Imaging of organ-confined prostate cancer: functional ultrasound, MRI and PET/computed tomography:

Perspectives on technology: Prostate Imaging-Reporting and Data System (PI-RADS) interobserver variability

OBJECTIVES

To explore the topic of Prostate Imaging-Reporting and Data System (PI-RADS) interobserver variability, including a discussion of major sources, mitigation approaches, and future directions.

METHODS

A narrative review of PI-RADS interobserver variability.

RESULTS

PI-RADS was developed in 2012 to set technical standards for prostate magnetic resonance imaging (MRI), reduce interobserver variability at interpretation, and improve diagnostic accuracy in the MRI-directed diagnostic pathway for detection of clinically significant prostate cancer. While PI-RADS has been validated in selected research cohorts with prostate cancer imaging experts, subsequent prospective studies in routine clinical practice demonstrate wide variability in diagnostic performance. Radiologist and biopsy operator experience are the most important contributing drivers of high-quality care among multiple interrelated factors including variability in MRI hardware and technique, image quality, and population and patient-specific factors such as prostate cancer disease prevalence. Iterative improvements in PI-RADS have helped flatten the curve for novice readers and reduce variability. Innovations in image quality reporting, administrative and organisational workflows, and artificial intelligence hold promise in improving variability even further.

CONCLUSION

Continued research into PI-RADS is needed to facilitate benchmark creation, reader certification, and independent accreditation, which are systems-level interventions needed to uphold and maintain high-quality prostate MRI across entire populations.

The Potential of Magnetic Nanoparticles for Diagnosis and Treatment of Cancer Based on Body Magnetic Field and Organ-on-the-Chip

Cancer is an abnormal cell growth which tends to proliferate in an uncontrolled way and, in some cases, leads to metastasis. If cancer is left untreated, it can immediately cause death. The use of magnetic nanoparticles (MNPs) as a drug delivery system will enable drugs to target tissues and cell types precisely. This study describes usual strategies and consideration for the synthesis of MNPs and incorporates payload drug on MNPs. They have advantages such as visual targeting and delivering which will be discussed in this review. In addition, we considered body magnetic field to make drug delivery process more effective and safer by the application of MNPs and tumor-on-chip.

Interpretation and reporting multiparametric prostate MRI: a primer for residents and novices

Multiparametric MRI has developed as a tool for prostate cancer lesion detection, characterization, staging, surveillance, and imaging of local recurrence. Given the disease frequency and the growing importance of imaging, as reliance on PSA declines, radiologists involved in prostate MRI imaging must become proficient with the fundamentals of multiparametric prostate MRI (T2WI, DWI, DCE-MRI, and MR spectroscopy). Interpretation and reporting must yield accuracy, consistency, and add value to clinical care. This review provides a primer to novices and trainees learning about multiparametric prostate MRI. MRI technique is presented along with the use of particular MRI sequences. Relevant prostate anatomy is outlined and imaging features of prostate cancer with staging are discussed. Finally structured reporting is introduced, and some limitations of prostate MRI are discussed.

Dynamic contrast-enhanced MRI for the detection of prostate cancer: meta-analysis

OBJECTIVE

The purpose of this study was to systematically review and meta-analyze dynamic contrast-enhanced MRI (DCE-MRI) for the detection of prostate cancer in comparison with standard evaluation with T2-weighted imaging.

MATERIALS AND METHODS

A PubMed electronic database search for the terms "dynamic contrast-enhanced," "prostate," and "MRI" was completed for articles up to September 17, 2013. All included studies had histopathologic correlation. Two by two contingency data were constructed for each study. A binormal bayesian ROC model was used to estimate and compare sensitivity, specificity, and AUC among eligible modalities.

RESULTS

Both DCE-MRI (0.82-0.86) and diffusion-weighted MRI (DWI) (0.84-0.88) yielded significantly better AUC than T2-weighted imaging (0.68-0.77). Moreover, partial AUC for the combination of DCE-MRI, DWI, and T2-weighted imaging was improved significantly (0.111; 0.103-0.119) when compared with DCE-MRI alone (0.079; 0.072-0.085) and T2-weighted imaging alone (0.079; 0.074-0.084) but not DWI alone (0.099; 0.091-0.108). Sensitivity and specificity were similar among the four modalities.

