Prostate cancer: prediction of extracapsular extension with endorectal MR imaging and three-dimensional proton MR spectroscopic imaging

Espectroscopia por ressonância magnética no diagnóstico do câncer de próstata: experiência inicial

OBJETIVO: Demonstrar a experiência na implantação de um protocolo de espectroscopia por ressonância magnética do 1H tridimensional (3D 1H MRSI), disponível comercialmente, aplicando-o em pacientes com suspeita de neoplasia prostática e com diagnóstico estabelecido de tumor prostático. MATERIAIS E MÉTODOS: Estudo realizado de forma prospectiva, em 41 pacientes com idades entre 51 e 80 anos (média de 67 anos). Dois grupos foram formados: pacientes com uma ou mais biópsias negativas para câncer e antígeno prostático específico elevado (grupo A) e pacientes com câncer confirmado por biópsia (grupo B). Procurou-se, a partir dos resultados da ressonância magnética e espectroscopia por ressonância magnética, determinar a área-alvo (grupo A) ou a extensão do câncer conhecido (grupo B). RESULTADOS: No diagnóstico de câncer de próstata a espectroscopia por ressonância magnética apresentou especificidade abaixo da descrita pela literatura, cerca de 47%. Já para o estadiamento do tumor diagnosticado, houve correspondência com a literatura. CONCLUSÃO: A implantação e padronização da espectroscopia por ressonância magnética permitiram a obtenção de informações importantes para o diagnóstico presuntivo da existência de câncer de próstata, combinando as imagens por ressonância magnética com os dados metabólicos da espectroscopia por ressonância magnética.

A meta-analysis of the accuracy of prostate cancer studies which use magnetic resonance spectroscopy as a diagnostic tool

Objective

We aimed to do a meta-analysis of the existing literature to assess the accuracy of prostate cancer studies which use magnetic resonance spectroscopy (MRS) as a diagnostic tool.

Materials and Methods

Prospectively, independent, blind studies were selected from the Cochrane library, Pubmed, and other network databases. The criteria for inclusion and exclusion in this study referenced the criteria of diagnostic research published by the Cochrane center. The statistical analysis was adopted by using Meta-Test version 6.0. Using the homogeneity test, a statistical effect model was chosen to calculate different pooled weighted values of sensitivity, specificity, and the corresponding 95% confidence intervals (95% CI). The summary receiver operating characteristic (SROC) curves method was used to assess the results.

Results

We chose two cut-off values (0.75 and 0.86) as the diagnostic criteria for discriminating between benign and malignant. In the first diagnostic criterion, the pooled weighted sensitivity, specificity, and corresponding 95% CI (expressed as area under curve [AUC]) were 0.82 (0.73, 0.89), 0.68 (0.58, 0.76), and 83.4% (74.97, 91.83). In the second criterion, the pooled weighted sensitivity, specificity, and corresponding 95% CI were 0.64 (0.55, 0.72), 0.86 (0.79, 0.91) and 82.7% (68.73, 96.68).

Conclusion

As a new method in the diagnostic of prostate cancer, MRS has a better applied value compared to other common modalities. Ultimately, large scale RCT randomized controlled trial studies are necessary to assess its clinical value.

Functional magnetic resonance imaging in prostate cancer

CONTEXT

Magnetic resonance imaging (MRI) combined with magnetic resonance spectroscopy imaging (MRSI), dynamic contrast-enhanced MRI, and diffusion-weighted MRI emerged as promising tests in the diagnosis of prostate cancer, and they show encouraging results.

OBJECTIVE

This review emphasizes different functional MRI techniques in the diagnosis of prostate cancer and includes information about their clinical value and usefulness.

EVIDENCE ACQUISITION

The authors searched the Medline, Embase, and Cochrane Library databases. There were no language restrictions. The last search was performed in October 2008.

EVIDENCE SYNTHESIS

The combination of conventional MRI with functional MRI techniques is more reliable for differentiating benign and malignant prostate tissues than any other diagnostic procedure. At present, no guideline is available that outlines which technique is best in a specific clinical situation. It also remains uncertain whether improved spatial resolution and signal-to-noise ratio of 3-T MRI will improve diagnostic performance.

CONCLUSIONS

A limited number of small studies suggest that functional MRI may improve the diagnosis and staging of prostate cancer. This finding needs further confirmation in larger studies, and cost-effectiveness needs to be established.

Clinical applications of metabolomics in oncology: a review

Metabolomics, an omic science in systems biology, is the global quantitative assessment of endogenous metabolites within a biological system. Either individually or grouped as a metabolomic profile, detection of metabolites is carried out in cells, tissues, or biofluids by either nuclear magnetic resonance spectroscopy or mass spectrometry. There is potential for the metabolome to have a multitude of uses in oncology, including the early detection and diagnosis of cancer and as both a predictive and pharmacodynamic marker of drug effect. Despite this, there is lack of knowledge in the oncology community regarding metabolomics and confusion about its methodologic processes, technical challenges, and clinical applications. Metabolomics, when used as a translational research tool, can provide a link between the laboratory and clinic, particularly because metabolic and molecular imaging technologies, such as positron emission tomography and magnetic resonance spectroscopic imaging, enable the discrimination of metabolic markers noninvasively in vivo. Here, we review the current and potential applications of metabolomics, focusing on its use as a biomarker for cancer diagnosis, prognosis, and therapeutic evaluation.

Dynamic contrast-enhanced magnetic resonance imaging in the evaluation of the prostate

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is a novel MR technique that allows to interrogate pharmacokinetic processes in the tissues at a voxel level and to generate parametric maps that can be displayed for clinical interpretation. Dynamic contrast-enhanced MRI is an important imaging technique for the imaging of angiogenesis and vasculogenesis because it probes the microvascular networks at a microscopic level by being sensitive to the compartmentalization of tissue into the vascular and extravascular-extracellular space and to the diffusion of contrast molecules across the vascular endothelium and capillary boundaries. Dynamic contrast-enhanced MRI has already shown to improve detection and localization of prostate cancer, to improve prediction of extracapsular extension, determination of tumor volume, and after treatment follow-up. In this article, we outline the fundamental principles of DCE-MRI and describe the application of DCE methods in the imaging of the prostate.

