December 2017Risk Stratification Among Men with Prostate Imaging Reporting and Data System version 2 Category 3 Transition Zone Lesions: Is Biopsy Always Necessary?
OBJECTIVE: The objective of our study was to determine the clinical and MRI characteristics of clinically significant prostate cancer (PCA) (Gleason score ≥ 3 + 4) in men with Prostate Imaging Reporting and Data System version 2 (PI-RADSv2) category 3 transition zone (TZ) lesions. MATERIALS AND METHODS: From 2014 to 2016, 865 men underwent prostate MRI and MRI/ultrasound (US) fusion biopsy (FB). A subset of 90 FB-naïve men with 96 PI-RADSv2 category 3 TZ lesions was identified. Patients were imaged at 3 T using a body coil. Images were assigned a PI-RADSv2 category by an experienced radiologist. Using clinical data and imaging features, we performed univariate and multivariate analyses to identify predictors of clinically significant PCA.
October 2017Focal Laser Ablation of Prostate Cancer: Feasibility of Magnetic Resonance Imaging-Ultrasound Fusion for Guidance.
PURPOSE: Focal laser ablation is a potential treatment in some men with prostate cancer. Currently focal laser ablation is performed by radiologists in a magnetic resonance imaging unit (in bore). We evaluated the safety and feasibility of performing focal laser ablation in a urology clinic (out of bore) using magnetic resonance imaging-ultrasound fusion for guidance. MATERIALS AND METHODS: A total of 11 men with intermediate risk prostate cancer were enrolled in this prospective, institutional review board approved pilot study. Magnetic resonance imaging-ultrasound fusion was used to guide laser fibers transrectally into regions of interest harboring intermediate risk prostate cancer. Thermal probes were inserted for real-time monitoring of intraprostatic temperatures during laser activation. Multiparametric magnetic resonance imaging (3 Tesla) was done immediately after treatment and at 6 months along with comprehensive fusion biopsy.
April 2017In-Bore 3-T MR-guided Transrectal Targeted Prostate Biopsy: Prostate Imaging Reporting and Data System Version 2-based Diagnostic Performance for Detection of Prostate Cancer.
PURPOSE: To determine the diagnostic yield of in-bore 3-T magnetic resonance (MR) imaging-guided prostate biopsy and stratify performance according to Prostate Imaging Reporting and Data System (PI-RADS) versions 1 and 2. MATERIALS AND METHODS: This study was HIPAA compliant and institution review board approved. In-bore 3-T MR-guided prostate biopsy was performed in 134 targets in 106 men who (a) had not previously undergone prostate biopsy, (b) had prior negative biopsy findings with increased prostate-specific antigen (PSA) level, or (c) had a prior history of prostate cancer with increasing PSA level. Clinical, diagnostic 3-T MR imaging was performed with in-bore guided prostate biopsy, and pathology data were collected. The diagnostic yields of MR-guided biopsy per patient and target were analyzed, and differences between biopsy targets with negative and positive findings were determined. Results of logistic regression and areas under the curve were compared between PI-RADS versions 1 and 2.
March 2017Targeted Biopsy to Detect Gleason Score Upgrading during Active Surveillance for Men with Low versus Intermediate Risk Prostate Cancer.
PURPOSE: We sought to determine the rate of upgrading to Gleason score 4 + 3 or greater using targeted biopsy for diagnosis and monitoring in men undergoing active surveillance of prostate cancer. MATERIALS AND METHODS: Study subjects comprised all 259 men, including 196 with Gleason score 3 + 3 and 63 with Gleason score 3 + 4, who were diagnosed by magnetic resonance imaging/ultrasound fusion guided biopsy from 2009 to 2015 and underwent subsequent fusion biopsy for as long as 4 years of active surveillance. The primary end point was the discovery of Gleason score 4 + 3 or greater prostate cancer. Followup biopsies included targeting of positive sites, which were tracked in an Artemis™ device. Kaplan-Meier curves were generated to determine upgrading rates, stratified by initial Gleason score and prostate specific antigen density.
February 2017Magnetic Resonance Imaging Underestimation of Prostate Cancer Geometry: Use of Patient Specific Molds to Correlate Images with Whole Mount Pathology.
PURPOSE: We evaluated the accuracy of magnetic resonance imaging in determining the size and shape of localized prostate cancer. MATERIALS AND METHODS: The subjects were 114 men who underwent multiparametric magnetic resonance imaging before radical prostatectomy with patient specific mold processing of the specimen from 2013 to 2015. T2-weighted images were used to contour the prostate capsule and cancer suspicious regions of interest. The contours were used to design and print 3-dimensional custom molds, which permitted alignment of excised prostates with magnetic resonance imaging scans. Tumors were reconstructed in 3 dimensions from digitized whole mount sections. Tumors were then matched with regions of interest and the relative geometries were compared.
September 2016Interobserver Reproducibility of the PI-RADS Version 2 Lexicon: A Multicenter Study of Six Experienced Prostate Radiologists.
Purpose To determine the interobserver reproducibility of the Prostate Imaging Reporting and Data System (PI-RADS) version 2 lexicon. Materials and Methods This retrospective HIPAA-compliant study was institutional review board-approved. Six radiologists from six separate institutions, all experienced in prostate magnetic resonance (MR) imaging, assessed prostate MR imaging examinations performed at a single center by using the PI-RADS lexicon. Readers were provided screen captures that denoted the location of one specific lesion per case. Analysis entailed two sessions (40 and 80 examinations per session) and an intersession training period for individualized feedback and group discussion. Percent agreement (fraction of pairwise reader combinations with concordant readings) was compared between sessions. k coefficients were computed. Results No substantial difference in interobserver agreement was observed between sessions, and the sessions were subsequently pooled. Agreement for PI-RADS score of 4 or greater was 0.593 in peripheral zone (PZ) and 0.509 in transition zone (TZ). In PZ, reproducibility was moderate to substantial for features related to diffusion-weighted imaging (k = 0.535-0.619); fair to moderate for features related to dynamic contrast material-enhanced (DCE) imaging (k = 0.266-0.439); and fair for definite extraprostatic extension on T2-weighted images (k = 0.289). In TZ, reproducibility for features related to lesion texture and margins on T2-weighted images ranged from 0.136 (moderately hypointense) to 0.529 (encapsulation). Among 63 lesions that underwent targeted biopsy, classification as PI-RADS score of 4 or greater by a majority of readers yielded tumor with a Gleason score of 3+4 or greater in 45.9% (17 of 37), without missing any tumor with a Gleason score of 3+4 or greater. Conclusion Experienced radiologists achieved moderate reproducibility for PI-RADS version 2, and neither required nor benefitted from a training session. Agreement tended to be better in PZ than TZ, although was weak for DCE in PZ. The findings may help guide future PI-RADS lexicon updates.
