Contrast enhanced color Doppler endorectal sonography of prostate: efficiency for detecting peripheral zone tumors and role for biopsy procedure

Alternatives for MRI in Prostate Cancer Diagnostics-Review of Current Ultrasound-Based Techniques

Simple Summary

Prostate cancer (PCa) is the most common solid malignant tumor in men worldwide with various clinical manifestations. Due to overdiagnosis and overtreatment of a clinically insignificant disease, multiparametric magnetic resonance imaging is recommended for every patient before performing prostate biopsy. However, the diagnostic pathway currently has many limitations and is still far from ideal. Therefore, further alternatives need to be investigated. As the novel ultrasound-based techniques, such as shear wave elastography, contrast-enhanced ultrasound or high frequency micro-ultrasound are able to, overcome the limitations of magnetic resonance imaging presenting good performance in recent studies, we have summarized and compared the results of each technique in the detection of PCa. Furthermore, we analyzed the future perspectives for ultrasound modalities that may soon significantly improve their diagnostic value.

Abstract

The purpose of this review is to present the current role of ultrasound-based techniques in the diagnostic pathway of prostate cancer (PCa). With overdiagnosis and overtreatment of a clinically insignificant PCa over the past years, multiparametric magnetic resonance imaging (mpMRI) started to be recommended for every patient suspected of PCa before performing a biopsy. It enabled targeted sampling of the suspicious prostate regions, improving the accuracy of the traditional systematic biopsy. However, mpMRI is associated with high costs, relatively low availability, long and separate procedure, or exposure to the contrast agent. The novel ultrasound modalities, such as shear wave elastography (SWE), contrast-enhanced ultrasound (CEUS), or high frequency micro-ultrasound (MicroUS), may be capable of maintaining the performance of mpMRI without its limitations. Moreover, the real-time lesion visualization during biopsy would significantly simplify the diagnostic process. Another value of these new techniques is the ability to enhance the performance of mpMRI by creating the image fusion of multiple modalities. Such models might be further analyzed by artificial intelligence to mark the regions of interest for investigators and help to decide about the biopsy indications. The dynamic development and promising results of new ultrasound-based techniques should encourage researchers to thoroughly study their utilization in prostate imaging.

Prostate Cancer Ultrasound: Is Still a Valid Tool?

Purpose of Review

The main purpose of this paper review is to highlight the latest ultrasound (US) imaging technologies of the prostate gland, an organ increasingly at the center of attention in the field of oncological diseases of the male sex, which needs a 360° evaluation in order to obtain tailored therapeutic planning. Specialist urological evaluation is designated for this purpose, together with integrated prostate imaging which currently tends to focus more and more on the use of US imaging and its state-of-the-art technologies in iconographic diagnosis, biopsy and, sometimes, treatment of prostatic cancer.

Recent Findings

In particular, the main tools to which reference is made, represent a valid aid to basic US technologies already widely known and diffused, like the grayscale US or the Doppler US, for a "multiparametric" evaluation of the prostate cancer. The concept of multiparametricity is explained by the integration of prostate imaging obtained both with the US evaluation of the gland before and after administration of contrast medium, with the elaboration of parametric maps of quantitative measurement of the enhancement, and with elastography that provides information about the tissue consistency, a finding that strongly relates with the degree of cellularity and with the tumor grading.

Summary

Prostate cancer screening consists of dosing serum levels of prostate-specific antigen (PSA) and performing digit-rectal examination (DRE), more or less associated with transrectal prostate ultrasound (TRUS). However, although these are the most common techniques in clinical practice, they have numerous limitations and make the diagnosis of prostate cancer often challenging. The purpose of mp-US is to enrich the clinical-laboratory data and, above all, the standard US imaging with further details to strengthen the suspicion of malignancy of a prostate tumor, which needs to be addressed to diagnostic deepening with biopsy. This review article provides a summary of the current evidence on mp-US imaging in the evaluation of a clinically significant prostate cancer, comparing the data obtained to the imaging of mp-MRI, the reference tool both in diagnosis and staging.

Advanced ultrasound in the diagnosis of prostate cancer

The diagnosis of prostate cancer (PCa) can be challenging due to the limited performance of current diagnostic tests, including PSA, digital rectal examination and transrectal conventional US. Multiparametric MRI has improved PCa diagnosis and is recommended prior to biopsy; however, mp-MRI does miss a substantial number of PCa. Advanced US modalities include transrectal prostate elastography and contrast-enhanced US, as well as improved B-mode, micro-US and micro-Doppler techniques. These techniques can be combined to define a novel US approach, multiparametric US (mp-US). Mp-US improves PCa diagnosis but is not sufficiently accurate to obviate the utility of mp-MRI. Mp-US using advanced techniques and mp-MRI provide complementary information which will become even more important in the era of focal therapy, where precise identification of PCa location is needed.

Transrectal Subharmonic Ultrasound Imaging for Prostate Cancer Detection

OBJECTIVE

To assess the prostate cancer (CaP) detection rates of contrast-enhanced, transrectal subharmonic ultrasound imaging (SHI).

MATERIALS AND METHODS

This IRB-approved study enrolled 55 subjects. The initial 5 subjects were studied for SHI optimization, while the remaining 50 were evaluated with contrast-enhanced sonography using continuous SHI, color, and power Doppler as well as conventional grayscale, continuous color, and power Doppler and SHI combined with maximum flash replenishment. A maximum of 6 directed biopsy cores were obtained from sites of greatest asymmetrical enhancement, followed by spatially distributed cores in a double sextant distribution. Subharmonic time-intensity parameters, including time to peak intensity, peak intensity, and estimated perfusion were also evaluated for each directed biopsy core. Receiver operating characteristic curve analysis and conditional logistic regression were employed to assess the benefit of each modality and the quantitative SHI parameters.

RESULTS

Cancer was detected in 22 of 50 subjects. Among subjects with clinically significant CaP (n = 11), targeted cores were more likely to be positive (odds ratio 1.39, P = .02). The majority of patients detected by SHI demonstrated significant CaP (5/8); SHI remained an independent marker of malignancy in a multivariate logistic regression model (P = .027). Receiver operating characteristic curve analysis of imaging findings compared to biopsy results yielded diagnostic accuracies ranging from 0.59 to 0.80 for all imaging modalities with the highest being for quantitative subharmonic perfusion estimates.

CONCLUSION

This first-in-humans study provides a preliminary estimate of the diagnostic accuracy of SHI for detection of clinically significant CaP (up to 80%).

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.