Value of 3-T magnetic resonance imaging in local staging of prostate cancer

Whole-body 3-T magnetic resonance (MR) scanners are presently becoming more widely available in the clinical setting. The increased signal-to-noise ratio inherent at 3 T as compared with 1.5 T offers potentials for clinical MR imaging such as shortening of imaging time and increased spatial, spectral, or temporal resolution or a combination of these. As a result, high-in-plane-resolution anatomic MR images can be obtained. This review will address the advantages and drawbacks of local staging with MR imaging at 3 T in patients with prostate cancer. Furthermore, the current diagnostic performance of prostate MR imaging in staging prostate cancer at high field strength is discussed.

Advances in MR spectroscopy of the prostate

Commercial MR imaging/magnetic resonance spectroscopic imaging (MRSI) packages for staging prostate cancer on 1.5-T MR scanners are now available. The technology is becoming mature enough to begin assessing its clinical utility in selecting, planning, and following prostate cancer therapy. Before therapy, 1.5-T MR imaging/MRSI has the potential to improve the local evaluation of prostate cancer presence and volume and has a significant incremental benefit in the prediction of pathologic stage when added to clinical nomograms. After therapy, two metabolic biomarkers of effective and ineffective therapy have been identified and are being validated with 10-year outcomes. Accuracy can be improved by performing MR imaging/MRSI at higher magnetic field strengths, using more sensitive hyperpolarized (13)C MRSI techniques and through the addition of other functional MR techniques.

Value of endorectal MRI and MRS in patients with elevated prostate-specific antigen levels and previous negative biopsies to localize peripheral zone tumours

AIM

To evaluate prospectively the role of endorectal magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) in detecting peripheral zone tumour in patients with total prostate-specific antigen (PSA) values>or=4 ng/ml and one or more negative transrectal ultrasound (TRUS) biopsy rounds.

MATERIAL AND METHODS

Fifty-four consecutive men (mean age 65.4+/-5.2 years, mean total PSA 10.8+/-7.5 ng/ml), underwent a combined MRI-MRS examination with endorectal coil. MRI included transverse, coronal, and sagittal T2-weighted and transverse T1-weighted fast spin-echo sequences. MRS data were acquired using a double spin-echo point resolved spectroscopy (PRESS) sequence. A 10-site scheme was adopted to evaluate the prostate peripheral zone. A peripheral prostatic site was classified as suspicious if low intensity signal was present on T2-weighted images and/or if the choline+creatine/citrate ratio was >0.86. Following MRI-MRS all patients were submitted to a standard 10-core biopsy scheme to which from one to three supplementary samples were added from suspicious MRI and/or MRS sites. In per-patient analysis findings were considered true-positive if biopsy positive patients were classified as suspicious, irrespectively of lesion site indication.

RESULTS

Prostate cancer (PC) was detected in 17 of 54 patients (31.5%); median Gleason score was 6 (range 4-8). On a per-patient basis sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were respectively 100, 64.9, 56.7, 100, and 75.9% for MRI; 82.2, 70.3, 57.7, 92.9, and 75.9% for MRS; and 100, 51.4, 48.6, 100, and 66.7% for combined MRI-MRS. In all the 17 PC patients, combined MRI-MRS correctly indicated the sites harbouring cancer, whereas both MRI and MRS gave erroneous indications in two patients.

CONCLUSION

The results of the present study show that MRI alone might be able to select negative patients in whom further biopsies are unnecessary. The combination of MRI and MRS might be able to drive biopsies in suspicious sites and increase the cancer detection rate. Further studies are required to confirm these data.

Hyperpolarized 13C lactate, pyruvate, and alanine: noninvasive biomarkers for prostate cancer detection and grading

An extraordinary new technique using hyperpolarized (13)C-labeled pyruvate and taking advantage of increased glycolysis in cancer has the potential to improve the way magnetic resonance imaging is used for detection and characterization of prostate cancer. The aim of this study was to quantify, for the first time, differences in hyperpolarized [1-(13)C] pyruvate and its metabolic products between the various histologic grades of prostate cancer using the transgenic adenocarcinoma of mouse prostate (TRAMP) model. Fast spectroscopic imaging techniques were used to image lactate, alanine, and total hyperpolarized carbon (THC = lactate + pyruvate + alanine) from the entire abdomen of normal mice and TRAMP mice with low- and high-grade prostate tumors in 14 s. Within 1 week, the mice were dissected and the tumors were histologically analyzed. Hyperpolarized lactate SNR levels significantly increased (P < 0.05) with cancer development and progression (41 +/- 11, 74 +/- 17, and 154 +/- 24 in normal prostates, low-grade primary tumors, and high-grade primary tumors, respectively) and had a correlation coefficient of 0.95 with the histologic grade. In addition, there was minimal overlap in the lactate levels between the three groups with only one of the seven normal prostates overlapping with the low-grade primary tumors. The amount of THC, a possible measure of substrate uptake, and hyperpolarized alanine also increased with tumor grade but showed more overlap between the groups. In summary, elevated hyperpolarized lactate and potentially THC and alanine are noninvasive biomarkers of prostate cancer presence and histologic grade that could be used in future three-dimensional (13)C spectroscopic imaging studies of prostate cancer patients.

MR imaging of the prostate in clinical practice

Magnetic resonance imaging (MRI) is the imaging tool of choice in the evaluation of prostate cancer. The main applications of MR imaging in the management of prostate cancer are: (1) to guide targeted biopsy when prostate cancer is clinically suspected and previous ultrasound-guided biopsy results are negative; (2) to localize and stage prostate cancer and provide a roadmap for treatment planning; and (3) to detect residual or locally recurrent cancer after treatment. Other MR techniques such as proton MR spectroscopic imaging (MRSI), diffusion-weighted imaging (DWI), and contrast-enhanced MRI (CE-MRI) complement conventional MR imaging by providing metabolic and functional information that can improve the accuracy of prostate cancer detection and characterization. In everyday clinical practice, and to account for patient comfort, MR imaging studies are limited to 1 h. To obtain consistently high-quality images, a well-designed protocol is necessary. Routine MR imaging can be supplemented by other MR techniques such as MRSI, DWI or CE-MRI depending on the expertise available and the clinical questions that need to be answered. This review summarizes the role of MR imaging in the management of prostate cancer and describes practical approaches to implementing anatomic, metabolic and functional MR imaging techniques in the clinic.

