Colour Doppler and microbubble contrast agent ultrasonography do not improve cancer detection rate in transrectal systematic prostate biopsy sampling

Novel non-MRI imaging techniques for primary diagnosis of prostate cancer: micro-ultrasound, contrast-enhanced ultrasound, elastography, multiparametric ultrasound, and PSMA PET/CT

BACKGROUND

Multiparametric magnetic resonance imaging (mpMRI) provides enhanced diagnostic accuracy in the detection of prostate cancer, but is not devoid of limitations. Given the recent evolution of non-MRI imaging techniques, this critical review of the literature aimed at summarizing the available evidence on ultrasound-based and nuclear medicine imaging technologies in the initial diagnosis of PCa.

METHODS

Three databases (PubMed®, Web of Science™, and Scopus®) were queried for studies examining their diagnostic performance in the primary diagnosis of PCa, weighted against a histological confirmation of PCa diagnosis, using a free-text protocol. Retrospective and prospective studies, both comparative and non-comparative, systematic reviews (SR) and meta-analysis (MA) were included. Based on authors' expert opinion, studies were selected, data extracted, and results qualitatively described.

RESULTS

Micro-ultrasound (micro-US) appears as an appealing diagnostic strategy given its high accuracy in detection of PCa, apparently non-inferior to mpMRI. The use of multiparametric US (mpUS) likely gives an advantage in terms of effectiveness coming from the combination of different modalities, especially when certain modalities are combined. Prostate-specific membrane antigen (PSMA) PET/CT may represent a whole-body, one-step approach for appropriate diagnosis and staging of PCa. The direct relationship between lesions avidity of radiotracers and histopathologic and prognostic features, and its valid diagnostic performance represents appealing characteristics. However, intrinsic limits of each of these techniques exist and further research is needed before definitively considering them reliable tools for accurate PCa diagnosis. Other novel technologies, such as elastography and multiparametric US, currently relies on a limited number of studies, and therefore evidence about them remains preliminary.

CONCLUSION

Evidence on the role of non-MRI imaging options in the primary diagnosis of PCa is steadily building up. This testifies a growing interest towards novel technologies that might allow overcoming some of the limitations of current gold standard MRI imaging.

Contrast-enhanced ultrasound targeted versus conventional ultrasound guided systematic prostate biopsy for the accurate diagnosis of prostate cancer: A meta-analysis

BACKGROUND

Conventional transrectal ultrasonography (TRUS) guided prostate biopsy is the standard method for accurate diagnosis of prostate cancer (PCa). However, the limitations of this technique in terms of missed diagnosis cannot be ignored. Based on previous studies, contrast-enhanced ultrasound (CEUS) may be able to more distinctly detect malignant lesions with increased microvessels. Therefore, to evaluate the diagnostic efficiency and clinical application prospects of CEUS-guided prostate biopsy for patients with suspected PCa, we performed a meta-analysis comparing CEUS-targeted with TRUS-guided systematic biopsy.

METHODS

A systematic search of PubMed, Web of Science, Embase and CNKI was performed up to March, 2022 for the relevant published studies. After data extraction and quality assessment, meta-analysis was performed using the RevMan 5.3 software.

RESULTS

The results showed that the overall sensitivity was higher for CEUS targeted biopsy than systematic biopsy (P = .03), so was the accuracy (P = .03). However, significant heterogeneity and inconsistent results from certain subgroup analyses challenged the validity of the results. Meanwhile, CEUS yielded a much higher sensitivity in patients with prostate specific antigen (PSA) level of 4 to 10 ng/mL (P = .007). On the other hand, the positive rate of each core (P < .001) and the detection rate of clinically significant PCa (P = .006) were significantly improved using CEUS.

CONCLUSION

CEUS showed the advantage of a higher detection rate of clinically significant PCa, which might provide more specific indications for subsequent treatment. More feasible, real-time data are required to confirm our findings.

Enhanced Transrectal Ultrasound, Real-Time Sonoelastography, and Contrast-Enhanced Transrectal Ultrasound in Heavily Prescreened Chinese Men With Naive and Repetitive Biopsy: A Comparison of Detection Rate of Prostate Cancer Per Man and Per Lesion

ABSTRACT

Multiparametric magnetic resonance imaging and targeted biopsy have been widely accepted as the most accurate technique to detect localize prostate cancer. It is a time-consuming and expensive option and may not be widely available in China, making ultrasound the first choice for the detection of prostate cancer. In this current retrospective study, the diagnostic values of enhanced transrectal ultrasound, contrast-enhanced transrectal ultrasound, and real-time sonoelastography were evaluated. Symptomatic 315 men older than 40 years with prostate-specific antigen level greater than 4.0 ng/mL, with abnormal digital rectal examinations, and with suspicious lesions for prostate cancer under enhanced transrectal ultrasound included in the study. Enhanced transrectal ultrasound was suspicious in all 315 men, with 189 of 315 men with prostate cancer according to the prostate biopsy report. Sonoelastography was suspicious in 294 of 315 men, with 166 of 315 men with prostate cancer according to the prostate biopsy report. Contrast-enhanced transrectal ultrasound was suspicious in 221 of 315 men, with 159 of 315 men with prostate cancer according to the prostate biopsy report. Real-time sonoelastography alone and contrast-enhanced transrectal ultrasound alone were missed in 27 (11%) and 39 (15%) lesions to report cancer through biopsies. Working area for enhanced transrectal ultrasound, real-time sonoelastography, and contrast-enhanced transrectal ultrasound for detection of prostate cancer were 0 to 1 diagnostic confidence, 0.11 to 0.895 diagnostic confidence, and 0.39 to 0.63 diagnostic confidence respectively. Real-time sonoelastography and contrast-enhanced transrectal ultrasound may improve the detection of prostate cancer in men with suspicious prostate lesions under enhanced transrectal ultrasound (Level of Evidence: III; Technical Efficacy Stage: 2).