The utility and limitations of contrast-enhanced ultrasound for the diagnosis and treatment of prostate cancer

In association with the widespread use of prostate specific antigen (PSA) screening, the numbers of men identified with early-stage prostate cancer (PCa) are increasing in the developed countries, including Japan. However, the accurate localization of PCa lesions in diagnostic imaging is still difficult because PCa has a tendency to be multifocal in the prostate gland. Contrast-enhanced ultrasound (CEUS) improves the detection of PCa by visualizing cancerous lesions in order to target a needle biopsy. CEUS has the potential to enable not only accurate diagnoses but also novel treatments such as focal therapy. The combination of CEUS and other modalities is expected to improve the diagnosis of PCa and its treatment.

Prostate biopsy for the interventional radiologist

Prostate biopsies are usually performed by urologists in the office setting using transrectal ultrasound (US) guidance. The current standard of care involves obtaining 10-14 cores from different anatomic sections. Biopsies are usually not directed into a specific lesion because most prostate cancers are not visible on transrectal US. Color Doppler, US contrast agents, elastography, magnetic resonance (MR) imaging, and MR imaging/US fusion are proposed as imaging methods to guide prostate biopsies. Prostate MR imaging and fusion biopsy create opportunities for diagnostic and interventional radiologists to play an increasingly important role in the screening, evaluation, diagnosis, targeted biopsy, surveillance, and focal therapy of patients with prostate cancer.

Doppler spectral waveform parameters at neurovascular bundle vessels in patients with prostate biopsy

INTRODUCTION AND OBJECTIVES

There is a need to improve prescreening determination of prostate cancer to better select patients who need biopsy. Such a strategy properly implemented, will decrease the number of negative biopsies for prostate cancer and in turn better balance the risks and morbidity for patients recommended for biopsy. The aim of study is to investigate Doppler spectral waveform parameters of neurovascular bundle (NVB) vessels and determine differences between benign and malignant pathologies.

PATIENTS AND METHODS

We performed a prospective analysis involving 292 patients who received prostate biopsy for elevated prostate-specific antigen (PSA) values or abnormal digital rectal examination, as well as 174 patients with symptomatic benign prostatic hyperplasia. Doppler spectral waveform (DSW) parameters (peak-systolic velocity [PSV], end-diastolic velocity [EDV], and resistive index [RI]) were measured at bilateral NVB vessels through Doppler transrectal ultrasound at the right lateral decubitus position, compared, and analyzed among patients with benign versus malignant histology for each side.

RESULTS

Overall, both PSV and EDV at malignant sides were significantly higher than those at benign sides, as well as lower RI (all p-values <0.05, unpaired t-test). In subgroup analysis with 93 patients of serum PSA between 10 and 20 ng/mL and 56 patients with one-side malignancy, higher EDV and lower RI were significantly associated with malignancies (all p<0.05). The values of PSV and EDV rather than RI might be influenced by the patients' position and RI by the prostate volume.

CONCLUSIONS

In this study, DSW parameters (mainly EDV and RI) at NVB vessels were significantly associated with prostate cancer, particularly in patients with serum PSA of 10-20 ng/mL. It should be in caution that the patients' position and prostate volume may influence the Doppler signal as demonstrated in the current study. These findings can provide more diagnostic information before prostate biopsy.

Focal low-dose rate brachytherapy for the treatment of prostate cancer

Whole-gland low-dose rate (LDR) brachytherapy has been a well-established modality of treating low-risk prostate cancer. Treatment in a focal manner has the advantages of reduced toxicity to surrounding organs. Focal treatment using LDR brachytherapy has been relatively unexplored, but it may offer advantages over other modalities that have established experiences with a focal approach. This is particularly true as prostate cancer is being detected at an earlier and more localized stage with the advent of better detection methods and newer imaging modalities.

The value and limitations of contrast-enhanced transrectal ultrasonography for the detection of prostate cancer

OBJECTIVES

To evaluate the role of contrast-enhanced transrectal ultrasonography (CE-TRUS) for detecting prostate carcinoma.

METHODS

Sixty-five patients with elevated serum prostate-specific antigen (PSA) and/or abnormal digital rectal examination (DRE) were assessed using transrectal ultrasound (TRUS) and CE-TRUS. In all the patients, CE-TRUS was performed with intravenous injection of contrast agent (SonoVue, 2.4 ml) before biopsy. The cancer detection rates of the two techniques were compared. False-positive and false-negative findings related to CE-TRUS were analyzed in comparison to the pathological results of biopsy or radical prostatectomy. The targeted biopsy to abnormal CE-TRUS areas was also compared to systematic biopsy.

RESULTS

Prostate cancer was detected in 29 of the 65 patients. CE-TRUS showed rapid focal enhancement or asymmetric vessels of peripheral zones in 28 patients; 23 of them had prostate cancer. CE-TRUS had 79.3% sensitivity, compared to 65.5% of TRUS (P<0.05). There were five false-positive and six false-negative findings from CE-TRUS. Benign prostate hyperplasia, and acute and chronic prostatitis were important causes related to the false-positive results of CE-TRUS. Prostate cancer originating from the transition zone or peripheral zone with lower PSA levels, small-size foci, and moderately or well-differentiated tumor was missed by CE-TRUS. The cancer detection rate of targeted biopsy (75%, 33/44 cores) was significantly higher than one of systematic biopsy (48.2%, 162/336) in those 28 cases (P<0.05). In addition, no significant correlation was found between the cancer detection rate with CE-TRUS and serum PSA levels.

CONCLUSION

CE-TRUS may improve the detection rate of prostate cancer through targeted biopsy of contrast-enhanced abnormalities. Our findings indicate that systematic biopsies should not be eliminated on the basis of false-positive and false-negative findings related to CE-TRUS.

Increased rate of positive biopsies using a combination of MR-Tomography, spectroscopy and diffusion-weighted magnetic resonance imaging prior to prostate biopsies in patients with persistent elevated prostate-specific antigen values: A retrospective analysis

Purpose:

Persistently elevated prostate-specific antigen (PSA) values following negative biopsies result in a diagnostic dilemma. In order to improve detection rates in patients with former negative biopsies and persistently elevated PSA values, magnetic resonance tomography (MRT), magnetic resonance spectroscopy (MRS), and diffusion-weighted magnetic resonance imaging (DW-MRI) were performed prior to prostate rebiopsies.