CONCLUSION

DCE-MRI improves AUC of tumor detection overall compared with T2-weighted imaging alone. Methods for DCE-MRI analysis require standardization, but visual analysis performs similar to semiquantitative methods. A two-parameter approach using DCE-MRI and T2-weighted imaging or DWI and T2-weighted imaging may be sufficient, and the latter may be more favorable for most routine prostate cancer imaging.

PROMIS--Prostate MR imaging study: A paired validating cohort study evaluating the role of multi-parametric MRI in men with clinical suspicion of prostate cancer

BACKGROUND

Transrectal ultrasound-guided prostate biopsies are prone to detection errors. Multi-parametric MRI (MP-MRI) may improve the diagnostic pathway.

METHODS

PROMIS is a prospective validating paired-cohort study that meets criteria for level 1 evidence in diagnostic test evaluation. PROMIS will investigate whether multi-parametric (MP)-MRI can discriminate between men with and without clinically-significant prostate cancer who are at risk prior to first biopsy. Up to 714 men will have MP-MRI (index), 10-12 core TRUS-biopsy (standard) and 5mm transperineal template mapping (TPM) biopsies (reference). The conduct and reporting of each test will be blinded to the others.

RESULTS

PROMIS will measure and compare sensitivity, specificity, and positive and negative predictive values of both MP-MRI and TRUS-biopsy against TPM biopsies. The MP-MRI results will be used to determine the proportion of men who could safely avoid biopsy without compromising detection of clinically-significant cancers. For the primary outcome, significant cancer on TPM is defined as Gleason grade >/= 4+3 and/or maximum cancer core length of ≥ 6 mm. PROMIS will also assess inter-observer variability among radiologists among other secondary outcomes. Cost-effectiveness of MP-MRI prior to biopsy will also be evaluated.

CONCLUSIONS

PROMIS will determine whether MP-MRI of the prostate prior to first biopsy improves the detection accuracy of clinically-significant cancer.

Multiparametric MRI-targeted TRUS prostate biopsies using visual registration

Prebiopsy multiparametric prostate MRI (mp-MRI), followed by transrectal ultrasound-guided (TRUS-G) target biopsies (TB) of the prostate is a key combination for the diagnosis of clinically significant prostate cancers (CSPCa), to avoid prostate cancer (PCa) overtreatment. Several techniques are available for guiding TB to the suspicious mp-MRI targets, but the simplest, cheapest, and easiest to learn is “cognitive,” with visual registration of MRI and TRUS data. This review details the successive steps of the method (target detection, mp-MRI reporting, intermodality fusion, TRUS guidance to target, sampling simulation, sampling, TRUS session reporting, and quality insurance), how to optimize each, and the global indications of mp-MRI-targeted biopsies. We discuss the diagnostic yield of visually-registered TB in comparison with conventional biopsy, and TB performed using other registration methods.

The optimal timing of post-prostate biopsy magnetic resonance imaging to guide nerve-sparing surgery

The goal of our study was to evaluate the impact of the interval between prostate biopsy and magnetic resonance imaging (MRI) on the accuracy of simple tumor localization, which is essential information that enables nerve-sparing surgery. We also sought to determine the optimal timing of a post-biopsy MRI. A total of 184 patients who had undergone MRI before radical prostatectomy at an institution without a predetermined schedule for MRI after a prostate biopsy were enrolled. The mean interval from the biopsy to the MRI was 30.8 ± 18.6 days. The accuracy of the MRI for simplified tumor location (right, left, bilateral and none) was 44.6%. In the group with discordant pathologic and MRI findings, the most common reason recorded was ‘MRI predicted a unilateral lesion, but pathology revealed bilateral lesions’ (58.3%), followed by ‘MRI predicted no lesion, but pathology revealed the presence of a lesion’ (32.0%). Multivariable analysis showed that the discordant group had a shorter interval (25.0 ± 14.3 vs 38.1 ± 20.6 days, P < 0.01) preceding the MRI and a higher rate of hemorrhage as observed by MRI (80.4% vs 54.8%, P < 0.01) in comparison with the accordant group. In receiver operating characteristics analysis, the area under the curve of the MRI interval in accurate prediction of the tumor location was 0.707 (P < 0.001). At the MRI interval's cutoff of 28.5 days, the sensitivity was 73.2% and the specificity was 63.7%. When the MRI was performed within 28 days, the accumulated accuracy was only 26.1% (23/88); however, when it was performed after 28 days, the reversely accumulated accuracy was 61.5% (59/96). These data support a waiting period of at least 4 weeks after a biopsy before performing an MRI for the purposes of surgical refinement.