Application of Multiple Ultrasonic Techniques in the Diagnosis of Prostate Cancer

Methods for diagnosing prostate cancer (PCa) are developing in the direction of imaging. Advanced ultrasound examination modes include micro-Doppler, computerized-transrectal ultrasound, elastography, contrast-enhanced ultrasound and microultrasound. When two or more of these modes are used in PCa diagnosis, the combined technique is called multiparameter ultrasound (mp-US). Mp-US provides complementary information to multiparameter magnetic resonance imaging (mp-MRI) for diagnosing PCa. At present, no study has attempted to combine the characteristics of different ultrasound modes with advanced classification systems similar to the PIRADS system in mpMRI for the diagnosis of PCa. As an imaging method, mp-US has great potential in the diagnosis of PCa.

Diagnostic accuracy of the Novel 29 MHz micro-ultrasound "ExactVuTM" for the detection of clinically significant prostate cancer: A prospective single institutional study. A step forward in the diagnosis of prostate cancer

INTRODUCTION AND OBJECTIVE

ExactVuTM is a real-time micro-ultrasound system which provides, according to the Prostate Risk Identification Using Micro-Ultrasound protocol (PRI-MUS), a 300% higher resolution compared to conventional transrectal ultrasound. To evaluate the performance of ExactVuTM in the detection of Clinically significant Prostate Cancer (CsPCa).

MATERIALS AND METHODS

Patients with Prostate Cancer diagnosed at fusion biopsy were imaged with ExactVuTM. CsPCa was defined as any Gleason Score ≥ 3+4. ExactVuTM examination was considered as positive when PRI-MUS score was ≥ 3. PRI-MUS scoring system was considered as correct when the fusion biopsy was positive for CsPCa. A transrectal fusion biopsy- proven CsPCa was considered as a gold standard. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and area under the receiver operator characteristic (ROC) curve (AUC) were calculated.

RESULTS

57 patients out of 68 (84%) had a csPCa. PRI-MUS score was correctly assessed in 68% of cases. Regarding the detection of CsPCa, ExactVuTM 's sensitivity, specificity, PPV, and NPV was 68%, 73%, 93%, and 31%, respectively and the AUC was 0.7 (95% CI 0.5-0-8). For detecting CsPCa in the transition/ anterior zone the sensitivity, specificity, PPV, and NPV was 45%, 66%, 83% and 25% respectively ant the AUC was 0.5 (95% CI 0.2-0.9). Accounting only the CsPCa located in the peripheral zone, sensitivity, specificity, PPV, and NPV raised up to 74%, 75%, 94%, 33%, respectively with AUC 0.75 (95% CI 0.5-0-9).

CONCLUSIONS

ExactVuTM provides high resolution of the prostatic peripheral zone and could represent a step forward in the detection of CsPCa as a triage tool. Further studies are needed to confirm these promising results.

Optimizing biopsy strategy for prostate cancer: Bayesian framework of network meta-analysis and hierarchical summary receiver operating characteristic model for diagnostic accuracy

Overdiagnosis and overtreatment are well known problems in prostate cancer (PCa). The transrectal ultrasound (TRUS) Guided biopsy (GB) as a current gold standard investigation has a low positive detection rate resulting in unnecessary biopsies. The choice of optimal biopsy strategy needs to be defined. Therefore, we undertook a Bayesian network meta analysis (NMA) and Bayesian prediction in the hierarchical summary receiver operating characteristic (HSROC) model to present a method for optimizing biopsy strategy in PCa. Twenty eight relevant studies were retrieved through online databases of EMBASE, MEDLINE, and CENTRAL up to February 2020. Markov chain Monte Carlo simulation and Surface Under the Cumulative RAnking curve were used to calculate the rank probability using odds ratio with 95% credible interval. HSROC model was used to formulate the predicted true sensitivity and specificity of each biopsy strategy. Six different PCa biopsy strategies including transrectal ultrasound GB (TRUS GB), fusion GB (FUS GB), fusion + transrectal ultrasound GB (FUS + TRUS GB), magnetic resonance imaging GB (MRI GB), transperineal ultrasound GB (TPUS GB), and contrast enhanced ultrasound GB were analyzed in this study with a total of 7584 patients. These strategies were analyzed on five outcomes including detection rate of overall PCa, clinically significant PCa, insignificant PCa, complication rate, and HSROC. The rank probability showed that the overall PCa detection rate was higher in FUS + TRUS GB, MRI GB, and FUS GB. In terms of clinically significant PCa detection, FUS + TRUS GB and FUS GB had a relatively higher clinically significant PCa detection rate, whereas TRUS GB had a relatively lower rate for clinically significant PCa detection rate. MRI GB (91% and 81%) and FUS GB (82% and 83%) had the highest predicted true sensitivity and specificity, respectively, whereas TRUS GB (62% and 83%) had a lower predicted true sensitivity and specificity. MRI GB, FUS GB, and FUS + TRUS GB were associated with lower complication rate, whereas TPUS GB and TRUS GB were more associated with higher complication rate. This NMA and HSROC model highlight the important finding that FUS + TRUS GB, FUS GB, and MRI GB were superior compared with other strategies to avoid the overdiagnosis and overtreatment of PCa. FUS GB, MRI GB, and FUS + TRUS GB had lower complication rates. These results may assist in shared decision making between patients, carers, and their surgeons.