July 2016Prostate Cancer Risk Stratification with Magnetic Resonance Imaging.
In recent years, multiparametric magnetic resonance imaging (mpMRI) has shown promise for prostate cancer (PCa) risk stratification. mpMRI, often followed by targeted biopsy, can be used to confirm low-grade disease before enrollment in active surveillance. In patients with intermediate or high-risk PCa, mpMRI can be used to inform surgical management. mpMRI has sensitivity of 44% to 87% for detection of clinically significant PCa and negative predictive value of 63% to 98% for exclusion of significant disease. In addition to tumor identification, mpMRI has also been shown to contribute significant incremental value to currently used clinical nomograms for predicting extraprostatic extension. In combination with conventional clinical criteria, accuracy of mpMRI for prediction of extraprostatic extension ranges from 92% to 94%, significantly higher than that achieved with clinical criteria alone. Supplemental sequences, such as diffusion-weighted imaging and dynamic contrast-enhanced imaging, allow quantitative evaluation of cancer-suspicious regions. Apparent diffusion coefficient appears to be an independent predictor of PCa aggressiveness. Addition of apparent diffusion coefficient to Epstein criteria may improve sensitivity for detection of significant PCa by as much as 16%. Limitations of mpMRI include variability in reporting, underestimation of PCa volume and failure to detect clinically significant disease in a small but significant number of cases.
July 2016Focal Laser Ablation of Prostate Cancer: Phase I Clinical Trial.
PURPOSE: Focal laser ablation is an investigational technique to treat prostate cancer in a region confined manner via coagulative necrosis. This phase I trial primarily examines the safety of transrectal magnetic resonance imaging guided (in-bore) focal laser ablation in men with intermediate risk prostate cancer. An exploratory end point is cancer control after 6 months. MATERIALS AND METHODS: In an institutional review board approved trial we studied focal laser ablation in 8 men with intermediate risk prostate cancer diagnosed using magnetic resonance-ultrasound fusion. Focal laser ablation was performed by inserting a cylindrically diffusing, water cooled laser fiber into magnetic resonance visible regions of interest, followed by interstitial heating at 10 to 15 W for up to 3 minutes. Secondary safety monitors (thermal probes) were inserted to assess the accuracy of magnetic resonance thermometry. Comprehensive magnetic resonance-ultrasound fusion biopsy was performed after 6 months. Adverse events and health related quality of life questionnaires were recorded.
June 2016MR-TRUS Fusion Biopsy.
The leading application of multiparametric magnetic resonance imaging (mpMRI) of the prostate is for lesion detection with the intention of tissue sampling (biopsy). Although direct in-bore magnetic resonance (MR)-guided biopsy allows for confirmation of the biopsy site, this can be expensive, time-consuming, and most importantly limited in availability. MR-transrectal ultrasound (MR-TRUS) image fusion targeted biopsy (TBx) allows for lesions identified on MRI to be targeted with the ease, efficiency, and availability of ultrasound.The learning objectives are optimized mpMRI protocol and reporting for image fusion targeted biopsy; methods of TRUS TBx; performance and limitations of MR-TRUS TBx; future improvements and applications.
May 2016In-bore Magnetic Resonance-guided Transrectal Biopsy for the Detection of Clinically Significant Prostate Cancer.
PURPOSE: To determine the safety and efficacy of in-bore magnetic resonance-guided prostate biopsy (MRGB) for detection of clinically significant disease (CSD) in untreated men with known or suspected prostate cancer (PCa). METHODS: 512 patients underwent multiparametric magnetic resonance imaging (Mp-MRI) followed by MRGB at one of three centers in this IRB-approved, HIPAA-compliant, retrospective study. Exclusion criteria were prior prostate cancer therapy and incomplete Mp-MRI (n = 51). Patients (n = 461) were analyzed in two subcohorts: no prior PCa (NP) (n = 381) and active surveillance (AS) (n = 80). Detection rates of PCa and CSD (Gleason Score ≥3 + 4) were calculated and compared among subcohorts and by Mp-MRI assessment grade. Logistic regression was performed to identify predictors for detection of PCa and CSD.
May 2016Serial Magnetic Resonance Imaging in Active Surveillance of Prostate Cancer: Incremental Value.
PURPOSE: We assessed whether changes in serial multiparametric magnetic resonance imaging can help predict the pathological progression of prostate cancer in men on active surveillance. MATERIALS AND METHODS: A retrospective cohort study was conducted of 49 consecutive men with Gleason 6 prostate cancer who underwent multiparametric magnetic resonance imaging at baseline and again more than 6 months later, each followed by a targeted prostate biopsy, between January 2011 and May 2015. We evaluated whether progression on multiparametric magnetic resonance imaging (an increase in index lesion suspicion score, increase in index lesion volume or decrease in index lesion apparent diffusion coefficient) could predict pathological progression (Gleason 3 + 4 or greater on subsequent biopsy, in systematic or targeted cores). Diagnostic performance of multiparametric magnetic resonance imaging was determined with and without clinical data using a binary logistic regression model.
May 2016Why We Need a Vendor Neutral Specification for Delineating Prostate Cancer with mpMRI.
Despite being the most common non-cutaneous cancer and second leading cause of cancer death in American men, the United States Preventive Service Task Force recommends against screening for prostate cancer because of the resultant overtreatment of indolent disease . With the demonstrated ability of multiparametric MRI (mpMRI) to identify cancer and the ability of mpMRI combined with transrectal ultrasound (TRUS) MRI fusion biopsy to increase the yield of significant cancer while decreasing the yield of insignificant cancer, there has been marked growth in volumes and indications for mpMRI of the prostate . TRUS/MRI technology is growing in popularity and acceptance, and it will soon become the standard of care. The National Comprehensive Cancer Network, for example, is expected to suggest its appropriateness for initial biopsy and has recently advocated its use in active surveillance. Building on the demonstration of TRUS/MRI fusion at the National Institutes of Health, we now have nearly a dozen different systems for TRUS/MRI fusion biopsy . This embarrassment of riches has come with an unexpected price—a similar number of commercial contour encoding systems and their associated workstations and image interpretation platforms have been developed for the segmentation of the prostate and suspicious regions within. Two immediate issues arise without vendor neutral specifications for handling contour metadata: the first is related to the problem of multiple referrers using multiple different TRUS/MRI fusion systems for targeted biopsy and its impact on workflow; the second related to archiving, retrieval, and transfer of patient data.