3-Tesla magnetic resonance imaging improves the prostate cancer detection rate in transrectral ultrasound-guided biopsy

The detection rate of prostate cancer (PCa) using traditional biopsy guided by transrectal ultrasound (TRUS) is not satisfactory. The aim of this study was to determine the utility of 3-Tesla (3-T) magnetic resonance imaging (MRI) prior to TRUS-guided prostate biopsy and to investigate which subgroup of patients had the most evident improvement in PCa detection rate. A total of 420 patients underwent 3-T MRI examination prior to the first prostate biopsy and the positions of suspicious areas were recorded respectively. TRUS-guided biopsy regimes included systematic 12-core biopsy and targeted biopsy identified by MRI. Patients were divided into subgroups according to their serum prostate-specific antigen (PSA) levels, PSA density (PSAD), prostate volume, TRUS findings and digital rectal examination (DRE) findings. The ability of MRI to improve the cancer detection rate was evaluated. The biopsy positive rate of PCa was 41.2% (173/420), and 41 of the 173 (23.7%) patients were detected only by targeted biopsy in the MRI-suspicious area. Compared with the systematic biopsy, the positive rate was significantly improved by the additional targeted biopsy (P=0.0033). The highest improvement of detection rate was observed in patients with a PSA level of 4–10 ng/ml, PSAD of 0.12–0.20 ng/ml², prostate volume >50 ml, negative TRUS findings and negative DRE findings (P<0.05). Therefore, it is considered that 3-T MRI examination could improve the PCa detection rate on first biopsy, particularly in patients with a PSA level of 4–10 ng/ml, PSAD of 0.12–0.20 ng/ml², prostate volume of >50 ml, negative TRUS findings and negative DRE findings.

Supporting prostate cancer focal therapy: a multidisciplinary International Consensus of Experts ("ICE")

Prostate cancer is a common malignancy among men, and the current screening, imaging and sampling approaches aim to detect early-stage, organ-confined disease. In such scenario, focal prostate cancer therapy currently relies on the index lesion concept as the dominant lesion that drives the disease natural history. Focal therapy demands the essential imaging and sampling techniques to strategically locate and qualify the disease, but, despite advances in technology, prostate imaging and biopsy have several limitations that need to be overcome if focal therapy is to be developed further. The I Prostate Cancer Focal Treatment International Symposium was convened to foster discussion on this topic that sits at the crossroads of multiple disciplines (Urology, Pathology, Radiology, Radiation Oncology and Medical Oncology) all of which were represented for this comprehensive multidisciplinary review of the current literature.

[Comparative study of histological results between resection and biopsy of the prostate]

PURPOSE

To evaluate the histological correlation between transuretral resection chips and biopsy cores within a population of patients who underwent resection of prostate (TURP) and prostate biopsies (BPx).

PATIENTS AND METHODS

Clinical and tumoral data of 77 patients who had both procedures simultaneously or with a slight delay were collected. According to the presence of prostate cancer (Pca), 4 groups were defined: group 1 (TURP and BPx negative), group 2 (TURP positive, BPx negative), group 3 (TURP negative, BPx positive), group 4 (TURP and BPx positive). Means and proportions were compared using Anova and χ(2) test, respectively.

RESULTS

The patients were older in groups 3 and 4 (79 and 76 respectively, P=0.65). The PSA was higher in the groups 3 and 4 (64 and 55 ng/mL) than the groups 1 and 2 (10.6 et 16 respectively, P=0.23). The number of positive biopsy was higher in the group 4 than the group 3 (5.6 vs. 4.6, P<0.0001), the chips were more invaded in the group 4 than the group 2 (41% vs. 11% P<0.0001), the Gleason score at TURP was higher in the group 4 than the group 2 (7.5 vs. 6.2 P<0.0001).

CONCLUSION

Our study underlines that the Pca of transition and peripheral zones seems to have distinct characteristics. When chips of TURP and BPx were both invaded, it was due to an aggressive cancer. The decision to explore the peripheral zone in the case of positive TURP must take clinical context into consideration.

Defining the level of evidence for technology adoption in the localized prostate cancer pathway

New technologies in prostate cancer are attempting to change the current prostate cancer pathway by aiming to reduce harms while maintaining the benefits associated with screening, diagnosis, and treatment. In this article, we discuss the optimal evaluation that new technologies should undergo to provide level 1 evidence typically required to change the practice. With this in mind, we focus on feasible and pragmatic trials that could be delivered in a timely fashion by many centers while retaining primary outcomes that focus on clinically meaningful outcomes.