Role of Transrectal Ultrasound Elastography in the Diagnosis of Prostate Carcinoma

Background

The purpose of this study was to evaluate the diagnostic value of transrectal real- time strain elastography (RTE) in identifying prostatic carcinoma (PCa).

Methods

60 patients suspected of having PCa based on abnormal digital rectal examination and raised prostate specific antigen levels underwent transrectal ultrasound (TRUS), color Doppler (CD) and RTE. Elastograms were scored on a five point scale based on distribution of strain in relation to hypoechoic area on TRUS. Twelve core systematic biopsy as well as targeted biopsy was performed from suspicious areas on TRUS and RTE. Diagnostic performance of sonoelastography was evaluated using histopathology as reference standard.

Results

Histopathology revealed cancer in 28 out of 60 patients (47%) studied. Gleason score ranged from 6 to 9. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of TRUS in detecting prostate cancer were 78.57%, 81.25%, 78.57%, and 81.25%, respectively. On CD evaluation 87.5% (n = 28) of benign lesions showed symmetric, radial flow compared to 14.3% (n = 4) of malignant lesions (P < 0.0001). The sensitivity and specificity of RTE was 89.29% and 56.25% with PPV and NPV being 58.13% and 82.35%, respectively. Higher elastography score was found to be significantly associated with malignant histopathology (P = 0.004). Cancer detection rate with RTE was greater for tumors with higher Gleason score.

Conclusion

RTE was found to have better sensitivity than TRUS as well as combination of TRUS and CD. Although less specific, RTE can be an effective adjuvant tool to TRUS for guidance of biopsy and improve detection rate of PCa.

Contrast-enhanced ultrasonography in interventional oncology

Contrast-enhanced ultrasound (CEUS) has evolved from the use of agitated saline to second generation bioengineered microbubbles designed to withstand insonation with limited destruction. While only one of these newer agents is approved by the Food and Drug Administration for use outside echocardiography, interventional radiologists are increasingly finding off-label uses for ultrasound contrast agents. Notably, these agents have an extremely benign safety profile with no hepatic or renal toxicities and no radiation exposure. Alongside diagnostic applications, CEUS has begun to develop its own niche within the realm of interventional oncology. Certainly, the characterization of focal solid organ lesions (such as hepatic and renal lesions) by CEUS has been an important development. However, interventional oncologists are finding that the dynamic and real-time information afforded by CEUS can improve biopsy guidance, ablation therapy, and provide early evidence of tumor viability after locoregional therapy. Even more novel uses of CEUS include lymph node mapping and sentinel lymph node localization. Critical areas of research still exist. The purpose of this article is to provide a narrative review of the emerging roles of CEUS in interventional oncology.

Optimal biopsy strategy for prostate cancer detection by performing a Bayesian network meta-analysis of randomized controlled trials

Objective: With the increasing recognition of the over-diagnosis and over-treatment of prostate cancer (PCa), the choice of a better prostate biopsy strategy had confused both the patients and clinical surgeons. Hence, this network meta-analysis was conducted to clarify this question. Methods: In the current network meta-analysis, twenty eligible randomized controlled trials (RCTs) with 4,571 participants were comprehensively identified through Pubmed, Embase and Web of Science databases up to July 2017. The pooled odds ratio (OR) with 95% credible interval (CrI) was calculated by Markov chain Monte Carlo methods. A Bayesian network meta-analysis was conducted by using R-3.4.0 software with the help of package "gemtc" version 0.8.2. Results: Six different PCa biopsy strategies and four clinical outcomes were ultimately analyzed in this study. Although, the efficacy of different PCa biopsy strategies by ORs with corresponding 95% CrIs had not yet reached statistical differences, the cumulative rank probability indicated that overall PCa detection rate from best to worst was FUS-GB plus TRUS-GB, FUS-GB, CEUS, MRI-GB, TRUS-GB and TPUS-GB. In terms of clinically significant PCa detection, CEUS, FUS-GB or FUS-GB plus TRUS-GB had a higher, whereas TRUS-GB or TPUS-GB had a relatively lower significant detection rate. Meanwhile, TPUS-GB or TRUS-GB had a higher insignificant PCa detection rate. As for TRUS-guided biopsy, the general trend was that the more biopsy cores, the higher overall PCa detection rate. As for targeted biopsy, it could yield a comparable or even a better effect with fewer cores, compared with traditional random biopsy. Conclusion: Taken together, in a comprehensive consideration of four clinical outcomes, our outcomes shed light on that FUS-GB or FUS-GB plus TRUS-GB showed their superiority, compared with other puncture methods in the detection of PCa. Moreover, TPUS or TRUS-GB was more easily associated with the over-diagnosis and over-treatment of PCa. In addition, targeted biopsy was obviously more effective than traditional random biopsy. The subsequent RCTs with larger sample sizes were required to validate our findings.