Evaluation of lactate and alanine as metabolic biomarkers of prostate cancer using 1H HR-MAS spectroscopy of biopsy tissues

The goal of this study was to investigate the use of lactate and alanine as metabolic biomarkers of prostate cancer using (1)H high-resolution magic angle spinning (HR-MAS) spectroscopy of snap-frozen transrectal ultrasound (TRUS)-guided prostate biopsy tissues. A long-echo-time rotor-synchronized Carr-Purcell-Meiboom-Gill (CPMG) sequence including an electronic reference to access in vivo concentrations (ERETIC) standard was used to determine the concentrations of lactate and alanine in 82 benign and 16 malignant biopsies (mean 26.5% +/- 17.2% of core). Low concentrations of lactate (0.61 +/- 0.28 mmol/kg) and alanine (0.14 +/- 0.06 mmol/kg) were observed in benign prostate biopsies, and there was no significant difference between benign predominantly glandular (N = 54) and stromal (N = 28) biopsies between patients with (N = 38) and without (N = 44) a positive clinical biopsy. In biopsies containing prostate cancer there was a highly significant (P < 0.0001) increase in lactate (1.59 +/- 0.61 mmol/kg) and alanine (0.26 +/- 0.07 mmol/kg), and minimal overlap with lactate concentrations in benign biopsies. This study demonstrates for the first time very low concentrations of lactate and alanine in benign prostate biopsy tissues. The significant increase in the concentration of both lactate and alanine in biopsy tissue containing as little as 5% cancer could be exploited in hyperpolarized (13)C spectroscopic imaging (SI) studies of prostate cancer patients.

3-T MRI with phased-array coil in local staging of prostatic cancer

RATIONALE AND OBJECTIVES

To evaluate the diagnostic accuracy of a 3-T magnetic resonance imaging (MRI) system with a phased-array coil (3T MRI) in the local staging of prostatic cancer.

MATERIALS AND METHODS

Between July 2004 and September 2007, 59 patients (mean age 66 years) with a histologic diagnosis of prostatic cancer underwent 3-T MRI with a phased-array coil. A total of 42/59 patients underwent a radical prostatectomy within 3 weeks of the MRI examination. Two radiologists with differing experience in the interpretation of prostatic imaging used a 1-5 scale score to assess extracapsular spread, seminal vesicle and neurovascular bundle infiltration, and prostatic apex involvement. The anatomopathologic examination conducted on histologic macrosections was the reference test used to evaluate the results of 3-T MRI. Interobserver reliability was assessed using the k value.

RESULTS

The sensitivity, specificity, and accuracy values obtained by the expert radiologist were 68%, 92%, and 83%, respectively, compared to 50%, 85%, and 71% for the identification of extracapsular spread and 81%, 62%, and 84% compared to 63%, 50%, and 55% for apex involvement. Interobserver reliability was good (k=0.71). Seminal vesicle infiltration was correctly identified in four of five cases and neurovascular bundle infiltration was identified in four of four cases.

CONCLUSIONS

Despite presenting diagnostic accuracy values lower than those reported in literature using 1.5-T endorectal coil MRI, the use of 3-T MRI with a phased-array coil could constitute a valid alternative to MRI techniques using endorectal coils in selected patients. Direct comparative studies between the two methods on large caseloads are required to confirm this hypothesis.

The role of endorectal coil MRI in preoperative staging and decision-making for the treatment of clinically localized prostate cancer

INTRODUCTION

The optimal management of newly diagnosed prostate cancer requires individualization of the treatment plan based upon the most accurate clinical characterization of tumor location and extent of disease. The role of imaging in prostate cancer staging continues to evolve. In this review, we address the utility of endorectal coil magnetic resonance imaging (eMRI) in both local staging and its ability to facilitate the decision in choosing one treatment strategy over another after the initial diagnosis of localized prostate cancer.

MATERIALS AND METHODS

Using the PubMed database and reference lists of key articles, we identified studies addressing the use of eMRI in tumor characterization and risk stratification in patients undergoing treatment for clinically localized prostate cancer.

RESULTS

The findings identified within 54 selected studies were incorporated into a summary discussing the current limitations in cancer staging and the role eMRI plays in both the preoperative assessment and clinical decision-making in an attempt to improve our ability to individualize management approaches and tailor treatment.

CONCLUSION

eMRI allows for more accurate local staging by complementing the existing clinical variables through improvements in spatial characterization of the prostatic zonal anatomy and molecular changes. These improvements in tumor staging enhance our ability to individualize treatment selection and tailor the approach to maximize cancer control while minimizing treatment related morbidity.

[Prostate MRI spectroscopy]

MRI spectroscopy is a non invasive method for detecting active metabolites used as markers. Chorine and citrate are used for analyzing prostate cancer. MRI spectroscopy combines morphologic imaging and metabolic cartography. This combination allows a new approach for the diagnosis of prostate cancer in patients with negative biopsy and high Levels of PSA. With MRI spectroscopy the Local staging of prostate cancer has a better accuracy than with MRI alone. It can also be used for the diagnosis of residual disease and recurrence in patients treated with conservative therapy.

Update of prostate magnetic resonance imaging at 3 T

More recently, 3-T magnetic resonance (MR) scanner become more clinically available, and clinical application of 3-T MR imaging (MRI) of the abdomen and pelvis is now feasible and being performed at many institutions. However, few prostrate 3-T MRI studies have been published. The increase in signal-to-noise ratio at 3 versus 1.5 T clearly improves spatiotemporal and spectral resolutions of the prostate. Thus, we asked whether 3-T MRI improves the localization and staging of prostate cancer versus 1.5-T MRI. To answer this question, this article reviews the current limitations of prostate 1.5-T MRI and addresses its pros and cons. Moreover, we present preliminary results of prostate 3-T MRI and introduce our experience for prostate 3-T MRI using a phased-array coil, with an emphasis on imaging sequences, for example, T2-weighted, dynamic contrast-enhanced, diffusion-weighted, and MR spectroscopic imaging.

Endorectal magnetic resonance imaging and magnetic resonance spectroscopy to monitor the prostate for residual disease or local cancer recurrence after transrectal high-intensity focused ultrasound

OBJECTIVE

To assess the role of magnetic resonance imaging (MRI) for evaluating changes in the prostate after transrectal high-intensity focused ultrasound (HIFU) for treating prostate cancer, correlating the findings with histology to assess its possible role in predicting the outcome, evaluating residual cancer or local recurrence of disease.