Prostate MRI: can we do without DCE sequences in 2013?

Multiparametric MRI (mp-MRI) of the prostate currently provides stable and reproducible performances. The usefulness of dynamic contrast-enhanced (DCE) sequences is currently challenged, as they sometimes only confirm what has already been observed on diffusion-weighted imaging (DWI) and require the additional purchase of a contrast agent. Eliminating these sequences may help accelerate the use of MRI in addition to, or in lieu of, prostate biopsies in selected patients. However, many studies show that these sequences can detect lesions invisible on T2-weighted and diffusion-weighted images, better assess cancer extension and aggressiveness, and finally help detecting recurrence after treatment. We present the various applications of dynamic MRI and discuss the possible consequences of its omission from the current protocol.

Multiparametric magnetic resonance imaging of prostate cancer

In India, prostate cancer has an incidence rate of 3.9 per 100,000 men and is responsible for 9% of cancer-related mortality. It is the only malignancy that is diagnosed with an apparently blind technique, i.e., transrectal sextant biopsy. With increasing numbers of high-Tesla magnetic resonance imaging (MRI) equipment being installed in India, the radiologist needs to be cognizant about endorectal MRI and multiparametric imaging for prostate cancer. In this review article, we aim to highlight the utility of multiparamteric MRI in prostate cancer. It plays a crucial role, mainly in initial staging, restaging, and post-treatment follow-up.

Morbidity of focal therapy in the treatment of localized prostate cancer

BACKGROUND

Focal therapy (FT) for prostate cancer (PCa) seems to be part of a natural evolution in the quest to improve the management of early organ-confined disease.

OBJECTIVE

To assess the morbidity of the initial experience of FT in a tertiary referral center for PCa management.

DESIGN, SETTING, AND PARTICIPANTS

From 2009 to 2011, a total of 1213 patients with clinically localized PCa were treated at our institution. Of these patients, 547 were considered to have indolent disease according to the D'Amico criteria for low-risk disease plus unilateral disease with a maximum of three positive biopsies. A total of 106 patients underwent FT using high-intensity focused ultrasonography (HIFU), brachytherapy, cryotherapy, or vascular-targeted photodynamic therapy (VTP).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Complications were prospectively recorded and graded according to the Clavien-Dindo scale. Data were prospectively collected and retrospectively analyzed.

RESULTS AND LIMITATIONS

This study included 106 patients, median age 66.5 yr (interquartile range [IQR]): 61-73), who had a prostate hemiablation; 50 patients (47%) had cryotherapy, 23 patients (22%) had VTP, 21 patients (20%) received HIFU, and 12 patients (11%) had brachytherapy. The median prostate-specific antigen (PSA) level was 6.1 ng/ml (IQR: 5-8.1), all the patients had a biopsy Gleason score of 6, and the median prostate weight was 43 g (IQR: 33-55). The median International Prostate Symptom Score was 6 (IQR: 3-10), and the median International Index of Erectile Function score was 20 (IQR: 15-23). After treatment, the median PSA at 3, 6, and 12 mo was 3.1 2.9, and 2.7 ng/ml (IQR: 2-5.1, 1.1-4.7, and 1-4.4), respectively. Thirteen percent of the patients experienced treatment-related complications. There were 11 minor medical complications (10 grade 1 complications and 1 grade 2 complication), 2 grade 3 complications, and no grade 4 or higher complications.

CONCLUSIONS

FT for a highly selected population with PCa is feasible and had an acceptable morbidity with <2% major complications.

MRI and surveillance

PURPOSE OF REVIEW

In this review, we summarize the recent advances in modern imaging, particularly multiparametric (mp) MRI and its role in the selection and monitoring of patients on active surveillance.

RECENT FINDINGS

Current diagnostic pathway has some limitations in selecting patients with insignificant prostate cancer for active surveillance. Hence, percentage of men under active surveillance for insignificant prostate cancer and reclassified as significant cancer at 2 years is 20-30%. It is mainly because of anterior cancer underdiagnosis by systematic posterior biopsies. mp-MRI is accurate for significant cancer detection and staging, including anterior cancers, which represent 20% of cancers in an unselected population of men with suspicious prostate-specific antigen elevation. One way to reduce the risk of underestimation is to target the needle on significant cancer identified at prebiopsy anatomical and functional imaging, so that detection and personalized risk stratification can be improved. MRI reveals greater volume of cancers and higher grade than systematic 12-core biopsies. MRI 95% negative predictive value has the potential to avoid biopsy series for monitoring patients under active surveillance.