Diagnostic performance of power doppler and ultrasound contrast agents in early imaging-based diagnosis of organ-confined prostate cancer: Is it possible to spare cores with contrast-guided biopsy?

OBJECTIVES

To evaluate the diagnostic performance of gray scale transrectal ultrasound-B-mode US (BMUS), power Doppler (PDUS), and sonographic contrast (CEUS) in early imaging-based diagnosis of localized prostate cancer (PCa) and to compare the diagnostic profitability of randomized biopsy (RB), US-targeted prostate biopsy by means of PDUS and CEUS.

MATERIAL AND METHODS

A single-center, prospective, transversal, epidemiological study was conducted from January 2010 to January 2014. We consecutively included patients who an imaging study of the prostate with BMUS, PDUS, and CEUS was performed, followed by prostate biopsy due to clinical suspicion of prostate cancer (PSA 4-20ng/mL and/or rectal exam suggestive of malignancy). The diagnostic performance of BMUS, PDUS, and CEUS was determined by calculating the Sensitivity (S), Specificity (Sp), Predictive values (PV), and diagnostic odds ratio (OR) of the diagnosis tests and, for these variables, in the population general and based on their clinical stage according to rectal exam (cT1 and cT2). PCa detection rates determined by means of a randomized 10-core biopsy scheme were compared with detection rates of CEUS-targeted (SonoVue) 2-core biopsies.

RESULTS

Of the initial 984 patients, US contrast SonoVue was administered to 179 (18.2%). The PCa detection rate by organ of BMUS/PDUS in the global population was 38% versus 43% in the subpopulation with CEUS. The mean age of the patients was 64.3±7.01years (95% CI, 63.75-64.70); mean total PSA was 8.9±3.61ng/mL (95% CI, 8.67-9.13) and the mean prostate volume was 56.2±29cc (95% CI, 54.2-58.1). The detection rate by organ of targeted biopsy with BMUS, PDUS, and CEUS were as follows: Global population (10.6, 8.2, 24.5%), stage cT1 (5.6, 4.2, 16.4%), and stage cT2 (32.4, 22.3, 43.5%). Comparing the detection rates of the CEUS-targeted biopsy and randomized biopsy, the following results were obtained: Global population (24.5% vs. 41.8%), stage cT1 (16% vs. 35%), and stage cT2 (43.5% vs. 66.6%), with a p value<0.05. Following the "core-by-core" analysis, the detection rates by core of CEUS-targeted biopsy versus randomized biopsy were: Global population (16% vs. 13%), stage cT1 (30.3% vs. 28%), and stage cT2 (48% vs. 37%), with a p value>0.05. The NNT for CEUS-targeted biopsy was 83.3.

CONCLUSIONS

The low sensitivity, specificity, positive predictive and negative predictive values of gray scale-B-mode, PDUS and CEUS represent scant diagnostic performance of these variables in prostate cancer detection. Prostate cancer detection rates yielded by randomized biopsy were superior than the detection rate of targeted biopsy using B-mode, PDUS and CEUS; as a result, randomized biopsy versus CEUS-targeted biopsies cannot be excluded from biopsy strategy plans for the diagnosis of prostate cancer.

Innovations in diagnostic imaging of localized prostate cancer

PURPOSE

In recent years, various imaging modalities have been developed to improve diagnosis, staging, and localization of early-stage prostate cancer (PCa).

METHODS

A MEDLINE literature search of the time frame between 01/2007 and 06/2013 was performed on imaging of localized PCa.

RESULTS

Conventional transrectal ultrasound (TRUS) is mainly used to guide prostate biopsy. Contrast-enhanced ultrasound is based on the assumption that PCa tissue is hypervascularized and might be better identified after intravenous injection of a microbubble contrast agent. However, results on its additional value for cancer detection are controversial. Computer-based analysis of the transrectal ultrasound signal (C-TRUS) appears to detect cancer in a high rate of patients with previous biopsies. Real-time elastography seems to have higher sensitivity, specificity, and positive predictive value than conventional TRUS. However, the method still awaits prospective validation. The same is true for prostate histoscanning, an ultrasound-based method for tissue characterization. Currently, multiparametric MRI provides improved tissue visualization of the prostate, which may be helpful in the diagnosis and targeting of prostate lesions. However, most published series are small and suffer from variations in indication, methodology, quality, interpretation, and reporting.

