co-registered histology inside the CTV, measured for Gleason scores [GSs] ≥6 and ≥7) and prostate sparing (proportions of prostate volume outside the CTV) were measured. Nonparametric histologic-coverage prediction intervals defined minimal margins yielding 95% coverage for prospective cases with 78% to 92% likelihood.

RESULTS

On analysis of 72 true-positive tumor detections, 95% coverage margins were 9 to 11 mm (GS ≥ 6) and 8 to 10 mm (GS ≥ 7) for single-sequence GTVs and were 8 mm (GS ≥ 6) and 6 mm (GS ≥ 7) for 3-sequence GTVs, yielding CTVs that spared 47% to 81% of prostate tissue for the majority of tumors. Inclusion of T2-weighted contours increased sparing for multiparametric CTVs with 95% coverage margins for GS ≥6, and inclusion of dynamic contrast-enhanced contours increased sparing for GS ≥7. Anisotropic 95% coverage margins increased the sparing proportions to 71% to 86%.

CONCLUSIONS

Multiparametric magnetic resonance imaging-defined GTVs expanded by appropriate margins may support focal boosting or treatment of PCa; however, these margins, accounting for interobserver and intertumoral variability, may preclude highly conformal CTVs. Multiparametric GTVs and anisotropic margins may reduce the required margins and improve prostate sparing.