Purpose To test the impact of existing Prostate Imaging Reporting and Data System (PI-RADS) version 2 (V2) decision rules, as well as of proposed adjustments to these decision rules, on detection of ...Gleason score (GS) 7 or greater (GS ≥7) prostate cancer. Materials and Methods Two radiologists independently provided PI-RADS V2 scores for the dominant lesion on 343 prostate magnetic resonance (MR) examinations. Diagnostic performance for GS ≥7 tumor was assessed by using MR imaging-ultrasonography fusion-targeted biopsy as the reference. The impact of existing PI-RADS V2 decision rules, as well as a series of exploratory proposed adjustments, on the frequency of GS ≥7 tumor detection, was evaluated. Results A total of 210 lesions were benign, 43 were GS 6, and 90 were GS ≥7. Lesions were GS ≥7 in 0%-4.1% of PI-RADS categories 1 and 2, 11.4%-27.1% of PI-RADS category 3, 44.4%-49.3% of PI-RADS category 4, and 72.1%-73.7% of PI-RADS category 5 lesions. PI-RADS category 4 or greater had sensitivity of 78.9%-87.8% and specificity of 75.5%-79.1 for detecting GS ≥7 tumor. The frequency of GS ≥7 tumor for existing PI-RADS V2 decision rules was 30.0%-33.3% in peripheral zone (PZ) lesions upgraded from category 3 to 4 based on dynamic contrast enhancement (DCE) score of positive; 50.0%-66.7% in transition zone (TZ) lesions upgraded from category 3 to 4 based on diffusion-weighted imaging (DWI) score of 5; and 71.7%-72.7% of lesions in both zones upgraded from category 4 to 5 based on size of 15 mm or greater. The frequency of GS ≥7 tumor for proposed adjustments to the decision rules was 30.0%-60.0% for TZ lesions upgraded from category 3 to 4 based on DWI score of 4; 33.3%-57.1% for TZ lesions upgraded from category 3 to 4 based on DCE score of positive when incorporating new criteria (unencapsulated sheetlike enhancement) for DCE score of positive in TZ; and 56.4%-61.9% for lesions in both zones upgraded from category 4 to 5 based on size of 10-14 mm. Other proposed adjustments yielded GS ≥7 tumor in less than 15% of cases for one or more readers. Conclusion Existing PI-RADS V2 decision rules exhibited reasonable performance in detecting GS ≥7 tumor. Several proposed adjustments to the criteria (in TZ, upgrading category 3 to 4 based on DWI score of 4 or modified DCE score of positive; in PZ or TZ, upgrading category 4 to 5 based on size of 10-14 mm) may also have value for this purpose.
RSNA, 2016 Online supplemental material is available for this article.
Abstract Background Increasing evidence supports the use of magnetic resonance (MR)–targeted prostate biopsy. The optimal method for such biopsy remains undefined, however. Objective To prospectively ...compare targeted biopsy outcomes between MR imaging (MRI)–ultrasound fusion and visual targeting. Design, setting, and participants From June 2012 to March 2013, prospective targeted biopsy was performed in 125 consecutive men with suspicious regions identified on prebiopsy 3-T MRI consisting of T2-weighted, diffusion-weighted, and dynamic-contrast enhanced sequences. Intervention Two MRI–ultrasound fusion targeted cores per target were performed by one operator using the ei-Nav|Artemis system. Targets were then blinded, and a second operator took two visually targeted cores and a 12-core biopsy. Outcome measurements and statistical analysis Biopsy information yield was compared between targeting techniques and to 12-core biopsy. Results were analyzed using the McNemar test. Multivariate analysis was performed using binomial logistic regression. Results and limitations Among 172 targets, fusion biopsy detected 55 (32.0%) cancers and 35 (20.3%) Gleason sum ≥7 cancers compared with 46 (26.7%) and 26 (15.1%), respectively, using visual targeting ( p = 0.1374, p = 0.0523). Fusion biopsy provided informative nonbenign histology in 77 targets compared with 60 by visual ( p = 0.0104). Targeted biopsy detected 75.0% of all clinically significant cancers and 86.4% of Gleason sum ≥7 cancers detected on standard biopsy. On multivariate analysis, fusion performed best among smaller targets. The study is limited by lack of comparison with whole-gland specimens and sample size. Furthermore, cancer detection on visual targeting is likely higher than in community settings, where experience with this technique may be limited. Conclusions Fusion biopsy was more often histologically informative than visual targeting but did not increase cancer detection. A trend toward increased detection with fusion biopsy was observed across all study subsets, suggesting a need for a larger study size. Fusion targeting improved accuracy for smaller lesions. Its use may reduce the learning curve necessary for visual targeting and improve community adoption of MR-targeted biopsy.