CONCLUSIONS

Among ultrasound-based techniques, real-time elastography and C-TRUS seem the most promising techniques. Multiparametric MRI appears to have advantages over conventional T2-weighted MRI in the detection of PCa. Despite these promising results, currently, no recommendation for the routine use of these novel imaging techniques can be made. Prospective studies defining the value of various imaging modalities are urgently needed.

Multiparametric ultrasound in the detection of prostate cancer: a systematic review

PURPOSE

To investigate the advances and clinical results of the different ultrasound modalities and the progress in combining them into multiparametric UltraSound (mpUS).

METHODS

A systematic literature search on mpUS and the different ultrasound modalities included: greyscale ultrasound, computerized transrectal ultrasound, Doppler and power Doppler techniques, dynamic contrast-enhanced ultrasound and (shear wave) elastography.

RESULTS

Limited research available on combining ultrasound modalities has presented improvement in diagnostic performance. The data of two studies suggest that even adding a lower performing ultrasound modality to a better performing modality using crude methods can already improve the sensitivity by 13-51 %. The different modalities detect different tumours. No study has tried to combine ultrasound modalities employing a system similar to the PIRADS system used for mpMRI or more advanced classifying algorithms.

CONCLUSION

Available evidence confirms that combining different ultrasound modalities significantly improves diagnostic performance.

[Sonographic imaging of the prostate]

Accurate identification of the location of carcinoma in the prostate is essential for long-term therapeutic success, in particular for minimally invasive procedures. In recent years many new positive study results for prostate imaging have been reported which must be compared and evaluated and previous conservative assessments may need to be re-evaluated. In addition, combinations of different imaging techniques are increasingly being used in daily clinical routine. Due to technical advancements in sonographic imaging, such as elastography and contrast-enhanced ultrasound (CEUS), the detection rate of prostate cancer can be increased. An overview of the different imaging modalities and current literature are presented in this article.

Endorectal multiparametric 3-tesla magnetic resonance imaging associated with systematic cognitive biopsies does not increase prostate cancer detection rate: a randomized prospective trial

PURPOSE

To investigate prostate cancer (PC) detection rate, employing endorectal multiparametric 3-tesla magnetic resonance imaging (MRI) driving subsequent cognitive systematic prostatic biopsy (CSPB) versus a homogenous group of patients who did not undergo endorectal MRI.

MATERIALS AND METHODS

A series of patients with a first negative biopsy were enrolled in the study. Patients were randomized into two groups: Group A: patients underwent MRI and subsequent CSPB; Group B: patients that did not undergo MRI. Each patient underwent a 13-core sampling. Patients from Group A had four cores more for each MRI suspected lesion. The cancer detection rate was calculated for each group with regard to possible matches or mismatches between MRI evidence and pathological reports.

RESULTS

Two hundred consecutive patients were investigated. Fifty out of 200 (25 %) patients had a diagnosis of PC, 24 in Group A and 26 in Group B. In Group A, 67 patients (67 %) were positive for suspected lesions at the MRI. The mismatch between MRI findings and the CSPB outcome was 61 % with an MRI-driven detection rate of 15 %. Group B detection rate was 26 % with no significant differences versus Group A (P = NS). Patient discomfort was higher in Group A (82 %). The accuracy of CSPB was 41 % with a positive predictive value of 22.3 %. This rate is lower in high-grade cancers (11.9 %). The cost-effectiveness was higher in Group A.

CONCLUSIONS

Prostate cancer detection rate does not improve by CSPB. The accuracy of CSPB was lower in high-grade PC, and a higher cost was found with CSPB.

Investigating the Generalizability of Economic Evaluations Conducted in Italy: A Critical Review

OBJECTIVES

To assess the methodological quality of Italian health economic evaluations and their generalizability or transferability to different settings.

METHODS

A literature search was performed on the PubMed search engine to identify trial-based, nonexperimental prospective studies or model-based full economic evaluations carried out in Italy from 1995 to 2013. The studies were randomly assigned to four reviewers who applied a detailed checklist to assess the generalizability and quality of reporting. The review process followed a three-step blinded procedure. The reviewers who carried out the data extraction were blind as to the name of the author(s) of each study. Second, after the first review, articles were reassigned through a second blind randomization to a second reviewer. Finally, any disagreement between the first two reviewers was solved by a senior researcher.

RESULTS

One hundred fifty-one economic evaluations eventually met the inclusion criteria. Over time, we observed an increasing transparency in methods and a greater generalizability of results, along with a wider and more representative sample in trials and a larger adoption of transition-Markov models. However, often context-specific economic evaluations are carried out and not enough effort is made to ensure the transferability of their results to other contexts. In recent studies, cost-effectiveness analyses and the use of incremental cost-effectiveness ratio were preferred.

CONCLUSIONS

Despite a quite positive temporal trend, generalizability of results still appears as an unsolved question, even if some indication of improvement within Italian studies has been observed.