PATIENTS AND METHODS

Ten patients with prostate cancer were assessed with MR and MR spectroscopy (MRS) before and at 1, 4 and 12 months after HIFU, assessing the glandular volume and MRI and MRS data after HIFU. These data were correlated with the prostate-specific antigen (PSA) levels at each examination (suspicious for residual cancer if >0.5 ng/mL) and with histological findings of prostate biopsy sampling at 6-8 months (random or targeted at suspicious MR areas).

RESULTS

Variations in volume during the follow-up were not associated with treatment outcome. MRI was suspicious for residual cancer in one patient at 1 month and in another two at 4 months; in all three patients (one with a PSA level of <0.5 ng/mL) targeted biopsies were positive for cancer. MRI was negative in seven patients; in six of these (one with a PSA level of >0.5 ng/mL) random biopsies were negative, and in one the random biopsies were positive for residual cancer. At 4 months there was a statistically significant difference (P = 0.015) between patients responsive to treatment and those with persistent disease, by combining negative MRI with a PSA level of <0.5 ng/mL; MRS data were suitable for analysis only in three patients with partial necrosis.

CONCLUSION

Our preliminary data support the role of MRI in association with PSA levels as a useful and accurate tool in the follow-up of patients treated with HIFU for prostate cancer. However, considering the economic issue, it should not be used routinely and should be limited to detecting residual cancer (in patients with a PSA level of >0.5 ng/mL) with the main purpose of improving the detection rate of transrectal ultrasonography (TRUS)-guided prostate biopsy. MRS data had no additional value over MRI. Further evaluation is needed to compare the use of contrast media and other techniques (e.g. colour Doppler TRUS) in detecting residual or local recurrent cancer.

Role of magnetic resonance imaging and magnetic resonance spectroscopic imaging before and after radiotherapy for prostate cancer

PURPOSE

To describe the practical technical aspects of magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI) and to summarize the current and potential future status of MRI and MRSI in the localization, staging, treatment planning, and post-treatment follow-up of prostate cancer.

TECHNIQUE

Published contemporary series of patients with prostate cancer evaluated by MRI and MRSI before or after radiation therapy were reviewed, with particular respect to the role of MRI and MRSI in treatment planning, outcome prediction, and detecting local recurrence.

RESULTS

Volumetric localization is of limited accuracy for tumors less than 0.5 cm(3). Staging by MRI, which is improved by the addition of MRSI, is of incremental prognostic significance in patients with moderate and high-risk tumors. The finding of more than 5 mm of extracapsular extension prior to radiation seems to be of particular negative prognostic significance, and the latter group may be candidates for more aggressive supplemental therapy. The use of MRI to assist radiation treatment planning has been shown to improve outcome. MRSI may be helpful in the detection of local recurrence after radiation.

CONCLUSIONS

Only MRI and MRSI allow combined structural and metabolic evaluation of prostate cancer location, aggressiveness, and stage. Combined MRI and MRSI provide clinically and therapeutically relevant information that may assist in planning and post-treatment monitoring in patients undergoing radiation therapy.

Endorectal magnetic resonance imaging staging of prostate cancer

BACKGROUND

There are important treatment and prognostic implications in distinguishing between organ-confined prostate cancer that has spread locally outside the capsule and that which has spread into the seminal vesicles. This study is the first Australian study to report local accuracy for the locoregional staging of prostate cancer with endorectal magnetic resonance imaging (MRI).

METHODS

From July 2002 to December 2005, 129 patients were referred for endorectal MRI for all indications. Inclusion criteria were biopsy-proven prostate cancer, minimum 4 weeks from previous biopsy and radical retropubic prostatectomy within 12 months of MRI. This yielded 47 patients. Those with prior hormonal and neoadjuvant radiotherapy or significant postbiopsy haemorrhage were excluded. In addition, those patients examined with our alternate-contrast-enhanced protocol were also excluded. A total of 38 patients met all inclusion criteria. A General Electric 1.5-T whole-body MR imaging unit with an endorectal coil was used with interpretation by two genito-urinary MR radiologists. Final histopathological report was used for correlation.

RESULTS

Median age was 60 years with a range 44-72 years. Median prostate-specific antigen was 6.3 with a range of 2-82, and median Gleason score was 6 with a range of 5-8. Sensitivity, specificity and accuracy for extracapsular extension and seminal vesicle invasion were 69, 82 and 76% and 60, 100 and 95%, respectively. For extraprostatic extension, 71, 86 and 79%, respectively.

CONCLUSIONS

Staging accuracy is similar to internationally published standards. Improvements in hardware and software and increased reader experience will add value to the local Australian prostate imaging programme.

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.

MR-guided prostate interventions

In this article the current issues of diagnosis and detection of prostate cancer are reviewed. The limitations for current techniques are highlighted and some possible solutions with MR imaging and MR-guided biopsy approaches are reviewed. There are several different biopsy approaches under investigation. These include transperineal open magnet approaches to closed-bore 1.5T transrectal biopsies. The imaging, image processing, and tracking methods are also discussed. In the arena of therapy, MR guidance has been used in conjunction with radiation methods, either brachytherapy or external delivery. The principles of the radiation treatment, the toxicities, and use of images are outlined. The future role of imaging and image-guided interventions lie with providing a noninvasive surrogate for cancer surveillance or monitoring treatment response. The shift to minimally invasive focal therapies has already begun and will be very exciting when MR-guided focused ultrasound surgery reaches its full potential.

Local Experience of Endorectal Magnetic Resonance Imaging of Prostate with Correlation to Radical Prostatectomy Specimens

Introduction: We evaluated the accuracy of endorectal magnetic resonance imaging (MRI) in the staging of prostate cancer. Materials and Methods: We retrospectively reviewed 32 patients who underwent endorectal MR prostate prior to radical prostatectomy. The tumour stage based on MR imaging was compared with the pathologic stage. The sensitivity and specificity of endorectal MR prostate in the evaluation of extracapsular extension (ECE) of the tumour were then determined. Results: MR correctly diagnosed 17 cases of organ-confined prostate carcinoma and 2 cases of locally advanced disease. In the evaluation of ECE, endorectal MR achieved a high specificity of 94.4%, low sensitivity of 14.3% and moderate accuracy of 59.4%. Conclusion: Endorectal MR prostate has high specificity for the detection of ECE. It is useful in the local staging of prostate cancer in patients with intermediate risk as this helps to ensure that few patients will be deprived of potentially curative surgery.