Materials and Methods:

Over a 14-month period, 67 patients (mean age of 66 years) with a history of 1-5 negative biopsies underwent endorectal magnetic resonance imaging (MRI) using T2-weighted MRT MRS and DW-MRI before an additional prostate biopsy was performed. Subsequently, 5 contrast-enhanced transrectal ultrasound-guided biopsies were performed according to a 10-core systematic scheme. Out of the 67 men, 25 patients had positive biopsies and opted for radical prostatectomy. Histological evaluation of cancer localization, PSA, diameters of primary tumors, numbers and diameters of satellite tumors, prostate volume, and staging pathology was performed. These findings were compared with MRI and MRS results.

Results:

Serum PSA levels ranged from 3.1 to 19.5 g/ml (median level of 7.96 ng/ml). After the 25 patients underwent radical prostatectomy, analysis of 20 whole-mount sections of 25 radical retropubic prostatectomy (RPE) specimens presented results agreeing with the tumor location from MRI and MRS data.

Conclusions:

The aim of image-guided diagnostics should be to provide more critical information prior to biopsy. Furthermore, the acquisition of such data is important for better risk stratification in therapeutic decisions.

Comparative study of thyroid puncture biopsy guided by contrast-enhanced ultrasonography and conventional ultrasound

The aim of this study was to investigate the application value of thyroid puncture biopsy guided by contrast-enhanced ultrasound (CEUS). A total of 48 patients with 51 solid thyroid nodules (suspected papillary thyroid carcinoma, PTC) were enrolled in the study. Following detection by conventional ultrasonography and CEUS, puncture biopsy of the suspicious lesions guided by conventional ultrasonography and CEUS was conducted, respectively. Then, pathological diagnosis was performed. The number of PTC positive nodules and puncture points detected by the two methods were compared. In 51 nodules with 310 punctures, 44 nodules (86.3%, 44/51) and 240 punctures (77.4%, 240/310) were pathologically diagnosed as PTC. In the 44 nodules diagnosed as PTC, 43 and 34 nodules were detected by CEUS and conventional ultrasound, respectively, with a significant difference between the two methods (P=0.022). Eleven (25%) nodules were independently detected by CEUS. The sensitivity and accuracy of puncture point detection by CEUS (82.9 and 82.6%, respectively) were significantly higher compared with those of conventional ultra-sound (48.3 and 56.5%, respectively; P<0.001). The specificity of puncture points detected by CEUS (81.4%) was significantly lower compared with that by conventional ultrasound (84.3%; P=0.009). Compared with conventional ultrasound, a greater number of PTC-positive nodules were detected by CEUS, with increased sensitivity and accuracy of the puncture points.

Diagnostic performance of contrast enhanced ultrasound in patients with prostate cancer: a meta-analysis

RATIONALE AND OBJECTIVES

We aimed to do a meta-analysis of the existing literature to assess the accuracy of prostate cancer (PCa) studies that use contrast-enhanced ultrasound (CEUS) as a diagnostic tool.

MATERIALS AND METHODS

The MEDLINE, EMBASE, and Cochrane Library databases were searched for relevant original articles published up to August 2012. Characteristics of Included studies were recorded. Methodological quality was assessed by using the quality assessment of diagnostic studies tool. Pooled weighted estimates of diagnostic odds ratio (DOR), sensitivity, specificity, and positive and negative likelihood ratio (LR) were calculated. A summary receiver operator characteristic (SROC) curve was constructed to calculate the area under the curve (AUC). Publication bias analysis was also performed.

RESULTS

Sixteen studies (2624 patients) were included in the meta-analysis. Various contrast agents and imaging modes were applied. The independent random-effects summary showed a variation in diagnostic values. The summary estimates of sensitivity, specificity, and DOR were 0.70, 0.74, and 9.09, respectively. The weighted positive and negative LR were 2.81 and 0.35, with statistically significant between-study heterogeneity (P < .001). Sensitivity was better in positive patient studies than positive biopsy cores ones (0.78 vs. 0.64). SROC plot displayed value for AUC (0.82). Begg's test (P = .822) and Egger's test (P = .198) did not show evidence of publication bias.

CONCLUSION

CEUS is a promising tool in the detection of PCa, but it cannot completely replace systematic biopsy under the present circumstances. It is necessary to standardize imaging techniques, contrast agents and diagnostic criteria. Large samples, multi-center studies and high-quality prospective trials are necessary to assess its clinical value.

Contrast enhanced transrectal ultrasound for the detection of prostate cancer: a randomized, double-blind trial of dutasteride pretreatment

PURPOSE

The identification of clinically significant disease is crucial for optimal treatment of prostate cancer. Selective detection of prostate cancer with increased microvessel density is possible with contrast enhanced ultrasound. Preliminary studies suggest that pretreatment with a 5α-reductase inhibitor may improve the efficiency of contrast enhanced ultrasound targeted biopsy. This study was designed to quantify prostate cancer detection with contrast enhanced ultrasound with or without short-term pretreatment with dutasteride.

MATERIALS AND METHODS

In this randomized, double-blind, placebo controlled trial of oral dutasteride pretreatment, contrast enhanced ultrasound findings were graded and used to direct targeted biopsy (up to 6 cores per prostate). A blinded 12-core systematic biopsy was subsequently performed on every subject based on standard medial and lateral sampling of each sextant.

RESULTS

Of 311 subjects who underwent randomization, 272 completed participation. Positive biopsies were obtained in 276 of 3,264 (8.5%) systematic cores and 203 of 1,237 (16.4%) targeted cores (OR 2.1, 95% CI 1.7-2.6, p <0.001). ROC analysis for the detection of all prostate cancers demonstrated an increase in diagnostic accuracy from pre-contrast imaging to contrast enhanced ultrasound (A(z) 0.60 vs 0.64, p = 0.005). For the detection of high grade cancer (Gleason score 7 or greater) ROC analysis demonstrated improved accuracy for pre-contrast imaging (A(z) 0.74) and contrast enhanced ultrasound (A(z) 0.80, p = 0.0005). For the detection of high grade cancer with greater than 50% biopsy core involvement, excellent accuracy was demonstrated with pre-contrast and contrast enhanced ultrasound, A(z) 0.83 and 0.90, respectively (p = 0.001). Pretreatment with dutasteride had no significant impact on the detection of prostate cancer (p = 0.97).

CONCLUSIONS

Contrast enhanced ultrasound targeted biopsy provides a significant benefit for the detection of high grade/high volume prostate cancer.

Value of contrast-enhanced sonographic micro flow imaging for prostate cancer detection with t-PSA level of 4-10 ng/mL

OBJECTIVES

To compare the efficiency of contrast-enhanced ultrasonographic micro flow imaging (MFI) with conventional transrectal ultrasound (TRUS) in detecting prostate cancer with serum total prostate-specific antigen (t-PSA) of 4.0-10.0 ng/mL. To evaluate the value of contrast-enhanced ultrasonographic MFI in detecting prostate cancer with t-PSA in diagnostic gray zone.