SUMMARY

Upon confirmation of these results, MRI may be used to better select patients for active surveillance inclusion. Incorporation of mp-MRI into active surveillance selection criterias for patients with low-risk prostate cancer can reduce the number of patients reclassified at subsequent biopsies because of better initial prognosis evaluation. In addition to additional cost, MRI requires a highly skilled team to obtain information adequate to drive clinical decisions.

Dual-imaging enabled cancer-targeting nanoparticles

The development of dual-imaging enabled cancer-targeting nanoparticles (DICT-NPs) is reported based on newly developed biodegradable photoluminescent polymers and superparamagnetic iron oxide nanoparticles. DICT-NPs possess capabilities of dual-imaging (magnetic resonance imaging and optical imaging), magnetic targeting, and potentially selective targeting for cancer cells. The development of DICT-NPs address the concerns in dual-imaging nanoparticles where photobleaching organic dyes and cytotoxic quantum dots are usually adopted.

Contrast-enhanced ultrasound as support for prostate brachytherapy treatment planning

PURPOSE

To investigate the possibility of localization of intraprostatic lesions (IL) with contrast-enhanced ultrasound (CEUS) to support the brachytherapy treatment planning of temporary implants.

MATERIAL AND METHODS

Two brachytherapy treatment plans were generated for 8 patients treated with external beam radiotherapy and pulsed-dose rate brachytherapy boost for prostate cancer. The first and second brachytherapy treatment plan was without and with knowledge of the localization of the ILs, respectively. Pairwise comparison was performed on prostate, rectum, and urethra dose-volume parameters and total reference air kerma (TRAK)-values.

RESULTS

Coverage of the ILs by the 140% isodose was increased from mean 66.0-67.7% for the standard plan to mean 92.5-95.7% for the adapted plan. The mean D90 of the ILs increased from 1.49-1.57 Gy/pulse to 1.76-1.81 Gy/pulse. Dose-volume parameters for the prostate, rectum, and urethra and the TRAK did not change.

CONCLUSIONS

CEUS technique is a promising method for IL localization to aid in brachytherapy treatment planning. Dose coverage on the IL could be improved without any increase of dose in organs at risk.

Focal therapy with high-intensity focused ultrasound for prostate cancer in the elderly. A feasibility study with 10 years follow-up

PURPOSE

To evaluate the long-term efficacy of prostate cancer control and complication rates, in the elderly, after focal therapy with high-intensity focused ultrasound (HIFU).

MATERIALS AND METHODS

Between June 1997 and March 2000, patients with localized prostate cancer were included into a focal therapy protocol. Inclusion criteria were: PSA ≤ 10 ng/mL, ≤ 3 positive biopsies with only 1 lobe involved, clinical stage ≤ T2a, Gleason score ≤ 7 (3+4), negative CT scan and bone scan. Hemi-ablation of the prostate was performed with the Ablatherm® device. Survival, complication rates and urinary continence were evaluated. Control biopsies were performed at 1 year. Treatment failure was defined as a positive biopsy or need for salvage therapy.

RESULTS

Twelve patients with a mean age 70 years were included. Median follow-up was 10 years. Control prostate biopsies were negative in 11/12 (91%) patients. Overall survival was 83% (10/12) and cancer specific survival was 100% at 10 years. Two patients died from other causes. Recurrence free survival was 90% (95% CI; 0.71-1) at 5 years, and 38% (95% CI; 0.04-0.73) at 10 years. Five patients had salvage therapy with repeat HIFU (n = 1) or hormonal therapy (n = 4) and all salvage patients were alive at 10 years. No patients developed lymph node or bone metastasis. No patients suffered from urinary incontinence. International Prostate Symptom Score was stable at 1 year. Complications included two urinary tract infections and one episode of acute urinary retention.

CONCLUSIONS

Hemi-prostate ablation with HIFU can be safely performed in selected elderly patients with adequate long-term cancer control and low complication rates. Results from larger prospective studies using improved imaging techniques and extensive biopsy protocols are awaited.

Focal therapy for prostate cancer: patient selection and evaluation

Recent stage migration toward low-risk prostate cancer, overtreatment of biologically insignificant tumors with radical prostatectomy at the additional expense of a non-negligible morbidity and undertreatment of patients improperly selected for active surveillance are the main reasons that have fueled the concept of focal therapy. Optimal selection of patients is the key for the successful implementation of focal therapy. Selection criteria for focal therapy vary widely and depend on clinical, histological and imaging characteristics of the patients that are highlighted in this article. In addition, the rationales, merits and limitations of the available methods for the assessment of potential candidates, the evaluation of treatment efficacy and follow-up of these patients are discussed.