MR imaging of the prostate: 1.5T versus 3T

Over the past several years, evidence supporting the use of MR imaging in the evaluation of prostate cancer has grown. Almost all this work has been performed at 1.5T. The gradual introduction of 3T scanners into clinical practice provides a potential opportunity to improve the quality and usefulness of prostate imaging. Increased signal to noise allows for imaging at higher resolution, higher temporal resolution, or higher bandwidth. Although this may improve the quality of conventional T2-weighted prostate imaging, which has been the standard sequence for detecting and localizing prostate cancer for years, the real potential for improvement at 3T involves more advanced techniques, such as spectroscopy, diffusion-weighted imaging, dynamic contrast imaging, and susceptibility imaging. This review presents the current data on 3T MR imaging of the prostate as well as the authors' impressions based on their experience at Yale-New Haven Hospital.

Multiparametric magnetic resonance imaging in prostate cancer: present and future

PURPOSE OF REVIEW

The purpose of this article is to review the current status of advanced MRI techniques based on anatomic, metabolic and physiologic properties of prostate cancer with a focus on their impact in managing prostate cancer patients.

RECENT FINDINGS

Prostate cancer can be identified based on reduced T2 signal intensity on MRI, increased choline and decreased citrate and polyamines on magnetic resonance spectroscopic imaging (MRSI), decreased diffusivity on diffusion tensor imaging (DTI), and increased uptake on dynamic contrast enhanced (DCE) imaging. All can be obtained within a 60-min 3T magnetic resonance exam. Each complementary method has inherent advantages and disadvantages: T2 MRI has high sensitivity but poor specificity; magnetic resonance spectroscopic imaging has high specificity but poor sensitivity; diffusion tensor imaging has high spatial resolution, is the fastest, but sensitivity/specificity needs to be established; dynamic contrast enhanced imaging has high spatial resolution, but requires a gadolinium based contrast agent injection, and sensitivity/specificity needs to be established.

SUMMARY

The best characterization of prostate cancer in individual patients will most likely result from a multiparametric (MRI/MRSI/DTI/DCE) exam using 3T magnetic resonance scanners but questions remain as to how to analyze and display this large amount of imaging data, and how to optimally combine the data for the most accurate assessment of prostate cancer. Histological correlations or clinical outcomes are required to determine sensitivity/specificity for each method and optimal combinations of these approaches.

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.

Detection of prostate cancer with MR spectroscopic imaging: an expanded paradigm incorporating polyamines

PURPOSE

To characterize benign and malignant prostate peripheral zone (PZ) tissue retrospectively by using a commercial magnetic resonance (MR) spectroscopic imaging package and incorporating the choline plus creatine-to-citrate ratio ([Cho + Cr]/Cit) and polyamine (PA) information into a statistically based voxel classification procedure.

MATERIALS AND METHODS

The institutional review board approved this HIPAA-compliant study and waived the requirement for informed consent. Fifty men (median age, 60 years; range, 44-69 years) with untreated biopsy-proved prostate cancer underwent combined endorectal MR imaging and MR spectroscopic imaging. Commercial software was used to acquire and process MR spectroscopic imaging data. The (Cho + Cr)/Cit and the PA level were tabulated for each voxel. The PA level was scored on a scale of 0 (PA undetectable) to 2 (PA peak as high as or higher than Cho peak). Whole-mount step-section histopathologic analysis constituted the reference standard. Classification and regression tree analysis in a training set generated a decision-making tree (rule) for classifying voxels as malignant or benign, which was validated in a test set. Receiver operating characteristic and generalized estimating equation regression analyses were used to assess accuracy and sensitivity, respectively.

RESULTS

The median (Cho + Cr)/Cit was 0.55 (mean +/- standard deviation, 0.59 +/- 0.03) in benign and 0.77 (mean, 1.08 +/- 0.20) in malignant PZ voxels (P = .027). A significantly higher percentage of benign (compared with malignant) voxels had higher PA than choline peaks (P < .001). In the 24-patient training set (584 voxels), the rule yielded 54% sensitivity and 91% specificity for cancer detection; in the 26-patient test set (667 voxels), it yielded 42% sensitivity and 85% specificity. The percentage of cancer in the voxel at histopathologic analysis correlated positively (P < .001) with the sensitivity of the classification and regression tree rule, which was 75% in voxels with more than 90% malignancy.

CONCLUSION

The statistically based classification rule developed indicated that PAs have an important role in the detection of PZ prostate cancer. With commercial software, this method can be applied in clinical settings.

MR imaging in local staging of prostate cancer

Clinical staging to differentiate between localized and advanced disease stage appear to be unreliable. Curative therapy can only be performed in patients with localized prostate cancer. Accurate staging is therefore especially important for proper disease management. Since 1984 magnetic resonance (MR) imaging has been applied for this purpose. However, the role of MR imaging of the prostate is debated extensively in the literature. Initially MR imaging was performed using a conventional body coil with subsequent limited anatomical detail due to insufficient spatial resolution. With the introduction of new MR sequences, new coils and other technical developments numerous studies have attempted to improve local staging. The diagnostic capability of MR imaging in preoperative staging of prostate cancer is currently being established. In this review the role of MR imaging in staging prostate cancer is discussed.

Prostate cancer: accurate determination of extracapsular extension with high-spatial-resolution dynamic contrast-enhanced and T2-weighted MR imaging--initial results

PURPOSE

To prospectively compare the sensitivity and specificity of high-spatial-resolution dynamic contrast material-enhanced magnetic resonance (MR) imaging with those of high-spatial-resolution T2-weighted MR imaging, performed with an endorectal coil (ERC), for assessment of extracapsular extension (ECE) and staging in patients with prostate cancer, with histopathologic findings as reference.

MATERIALS AND METHODS

The study was approved by the institutional internal review board; a signed informed consent was obtained. MR imaging of the prostate at 1.5 T was performed with combined surface coils and ERCs in 32 patients (mean age, 65 years; range, 42-78 years) before radical prostatectomy. High-spatial-resolution T2-weighted fast spin-echo and high-spatial-resolution dynamic contrast-enhanced three-dimensional gradient-echo images were acquired with gadopentetate dimeglumine. Dynamic contrast-enhanced MR images were analyzed with a computer-generated color-coded scheme. Two experienced readers independently assessed ECE and tumor stage. MR imaging-based staging results were compared with histopathologic results. For the prediction of ECE, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. Staging accuracy was determined with the area under the receiver operating characteristic curve (AUC) by using the Wilcoxon-Mann-Whitney index of diagnostic accuracy.