Transrectal Ultrasound (US), Contrast-enhanced US, Real-time Elastography, HistoScanning, Magnetic Resonance Imaging (MRI), and MRI-US Fusion Biopsy in the Diagnosis of Prostate Cancer

CONTEXT

Debates on overdiagnosis and overtreatment of prostate cancer (PCa) are ongoing and there is still huge uncertainty regarding misclassification of prostate biopsy results. Several imaging techniques that have emerged in recent years could overcome over- and underdiagnosis in PCa.

OBJECTIVE

To review the literature on transrectal ultrasound (TRUS)-based techniques (contrast enhancement, HistoScanning, elastography) and magnetic resonance imaging (MRI)-based techniques for a nonsystematic overview of their benefits and limitations.

EVIDENCE ACQUISITION

A comprehensive search of the PubMed database between August 2004 and August 2014 was performed. Studies assessing grayscale TRUS, contrast-enhanced (CE)-TRUS, elastography, HistoScanning, multiparametric MRI (mpMRI), and MRI-TRUS fusion biopsy were included. Publications before 2004 were included if they reported the principle or the first clinical results for these techniques.

EVIDENCE SYNTHESIS

Grayscale TRUS alone cannot detect PCa foci (detection rate 23-29%). TRUS-based (elastography) and MRI-based techniques (MRI-TRUS fusion biopsy) have significantly improved PCa diagnostics, with sensitivity of 53-74% and specificity of 72-95%. HistoScanning does not provide convincing or homogeneous results (specificity 19-82%). CE-TRUS seems to be user dependent; it is used in a low number of high-volume centers and has wide ranges for sensitivity (54-79%) and specificity (42-95%). For all the techniques reviewed, prospective multicenter studies with consistent definitions are lacking.

CONCLUSIONS

Standard grayscale TRUS is unreliable for PCa detection. Among the techniques reviewed, mpMRI and MRI-TRUS fusion biopsy seem to be suitable for enhancing PCa diagnostics. Elastography shows promising results according to the literature. CE-TRUS yields very inhomogeneous results and might not be the ideal technique for clinical practice. The value of HistoScanning must be questioned according to the literature.

PATIENT SUMMARY

New imaging modalities such as elastography and magnetic resonance imaging/transrectal ultrasound fusion biopsies have improved the detection of prostate cancer. This may lower the burden of overtreatment as a result of more precise diagnosis.

Repeat Targeted Prostate Biopsy under Guidance of Multiparametric MRI-Correlated Real-Time Contrast-Enhanced Ultrasound for Patients with Previous Negative Biopsy and Elevated Prostate-Specific Antigen: A Prospective Study

OBJECTIVES

To prospectively determine whether multi-parametric MRI (mpMRI) - contrast-enhanced ultrasound (CEUS) correlated, imaging-guided target biopsy (TB) method could improve the detection of prostate cancer in re-biopsy setting of patients with prior negative biopsy.

METHODS

From 2012 to 2014, a total of 42 Korean men with a negative result from previous systematic biopsy (SB) and elevated prostate-specific antigen underwent 3T mpMRI and real-time CEUS guided TB. Target lesions were determined by fusion of mpMRI and CEUS. Subsequently, 12-core SB was performed by a different radiologist. We compared core-based cancer detection rates (CaDR) using the generalized linear mixed model (GLIMMIX) for each biopsy method.

RESULTS

Core-based CaDR was higher in TB (17.92%, 38 of 212 cores) than in SB (6.15%, 31 of 504 cores) (p < 0.0001; GLIMMIX). In the cancer-positive TB cores, CaDR with suspicious lesions by mpMRI was higher than that by CEUS (86.8% vs. 60.5%, p= 0.02; paired t-test) and concordant rate between mpMRI and CEUS was significantly different with discordant rate (48% vs. 52%, p=0.04; McNemar's test).

CONCLUSION

The mpMRI-CEUS correlated TB technique for the repeat prostate biopsy of patients with prior negative biopsy can improve CaDR based on the number of cores taken.

Growing indications for CEUS: The kidney, testis, lymph nodes, thyroid, prostate, and small bowel

Contrast enhanced ultrasonography (CEUS) is increasingly used for non-hepatic applications as well, so that nearly all organs have been investigated. Among them, there is a growing clinical use for a variety of pathologies of the kidney, testis, and small bowel. The possibility to differentiate benign from malignant nodes in cancer patients has been investigated. A new application is in the detection of sentinel nodes after intradermal microbubble injection. The need to distinguish thyroid nodules eligible for fine needle aspiration cytology has led to the use of CEUS in thyroid examinations as well. The potential of CEUS for prostate cancer detection has been extensively investigated, with encouraging initial results. Early promise, however, has not been fulfilled. New perspective regards evaluation of the extent of prostate tissue devascularization following ablative treatments.