February 2016Utilizing Time-driven Activity-based Costing to Understand the Short- and Long-term Costs of Treating Localized, Low-risk Prostate Cancer.
BACKGROUND: Given the costs of delivering care for men with prostate cancer remain poorly described, this article reports the results of time-driven activity-based costing (TDABC) for competing treatments of low-risk prostate cancer. METHODS: Process maps were developed for each phase of care from the initial urologic visit through 12 years of follow-up for robotic-assisted laparoscopic prostatectomy (RALP), cryotherapy, high-dose rate (HDR) and low-dose rate (LDR) brachytherapy, intensity-modulated radiation therapy (IMRT), stereotactic body radiation therapy (SBRT), and active surveillance (AS). The last modality incorporated both traditional transrectal ultrasound (TRUS) biopsy and multiparametric-MRI/TRUS fusion biopsy. The costs of materials, equipment, personnel, and space were calculated per unit of time and based on the relative proportion of capacity used. TDABC for each treatment was defined as the sum of its resources.
January 2016Synopsis of the PI-RADS v2 Guidelines for Multiparametric Prostate Magnetic Resonance Imaging and Recommendations for Use.
Rapid technical advances have enabled multiparametric magnetic resonance imaging (mpMRI) combined with magnetic resonance (MR)–targeted biopsy to become valuable tools for early detection of clinically significant prostate cancer (PCa) while reducing overdiagnosis of indolent PCa. There has been concern, however, that the widespread implementation and acceptance of mpMRI could be impaired by a lack of standardisation of image acquisition, interpretation and reporting guidance, and inter- and intraobserver variability that could result in poor clinical test performance in daily practise.
January 2016PI-RADS Prostate Imaging - Reporting and Data System: 2015, Version 2.
The Prostate Imaging - Reporting and Data System Version 2 (PI-RADSTM v2) is the product of an international collaboration of the American College of Radiology (ACR), European Society of Uroradiology (ESUR), and AdMetech Foundation. It is designed to promote global standardization and diminish variation in the acquisition, interpretation, and reporting of prostate multiparametric magnetic resonance imaging (mpMRI) examination, and it is based on the best available evidence and expert consensus opinion. It establishes minimum acceptable technical parameters for prostate mpMRI, simplifies and standardizes terminology and content of reports, and provides assessment categories that summarize levels of suspicion or risk of clinically significant prostate cancer that can be used to assist selection of patients for biopsies and management. It is intended to be used in routine clinical practice and also to facilitate data collection and outcome monitoring for research.
January 2016High-Resolution 3-T Endorectal Prostate MRI: A Multireader Study of Radiologist Preference and Perceived Interpretive Quality of 2D and 3D T2-Weighted Fast Spin-Echo MR Images.
OBJECTIVE: The goal of this study was to compare the perceived quality of 3-T axial T2-weighted high-resolution 2D and high-resolution 3D fast spin-echo (FSE) endorectal MR images of the prostate. MATERIALS AND METHODS: Six radiologists independently reviewed paired 3-T axial T2-weighted high-resolution 2D and 3D FSE endorectal MR images of the prostates of 85 men in two sessions. In the first session (n = 85), each reader selected his or her preferred images; in the second session (n = 28), they determined their confidence in tumor identification and compared the depiction of the prostatic anatomy, tumor conspicuity, and subjective intrinsic image quality of images. A meta-analysis using a random-effects model, logistic regression, and the paired Wilcoxon rank-sum test were used for statistical analyses.
November 2015Multiparametric Magnetic Resonance Imaging for Prostate Cancer Improves Gleason Score Assessment in Favorable Risk Prostate Cancer.
PURPOSE: Magnetic resonance imaging (MRI) guidance may improve the accuracy of Gleason score (GS) determination by directing the biopsy to regions of interest (ROI) that are likely to harbor high-grade prostate cancer (CaP). The aim of this study was to determine the frequency and predictors of GS upgrading when a subsequent MRI-guided biopsy is performed on patients with a diagnosis of GS 6 disease on the basis of conventional, transrectal ultrasound-guided biopsy. METHODS AND MATERIALS: A consecutive series of 245 men with a diagnosis of low-risk CaP (ie, cT1c, GS 6, prostate-specific antigen <10) based on transrectal ultrasound-guided biopsy was enrolled in an active surveillance protocol that used subsequent MRI-guided biopsy for confirmation of GS. ROIs were categorized on a scale of 1 to 5. The Artemis ultrasound-MRI fusion device was used to perform targeted biopsies of ROIs as well as systematic biopsies from a software-based 12-point map. Predictors of GS upgrading were analyzed using univariate and multivariate analyses.
November 2015Accelerated Echo Planar J-resolved Spectroscopic Imaging in Prostate Cancer: a Pilot Validation of Non-linear Reconstruction Using Total Variation and Maximum Entropy.
The overlap of metabolites is a major limitation in one-dimensional (1D) spectral-based single-voxel MRS and multivoxel-based MRSI. By combining echo planar spectroscopic imaging (EPSI) with a two-dimensional (2D) J-resolved spectroscopic (JPRESS) sequence, 2D spectra can be recorded in multiple locations in a single slice of prostate using four-dimensional (4D) echo planar J-resolved spectroscopic imaging (EP-JRESI). The goal of the present work was to validate two different non-linear reconstruction methods independently using compressed sensing-based 4D EP-JRESI in prostate cancer (PCa): maximum entropy (MaxEnt) and total variation (TV). Twenty-two patients with PCa with a mean age of 63.8 years (range, 46-79 years) were investigated in this study. A 4D non-uniformly undersampled (NUS) EP-JRESI sequence was implemented on a Siemens 3-T MRI scanner. The NUS data were reconstructed using two non-linear reconstruction methods, namely MaxEnt and TV. Using both TV and MaxEnt reconstruction methods, the following observations were made in cancerous compared with non-cancerous locations: (i) higher mean (choline + creatine)/citrate metabolite ratios; (ii) increased levels of (choline + creatine)/spermine and (choline + creatine)/myo-inositol; and (iii) decreased levels of (choline + creatine)/(glutamine + glutamate). We have shown that it is possible to accelerate the 4D EP-JRESI sequence by four times and that the data can be reliably reconstructed using the TV and MaxEnt methods. The total acquisition duration was less than 13 min and we were able to detect and quantify several metabolites. Copyright © 2015 John Wiley & Sons, Ltd.
November 2015Prostate Diffusion Imaging with Distortion Correction.