RESULTS

The mean sensitivity, specificity, PPV, and NPV for assessment of ECE with the combined data sets for both readers were 86%, 95%, 90%, and 93%, respectively. The sensitivity of MR images for determination of ECE was significantly improved for both readers (>25%) with combined data sets compared with T2-weighted MR images alone. The combined data sets had a mean overall staging accuracy for both readers of 95%, as determined with AUC. Staging results for both readers were significantly improved (P<.05) with the combined data sets compared with T2-weighted MR images alone.

CONCLUSION

The combination of high-spatial-resolution dynamic contrast-enhanced MR imaging and T2-weighted MR imaging yields improved assessment of ECE and better results for prostate cancer staging compared with either technique independently.

Proton MR spectroscopy of the prostate

PURPOSE

To summarize current technical and biochemical aspects and clinical applications of proton magnetic resonance spectroscopy (MRS) of the human prostate in vivo.

MATERIAL AND METHODS

Pertinent radiological and biochemical literature was searched and retrieved via electronic media (medline, pubmed. Basic concepts of MRS of the prostate and its clinical applications were extracted.

RESULTS

Clinical MRS is usually based on point resolved spectroscopy (PRESS) or spin echo (SE) sequences, along with outer volume suppression of signals from outside of the prostate. MRS of the prostate detects indicator lines of citrate, choline, and creatine. While healthy prostate tissue demonstrates high levels of citrate and low levels of choline that marks cell wall turnover, prostate cancer utilizes citrate for energy metabolism and shows high levels of choline. The ratio of (choline+creatine)/citrate distinguishes between healthy tissue and prostate cancer. Particularly when combined with magnetic resonance (MR) imaging, three-dimensional MRS imaging (3D-CSI, or 3D-MRSI) detects and localizes prostate cancer in the entire prostate with high sensitivity and specificity. Combined MR imaging and 3D-MRSI exceed the sensitivity and specificity of sextant biopsy of the prostate. When MRS and MR imaging agree on prostate cancer presence, the positive predictive value is about 80-90%. Distinction between healthy tissue and prostate cancer principally is maintained after various therapeutic treatments, including hormone ablation therapy, radiation therapy, and cryotherapy of the prostate.

CONCLUSIONS

Since it is non-invasive, reliable, radiation-free, and essentially repeatable, combined MR imaging and 3D-MRSI of the prostate lends itself to the planning of biopsy and therapy, and to post-therapeutic follow-up. For broad clinical acceptance, it will be necessary to facilitate MRS examinations and their evaluation and make MRS available to a wider range of institutions.

Current role and future perspectives of magnetic resonance spectroscopy in radiation oncology for prostate cancer

Prostatic neoplasms are not uniformly distributed within the prostate volume. With recent developments in three-dimensional intensity-modulated and image-guided radiation therapy, it is possible to treat different volumes within the prostate to different thresholds of doses. This approach has the potential to adapt the dose to the biologic aggressiveness of various clusters of tumor cells within the gland. The definition of tumor burden volume in prostate cancer can be facilitated by the use of magnetic resonance spectroscopy (MRS). The increasing sensitivity and specificity of MRS to the prostate is causing new interest in its potential role in the definition of target subvolumes at higher risk of failure following radical radiotherapy. Prostate MRS might also play a role as a noninvasive predictive factor for tumor response and treatment outcome. We review the use of MRS in radiation therapy for prostate cancer by evaluating its accuracy in the classification of aggressive cancer regions and target definition; its current role in the radiotherapy planning process, with special interest in technical issues behind the successful inclusion of MRS in clinical use; and available early experiences as a prognostic tool.

3D MR spectroscopic imaging in the evaluation of prostate cancer

The management of prostate cancer is a complex issue with a varying range of treatment options available. Magnetic resonance (MR) imaging of the prostate has been available for sometime but has the limitation of only anatomical evaluation. Three-dimensional MR spectroscopy is emerging as a new and sensitive tool in the metabolic evaluation of prostate cancer. This article reviews the principle, techniques, and methods of evaluation of spectroscopy and also discusses the applications of spectroscopy in the current management of prostate cancer.

Prostate Cancer: Body-Array versus Endorectal Coil MR Imaging at 3 T—Comparison of Image Quality, Localization, and Staging Performance

PURPOSE

To prospectively compare image quality and accuracy of prostate cancer localization and staging with body-array coil (BAC) versus endorectal coil (ERC) T2-weighted magnetic resonance (MR) imaging at 3 T, with histopathologic findings as the reference standard.

MATERIALS AND METHODS

After institutional review board approval and written informed consent, 46 men underwent 3-T T2-weighted MR imaging with a BAC (voxel size, 0.43 x 0.43 x 4.00 mm) and an ERC (voxel size, 0.26 x 0.26 x 2.50 mm) before radical prostatectomy. Four radiologists independently evaluated data sets obtained with the BAC and ERC separately. Ten image quality characteristics related to prostate cancer localization and staging were assigned scores. Prostate cancer presence was recorded with a five-point probability scale in each of 14 segments that included the whole prostate. Disease stage was classified as organ-confined or locally advanced with a five-point probability scale. Whole-mount-section histopathologic examination was the reference standard. Areas under the receiver operating characteristic curve (AUCs) and diagnostic performance parameters were determined. A difference with a P value of less than .05 was considered significant.

RESULTS

Forty-six patients (mean age, 61 years) were included for analysis. Significantly more motion artifacts were present with ERC imaging (P<.001). All other image quality characteristics improved significantly (P<.001) with ERC imaging. With ERC imaging, the AUC for localization of prostate cancer was significantly increased from 0.62 to 0.68 (P<.001). ERC imaging significantly increased the AUCs for staging, and sensitivity for detection of locally advanced disease by experienced readers was increased from 7% (one of 15) to a range of 73% (11 of 15) to 80% (12 of 15) (P<.05), whereas a high specificity of 97% (30 of 31) to 100% (31 of 31) was maintained. Extracapsular extension as small as 0.5 mm at histopathologic examination could be accurately detected only with ERC imaging.