METHODS

47 patients with t-PSA 4.0-10.0 ng/mL underwent gray scale, power Doppler TRUS and MFI examinations before ultrasound guided biopsies. Biopsies were performed at twelve sites in the base, the mid-gland and the apex of the prostate in each patient, when there was no abnormal ultrasound finding. When an abnormality was present at MFI, the biopsy specimen from the corresponding site was directed toward the abnormal finding. With histological results of prostate biopsy as reference standards, we assessed the cancer detection of these three methods.

RESULTS

564 specimens were collected in this study, in which 101 were prostate cancer confirmed histologically. 152 of 564 specimens were demonstrated abnormal on MFI images, in which 71 were malignant and 81 were benign confirmed histologically. The sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) for MFI in detecting prostate caner were 70.3%, 82.5%, 80.3%, 46.7% and 92.7%, respectively. The sensitivity and NPV for MFI were significantly better than gray scale (38.6%, 86.9%) and power Doppler (32.7%, 86.0%) (P<0.001) TRUS.

CONCLUSIONS

Contrast-enhanced ultrasonographic MFI could significantly improve the detection rate of prostate cancer with t-PSA in diagnostic gray zone (4-10 ng/mL) than conventional ultrasound.

[New ultrasound technologies for the diagnostics of prostate cancer]

CLINICAL/METHODOLOGICAL ISSUE

Prostate cancer is the most common cancer in men. The diagnosis is based on prostate-specific antigen (PSA), digital rectal examination (DRE) and transrectal ultrasound (TRUS) guided biopsy. These techniques have considerable limitations, which result in unnecessary biopsies. Furthermore the biopsies are associated with morbidity and costs.

STANDARD RADIOLOGICAL METHODS

Standard gray-scale ultrasound has a low sensitivity and specificity for prostate cancer detection.

METHODOLOGICAL INNOVATIONS

New ultrasound technologies, including color- and power Doppler ultrasound, contrast enhanced US and real-time sonoelastography have shown to improve prostate cancer diagnosis.

PERFORMANCE

Contrast-enhanced ultrasound has shown a sensitivity of 100% (95% CI, 95%), a negative predictive value (NPV) of 99.8% and a positive predictive value (PPV) of 88.8% for prostate cancer detection. Real-time sonoelastography has shown a sensitivity of 86%, a specificity of 81% and NPV of 91% for prostate cancer diagnosis.

ACHIEVEMENTS

Most studies show that these new ultrasound modalities demonstrate a 1.5 to 2.5 times higher detection of prostate cancer per biopsy specimen compared with systematic biopsy. Multicenter studies results are at present lacking but are, however ongoing.

PRACTICAL RECOMMENDATIONS

In patients with suspected prostate cancer (elevated PSA, suspicious DRE) these new ultrasound techniques should be used. These techniques can detect prostate cancer and allow a targeted biopsy approach.

Report of a consensus meeting on focal low dose rate brachytherapy for prostate cancer

What's known on the subject? and What does the study add? Whole gland brachytherapy has been used to successfully treat prostate cancer but the protocol for focal therapy has not previously been established. The consensus findings provide guidance on patient selection for focal brachytherapy as well as recommendations for conducting therapy and patient follow-up. Low dose rate prostate brachytherapy is an effective treatment for localized prostate cancer. Recently, it has been considered for use in a focused manner whereby treatment is targeted only to areas of prostate cancer. The objective of focal brachytherapy is to provide effective cancer control for low-risk disease but with reduced genitourinary and rectal side-effects in a cost-effective way. We report on the outputs of a consensus meeting of international experts in brachytherapy and focal therapy convened to consider the feasibility and potential development of focal brachytherapy. A number of factors were considered for focal brachytherapy including optimal patient selection, disease characterization and localization, treatment protocols and outcome measures. The consensus meeting also addressed the design of a clinical trial that would assess the oncological outcomes and side-effect profiles resulting from focal brachytherapy.

Contrast-enhanced ultrasonography with contrast-tuned imaging technology for the detection of prostate cancer: comparison with conventional ultrasonography

Study Type - Diagnostic (exploratory cohort) Level of Evidence 2b What's known on the subject? and What does the study add? The present study was to perform contrast-tuned imaging (CnTI) technology to detect prostate cancer and compare the use of CnTI technology for the detection of prostate cancer with conventional ultrasonography. The preliminary data from our study suggested that targeted biopsy of the prostate with CnTI technology could improve the cancer detection and detect higher grade prostate cancers.

OBJECTIVES

To perform contrast-enhanced ultrasonography (CEUS) using contrast-tuned imaging (CnTI) technology to detect prostate cancer. To evaluate the detection of prostate cancer with CnTI compared with conventional grey-scale and power Doppler ultrasonography.

PATIENTS AND METHODS

In all, 150 patients referred for prostate biopsy were evaluated using transrectal grey-scale, power Doppler and CnTI ultrasonography. Biopsy was performed at 10 sites in each patient. If an abnormality was found at any of these three ultrasonography examinations, a biopsy specimen was targeted towards from the corresponding site. The performances of the three ultrasonography techniques for prostate cancer detection were compared.

RESULTS

Prostate cancer was detected at 383 sites from 73 patients. The combination of these three examinations detected more patients with prostate cancer than grey-scale (P= 0.002), power Doppler (P= 0.001) or baseline imaging (the combination of grey-scale and power Doppler; P= 0.031) alone. By biopsy site, CnTI had higher sensitivity and accuracy (73.1% and 83.7%) than grey-scale (50.9%; P < 0.001 and 78.8%; P < 0.001) or power Doppler (48.3%; P < 0.001 and 77.7%; P < 0.001), while the specificity was similar for grey-scale (88.4%), power Doppler (87.8%) and CnTI (87.3%; P > 0.05 in each case). CnTI had higher sensitivity (73.1% vs 62.9%; P < 0.001), specificity (87.3% vs 82.1%; P < 0.001) and accuracy (83.7% vs 77.2%; P < 0.001) than baseline imaging. The mean Gleason score of CnTI-positive cases was significantly higher than CnTI-negative cases (7.1 vs 6.3; P= 0.002).

CONCLUSIONS

CEUS using CnTI technology enables a visualization of the microvasculature associated with prostate cancer. CnTI technology could be used to guide biopsy and improve the detection rate of prostate cancer. CnTI technology was able to detect higher grade prostate cancers.

Value of contrast-enhanced sonography with micro flow imaging in the diagnosis of prostate cancer

BACKGROUND

To evaluate the effectiveness of contrast-enhanced sonographic micro flow imaging (MFI) in the diagnosis of prostate cancer.