PURPOSE: Diffusion imaging in the prostate is susceptible to distortion from B0 inhomogeneity. Distortion correction in prostate imaging is not routinely performed, resulting in diffusion images without accurate localization of tumors. We performed and evaluated distortion correction for diffusion imaging in the prostate. MATERIALS AND METHODS: 28 patients underwent pre-operative MRI (T2, Gadolinium perfusion, diffusion at b=800s/mm(2)). The restriction spectrum protocol parameters included b-values of 0, 800, 1500, and 4000s/mm(2) in 30 directions for each nonzero b-value. To correct for distortion, forward and reverse trajectories were collected at b=0s/mm(2). Distortion maps were generated to reflect the offset of the collected data versus the corrected data. Whole-mount histology was available for correlation.
September 2015Targeted Prostate Biopsy: Lessons Learned Midst the Evolution of a Disruptive Technology.
Lessons learned during a 6-year experience with more than 1200 patients undergoing targeted prostate biopsy via MRI/ultrasound fusion are reported: (1) the procedure is safe and efficient, requiring some 15-20 minutes in an office setting; (2) MRI is best performed by a radiologist with specialized training, using a transabdominal multiparametric approach and preferably a 3T magnet; (3) grade of MRI suspicion is the most powerful predictor of biopsy results, eg, Grade 5 usually represents cancer; (4) some potentially important cancers (15%-30%) are MRI-invisible; (5) Targeted biopsies provide >80% concordance with whole-organ pathology. Early enthusiasm notwithstanding, cost-effectiveness is yet to be resolved, and the technologies remain in evolution.
August 2015Recent Advances in Image-guided Targeted Prostate Biopsy.
Prostate cancer is a common malignancy in the United States that results in over 30,000 deaths per year. The current state of prostate cancer diagnosis, based on PSA screening and sextant biopsy, has been criticized for both overdiagnosis of low-grade tumors and underdiagnosis of clinically significant prostate cancers (Gleason score ≥7). Recently, image guidance has been added to perform targeted biopsies of lesions detected on multi-parametric magnetic resonance imaging (mpMRI) scans. These methods have improved the ability to detect clinically significant cancer, while reducing the diagnosis of low-grade tumors. Several approaches have been explored to improve the accuracy of image-guided targeted prostate biopsy, including in-bore MRI-guided, cognitive fusion, and MRI/transrectal ultrasound fusion-guided biopsy. This review will examine recent advances in these image-guided targeted prostate biopsy techniques.
August 2015Correlation of Gleason Scores with Magnetic Resonance Diffusion Tensor Imaging in Peripheral Zone Prostate Cancer.
BACKGROUND: To investigate tumor aggressiveness in peripheral zone prostate cancer (PCa) by correlating Gleason score (GS) with diffusion tensor imaging (DTI) from multiparametric magnetic resonance imaging (MRI) at 3.0 Tesla (T). METHODS: Eighty-three patients with pathological proven peripheral zone PCa whose GS in at least one core biopsy met the criteria(GS ≤ 3+3, GS 3+4, GS 4+3, or GS ≥ 4+4) were included in this study. DTI was performed using b values of 0 and 800 s/mm(2) with 32 directions in all patients on a 3.0T MRI scanner. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were calculated from the DTI data of patients with the previously mentioned four categories of Gleason scores. An association between DTI measurements(FA, ADC) and GS was tested using the Spearman rank correlation analysis.
July 2015Preoperative mp-MRI of the Prostate Provides Little Information About Staging of Prostate Carcinoma in Daily Clinical Practice.
PURPOSE: To evaluate the staging accuracy of preoperative multiparametric MRI (mp-MRI), its influence on the technique of radical retropubic prostatectomy (RRP), and its value for daily clinical practice. METHODS: A total of 106 patients underwent RRP (January 2011-June 2012) and had preoperative MRI staging data available for review. Staging results acquired by mp-MRI were correlated to both biopsy and histopathology results. Surgical reports were reviewed for intraoperative aspect of tumor extension, technique of RRP (nerve sparing or extended), and extent of lymphadenectomy.
July 2015Characteristics of Detected and Missed Prostate Cancer Foci on 3-T Multiparametric MRI Using an Endorectal Coil Correlated With Whole-Mount Thin-Section Histopathology.
OBJECTIVE: The objective of this study was to determine the characteristics of prostate cancer foci missed on 3-T multiparametric MRI performed with an endorectal coil. MATERIALS AND METHODS: The MRI examinations of 122 patients who underwent 3-T multiparametric MRI of the prostate with an endorectal coil were compared with whole-mount histopathology obtained after radical prostatectomy. The mean age of the patients was 60.6 years (SD, 7.6 years), and the mean prostate-specific antigen value was 7.2 ng/mL (SD, 5.9 ng/mL). The clinical, multiparametric MRI (i.e., T2-weighted imaging, diffusion-weighted imaging, and dynamic contrast-enhanced imaging), and histopathologic features were obtained. After an independent review, two blinded genitourinary radiologists matched each case with a genitourinary pathologist. A structured reporting system was used to classify the multiparametric MRI features of each MRI-detected lesion. A chi-square analysis was performed for categoric variables, and the t test was performed for continuous variables.
March 2015Multifocality and Prostate Cancer Detection by Multiparametric Magnetic Resonance Imaging: Correlation with Whole-mount Histopathology.
BACKGROUND: Multiparametric magnetic resonance imaging (mp-MRI) is increasingly used in prostate cancer (CaP). Understanding the limitations of tumor detection, particularly in multifocal disease, is important in its clinical application. OBJECTIVE: To determine predictors of CaP detection by mp-MRI as confirmed by whole-mount histopathology. DESIGN, SETTING, AND PARTICIPANTS: A retrospective study was performed of 122 consecutive men who underwent mp-MRI before radical prostatectomy at a single referral academic center. A genitourinary radiologist and pathologist collectively determined concordance. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The odds of tumor detection were calculated for clinical, MRI, and histopathologic variables using a multivariate logistic regression model.
March 2015Novel Technique for Characterizing Prostate Cancer Utilizing MRI Restriction Spectrum Imaging: Proof of Principle and Initial Clinical Experience with Extraprostatic Extension.
Background:Standard magnetic resonance imaging (MRI) of the prostate lacks sensitivity in the diagnosis and staging of prostate cancer (PCa). To improve the operating characteristics of prostate MRI in the detection and characterization of PCa, we developed a novel, enhanced MRI diffusion technique using restriction spectrum imaging (RSI-MRI).Methods:We compared the efficacy of our novel RSI-MRI technique with standard MRI for detecting extraprostatic extension (EPE) among 28 PCa patients who underwent MRI and RSI-MRI prior to radical prostatectomy, 10 with histologically proven pT3 disease. RSI cellularity maps isolating the restricted isotropic water fraction were reconstructed based on all b-values and then standardized across the sample with z-score maps. Distortion correction of the RSI maps was performed using the alternating phase-encode technique.