CONCLUSION

Image quality and localization improved significantly with ERC imaging compared with BAC imaging. For experienced radiologists, the staging performance was significantly better with ERC imaging.

Value of magnetic resonance imaging in prostate cancer diagnosis

MRI has shown its potential in prostate cancer (PCa) imaging. MRI is able to demonstrate zonal anatomy with excellent contrast resolution. Furthermore it can detect PCa dependent not only on tumor-size, histological grading, PSA levels, but also on technical equipment and reader's experience. Non-palpable PCas in the inner and outer gland can be detected by this technique. Another potential is that MRI is helpful for tumor staging and treatment planning as well as response evaluation. Besides the morphological information, MRI can give functional information based on metabolic evaluation with proton magnetic resonance spectroscopy and of tumor angiogenesis based on dynamic contrast-material enhanced MRI and diffusion-weighted imaging. In addition MRI can be used for targeted prostate biopsies; however, the clinical practicability is questionable. Furthermore many data about the value of MRI for PCa diagnosis are based on transrectal ultrasound (TRUS) biopsy findings. Since there is lack of accuracy in fusing MRI images with TRUS images these limit the results of MRI for cancer diagnosis. However, in the future MRI may play an additional role in planning and monitoring minimally invasive PCa therapies. Although, MRI of the prostate seems to be useful, nevertheless this method remains expensive and lacks availability regarding the oncoming requirements.

[MRI of prostate cancer]

Endorectal MRI, now a fast and reliable examination, is an essential part of the local work-up for prostate cancer, regardless of the treatment envisioned. MRI spectroscopy, an actively maturing technique, makes it possible to combine anatomical and metabolic information that can be used for detection, staging, and posttreatment follow-up of prostate cancer. In patients with repeated negative biopsies, spectroscopy and dynamic gadolinium injection will be able to detect atypical cancer sites that escape routine biopsies. MRI of lymph nodes with ultrasmall superparamagnetic iron oxide (USPIO) injection will improve diagnostic performance in the detection of lymph node metastases. In the planning of conservative treatment, MRI and especially spectroscopic MRI will increasingly replace computed tomography. Finally, endorectal MRI of the prostate, spectroscopy, and dynamic injection will show local recurrences.

11C-Choline positron-emission tomography/computed tomography and transrectal ultrasonography for staging localized prostate cancer

OBJECTIVE

To evaluate and compare the role of (11)C-choline positron emission tomography (PET) and transrectal ultrasonography (TRUS) in the preoperative staging of clinically localized prostate cancer.

PATIENTS AND METHODS

Fifty-five consecutive patients with biopsy-confirmed prostate cancer had TRUS and (11)C-choline PET as a part of their clinical staging programme before radical retropubic prostatectomy (RP). The PET images were prospectively interpreted by a consensus decision of two nuclear medicine physicians and one radiologist with special expertise in the field. The TRUS was done by one experienced urologist. The criteria evaluated prospectively in each patient were extracapsular extension (ECE), seminal vesicle invasion (SVI) and bladder neck invasion (BNI). The results were compared with the histopathological findings after RP.

RESULTS

At pathology, 32 patients were classified pT2, 16 as pT3a and three had pT3b lesions. In four patients the histopathological examination showed pT4 with BNI. The overall accuracy of PET in defining local tumour stage (pT2 and pT3a-4) was 70%; the overall accuracy by TRUS was 26%. PET was more sensitive than TRUS for detecting ECE (pT3a) and SVI (pT3b) in advanced stages, and in pT4 stages. The sensitivity and positive predictive value (PPV) (95% confidence interval) in stages pT3a-pT4 for PET were 36 (17-59)% and 73 (39-89)%. The sensitivity and PPV in stages pT3a-pT4 for TRUS were 14 (3-35)% and 100 (29-100)%.

CONCLUSIONS

(11)C-choline PET and TRUS tended to understage prostate cancer. This series shows the current limited value of TRUS and PET for making treatment decisions in patients with clinically localized prostate cancer, especially if a nerve-sparing RP is considered. Treatment decisions should not be based on TRUS and (11)C-choline PET findings alone. In future studies, the combination of metabolic and anatomical information of PET and endorectal magnetic resonance imaging should be evaluated, as this might optimize the preoperative staging in prostate cancer.

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.

Prostate cancer detection: magnetic resonance (MR) spectroscopic imaging

Magnetic resonance spectroscopic imaging (MRSI) represents a noninvasive technique to extend the diagnostic evaluation of prostatic cancer, beyond the morphologic information provided by MR imaging throughout the detection of cellular metabolites (choline and citrate). MRSI combined with the anatomical information provided by MRI can improve the assessment cancer location and extent within the prostate, extracapsular spread and cancer aggressiveness; both before and after treatment. We review the performance of MRI with MRSI and the role in the detection, localization, staging and management of the patient pre- and posttherapy for prostate cancer.

Imaging prostate cancer: a multidisciplinary perspective

The major goal for prostate cancer imaging in the next decade is more accurate disease characterization through the synthesis of anatomic, functional, and molecular imaging information. No consensus exists regarding the use of imaging for evaluating primary prostate cancers. Ultrasonography is mainly used for biopsy guidance and brachytherapy seed placement. Endorectal magnetic resonance (MR) imaging is helpful for evaluating local tumor extent, and MR spectroscopic imaging can improve this evaluation while providing information about tumor aggressiveness. MR imaging with superparamagnetic nanoparticles has high sensitivity and specificity in depicting lymph node metastases, but guidelines have not yet been developed for its use, which remains restricted to the research setting. Computed tomography (CT) is reserved for the evaluation of advanced disease. The use of combined positron emission tomography/CT is limited in the assessment of primary disease but is gaining acceptance in prostate cancer treatment follow-up. Evidence-based guidelines for the use of imaging in assessing the risk of distant spread of prostate cancer are available. Radionuclide bone scanning and CT supplement clinical and biochemical evaluation (prostate-specific antigen [PSA], prostatic acid phosphate) for suspected metastasis to bones and lymph nodes. Guidelines for the use of bone scanning (in patients with PSA level > 10 ng/mL) and CT (in patients with PSA level > 20 ng/mL) have been published and are in clinical use. Nevertheless, changes in practice patterns have been slow. This review presents a multidisciplinary perspective on the optimal role of modern imaging in prostate cancer detection, staging, treatment planning, and follow-up.