Transatlantic Consensus Group on active surveillance and focal therapy for prostate cancer

What's known on the subject? and What does the study add? Active surveillance for prostate cancer is gaining increasing acceptance for low risk prostate cancer. Focal therapy is an emerging tissue preservation strategy that aims for treat only areas of cancer. Early phase trials have shown that side-effects can be significantly reduced using focal therapy. There is significant uncertainty in both active surveillance and focal therapy. This consensus group paper provides a road-map for clinical practice and research for both tissue-preserving strategies in the areas of patient population, tools for risk stratification and cancer localisation, treatment interventions as well as comparators and outcome measures in future comparative trials.

OBJECTIVE

To reach consensus on key issues for clinical practice and future research in active surveillance and focal therapy in managing localized prostate cancer.

PATIENTS AND METHODS

A group of expert urologists, oncologists, radiologists, pathologists and computer scientists from North America and Europe met to discuss issues in patient population, interventions, comparators and outcome measures to use in both tissue-preserving strategies of active surveillance and focal therapy. Break-out sessions were formed to provide agreement or highlight areas of disagreement on individual topics which were then collated by a writing group into statements that formed the basis of this report and agreed upon by the whole Transatlantic Consensus Group.

RESULTS

The Transatlantic group propose that emerging diagnostic tools such as precision imaging and transperineal prostate mapping biopsy can improve prostate cancer care. These tools should be integrated into prostate cancer management and research so that better risk stratification and more effective treatment allocation can be applied. The group envisaged a process of care in which active surveillance, focal therapy, and radical treatments lie on a continuum of complementary therapies for men with a range of disease grades and burdens, rather than being applied in the mutually exclusive and competitive way they are now.

CONCLUSION

The changing landscape of prostate cancer epidemiology requires the medical community to re-evaluate the entire prostate cancer diagnostic and treatment pathway in order to minimize harms resulting from over-diagnosis and over-treatment. Precise risk stratification at every point in this pathway is required alongside paradigm shifts in our thinking about what constitutes cancer in the prostate.

Targeted focal therapy for prostate cancer: a review of the literature

Improvements in prostate cancer diagnosis and treatment have resulted in a decreasing age-adjusted death rate. But improved diagnostic tools have not delivered a proportionate decrease in mortality, primarily because physicians now are diagnosing - and treating - more clinically insignificant tumors. Targeted focal therapy (TFT) uses three dimensional (3D) mapping biopsies to guide cryotherapy so that it targets lesions themselves while sparing surrounding healthy tissues, thereby avoiding side effects associated with more invasive treatments. As such, TFT can provide a bridge between active surveillance and more aggressive treatments for patients with low-risk tumors. It is appropriate for men who either do not want or are not good candidates for more aggressive therapies. Identifying patients who are appropriate candidates for TFT is challenging, but the mapping biopsy technique helps identify individuals who have localized disease and could benefit from this treatment. In recent years, improvements in cryotherapy have increased its efficacy while decreasing complications. At the present time using cryotherapy to target and destroy the cancer(s) is appealing. Other approaches to less aggressive therapies are discussed including gland hemi ablation, high intensity ultrasound (HIFU) and others. Going forward, patients will benefit further from development of better imaging technologies and completion of long-term survival studies.

Impact of clinical parameters on the diagnostic accuracy of endorectal coil MRI for the detection of prostate cancer

OBJECTIVES

Endorectal coil MRI (endoMRI) of the prostate is useful to evaluate tumor localization. There is little evidence on patient characteristics affecting its diagnostic performance. We evaluate the influence of clinical and histological parameters on the accuracy of endoMRI.

METHODS

Sixty-nine patients with prostate cancer were included. After virtually dividing the prostate into pixels of 1 cm2, results of endoMRI were compared with those from prostatectomy specimens' whole-mount sections. Univariate and multivariate analyses were performed to calculate the impact of clinical and histological parameters on the number of appropriately described pixels.