November 2014Magnetic Resonance Imaging-Ultrasound Fusion Biopsy for Prediction of Final Prostate Pathology.
PURPOSE: We explore the impact of magnetic resonance imaging-ultrasound fusion prostate biopsy on the prediction of final surgical pathology. MATERIALS AND METHODS: A total of 54 consecutive men undergoing radical prostatectomy at UCLA after fusion biopsy were included in this prospective, institutional review board approved pilot study. Using magnetic resonance imaging-ultrasound fusion, tissue was obtained from a 12-point systematic grid (mapping biopsy) and from regions of interest detected by multiparametric magnetic resonance imaging (targeted biopsy). A single radiologist read all magnetic resonance imaging, and a single pathologist independently rereviewed all biopsy and whole mount pathology, blinded to prior interpretation and matched specimen. Gleason score concordance between biopsy and prostatectomy was the primary end point.
October 2014Correlation of Quantitative Diffusion-Weighted and Dynamic Contrast-enhanced MRI Parameters with Prognostic Factors in Prostate Cancer.
INTRODUCTION: The aim of this study was to determine if correlations exist between quantitative parameters from dynamic contrast-enhanced (DCE) and diffusion-weighted (DW) MRI with National Comprehensive Cancer Network (NCCN) risk group, Gleason score (GS), maximum tumour diameter (MTD), pre-treatment prostate-specific antigen (PSA), clinical T stage and MRI prostate volume in prostate cancer. METHOD: We retrospectively reviewed 3T multiparametric MRI reports on biopsy-proven prostate cancer patients performed during radiation treatment evaluation or an active surveillance protocol. DCE-MRI parameters included K(trans) (influx volume transfer coefficient), Kep (efflux reflux rate constant) and iAUC (initial area under the curve). Average DCE and apparent diffusion coefficient (ADC) values were recorded for regions of interest on DW-MRI. Relationships between MRI metrics and risk group, GS, MTD, PSA, clinical T stage and MRI prostate volume were examined using analysis of variance. Central and peripheral tumours were also analysed separately in a sub-analysis. Statistical significance was defined as P < 0.0125.
October 2014Initial Experience with Electronic Tracking of Specific Tumor Sites in Men Undergoing Active Surveillance of Prostate Cancer.
OBJECTIVES: Targeted biopsy, using magnetic resonance (MR)-ultrasound (US) fusion, may allow tracking of specific cancer sites in the prostate. We aimed to evaluate the initial use of the technique to follow tumor sites in men on active surveillance of prostate cancer. METHODS AND MATERIALS: A total of 53 men with prostate cancer (all T1c category) underwent rebiopsy of 74 positive biopsy sites, which were tracked and targeted using the Artemis MR-US fusion device (Eigen, Grass Valley, CA) from March 2010 through January 2013. The initial biopsy included 12 cores from a standard template (mapped by software) and directed biopsies from regions of interest seen on MR imaging (MRI). In the repeat biopsy, samples were taken from sites containing cancer at the initial biopsy. Outcomes of interest at second MR-US biopsy included (a) presence of any cancer and (b) presence of clinically significant cancer.
August 2014Targeted Prostate Biopsy in Select Men for Active Surveillance-do the Epstein Criteria Still Apply?
PURPOSE: Established in 1994, the Epstein histological criteria (Gleason score 6 or less, 2 or fewer cores positive and 50% or less of any core) have been widely used to select men for active surveillance. However, with the advent of targeted biopsy, which may be more accurate than conventional biopsy, we reevaluated the likelihood of reclassification upon confirmatory rebiopsy using multiparametric magnetic resonance imaging-ultrasound fusion. MATERIALS AND METHODS: We identified 113 men enrolled in active surveillance at our institution who met Epstein criteria and subsequently underwent confirmatory targeted biopsy via multiparametric magnetic resonance imaging-ultrasound fusion. Median patient age was 64 years, median prostate specific antigen was 4.2 ng/ml and median prostate volume was 46.8 cc. Targets or regions of interest on multiparametric magnetic resonance imaging-ultrasound fusion were graded by suspicion level and biopsied at 3 mm intervals along the longest axis (median 10.5 mm). Also, 12 systematic cores were obtained during confirmatory rebiopsy. Our reporting is consistent with START (Standards of Reporting for MRI-targeted Biopsy Studies) criteria.
August 2014Target Detection: Magnetic Resonance Imaging-ultrasound Fusion-guided Prostate Biopsy.
Recent advances in multiparametric magnetic resonance imaging (MRI) have enabled image-guided detection of prostate cancer. Fusion of MRI with real-time ultrasound (US) allows the information from MRI to be used to direct biopsy needles under US guidance in an office-based procedure. Fusion can be performed either cognitively or electronically, using a fusion device. Fusion devices allow superimposition (coregistration) of stored MRI images on real-time US images; areas of suspicion found on MRI can then serve as targets during US-guided biopsy. Currently available fusion devices use a variety of technologies to perform coregistration: robotic tracking via a mechanical arm with built-in encoders (Artemis/Eigen, BioJet/Geoscan); electromagnetic tracking (UroNav/Philips-Invivo, Hi-RVS/Hitachi); or tracking with a 3D US probe (Urostation/Koelis). Targeted fusion biopsy has been shown to identify more clinically significant cancers and fewer insignificant cancers than conventional biopsy. Fusion biopsy appears to be a major advancement over conventional biopsy because it allows (1) direct targeting of suspicious areas not seen on US and (2) follow-up biopsy of specific cancerous sites in men undergoing active surveillance.
May 2014Multiparametric MRI Identifies and Stratifies Prostate Cancer Lesions: Implications for Targeting Intraprostatic Targets.
PURPOSE: To assess the ability of multiparametric (mp) MRI (mp-MRI) to identify, stratify, and localize biopsy-proven prostate cancer lesions in a risk-stratified patient population. METHODS AND MATERIALS: We retrospectively analyzed 57 patients who had mp-MRI and core needle biopsy during diagnostic prostate cancer evaluation. The MRI sequences were scored for suspicion of cancer with a previously described system. Distributions of mp-MRI scores were compared across National Comprehensive Cancer Network prostate cancer risk groups. The mp-MRI-identified lesions were compared with the location of positive core needle biopsies to assess mp-MRI localization of true lesions.
April 2014Value of Targeted Prostate Biopsy Using Magnetic Resonance-Ultrasound Fusion in Men with Prior Negative Biopsy and Elevated Prostate-specific Antigen.