METHODS

A total of 74 patients referred for prostate biopsy were prospectively evaluated with MFI. The abnormalities were categorized into four patterns: pattern 1: indistinct separation between the inner and outer gland; pattern 2: asymmetrical or focally increased enhancement in the outer gland; pattern 3: enhancement with focal defect; pattern 4: enhancement in the outer gland equal to that of the inner gland. The findings were correlated with Gleason scores.

RESULTS

Prostate cancer was detected in 264 sites in 41 patients. The sensitivity, specificity, accuracy, and positive and negative predictive values for MFI were 81.1%, 84.3%, 83.3%, 68.6%, and 91.3%, respectively. Positive predictive values for the four patterns were 46.0 (pattern 1), 53.6 (pattern 2), 94.3 (pattern 3), and 95.4 (pattern 4). Gleason scores of cancers with patterns 3 (7.09) or 4 (7.51) were significantly higher than those with patterns 1 (6.17) or 2 (6.59) (p = 0.001, p = 0.005, p < 0.001, p < 0.001).

CONCLUSIONS

Some MFI patterns had high positive predictive values and were associated with more aggressive cancers. This could be used to reduce the number of biopsy sites and detect clinically significant cancers.

The value of contrast-enhanced transrectal ultrasound in predicting the nature of prostate diseases and the Gleason score of prostate cancer by a subjective blood flow grading scale

OBJECTIVES

To investigate the value of contrast-enhanced transrectal ultrasound (CETRUS) in predicting the nature of prostate diseases and prostate cancer Gleason score.

METHODS

106 patients suspected of prostate cancer were evaluated with CETRUS followed by systematic biopsy. Prostate blood flow of CETRUS was graded using a subjective 5-point scale. The relationships between ultrasound findings and biopsy outcomes, as well as prostate cancer Gleason score were analyzed. Receiver operating characteristic (ROC) analysis was performed to evaluate the diagnostic performance of CETRUS.

RESULTS

Biopsy revealed prostate cancer in 43 of 106 patients. The proportions of malignant histology in the groups with CETRUS scores of 1-5 were 0% (0/10), 8.3% (2/24), 31.7% (13/41), 88.9% (16/18) and 92.3% (12/13), respectively. The rate of prostate cancer with a Gleason score ≥7 in the groups with a CETRUS score of 2-5 were 0% (0/2), 15.4% (2/13), 37.5% (6/16) and 91.7% (11/12), respectively. The blood flow grading scale correlated with pathological outcomes and Gleason score significantly (r = 0.66, p < 0.001; and r = 0.61, p < 0.001, respectively). ROC analysis showed the area under the ROC curve to be 0.87.

CONCLUSIONS

CETRUS-based blood flow grading scale is a reliable tool for predicting the pathological outcome of prostate diseases and prostate cancer Gleason score noninvasively.

Enhanced transrectal ultrasound modalities in the diagnosis of prostate cancer

Standard grayscale transrectal ultrasound has a poor sensitivity for detection of prostate cancer. Saturation biopsy schemes have improved prostate cancer detection rates over standard template biopsy schemes, but carry additional morbidity and cost. Enhanced ultrasound modalities (EUM), including color and power Doppler, contrast-enhancement, harmonic and flash replenishment imaging, and elastography have demonstrated improved prostate cancer detection. EUM targeting areas with increased or abnormal vascularity or firmness for biopsy offer improved prostate cancer detection. EUM, detect prostate cancer more efficiently than standard ultrasound guided biopsies. These emerging technologies may potentially augment standard prostate biopsy in clinical practice.

Imaging angiogenesis of genitourinary tumors

Angiogenesis is a key process in the growth and metastasis of cancer, and genitourinary tumors are no exception. The evolution of angiogenesis as an important target for novel anticancer therapeutics has brought with it new challenges for in vivo imaging. Most imaging techniques quantify physiological parameters, such as blood volume and capillary endothelial permeability. Although CT, PET and ultrasonography have shown promise, MRI is the most common method used to evaluate angiogenesis in clinical trials of genitourinary tumors. Pilot studies of MRI, CT and ultrasonography in patients with renal cancer have produced promising results; reductions in vascular permeability and blood flow have been correlated with progression-free survival. The vascular characteristics of prostate cancer have been evaluated by MRI, and this has been suggested as a means of assessing tumor response to hormone deprivation therapy. Current evidence highlights the potential of angiogenesis imaging in the diagnosis, staging and possibly response monitoring of bladder cancer. In the future, assessment of the angiogenic process at the structural, functional and molecular levels, before, during and after antiangiogenic therapy will undoubtedly be integrated into wider clinical practice.

Contrast-enhanced harmonic ultrasonography for the assessment of prostate cancer aggressiveness: a preliminary study

OBJECTIVE

To determine whether contrast-enhanced harmonic ultrasonography can be used to predict the aggressiveness of prostate cancer.

MATERIALS AND METHODS

Contrast-enhanced harmonic ultrasonography was performed in 103 patients suspected of prostate cancer before biopsy. Time intensity curves were reconstructed for systematic biopsy sites and sonographic abnormalities. The characteristics of the curves were described using hemodynamic indices including arrival time (AT), time-to-peak (TTP), and peak intensity (PI). The differences of hemodynamic indices between high-grade and low-grade cancer were analyzed and the correlations between the hemodynamic indices and biopsy Gleason score were studied.

RESULTS

Prostate cancer was detected in 41 of 103 patients and there were significant differences in the hemodynamic indices between the biopsy sites of the non-malignant patients and prostate cancer lesions (p < 0.05). The prostate biopsies revealed 154 prostate cancer lesions, including 31 low-grade lesions and 123 high-grade lesions. The hemodynamic indices AT and TTP of high-grade tumors were significantly shorter than those of low-grade tumors (p = 0.001, 0.002). In addition, high-grade peripheral zone (PZ) tumors had higher PI than low-grade PZ tumors (p = 0.009). The PZ prostate cancer Gleason score correlated with PI, AT and TTP, with Spearman correlation coefficients of 0.223, -0.335, and -0.351, respectively (p = 0.013, < 0.001 and < 0.001).

CONCLUSION

Contrast-enhanced ultrasound measurements of hemodynamic indices correlate with the prostate cancer Gleason score.

Mucinous adenocarcinoma of the prostate: MRI and MR spectroscopy features

OBJECTIVE

The purpose of this study was to investigate the MRI and MR spectroscopy features of mucinous adenocarcinoma of the prostate.