To compare the recently proposed Prostate Imaging Reporting and Data System (PI-RADS) scale that incorporates fixed criteria and a standard Likert scale based on overall impression in prostate cancer ...localization using multiparametric magnetic resonance (MR) imaging.
This retrospective study was HIPAA compliant and institutional review board approved. Seventy patients who underwent 3-T pelvic MR imaging, including T2-weighted imaging, diffusion-weighted imaging, and dynamic contrast material-enhanced imaging, with a pelvic phased-array coil before radical prostatectomy were included. Three radiologists, each with 6 years of experience, independently scored 18 regions (12 peripheral zone PZ, six transition zone TZ) using PI-RADS (range, scores 3-15) and Likert (range, scores 1-5) scales. Logistic regression for correlated data was used to compare scales for detection of tumors larger than 3 mm in maximal diameter at prostatectomy.
Maximal accuracy was achieved with score thresholds of 8 and higher and of 3 and higher for PI-RADS and Likert scales, respectively. At these thresholds, in the PZ, similar accuracy was achieved with the PI-RADS scale and the Likert scale for radiologist 1 (89.0% vs 88.2%, P = .223) and radiologist 3 (88.5% vs 88.2%, P = .739) and greater accuracy was achieved with the PI-RADS scale than the Likert scale for radiologist 2 (89.6% vs 87.1%, P = .008). In the TZ, accuracy was lower with the PI-RADS scale than with the Likert scale for radiologist 1 (70.0% vs 87.1%, P < .001), radiologist 2 (87.6% vs 92.6%, P = .002), and radiologist 3 (82.9% vs 91.2%, P < .001). For tumors with Gleason score of at least 7, sensitivity was higher with the PI-RADS scale than with the Likert scale for radiologist 1 (88.6% vs 82.6%, P = .032), and sensitivity was similar for radiologist 2 (78.0% vs 76.5, P = .467) and radiologist 3 (77.3% vs 81.1%, P = .125).
Radiologists performed well with both PI-RADS and Likert scales for tumor localization, although, in the TZ, performance was better with the Likert scale than the PI-RADS scale.
http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13122233/-/DC1.
Purpose To compare standard diffusion-weighted (DW) imaging and diffusion kurtosis (DK) imaging for prostate cancer (PC) detection and characterization in a large patient cohort, with attention to ...the potential added value of DK imaging. Materials and Methods This retrospective institutional review board-approved study received a waiver of informed consent. Two hundred eighty-five patients with PC underwent 3.0-T phased-array coil prostate magnetic resonance (MR) imaging, including a DK imaging sequence (b values 0, 500, 1000, 1500, and 2000 sec/mm
) before prostatectomy. Maps of apparent diffusion coefficient (ADC) and diffusional kurtosis (K) were derived by using maximal b values of 1000 and 2000 sec/mm
, respectively. Mean ADC and K were obtained from volumes of interest (VOIs) placed on each patient's dominant tumor and benign prostate tissue. Metrics were compared between benign and malignant tissue, between Gleason score (GS) ≤ 3 + 3 and GS ≥ 3 + 4 tumors, and between GS ≤ 3 + 4 and GS ≥ 4 + 3 tumors by using paired t tests, analysis of variance, receiver operating characteristic (ROC) analysis, and exact tests. Results ADC and K showed significant differences for benign versus tumor tissues, GS ≤ 3 + 3 versus GS ≥ 3 + 4 tumors, and GS ≤ 3 + 4 versus GS ≥ 4 + 3 tumors (P < .001 for all). ADC and K were highly correlated (r = -0.82; P < .001). Area under the ROC curve was significantly higher (P = .002) for ADC (0.921) than for K (0.902) for benign versus malignant tissue but was similar for GS ≤ 3 + 3 versus GS ≥ 3 + 4 tumors (0.715-0.744) and GS ≤ 3 + 4 versus GS ≥ 4 + 3 tumors (0.694-0.720) (P > .15). ADC and K were concordant for these various outcomes in 80.0%-88.6% of patients; among patients with discordant results, ADC showed better performance than K for GS ≤ 3 + 4 versus GS ≥ 4 + 3 tumors (P = .016) and was similar to K for other outcomes (P > .136). Conclusion ADC and K were highly correlated, had similar diagnostic performance, and were concordant for the various outcomes in the large majority of cases. These observations did not show a clear added value of DK imaging compared with standard DW imaging for clinical PC evaluation.
RSNA, 2017 Online supplemental material is available for this article.