RESULTS

In 9, no tumor could be demonstrated by endoMRI. 48.3% of patients were staged correctly, 23.3% were over- and 28.3% understaged. Mean rates of correctly labeled pixels were 0.44 (± 0.04 SEM) for tumor and 0.90 (± 0.01) for benign segments. In univariate analysis, the rate of correctly labeled tumor segments showed significant positive correlations with Gleason score ≥7 and negative correlations with prostate weight and multifocality. The rate of correctly labeled benign segments showed significant negative correlation with tumor weight. All factors were independent variables in multivariate analysis.

CONCLUSIONS

The reliability of endoMRI depends on clinical parameters. Higher Gleason scores, unifocal tumors and smaller prostate volumes ameliorate endoMRI performance.

Clinically low-risk prostate cancer: evaluation with transrectal doppler ultrasound and functional magnetic resonance imaging

OBJECTIVES

To evaluate transrectal ultrasound, amplitude Doppler ultrasound, conventional T2-weighted magnetic resonance imaging, spectroscopy and dynamic contrast-enhanced magnetic resonance imaging in localizing and locally staging low-risk prostate cancer.

INTRODUCTION

Prostate cancer has been diagnosed at earlier stages and the most accepted classification for low-risk prostate cancer is based on clinical stage T1c or T2a, Gleason score ≤6, and prostate-specific antigen (PSA) ≤10 ng/ml.

METHODS

From 2005 to 2006, magnetic resonance imaging was performed in 42 patients, and transrectal ultrasound in 26 of these patients. Seven patients were excluded from the study. Mean patient age was 64.94 years and mean serum PSA was 6.05 ng/ml. The examinations were analyzed for tumor identification and location in prostate sextants, detection of extracapsular extension, and seminal vesicle invasion, using surgical pathology findings as the gold standard.

RESULTS

Sixteen patients (45.7%) had pathologically proven organ-confined disease, 11 (31.4%) had positive surgical margin, 8 (28.9%) had extracapsular extension, and 3 (8.6%) presented with extracapsular extension and seminal vesicle invasion. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy values for localizing low-risk prostate cancer were 53.1%, 48.3%, 63.4%, 37.8% and 51.3% for transrectal ultrasound; 70.4%, 36.2%, 65.1%, 42.0% and 57.7% for amplitude Doppler ultrasound; 71.5%, 58.9%, 76.6%, 52.4% and 67.1% for magnetic resonance imaging; 70.4%, 58.7%, 78.4%, 48.2% and 66.7% for magnetic resonance spectroscopy; 67.2%, 65.7%, 79.3%, 50.6% and 66.7% for dynamic contrast-enhanced magnetic resonance imaging, respectively. Sensitivity, specificity, PPV, NPV and accuracy values for detecting extracapsular extension were 33.3%, 92%, 14.3%, 97.2% and 89.7% for transrectal ultrasound and 50.0%, 77.6%, 13.7%, 95.6% and 75.7% for magnetic resonance imaging, respectively. For detecting seminal vesicle invasion, these values were 66.7%, 85.7%, 22.2%, 97.7% and 84.6% for transrectal ultrasound and 40.0%, 83.1%, 15.4%, 94.7% and 80.0% for magnetic resonance imaging.

CONCLUSION

Although preliminary, our results suggest that imaging modalities have limited usefulness in localizing and locally staging clinically low-risk prostate cancer.

Magnetic resonance imaging for the detection, localisation, and characterisation of prostate cancer: recommendations from a European consensus meeting

BACKGROUND

Multiparametric magnetic resonance imaging (mpMRI) may have a role in detecting clinically significant prostate cancer in men with raised serum prostate-specific antigen levels. Variations in technique and the interpretation of images have contributed to inconsistency in its reported performance characteristics.

OBJECTIVE

Our aim was to make recommendations on a standardised method for the conduct, interpretation, and reporting of prostate mpMRI for prostate cancer detection and localisation.

DESIGN, SETTING, AND PARTICIPANTS

A consensus meeting of 16 European prostate cancer experts was held that followed the UCLA-RAND Appropriateness Method and facilitated by an independent chair.

MEASUREMENT

Before the meeting, 520 items were scored for "appropriateness" by panel members, discussed face to face, and rescored.

RESULTS AND LIMITATIONS

Agreement was reached in 67% of 260 items related to imaging sequence parameters. T2-weighted, dynamic contrast-enhanced, and diffusion-weighted MRI were the key sequences incorporated into the minimum requirements. Consensus was also reached on 54% of 260 items related to image interpretation and reporting, including features of malignancy on individual sequences. A 5-point scale was agreed on for communicating the probability of malignancy, with a minimum of 16 prostatic regions of interest, to include a pictorial representation of suspicious foci. Limitations relate to consensus methodology. Dominant personalities are known to affect the opinions of the group and were countered by a neutral chairperson.