CONCLUSION

MRI and MR spectroscopy do not appear to provide the ability to reliably detect the lakes of extracellular mucin seen in mucinous adenocarcinoma of the prostate.

HIFU and cryoablation – non or minimal touch techniques for the treatment of prostate cancer. Is there a role for contrast enhanced ultrasound?

The incidence of prostate cancer is increasing, and therefore also the need for optimal treatment. Because of the appearance of many different disease stages different treatment modalities are desirable for the treatment of localized prostate cancer. The established therapies, radical prostatectomy and radiation therapy, are associated with a lot of risks, complications and co-morbidity, and not all patients are eligible for these treatments. That is why the need for reliable minimally invasive alternatives has developed. For this paper a literature search was conducted on published studies and review articles to determine the role of HIFU (high intensity focused ultrasound) and cryoablation as minimally invasive treatment modalities for localized prostate cancer. Both therapies are being used as a primary or secondary (salvage) treatment, but can they replace surgery or radiation? And is there a role for contrast enhanced ultrasound (CEUS) of the prostate to improve diagnostics, treatment outcomes and follow-up? To date the outcomes of both therapies are promising but no prospective and comparative randomized studies with a long term follow-up were available for analysis. From this review we can conclude that until those studies are available, HIFU and cryoablation are good alternatives for patients not eligible for prostatectomy or radiation. They should not be used as a first treatment option as long as diagnostics and follow-up have not improved.

Prostate cancer segmentation with simultaneous estimation of Markov random field parameters and class

Prostate cancer is one of the leading causes of death from cancer among men in the United States. Currently, high-resolution magnetic resonance imaging (MRI) has been shown to have higher accuracy than trans-rectal ultrasound (TRUS) when used to ascertain the presence of prostate cancer. As MRI can provide both morphological and functional images for a tissue of interest, some researchers are exploring the uses of multispectral MRI to guide prostate biopsies and radiation therapy. However, success with prostate cancer localization based on current imaging methods has been limited due to overlap in feature space of benign and malignant tissues using any one MRI method and the interobserver variability. In this paper, we present a new unsupervised segmentation method for prostate cancer detection, using fuzzy Markov random fields (fuzzy MRFs) for the segmentation of multispectral MR prostate images. Typically, both hard and fuzzy MRF models have two groups of parameters to be estimated: the MRF parameters and class parameters for each pixel in the image. To date, these two parameters have been treated separately, and estimated in an alternating fashion. In this paper, we develop a new method to estimate the parameters defining the Markovian distribution of the measured data, while performing the data clustering simultaneously. We perform computer simulations on synthetic test images and multispectral MR prostate datasets to demonstrate the efficacy and efficiency of the proposed method and also provide a comparison with some of the commonly used methods.

[Assessment of tumour angiogenesis using contrast-enhanced ultrasound]

Microbubbles are useful for imaging tumour angiogenesis and relatively crude forms of this approach are now routinely used for subjective diagnosis, especially in the liver. More sophisticated methods use quantitative approaches to measure the amount and the time course of bolus or reperfusion curves and have shown great promise in revealing effective tumour response to anti-angiogenic drugs in humans before tumour shrinkage occurs. These are beginning to be accepted into clinical practice. In the long term, targeted microbubbles for molecular imaging and eventually for directed anti-tumour therapy are expected to be tested.

Real-time elastography in the diagnosis of prostate tumor

AIM

To assess the diagnostic gain of transrectal real-time elastography (RTE) compared to transrectal B-mode ultrasonography (US) in the detection of tumors in patients suspected of having prostate cancer.

MATERIALS AND METHODS

Eighty-four patients suspected of having prostate cancer on the basis of clinical and biochemical evaluation underwent transrectal US, RTE and transperineal prostate biopsy.

RESULTS

Biopsy was considered the gold standard. Analysis related to the total number of patients showed a B-mode US sensitivity of 56%, specificity 80%, positive predictive value (PPV) 70% and negative predictive value (NPV) 67%. Analysis related to the total number of biopsy cores showed sensitivity 33%, specificity 92%, PPV 69% and NPV 73%. In the patient-related analysis, RTE sensitivity was 51%, specificity 75%, PPV 64% and NPV 64%, while the core-related analysis showed sensitivity 36%, specificity 93%, PPV 72% and NPV 74%. Comparison of B-mode US and RTE diagnostic accuracy in the detection of tumors located in the peripheral zone of the prostate gland showed a significant difference. Analysis related to the total number of biopsy cores harvested in the peripheral zone of the prostate gland showed a B-mode US sensitivity of 48%, specificity 81%, PPV 75% and NPV 58%, whereas RTE achieved the following values: sensitivity 66%, specificity 78%, PPV 77%, and NPV 67%.

CONCLUSIONS

RTE is a valid addition to B-mode US, and RTE reached a higher accuracy than B-mode US in the evaluation of the peripheral zone of the prostate gland and in the selection of appropriate biopsy sites.

The role of prostate specific membrane antigen and pepsinogen C tissue expression as an adjunctive method to prostate cancer diagnosis

PURPOSE

The diagnosis of prostate cancer in men with persistently increased prostate specific antigen after a negative prostate biopsy has become a great challenge for urologists and pathologists. We analyzed the diagnostic value of 6 genes in the tissue of patients with prostate cancer.

MATERIALS AND METHODS

The study was comprised of 50 patients with localized disease who underwent radical prostatectomy. Gene selection was based on a previous microarray analysis. Among 4,147 genes with different expressions between 2 pools of patients 6 genes (PSMA, TMEFF2, GREB1, TH1L, IgH3 and PGC) were selected. These genes were tested for diagnostic value using the quantitative reverse transcription polymerase chain reaction method. Initially malignant tissue samples from 33 patients were analyzed and in the second part of the study we analyzed benign tissue samples from the other 17 patients with prostate cancer. The control group was comprised of tissue samples of patients with benign prostatic hyperplasia.

RESULTS

Analysis of malignant prostatic tissue demonstrated that prostate specific membrane antigen was over expressed (mean 9 times) and pepsinogen C was under expressed (mean 1.3 x 10(-4) times) in all cases compared to benign prostatic hyperplasia. The other 4 tested genes showed a variable expression pattern not allowing for differentiation between benign and malignant cases. When we tested these results in the benign prostate tissues from patients with cancer, pepsinogen C maintained the expression pattern. In terms of prostate specific membrane antigen, despite over expression in most cases (mean 12 times), 2 cases (12%) presented with under expression.

CONCLUSIONS

Pepsinogen C tissue expression may constitute a powerful adjunctive method to prostate biopsy in the diagnosis of prostate cancer cases.