Purpose We compared prostate tumor boundaries on magnetic resonance imaging and radical prostatectomy histological assessment using detailed software assisted co-registration to define an optimal ...treatment margin for achieving complete tumor destruction during image guided focal ablation. Materials and Methods Included in study were 33 patients who underwent 3 Tesla magnetic resonance imaging before radical prostatectomy. A radiologist traced lesion borders on magnetic resonance imaging and assigned a suspicion score of 2 to 5. Three-dimensional reconstructions were created from high resolution digitalized slides of radical prostatectomy specimens and co-registered to imaging using advanced software. Tumors were compared between histology and imaging by the Hausdorff distance and stratified by the magnetic resonance imaging suspicion score, Gleason score and lesion diameter. Cylindrical volume estimates of treatment effects were used to define the optimal treatment margin. Results Three-dimensional software based registration with magnetic resonance imaging was done in 46 histologically confirmed cancers. Imaging underestimated tumor size with a maximal discrepancy between imaging and histological boundaries for a given tumor of an average ± SD of 1.99 ± 3.1 mm, representing 18.5% of the diameter on imaging. Boundary underestimation was larger for lesions with an imaging suspicion score 4 or greater (mean 3.49 ± 2.1 mm, p <0.001) and a Gleason score of 7 or greater (mean 2.48 ± 2.8 mm, p = 0.035). A simulated cylindrical treatment volume based on the imaging boundary missed an average 14.8% of tumor volume compared to that based on the histological boundary. A simulated treatment volume based on a 9 mm treatment margin achieved complete histological tumor destruction in 100% of patients. Conclusions Magnetic resonance imaging underestimates histologically determined tumor boundaries, especially for lesions with a high imaging suspicion score and a high Gleason score. A 9 mm treatment margin around a lesion visible on magnetic resonance imaging would consistently ensure treatment of the entire histological tumor volume during focal ablative therapy.
While magnetic resonance imaging-ultrasound fusion targeted biopsy allows for improved detection of clinically significant prostate cancer, a concerning amount of clinically significant disease is ...still missed. We hypothesized that a number of these misses are due to the learning curve associated with magnetic resonance imaging-ultrasound fusion targeted biopsy. We report the results of repeat magnetic resonance imaging-ultrasound fusion targeted biopsy in men with continued suspicion for cancer and the institutional learning curve in the detection of clinically significant prostate cancer with time.
We analyzed the records of 1,813 prostate biopsies in a prospectively acquired cohort of men who presented for prostate biopsy in a 4-year period. All men were offered prebiopsy magnetic resonance imaging and were assigned a maximum PI-RADS™ (Prostate Imaging Reporting and Data System version 2) score. Biopsy outcomes in men with a suspicious region of interest were compared. The relationship between time and clinically significant prostate cancer detection was analyzed.
The clinically significant prostate cancer detection rate increased 26% with time in men with a PI-RADS 4/5 region of interest. On repeat magnetic resonance imaging-ultrasound fusion targeted biopsy in men with continued suspicion for cancer 53% of those with a PI-RADS 4/5 region of interest demonstrated clinically significant discordance from the initial magnetic resonance imaging-ultrasound fusion targeted biopsy compared to only 23% with a PI-RADS 1/2 region of interest. Significantly less clinically significant prostate cancer was missed or under graded in the most recent biopsies compared to the earliest biopsies.
The high upgrade rate on repeat magnetic resonance imaging-ultrasound fusion targeted biopsy and the increasing cancer detection rate with time show the significant learning curve associated with magnetic resonance imaging-ultrasound fusion targeted biopsy. Men with low risk or negative biopsies with a persistent, concerning region of interest should be promptly rebiopsied. Improved targeting accuracy with operator experience can help decrease the number of missed cases of clinically significant prostate cancer.
The purpose of this study is to evaluate the roles of self-directed learning and continual feedback in the learning curve for tumor detection by novice readers of prostate MRI.
A total of 124 ...prostate MRI examinations classified as positive (n = 52; single Prostate Imaging Reporting and Data System PI-RADS category 3 or higher lesion showing Gleason score ≥ 7 tumor at MRI-targeted biopsy) or negative (n = 72; PI-RADS category 2 or lower and negative biopsy) for detectable tumor were included. These were divided into four equal-sized batches, each with matching numbers of positive and negative examinations. Six second-year radiology residents reviewed examinations to localize tumors. Three of the six readers received feedback after each examination showing the preceding case's solution. The learning curve, plotting accuracy over time, was assessed by the Akaike information criterion (AIC). Logistic regression and mixed-model ANOVA were performed.