CONCLUSIONS

Consensus was reached on a number of areas related to the conduct, interpretation, and reporting of mpMRI for the detection, localisation, and characterisation of prostate cancer. Before optimal dissemination of this technology, these outcomes will require formal validation in prospective trials.

[Photodynamic therapy and prostate cancer]

PURPOSE

Photodynamic therapy (PDT) is an innovative therapeutic modality in urologic oncology.

MATERIAL AND METHODS

We reviewed the current literature on principles and modalities of PDT in prostatic oncology.

RESULTS

Focal therapy of prostate cancer is an application field of PDT. Clinical phase II studies are ongoing to determine PDT efficacy and safety in this indication. PDT as salvage treatment after prostatic radiotherapy has been tested. Carcinologic results were promising but important side effects were reported. Individual dosimetric planification is necessary to avoid this toxicity.

CONCLUSION

PDT first clinical experience for prostate cancer has showed its technical feasibility. Several research ways are currently in study to improve carcinologic efficacy and to limit potential side effects.

Magnetic resonance guided, focal laser induced interstitial thermal therapy in a canine prostate model

PURPOSE

We evaluated a newly Food and Drug Administration cleared, closed loop, magnetic resonance guided laser induced interstitial thermal therapy system for targeted ablation of prostate tissue to assess the feasibility of targeting, real-time monitoring and predicting lesion generation in the magnetic resonance environment.

MATERIALS AND METHODS

Seven mongrel dogs (University of Texas Health Science Center, Houston, Texas) with (2) and without (5) canine transmissible venereal tumors in the prostate were imaged with a 1.5 T magnetic resonance imaging scanner. Real-time 3-dimensional magnetic resonance imaging was used to accurately position water cooled, 980 nm laser applicators to predetermined targets in the canine prostate. Destruction of targeted tissue was guided by real-time magnetic resonance temperature imaging to precisely control thermal ablation. Magnetic resonance predictions of thermal damage were correlated with posttreatment imaging results and compared to histopathology findings.

RESULTS

Template based targeting using magnetic resonance guidance allowed the laser applicator to be placed within a mean ± SD of 1.1 ± 0.7 mm of the target site. Mean width and length of the ablation zone on magnetic resonance imaging were 13.7 ± 1.3 and 19.0 ± 4.2 mm, respectively, using single and compound exposures. The damage predicted by magnetic resonance based thermal damage calculations correlated with the damage on posttreatment imaging with a slope near unity and excellent correlation (r(2) = 0.94).

CONCLUSIONS

This laser induced interstitial thermal therapy system provided rapid, localized tissue heating under magnetic resonance temperature imaging control. Combined with real-time monitoring and template based planning, magnetic resonance guided, laser induced interstitial thermal therapy is an attractive modality for prostate cancer focal therapy.

Update on prostate imaging

Successful and accurate imaging of prostate cancer is integral to its clinical management from detection and staging to subsequent monitoring. Various modalities are used including ultrasound, computed tomography, and magnetic resonance imaging, with the greatest advances seen in the field of magnetic resonance.

Current status of MRI for the diagnosis, staging and prognosis of prostate cancer: implications for focal therapy and active surveillance

PURPOSE OF REVIEW

To review the current status of MRI techniques in identification of organ-confined prostate cancer with a focus on their implication for focal therapy and active surveillance.

RECENT FINDINGS

MRI is currently focusing on intraprostatic prostate cancer identification and at 1.5T, it provides excellent imaging of the whole gland including the challenging anterior part. Improvements in accuracy for cancer detection and volume estimation result from dynamic contrast-enhanced and diffusion-weighted MRI sequences. 3T MRI might improve cancer identification. Histological correlations showed high sensitivity and specificity for significant volume cancers larger than 0.5 cm3. Important knowledge on modelling of cancer morphology such as zone of origin and intraprostatic patterns of spread at histopathology was made available for imaging interpretation and treatment planning decision. MRI results allow focused use of biopsy which led to better cancer characterization such as extent and grade. Ongoing focal therapy protocols and active surveillance treatments should benefit from these imaging advances.

SUMMARY

At present, high-resolution MRI with pelvic coil appears to offer the most readily available and useful imaging. Future studies should work towards helping define standard, reproducible approaches to imaging and image reporting for research and clinical practice.