Contrast-enhanced ultrasound and prostate cancer; a multicentre European research coordination project

CONTEXT

Contrast-enhanced ultrasound is a real-time imaging technique with the capability of visualizing perfusion patterns. Since tumour growth is associated with changes in vascularisation, this modality is under research for imaging of various tumour types. Studies have shown promising results for the diagnosis of prostate cancer for various imaging techniques; however, the exact value of each technique is still unclear.

OBJECTIVE

To determine the value of contrast-enhanced ultrasound (CEUS) in the detection, localisation, and follow-up of treatment for prostate cancer.

EVIDENCE ACQUISITION

In the period 2002-2006, research in four European centres regarding CEUS of the prostate was coordinated in a combined program. This paper describes and combines the results of these studies.

EVIDENCE SYNTHESIS

Various techniques were developed and researched during the period of this program. Studies showed that prostate cancer could be visualized and localized in up to 78%. Visualization of the tumour enabled better detection; targeted biopsies lead to fewer biopsies per session without loss of detection rate. A combined approach offered the highest detection rate. CEUS could be used to visualize the effects of high-intensity focussed ultrasound and hormonal therapy for prostate cancer with success, and identified patients with an early relapse. Unfortunately, pretreatment evaluation could not identify the nonresponders beforehand.

CONCLUSIONS

This research project was a first step towards routine use of CEUS in the clinical detection and follow-up of prostate cancer; and new combined studies are initiated.

Prostate cancer: role of pretreatment MR in predicting outcome after external-beam radiation therapy--initial experience

PURPOSE

To retrospectively determine if pretreatment endorectal magnetic resonance (MR) imaging findings are predictive of outcome in patients who undergo external-beam radiation therapy for prostate cancer.

MATERIALS AND METHODS

Committee on Human Research approval, with waiver of the requirement for informed consent, was obtained for this HIPAA-compliant study. Eighty men with biopsy-proved prostate cancer (mean age, 59 years; range, 47-75 years) who underwent endorectal MR imaging of the prostate prior to external-beam radiation therapy were retrospectively identified; details of baseline tumor characteristics, treatment, and outcome were recorded. Two experienced readers independently reviewed all MR imaging studies and recorded tumor T stage and the radial diameter of extracapsular extension (if present). Univariate and multivariate stepwise Cox regression analyses were used to investigate the relationship between baseline imaging and clinical predictive variables and the end point of metastatic failure.

RESULTS

At MR imaging, readers 1 and 2, respectively, considered 50 and 60 patients to have T1 or T2 disease (ie, organ-confined disease) and 30 and 20 patients to have T3 disease. After a mean follow-up of 43 months, four patients developed metastases. Univariate Cox analysis revealed that baseline serum prostate-specific antigen level, presence of extracapsular extension at MR imaging (according to either reader), and degree of extracapsular extension (according to either reader) were all significantly (P < .05) related to the development of metastases. Multivariate Cox analysis revealed that the sole independent predictive variable was mean diameter of extracapsular extension (relative hazard ratio, 2.06; 95% confidence interval: 1.22, 3.48; P = .007). In particular, three of five patients with extracapsular extension of more than 5 mm at pretreatment MR imaging developed metastases 24, 43, and 63 months after therapy.

CONCLUSION

The presence and degree of extracapsular extension at MR imaging prior to external-beam radiation therapy are important predictors of posttreatment metastatic recurrence.

Peripheral zone prostate cancer: accuracy of different interpretative approaches with MR and MR spectroscopic imaging

PURPOSE

To retrospectively compare relative accuracy of different interpretative approaches to magnetic resonance (MR) and MR spectroscopic imaging of peripheral zone prostate cancer, by using histologic examination results as the reference standard.

MATERIALS AND METHODS

This HIPAA-compliant study had institutional Committee on Human Research approval, with waiver of written consent requirement. Spectroscopic voxels of unequivocally benign (n = 66) or malignant (n = 77) peripheral zone tissue were identified by using step-section histopathologic tumor maps created for 28 men (mean age, 60 years; range, 46-71 years) who underwent endorectal MR and MR spectroscopic imaging before radical prostatectomy. Two readers (9 and 8 years of experience) independently scored the selected voxels on a scale from 1 (likely benign) to 5 (likely malignant) at randomized review of the corresponding tissue outlined on a transverse T2-weighted MR image (T2 approach), the MR spectrum from the selected voxel only (single-voxel approach), the MR spectra from all voxels at the same axial level (multivoxel approach), and both the corresponding tissue outlined on a transverse T2-weighted image and the MR spectra from all voxels at the same axial level (integrated approach). Readers were aware that spectra were derived in patients with biopsy-proved diagnoses of prostate cancer and represented either benign or malignant tissue but were unaware of which voxels had been labeled benign or malignant and of all other clinical, histopathologic, and MR imaging findings. Receiver operating characteristic (ROC) curve analysis was performed. Generalized estimating equation method was used to estimate sensitivity and specificity for specific cutoff values.

RESULTS

Mean areas under the ROC curve (AUCs) for the T2, single-voxel, multivoxel, and integrated approaches were 0.69, 0.72, 0.72, and 0.76, respectively. AUC of the integrated approach was significantly higher than those of the other three approaches (P < .001). kappa Values for assessment of interobserver variability for the T2, single-voxel, multivoxel, and integrated approaches were 0.39, 0.39, 0.34, and 0.48, respectively.

CONCLUSION

Addition of MR spectroscopic imaging to MR imaging significantly improves characterization of peripheral zone prostate tissue as benign or malignant; improved performance is obtained when both data sets are interpreted in an integrated fashion.

Advances in transrectal ultrasound imaging of the prostate

Grayscale imaging of the prostate is the basic method for diagnostic evaluation and biopsy guidance. Doppler imaging may improve sensitivity for detection of prostate cancer. Microbubble contrast agents represent a major advance to more selectively demonstrate neovascular flow within the prostate. Recently, real-time elastography has been introduced to improve detection of cancer based upon changes in tissue stiffness. As diagnostic methods improve, the ultimate hope is to eliminate biopsy in patients without cancer. New ultrasound-based treatment systems, such as high-intensity focused ultrasound ablative therapy for prostate cancer, may someday allow diagnosis and treatment of prostate cancer to be completed in one sitting.

Contrast-enhanced ultrasound for diagnosis of prostate cancer and kidney lesions

PURPOSE OF REVIEW

Conventional ultrasonography of both, kidney and prostate, is limited due to the poor contrast of B-mode imaging for parenchymal disease and limited sensitivity of colour Doppler for the detection of capillaries and deep pedicular vessels. Contrast-enhanced ultrasound (CEUS) overcomes these limitations.