BACKGROUND: Conventional biopsy fails to detect the presence of some prostate cancers (PCas). Men with a prior negative biopsy but persistently elevated prostate-specific antigen (PSA) pose a diagnostic dilemma, as some harbor elusive cancer. OBJECTIVE: To determine whether use of magnetic resonance-ultrasound (MR-US) fusion biopsy results in improved detection of PCa compared to repeat conventional biopsy. DESIGN, SETTING, AND PARTICIPANTS: In a consecutive-case series, 105 subjects with prior negative biopsy and elevated PSA values underwent multiparametric magnetic resonance imaging (MRI) and fusion biopsy in an outpatient setting. INTERVENTION: Suspicious areas on multiparametric MRI were delineated and graded by a radiologist; MR-US fusion biopsy was performed by a urologist using the Artemis device; targeted and systematic biopsies were obtained regardless of MRI result. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Detection rates of all PCa and clinically significant PCa (Gleason ≥3+4 or Gleason 6 with maximal cancer core length ≥4 mm) were determined. The yield of targeted biopsy was compared to systematic biopsy. The ability of an MRI grading system to predict clinically significant cancer was investigated. Stepwise multivariate logistic regression analysis was performed to determine predictors of significant cancer on biopsy.
February 2014The Role of Magnetic Resonance Imaging in Delineating Clinically Significant Prostate Cancer.
OBJECTIVE: To determine whether multiparametric magnetic resonance imaging might improve the identification of patients with higher risk disease at diagnosis and thereby reduce the incidence of undergrading or understaging. METHODS: We retrospectively reviewed the clinical records of 115 patients who underwent multiparametric magnetic resonance imaging before radical prostatectomy. We used Epstein's criteria of insignificant disease with and without a magnetic resonance imaging (MRI) parameter (apparent diffusion coefficient) to calculate sensitivity, specificity, as well as negative and positive predictive values [NPV and PPV] across varying definitions of clinically significant cancer based on Gleason grade and tumor volume (0.2 mL, 0.5 mL, and 1.3 mL) on whole-mount prostate specimens. Logistic regression analysis was performed to determine the incremental benefit of MRI in delineating significant cancer.
January 2014Multidimensional MR Spectroscopic Imaging of Prostate Cancer in vivo.
Prostate cancer (PCa) is the second most common type of cancer among men in the United States. A major limitation in the management of PCa is an inability to distinguish, early on, cancers that will progress and become life threatening. One-dimensional (1D) proton ((1) H) MRS of the prostate provides metabolic information such as levels of choline (Ch), creatine (Cr), citrate (Cit), and spermine (Spm) that can be used to detect and diagnose PCa. Ex vivo high-resolution magic angle spinning (HR-MAS) of PCa specimens has revealed detection of more metabolites such as myo-inositol (mI), glutamate (Glu), and glutamine (Gln). Due to the J-modulation and signal overlap, it is difficult to quantitate Spm and other resonances in the prostate clearly by single- and multivoxel-based 1D MR spectroscopy. This limitation can be minimized by adding at least one more spectral dimension by which resonances can be spread apart, thereby increasing the spectral dispersion. However, recording of multivoxel-based two-dimensional (2D) MRS such as J-resolved spectroscopy (JPRESS) and correlated spectroscopy (L-COSY) combined with 2D or three-dimensional (3D) magnetic resonance spectroscopic imaging (MRSI) using conventional phase-encoding can be prohibitively long to be included in a clinical protocol. To reduce the long acquisition time required for spatial encoding, the echo-planar spectroscopic imaging (EPSI) technique has been combined with correlated spectroscopy to give four-dimensional (4D) echo-planar correlated spectroscopic imaging (EP-COSI) as well as J-resolved spectroscopic imaging (EP-JRESI) and the multi-echo (ME) variants. Further acceleration can be achieved using non-uniform undersampling (NUS) and reconstruction using compressed sensing (CS). Earlier versions of 2D MRS, theory of 2D MRS, spectral apodization filters, newer developments and the potential role of multidimensional MRS in PCa detection and management will be reviewed here.
October 2013Standards of Reporting for MRI-targeted Biopsy Studies (START) of the Prostate: Recommendations from an International Working Group.
BACKGROUND: A systematic literature review of magnetic resonance imaging (MRI)-targeted prostate biopsy demonstrates poor adherence to the Standards for the Reporting of Diagnostic Accuracy (STARD) recommendations for the full and transparent reporting of diagnostic studies. OBJECTIVE: To define and recommend Standards of Reporting for MRI-targeted Biopsy Studies (START). DESIGN, SETTING, AND PARTICIPANTS: Each member of a panel of 23 experts in urology, radiology, histopathology, and methodology used the RAND/UCLA appropriateness methodology to score a 258-statement premeeting questionnaire. The collated responses were presented at a face-to-face meeting, and each statement was rescored after group discussion. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Measures of agreement and consensus were calculated for each statement. The most important statements, based on group median score, the degree of group consensus, and the content of the group discussion, were used to create a checklist of reporting criteria (the START checklist).
August 2013Fine-Tuning Robot-Assisted Radical Prostatectomy Planning with MRI.
OBJECTIVES: Robot-assisted radical prostatectomy (RARP) has now become the most common surgical treatment option for prostate cancer (CaP). Clinicopathologic data (i.e., biopsy, digital rectal exam, prostate specific antigen level) and patient-specific factors (e.g., age, erectile function, co-morbidities) are the primary sources of information that urologists use for counseling and treatment decision making. Magnetic resonance imaging (MRI) has evolved along a similar temporal arc to RARP, with increased utilization and precision over the past decade. MRI prior to RARP provides multifaceted adjunctive information, including enhancement of locoregional staging, delineation of spatial anatomic information, and identification of aberrant anatomy, all of which aid in patient treatment counseling and operative planning. This article is designed for urologic surgeons who perform RARP, with the aim of providing a review of prostate MRI imaging and highlighting findings which may specifically alter the operation.
April 2013Correlation of Quantitative Diffusion-Weighted and Dynamic Contrast-Enhanced MRI Parameters With NCCN Risk Group, Gleason Score, and Maximum Tumor Diameter in Prostate Cancer.
To determine if there is a correlation between quantitative parameters from diffusion-weighted (DWI) and dynamic contrast-enhanced (DCE) MRI with NCCN risk group, Gleason score (GS), and maximum tumor diameter (MTD) in prostate cancer.
September 2012MR Spectroscopic Imaging and Diffusion-Weighted Imaging of Prostate Cancer with Gleason Acores.