Prostate cancer: value of magnetic resonance spectroscopy 3D chemical shift imaging

The results of recent studies of magnetic resonance imaging (MRI) combined with three-dimensional magnetic resonance spectroscopic imaging (3D-MRSI) demonstrate that the MRI/3D-MRSI exam is a unique method by which to noninvasively study the cellular metabolism and anatomy of the prostate. 3D-MRSI is emerging as the most specificity tool for non-invasive evaluation of the prostate cancer. The results of current MRI/3D-MRSI studies also provide evidence that the magnitude of metabolic changes in regions of cancer before therapy, as well as the extent of the time course of metabolic changes after therapy, may improve our understanding of cancer aggressiveness. Assessment of cancer spread outside the prostate can be significantly improved by combining MRI findings with estimates of metabolic abnormalities provided by 3D-MRSI. Clinically, combined MRI/3D-MRSI has already demonstrated a potential for improved diagnosis, staging, and treatment planning for patients with prostate cancer. This article reviewed the value of 3D-MRS imaging for the diagnosis, localization, staging, aggressiveness, and treatment planning of prostate cancer.

The utility of magnetic resonance imaging and spectroscopy for predicting insignificant prostate cancer: an initial analysis

OBJECTIVE

To design new models that combine clinical variables and biopsy data with magnetic resonance imaging (MRI) and MR spectroscopic imaging (MRSI) data, and assess their value in predicting the probability of insignificant prostate cancer.

PATIENTS AND METHODS

In all, 220 patients (cT stage T1c or T2a, prostate-specific antigen level <20 ng/mL, biopsy Gleason score 6) had MRI/MRSI before surgery and met the inclusion criteria for the study. The probability of insignificant cancer was recorded retrospectively and separately for MRI and combined MRI/MRSI on a 0-3 scale (0, definitely insignificant; - 3, definitely significant). Insignificant cancer was defined from surgical pathology as organ-confined cancer of </= 0.5 cm(3) with no poorly differentiated elements. The accuracy of predicting insignificant prostate cancer was assessed using areas under receiver operating characteristic curves (AUCs), for previously reported clinical models and for newly generated MR models combining clinical variables, and biopsy data with MRI data (MRI model) and MRI/MRSI data (MRI/MRSI model).

RESULTS

At pathology, 41% of patients had insignificant cancer; both MRI (AUC 0.803) and MRI/MRSI (AUC 0.854) models incorporating clinical, biopsy and MR data performed significantly better than the basic (AUC 0.574) and more comprehensive medium (AUC 0.726) clinical models. The P values for the differences between the models were: base vs medium model, <0.001; base vs MRI model, <0.001; base vs MRI/MRSI model, <0.001; medium vs MRI model, <0.018; medium vs MRI/MRSI model, <0.001.

CONCLUSIONS

The new MRI and MRI/MRSI models performed better than the clinical models for predicting the probability of insignificant prostate cancer. After appropriate validation, the new MRI and MRI/MRSI models might help in counselling patients who are considering choosing deferred therapy.

Validity of prostate-specific antigen as a tumour marker in men with prostate cancer managed by watchful-waiting: correlation with findings at serial endorectal magnetic resonance imaging and spectroscopic imaging

OBJECTIVE

To investigate the validity of prostate-specific antigen (PSA) as a tumour marker in men with clinically localized prostate cancer who have selected watchful waiting, by determining if serial PSA level measurements are correlated with findings of malignancy or benign prostatic hyperplasia (BPH) at serial endorectal magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI).

PATIENTS AND METHODS

We retrospectively identified 69 men with biopsy-proven prostate cancer being managed by watchful waiting, who underwent serial endorectal MRI/MRSI and who had contemporaneous serial PSA measurements. The mean (range) follow-up was 392 (294-571) days. A panel of three experienced readers reviewed the initial and follow-up MRI/MRSI studies, and classified findings of prostate cancer as stable or progressive. Another reader assessed BPH by calculating total gland and central gland volumes on all studies.

RESULTS

At the follow-up MRI/MRSI, 51, 17 and one patient had stable, progressive, or unevaluable prostate cancer, respectively. The mean PSA velocity was significantly greater in patients with radiologically progressive disease (1.42 vs 0.42 ng/mL/year, P = 0.04). A PSA velocity of >0.75 ng/mL/year identified those with radiologically progressive disease with a true-positive fraction of 0.71 and a false-positive fraction of 0.39. PSA levels were not correlated with changes in total or central gland volumes (P > 0.05).

CONCLUSIONS

In men with clinically localized prostate cancer who select watchful waiting, serial PSA levels are correlated with findings of malignancy but not BPH at serial endorectal MRI/MRSI, suggesting that PSA is a useful longitudinal tumour marker in this population.

Contribution of the MR spectroscopic imaging in the diagnosis of prostate cancer in the peripheral zone

PURPOSE

To establish the additional value of 3D magnetic resonance spectroscopy (3D-MRS) imaging to endorectal MR imaging in the diagnosis of prostrate cancer in the peripheral zone.

MATERIALS AND METHODS

MR imaging and MRS imaging were performed in 79 patients with suspicion of prostate cancer on the basis of digital rectal exploration, transrectal ultrasound and PSA level. All the examinations were performed with 1.5 T MR scan using an endorectal coil (transverse and coronal FSE T2-weighted sequences, axial SE T1-weighted and PRESS 3D CSI). MR examinations have been evaluated by two Radiologists blind of the clinical data in a "per patients" analysis. MR imaging and MRS imaging findings were compared with the result of histological data from radical prostatectomy in 53 patients and biopsy in 17 patients.

RESULTS

Nine patients (11.4%) were excluded because of serious artefacts in the MR spectrum. The reported values of sensitivity, specificity, PPV and NPV for MR imaging alone were respectively 84%, 50%, 76% and 63% (LR+ 1.7; LR- 0.3). Instead the reported values of sensitivity, specificity, PPV and NPV for the combination of MR imaging to MRS imaging were respectively 89%, 79%, 89% and 79% (LR+ 4.28; LR- 0.14). We found an incremental benefit of MRS imaging to MR imaging for tumour diagnosis although these results did not show statistically significant differences.

CONCLUSIONS

The MRS imaging improves the accuracy of the endorectal MR imaging in the diagnosis of prostate cancer.