RECENT FINDINGS

CEUS investigates the blood flow of the prostate, allows for prostate cancer visualization and for targeted biopsies. Comparisons between systematic and CEUS-targeted biopsies have shown that the targeted approach detects more cancers with a lower number of biopsy cores and with higher Gleason scores compared with the systematic approach. Also the kidney offers promising applications as CEUS improves the detection of abnormal microvascular and macrovascular disorders.

SUMMARY

In recent literature CEUS has shown its value for diagnosis of both, prostate cancer and kidney lesions. This paper describes recent improvements and future perspectives of CEUS.

Contrast enhanced ultrasound flash replenishment method for directed prostate biopsies

PURPOSE

We evaluated prostate cancer detection with contrast enhanced ultrasound of the prostate using MicroFlow Imaging (Toshiba America Medical Systems, Tustin, California) compared to systematic biopsy.

MATERIALS AND METHODS

A total of 60 patients referred for prostate biopsy were evaluated with pre-contrast and contrast enhanced MicroFlow Imaging transrectal ultrasound. MicroFlow Imaging is a flash replenishment technique that uses high power flash pulses to destroy contrast microbubbles, followed by low power pulses to demonstrate contrast replenishment. A composite image depicting the vascular architecture is constructed through maximum intensity capture of temporal data in consecutive low power images. Using MicroFlow Imaging up to 5 directed biopsy cores were obtained from areas of abnormal vascular enhancement or morphology, followed by a systematic 10-core biopsy protocol.

RESULTS

A biopsy positive for cancer was found in 79 of the 825 cores (10%) from 18 of the 60 subjects (30%). Positive biopsies were obtained in 50 of 600 systematic core biopsies (8.3%) and in 29 of 225 directed cores (13%) (OR 2.02, p = 0.034). Five of the 18 patients diagnosed with cancer were identified only by systematic biopsy, 2 were identified only by directed biopsy with MicroFlow Imaging and 11 were identified by the 2 techniques (p >0.25). Twice the number of patients was detected per core with directed vs systematic biopsy (0.058 vs 0.027).

CONCLUSIONS

The vascular detail provided by MicroFlow Imaging allowed directed biopsy of these areas with increased detection of prostate cancer. Although a minority of cancers were not detected with MicroFlow Imaging directed biopsy, this technique detected twice as many patients with prostate cancer per biopsy core.

Transrectal high-intensity focused ultrasound ablation of prostate cancer: Effective treatment requiring accurate imaging

Transrectal HIFU ablation has become a reasonable option for the treatment of localized prostate cancer in non-surgical patients, with 5-year disease-free survival similar to that of radiation therapy. It is also a promising salvage therapy of local recurrence after radiation therapy. These favourable results are partly due to recent improvements in prostate cancer imaging. However, further improvements are needed in patient selection, pre-operative localization of the tumor foci, assessment of the volume treated and early detection of recurrence. A better knowledge of the factors influencing the HIFU-induced tissue destruction and a better pre-operative assessment of them by imaging techniques should improve treatment outcome. Whereas prostate HIFU ablation is currently performed under transrectal ultrasound guidance, MR guidance with real-time operative monitoring of temperature will be available in the near future. If this technique will give better targeting and more uniform tissue destruction, its cost-effectiveness will have to be carefully evaluated. Finally, a recently reported synergistic effect between HIFU ablation and chemotherapy opens possibilities for treatment in high-risk or clinically advanced tumors.

Prostate cancer: sextant localization with MR imaging, MR spectroscopy, and 11C-choline PET/CT

PURPOSE

To retrospectively compare sensitivity and specificity of magnetic resonance (MR) imaging, three-dimensional (3D) MR spectroscopy, combined MR imaging and 3D MR spectroscopy, and carbon 11 (11C)-choline positron emission tomography (PET)/computed tomography (CT) for intraprostatic tumor sextant localization, with histologic findings as reference standard.

MATERIALS AND METHODS

The local ethics committee on human research provided approval and a waiver of informed consent for the retrospective study. MR imaging, 3D MR spectroscopy, and 11C-choline PET/CT results were retrospectively reviewed in 26 men with biopsy-proved prostate cancer (mean age, 64 years; range, 51-75 years) who underwent radical prostatectomy. Cancer was identified as areas of nodular low signal intensity on T2-weighted MR images. At 3D MR spectroscopy, choline-plus-creatine-to-citrate and choline-to-creatine ratios were used to distinguish healthy from malignant voxels. At PET/CT, focal uptake was visually assessed, and maximum standardized uptake values (SUVs) were recorded. Agreement between 3D MR spectroscopic and PET/CT results was calculated, and ability of maximum SUV to help localize cancer was assessed with receiver operating characteristic analysis. Significant differences between positive and negative sextants with respect to mean maximum SUV were calculated with a paired t test.

RESULTS

Sensitivity, specificity, and accuracy were, respectively, 55%, 86%, and 67% at PET/CT; 54%, 75%, and 61% at MR imaging; and 81%, 67%, and 76% at 3D MR spectroscopy. The highest sensitivity was obtained when either 3D MR spectroscopic or MR imaging results were positive (88%) at the expense of specificity (53%), while the highest specificity was obtained when results with both techniques were positive (90%) at the expense of sensitivity (48%). Concordance between 3D MR spectroscopic and PET/CT findings was slight (kappa=0.139).

CONCLUSION

In localizing cancer within the prostate, comparable specificity was obtained with either 3D MR spectroscopy and MR imaging or PET/CT; however, PET/CT had lower sensitivity relative to 3D MR spectroscopy alone or combined with MR imaging.

Transrectal contrast enhanced ultrasound for diagnosis of prostate cancer

The diagnosis of prostate cancer is based on histology. Prostate biopsies are obtained based on the triad of prostate specific antigen (PSA), digital rectal examination (DRE) and transrectal ultrasound. Because prostate biopsies still have a large percentage of negative outcomes, patient selection and biopsy direction need improvement. This paper describes the recent improvements in prostate cancer imaging, especially contrast-enhanced transrectal ultrasound.

Imaging in genitourinary cancer from the urologists' perspective

It is well established that advances in imaging may lead to early cancer detection, more accurate tumour staging and consequently adequate treatment, better monitoring of the disease and enhanced surveillance for recurrences after treatment. This manuscript reviews the current use of imaging in genitourinary cancer and explores the impact of imaging findings in clinical management. Additionally, an effort has been made to present the emerging imaging modalities and also their possible role in diagnosis and treatment of these cancers.