Direct Comparison of Targeted MRI-Guided Biopsy with Systematic Transrectal Ultrasound-Guided Biopsy in Patients with Previous Negative Prostate Biopsies

Objective: To directly compare the diagnostic performance of targeted MRI-guided biopsy (MR-GB) and systematic transrectal ultrasound-guided biopsy (TRUS-GB). Methods: Thirty-five patients with at least one negative TRUS-GB, persistently elevated or rising prostate-specific antigen and a lesion suspicious for prostate cancer (PC) on multiparametric MRI (mpMRI) scored by using the Prostate Imaging Reporting and Data System (PI-RADS) were included. A median of three targeted biopsies per lesion were obtained and systematic TRUS-GB was performed subsequently by an independent urologist without knowledge of the MRI findings. Definite pathology reports were analyzed for anatomical location and criteria of clinical significance. Results: The tumor detection rate was significantly higher with MR-GB compared with TRUS-GB (16/35, 46% and 8/35, 23%, respectively, p < 0.05). MR-GB detected PC in all patients with positive TRUS-GB. All tumors detected by MR-GB exhibited at least one criterion of clinical significance. PC lesions showed a significantly higher PI-RADS sum score compared with benign lesions. Conclusions: MR-GB is more effective compared with TRUS-GB in detecting clinically significant PC in men after previous negative TRUS-GB. PI-RADS scores give additional information and could be part of the decision-making process when considering retrial biopsy. Additional systematic biopsy can be omitted in patients undergoing targeted MR-GB.

Imaging and intervention in prostate cancer: Current perspectives and future trends

Prostate cancer is the commonest malignancy in men that causes significant morbidity and mortality worldwide. Screening by digital rectal examination (DRE) and serum prostate-specific antigen (PSA) is used despite its limitations. Gray-scale transrectal ultrasound (TRUS), used to guide multiple random prostatic biopsies, misses up to 20% cancers and frequently underestimates the grade of malignancy. Increasing the number of biopsy cores marginally increases the yield. Evolving techniques of real-time ultrasound elastography (RTE) and contrast-enhanced ultrasound (CEUS) are being investigated to better detect and improve the yield by allowing “targeted” biopsies. Last decade has witnessed rapid developments in magnetic resonance imaging (MRI) for improved management of prostate cancer. In addition to the anatomical information, it is capable of providing functional information through diffusion-weighted imaging (DWI), magnetic resonance spectroscopy (MRS), and dynamic contrast-enhanced (DCE) MRI. Multi-parametric MRI has the potential to exclude a significant cancer in majority of cases. Inclusion of MRI before prostatic biopsy can reduce the invasiveness of the procedure by limiting the number of cores needed to make a diagnosis and support watchful waiting in others. It is made possible by targeted biopsies as opposed to random. With the availability of minimally invasive therapeutic modalities like high-intensity focused ultrasound (HIFU) and interstitial laser therapy, detecting early cancer is even more relevant today. [18F]--fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸FDG PET/CT) has no role in the initial evaluation of prostate cancer. Choline PET has been recently found to be more useful. Fluoride-PET has a higher sensitivity and resolution than a conventional radionuclide bone scan in detecting skeletal metastases.

Comparison of image-guided targeted biopsies versus systematic randomized biopsies in the detection of prostate cancer: a systematic literature review of well-designed studies

OBJECTIVE

The clinical utility of image-targeted biopsies can only be judged by a comparison of the current standard of systematic 10-12 core biopsy schemes. The aim of this review was to gather the current evidence in favor of or against targeted biopsies in the detection of prostate cancer based on well-designed, controlled studies, in order to draw clinical relevant conclusions.

SUBJECTS/PATIENTS AND METHODS

A systematic literature review was performed addressing studies that compared the prostate cancer detection rates of targeted and systematic biopsy schemes using the imaging techniques of elastography, contrast-enhanced ultrasound, histoscanning and multiparametric MRI. Only well-designed, controlled studies were included and the results summarized.

RESULTS

All imaging techniques are associated with varying results regarding better or poorer detection rates relative to systematic biopsies. No technique provides a clear trend in favor of or against image-targeted biopsies. In almost all studies, the combination of targeted and systematic biopsies provided sometimes a substantial, increase in the detection rate relative to systematic biopsies alone. MRI-targeted biopsies show no advantage in the initial biopsy setting, whereas in the repeat biopsy setting improvements in the detection rates are often observed relative to systemic biopsies.

CONCLUSION

Based on well-designed, controlled studies no clear advantage of targeted biopsies over the current standard of systematic biopsies can be observed. Therefore, targeted biopsies cannot replace systematic biopsies in the diagnosis of prostate cancer. In all indications, the combination of systematic and targeted biopsy schemes provides the highest detection rate.

MRI in prostate cancer

Imaging studies play an important role in detection and management of prostate cancer and MRI especially with the use of endorectal coil because of high contrast resolution is recognized as the best imaging modality in evaluation of prostate cancer. Multiparametric MR study including T1 and T2 weighted images, diffusion weighted images, dynamic contrast study and MR spectroscopy is useful for detection and local staging of prostate cancer as well as posts treatment evaluation of patients either after surgery or radiation therapy for detection of local recurrence.