PURPOSE: To investigate functional changes in prostate cancer patients with three pathologically proven different Gleason scores (GS) (3+3, 3+4, and 4+3) using magnetic resonance spectroscopic imaging (MRSI) and diffusion-weighted imaging (DWI). MATERIALS AND METHODS: In this study MRSI and DWI data were acquired in 41 prostate cancer patients using a 1.5T MRI scanner with a body matrix combined with an endorectal coil. The metabolite ratios of (Cho+Cr)/Cit were calculated from the peak integrals of total choline (Cho), creatine (Cr), and citrate (Cit) in MRSI. Apparent diffusion coefficient (ADC) values were derived from DWI for three groups of Gleason scores. The sensitivity and specificity of MRSI and DWI in patients were calculated using receiver operating characteristic curve (ROC) analysis.
August 2012Radical Prostatectomy: Value of Prostate MRI in Surgical Planning
The introduction of serum prostate-specific antigen to the prostate cancer screening algorithm has led to an increase in prostate cancer diagnosis as well as a migration toward lower-stage cancer at the time of diagnosis. This stage migration has coincided with changes in treatment options; these include active surveillance, new therapies, and advances in surgical techniques. Use of robot-assisted radical prostatectomy (RARP) as a surgical technique has seen a significant increase over the past several years: the number of patients undergoing RARP has risen from 1% to 40% of all prostatectomies from 20012006 to as many as 80% in 2010. The robotic interface provides a 3D magnified view of the surgical field, intuitive instrument manipulation, motion scaling, tremor filtration, and excellent dexterity and range of motion. However, in some cases, the lack of tactile (haptic) feedback may limit the surgeon's decision making ability in assessing malignant involvement of the neurovascular bundles. Pre-operative planning relies on nomograms based on limited clinical and prostate biopsy information. The surgical decision to spare or resect the neurovascular bundles is based on clinical information which is not spatially or anatomically based. Advances in magnetic resonance imaging (MRI) may provide spatially localized information to fill this void and aid surgical planning, particularly for robotic surgeons. In this review, we discuss the potential role of pre-operative MRI in surgical planning for radical prostatectomy.
July 2012Diffusion Tensor Magnetic Resonance Tractography of the Prostate: Feasibility for Mapping Periprostatic Fibers.
OBJECTIVE: To evaluate the feasibility of diffusion tensor imaging (DTI) tractography of the prostate for mapping of periprostatic neurovascular anatomy. METHODS: Eight men with prostate cancer scheduled to undergo nerve-sparing robot-assisted radical prostatectomy (RARP) underwent endorectal multiparametric magnetic resonance imaging (MRI) of the prostate with DTI. Tract mapping was accomplished by positioning spherical regions of interest contiguously along the prostatic capsule at the prostatic apex, midgland, and base.
June 2012Application of Compressed Sensing to Multidimensional Spectroscopic Imaging in Human Prostate.
The application of compressed sensing is demonstrated in a recently implemented four-dimensional echo-planar based J-resolved spectroscopic imaging sequence combining two spatial and two spectral dimensions. The echo-planar readout simultaneously acquires one spectral and one spatial dimension. Therefore, the compressed sensing undersampling is performed along the indirectly acquired spatial and spectral dimensions, and the reconstruction is performed using the split Bregman algorithm, an efficient TV-minimization solver. The four-dimensional echo-planar-based J-resolved spectroscopic imaging data acquired in a prostate phantom containing metabolites at physiological concentrations are accurately reconstructed with as little as 20% of the original data. Experimental data acquired in six healthy prostates using the external body matrix "receive" coil on a 3T magnetic resonance imaging scanner are reconstructed with acquisitions using only 25% of the Nyquist-Shannon required amount of data, indicating the potential for a 4-fold acceleration factor in vivo, bringing the required scan time for multidimensional magnetic resonance spectroscopic imaging within clinical feasibility.
March 2012Use of MR Imaging to Determine Preservation of the Neurovascular Bundles at Robotic-assisted Laparoscopic Prostatectomy.
PURPOSE: To determine whether findings at preoperative endorectal coil magnetic resonance (MR) imaging influence the decision to preserve neurovascular bundles and the extent of surgical margins in robotic-assisted laparoscopic prostatectomy (RALP). MATERIALS AND METHODS: This study was approved by the investigational review board and was compliant with the HIPAA; the requirement to obtain informed consent was waived. The authors prospectively evaluated 104 consecutive men with biopsy-proved prostate cancer who underwent preoperative endorectal coil MR imaging of the prostate and subsequent RALP. MR imaging was performed at 1.5 T between January 2004 and April 2008 and included T2-weighted imaging (n = 104), diffusion-weighted imaging (n = 88), dynamic contrast-enhanced imaging (n = 51), and MR spectroscopy (n = 91). One surgeon determined the planned preoperative extent of resection bilaterally on the basis of clinical information and then again after review of the final MR imaging report. The differences in the surgical plan before and after review of the MR imaging report were determined and compared with the actual surgical and pathologic results by using logistic regression analysis. Continuous and ranked variables underwent Pearson and Spearman analysis.
2012Correlation of Gleason Scores with Diffusion-Weighted Imaging Findings of Prostate Cancer.
The purpose of our study was to compare the apparent diffusion coefficient (ADC) derived from diffusion-weighted imaging (DWI) of prostate cancer (PCa) patients with three classes of pathological Gleason scores (GS). Patients whose GS met these criteria (GS 3 + 3, GS 3 + 4, and GS 4 + 3) were included in this study. The DWI was performed using b values of 0, 50, and 400s/mm(2) in 44 patients using an endorectal coil on a 1.5T MRI scanner. The apparent diffusion coefficient (ADC) values were calculated from the DWI data of patients with three different Gleason scores. In patients with a high-grade Gleason score (4 + 3), the ADC values were lower in the peripheral gland tissue, pathologically determined as tumor compared to low grade (3 + 3 and 3 + 4). The mean and standard deviation of the ADC values for patients with GS 3 + 3, GS 3 + 4, and GS 4 + 3 were 1.135 0.119, 0.976 0.103 and 0.831 0.087mm(2)/sec. The ADC values were statistically significant (P < 0.05) between the three different scores with a trend of decreasing ADC values with increasing Gleason scores by one-way ANOVA method. This study shows that the DWI-derived ADC values may help differentiate aggressive from low-grade PCa.
May-June 2011Clinical Application of a 3D Ultrasound-Guided Prostate Biopsy System.
OBJECTIVES: Prostate biopsy (Bx) has for 3 decades been performed in a systematic, but blind fashion using 2D ultrasound (US). Herein is described the initial clinical evaluation of a 3D Bx tracking and targeting device (Artemis; Eigen, Grass Valley, CA). Our main objective was to test accuracy of the new 3D method in men undergoing first and follow-up Bx to rule out prostate cancer (CaP). MATERIALS ANDd METHODS: Patients in the study were men ages 3587 years (66.1 9.9), scheduled for Bx to rule out CaP, who entered into an IRB-approved protocol. A total of 218 subjects underwent conventional trans-rectal US (TRUS); the tracking system was then attached to the US probe; the prostate was scanned and a 3D reconstruction was created. All Bx sites were visualized in 3D and tracked electronically. In 11 men, a pilot study was conducted to test ability of the device to return a Bx to an original site. In 47 men, multi-parametric 3 Tesla MRI, incorporating T2-weighted images, dynamic contrast enhancement, and diffusion-weighted imaging, was performed in advance of the TRUS, allowing the stored MRI images to be fused with real-time US during biopsy. Lesions on MRI were delineated by a radiologist, assigned a grade of CaP suspicion, and fused into TRUS for biopsy targeting.
April 2010Correlation of Endorectal 2D JPRESS Findings with Pathological Gleason Scores in Prostate Cancer Patients.
To determine the metabolite ratios of (Cho + Cr)/Cit and (Cho + Cr)/Spm in patients with two ranges of pathological Gleason scores, namely (3 + 4) and (4 + 3). By using the localized two-dimensional (2D) J-resolved spectroscopy (JPRESS) technique, the metabolites ratios can be calculated and correlated with prostate cancer aggressiveness. A total of 24 patients who underwent endorectal 2D JPRESS between April 2006 and July 2007 were included in this study. The 2D JPRESS voxel was localized predominantly in the peripheral zone suspected for malignancy based on pathology. Using the metabolites such as total choline (Cho), creatine (Cr), spermine (Spm) and citrate (Cit), the ratios (Cho + Cr)/Cit and (Cho + Cr)/Spm were calculated. In 14 prostate cancer patients who had a final pathologic Gleason scores of i) (3 + 4 = 7, n = 7) and ii) (4 + 3 = 7, n = 7), the metabolite ratios (mean +/- SD) of (Cho + Cr)/Cit and (Cho + Cr)/Spm were calculated using the 2D JPRESS spectra as follows: i) (1.48 +/- 0.83) and (1.59 +/- 0.73); ii) (2.90 +/- 0.94) and (2.71 +/- 1.47), respectively. Higher percentage of aggressive disease correlates with higher metabolites ratio. Our pilot study suggests that 2D JPRESS can be reliably evaluated in a clinical setting using an endorectal coil. In addition to the citrate ratio, the spermine ratio also correlates with pathology based Gleason score.
November 2008Two-Dimensional MR Spectroscopy of Healthy and Cancerous Prostates in vivo.
OBJECTIVES: A major goal of this article is to summarize the current status of evaluating prostate metabolites non-invasively using spatially resolved two-dimensional (2D) MR Spectroscopy (MRS). MATERIALS AND METHODS: Due to various technical challenges, the spatially resolved versions of 2D MRS techniques are currently going through the developmental stage. During the last decade, four different versions of 2D MRS sequences have been successfully implemented on 3T and 1.5T MRI scanners manufactured by three different vendors. These sequences include half and maximum echo sampled J-resolved spectroscopy (JPRESS), S-PRESS and L-COSY, which are single volume localizing sequences, and the multi-voxel based JPRESS sequence.
November 2007Molecular Imaging Techniques in Body Imaging.
Molecular imaging of the body involves new techniques to image cellular biochemical processes, which results in studies with high sensitivity, specificity, and signal-to-background. The most prevalently used molecular imaging technique in body imaging is currently fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET). FDG PET has become the method of choice for the staging and restaging of many of the most common cancers, including lymphoma, lung cancer, breast cancer, and colorectal cancer. FDG PET has also become extremely valuable in monitoring the response to therapeutic drugs in many cancers. New PET agents, such as fluorothymidine and acetate, have also shown promise in the evaluation of response to therapy and in the staging of prostate cancer. Magnetic resonance (MR) spectroscopy has shown promise in the evaluation of prostate cancer. Breast cancer evaluation benefits from advances in spectroscopic imaging and contrast-enhanced kinetic evaluation of vascular permeability, which is altered in neoplastic processes because of release of angiogenic factors. Superparamagnetic iron oxide (SPIO) particles represent the first of an expanding line of MR contrast agents that target specific cellular processes. SPIO particles have also been used in the evaluation of the cirrhotic liver and at MR lymphangiography.
May 2005In vivo Prostate Magnetic Resonance Spectroscopic Imaging Using Two-Dimensional J-Resolved PRESS at 3 T.
In vivo magnetic resonance spectroscopic imaging of the prostate using single-voxel and multivoxel two-dimensional (2D) J-resolved sequences is investigated at a main magnetic field strength of 3 T. Citrate, an important metabolite often used to aid the detection of prostate cancer in magnetic resonance spectroscopic exams, can be reliably detected along with the other metabolites using this method. We show simulations and measurements of the citrate metabolite using 2D J-resolved spectroscopy to characterize the spectral pattern. Furthermore, using spiral readout gradients, the single-voxel 2D J-resolved method is extended to provide the spatial distribution information as well all within a reasonable scan time (17 min). Phantom and in vivo data are presented to illustrate the multivoxel 2D J-resolved spiral chemical shift imaging sequence.
September 2004In vivo Diffusion Tensor Imaging of the Human Prostate.
This study demonstrates the feasibility of in vivo prostate diffusion tensor imaging (DTI) in human subjects. We implemented an EPI-based diffusion-weighted (DW) sequence with seven-direction diffusion gradient sensitization, and acquired DT images from six subjects using cardiac gating with a phased-array prostate surface coil operating in a linear mode. We calculated two indices to quantify diffusion anisotropy. The direction of the eigenvector corresponding to the leading eigenvalue was displayed by means of a color-coding scheme. The average diffusion values of the prostate peripheral zone (PZ) and central gland (CG) were 1.95 +/- 0.08 x 10(-3) mm2 s and 1.53 +/- 0.34 x 10(-3) mm2 s, respectively. The average fractional anisotropy (FA) values for the PZ and CG were 0.46 +/- 0.04 and 0.40 +/- 0.08, respectively. The diffusion ellipsoid in prostate tissue was anisotropic and approximated a prolate model, as shown in the color maps of the anisotropy. Consistent with the tissue architecture, the prostate fiber orientations were predominantly in the superior-inferior (SI) direction for both the PZ and CG. This study shows the feasibility of in vivo DTI and establishes normative DT values for six subjects.