[Imaging of the prostate]

Recently several new technologies for prostate imaging have been developed. The aim of these technologies was to improve the diagnosis of prostate cancer. Especially the transrectal ultrasound (TRUS) has been refined to the so-called enhanced ultrasound, as regular grey scale TRUS has limited ability to identify cancer lesions in the prostate. In several studies elastography has shown good capability to identify cancer lesions in the prostate as well as to absolutely increase the detection rate of randomized biopsies by up to 10 %.. Contrast-enhanced ultrasound shows varying results in the published literature with increased detection rates on the one hand and unchanged detection rates relative to randomized biopsy on the other hand. The online available ANNA/C-TRUS system shows detection rates with six targeted biopsies that are comparable to the published detection rates of randomized saturation biopsies. Direct systematic comparison to randomized biopsies is missing. The Histoscanning system currently provides the poorest data as no biopsy studies are available. Multicenter trials are mandatory for all new imaging technologies in order to implement them as standard into clinical practice.

Focal therapy for prostate cancer: rationale and treatment opportunities

Focal therapy is an emerging treatment modality for localised prostate cancer that aims to reduce the morbidity seen with radical therapy, while maintaining cancer control. Focal therapy treatment strategies minimise damage to non-cancerous tissue, with priority given to the sparing of key structures such as the neurovascular bundles, external sphincter, bladder neck and rectum. There are a number of ablative technologies that can deliver energy to destroy cancer cells as part of a focal therapy strategy. The most widely investigated are cryotherapy and high-intensity focussed ultrasound. Existing radical therapies, such as brachytherapy and external beam radiotherapy, also have the potential to be applied in a focal manner. The functional outcomes of focal therapy from several phase I and II trials have been encouraging, with low rates of urinary incontinence and erectile dysfunction. Robust medium- and long-term cancer control outcomes are currently lacking. Controversies in focal therapy remain, notably treatment paradigms based on the index lesion hypothesis, appropriate patient selection for focal therapy and how the efficacy of focal therapy should be assessed. This review articles discusses the current status of focal therapy, highlighting controversies and emerging strategies that can influence treatment outcomes for the future.

Impact of Real-Time Elastography versus Systematic Prostate Biopsy Method on Cancer Detection Rate in Men with a Serum Prostate-Specific Antigen between 2.5 and 10 ng/mL

The actual gold standard for the diagnosis of prostate cancer includes the serum prostate-specific antigen, the digital rectal examination, and the ultrasound-guided systematic prostate biopsy sampling. In the last years, the real-time elastography has been introduced as an imaging technique to increase the detection rate of prostate cancer and simultaneously reduce the number of biopsies sampled for a single patient. Here, we evaluated a consecutive series of 102 patients with negative digital-rectal examination and transrectal ultrasound, and prostate-specific antigen value ranging between 2.5 ng/mL and 10 ng/mL, in order to assess the impact of real-time elastography versus the systematic biopsy on the detection of prostate cancer. We found that only 1 out of 102 patients resulted true positive for prostate cancer when analysed with real-time elastography. In the other 6 cases, real-time elastography evidenced areas positive for prostate cancer, although additional neoplastic foci were found using systematic biopsy sampling in areas evidenced by real-time elastography as negative. Although additional studies are necessary for evaluating the effectiveness of this imaging technique, the present study indicates that the limited accuracy, sensitivity, and specificity do not justify the routine application of real-time elastography in prostate cancer detection.

Prostate cancer imaging: what the urologist wants to know

No consensus exists at present regarding the use of imaging for the evaluation of prostate cancer. Ultrasonography is mainly used for biopsy guidance and magnetic resonance imaging is the mainstay in evaluating the extent of local tumor. Computed tomography and radionuclide bone scanning are mainly reserved for assessment of advanced disease. Positron emission tomography is gaining acceptance in the evaluation of treatment response and recurrence. The combination of anatomic, functional, and metabolic imaging modalities has promise to improve treatment. This article reviews current imaging techniques and touches on the evolving technologies being used for detection and follow-up of prostate cancer.

Image guidance in the focal treatment of prostate cancer

PURPOSE OF REVIEW

The advent of prostate-specific antigen screening has led to a seven-fold increase in the incidence of prostate cancer without a resultant decrease in mortality rate. This has led to the belief that urologists are overdetecting and overtreating clinically insignificant disease. To maintain the delicate balance between high cancer cure rate and overtreatment, which could potentially lead to unnecessary morbidities, focal therapy has emerged as the reasonable middle ground. In this article, we present the conceptual basis and the challenges of focal therapy, while emphasizing the critical role of imaging in focal treatment of prostate cancer.

RECENT FINDINGS

Multiple phase I trials have demonstrated the feasibility, short-term efficacy, and safety of focal therapy. Fundamental to the success of these trials and the ultimate acceptance of focal therapy is the integral role of imaging in optimal patient selection. Among the different imaging modalities, only ultrasound and multiparametric MRI are intimately involved in the detection, diagnosis, staging, and treatment of prostate cancer. Each modality has its own unique advantages and shortcomings. Recent advances in enhanced ultrasound modalities, functional MRIs, and biopsy platforms have taken focal therapy one step closer to becoming the standard of care.

SUMMARY

Although early results of phase I focal therapy trials are encouraging, long-term oncological outcomes remain to be elucidated. Incorporation of these technological advances into large prospective trials is needed to establish focal therapy as an important asset in the urologist's armamentarium against prostate cancer.