For readers with and without feedback, the learning curve exhibited an initial rapid improvement that slowed after 40 examinations (change in AIC > 0.2%). Accuracy improved from 58.1% (batch 1) to 71.0-75.3% (batches 2-4) without feedback and from 58.1% to 72.0-77.4% with feedback (p = 0.027-0.046), without a difference in the extent of improvement (p = 0.800). Specificity improved from 53.7% to 68.5-81.5% without feedback and from 55.6% to 74.1-81.5% with feedback (p = 0.006-0.010), without a difference in the extent of improvement (p = 0.891). Sensitivity improved from 59.0-61.5% (batches 1-2) to 71.8-76.9% (batches 3-4) with feedback (p = 0.052), though did not improve without feedback (p = 0.602). Sensitivity for transition zone tumors exhibited larger changes (p = 0.024) with feedback than without feedback. Sensitivity for peripheral zone tumors did not improve in either group (p > 0.3). Reader confidence increased only with feedback (p < 0.001).
The learning curve in prostate tumor detection largely reflected self-directed learning. Continual feedback had a lesser effect. Clinical prostate MRI interpretation by novice radiologists warrants caution.
Purpose Optimization of prostate biopsy requires addressing the shortcomings of standard systematic transrectal ultrasound guided biopsy, including false-negative rates, incorrect risk ...stratification, detection of clinically insignificant disease and the need for repeat biopsy. Magnetic resonance imaging is an evolving noninvasive imaging modality that increases the accurate localization of prostate cancer at the time of biopsy, and thereby enhances clinical risk assessment and improves the ability to appropriately counsel patients regarding therapy. In this review we 1) summarize the various sequences that comprise a prostate multiparametric magnetic resonance imaging examination along with its performance characteristics in cancer detection, localization and reporting standards; 2) evaluate potential applications of magnetic resonance imaging targeting in prostate biopsy among men with no previous biopsy, a negative previous biopsy and those with low stage cancer; and 3) describe the techniques of magnetic resonance imaging targeted biopsy and comparative study outcomes. Materials and Methods A bibliographic search covering the period up to October 2013 was conducted using MEDLINE®/PubMed®. Articles were reviewed and categorized based on which of the 3 objectives of this review was addressed. Data were extracted, analyzed and summarized. Results Multiparametric magnetic resonance imaging consists of anatomical T2-weighted imaging coupled with at least 2 functional imaging techniques. It has demonstrated improved prostate cancer detection sensitivity up to 80% in the peripheral zone and 81% in the transition zone. A prostate cancer magnetic resonance imaging suspicion score has been developed, and is depicted using the Likert or PI-RADS (Prostate Imaging Reporting and Data System) scale for better standardization of magnetic resonance imaging interpretation and reporting. Among men with no previous biopsy, magnetic resonance imaging increases the frequency of significant cancer detection to 50% in low risk and 71% in high risk patients. In low risk men the negative predictive value of a combination of negative magnetic resonance imaging with prostate volume parameters is nearly 98%, suggesting a potential role in avoiding biopsy and reducing over detection/overtreatment. Among men with a previous negative biopsy 72% to 87% of cancers detected by magnetic resonance imaging guidance are clinically significant. Among men with a known low risk cancer, repeat biopsy using magnetic resonance targeting demonstrates a high likelihood of confirming low risk disease in low suspicion score lesions and of upgrading in high suspicion score lesions. Techniques of magnetic resonance imaging targeted biopsy include visual estimation transrectal ultrasound guided biopsy; software co-registered magnetic resonance imaging-ultrasound, transrectal ultrasound guided biopsy; and in-bore magnetic resonance imaging guided biopsy. Although the improvement in accuracy and efficiency of visual estimation biopsy compared to systematic appears limited, co-registered magnetic resonance imaging-ultrasound biopsy as well as in-bore magnetic resonance imaging guided biopsy appear to increase cancer detection rates in conjunction with increasing suspicion score. Conclusions Use of magnetic resonance imaging for targeting prostate biopsies has the potential to reduce the sampling error associated with conventional biopsy by providing better disease localization and sampling. More accurate risk stratification through improved cancer sampling may impact therapeutic decision making. Optimal clinical application of magnetic resonance imaging targeted biopsy remains under investigation.
Abstract 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). Results and limitations The strongest recommendations were to report histologic results of standard and targeted cores separately using Gleason score and maximum cancer core length. A table comparing detection rates of clinically significant and clinically insignificant disease by targeted and standard approaches should also be used. It was recommended to report the recruitment criteria for MRI-targeted biopsy, prior biopsy status of the population, a brief description of the MRI sequences, MRI reporting method, radiologist experience, and image registration technique. There was uncertainty about which histologic criteria constitute clinically significant cancer when the prostate is sampled using MRI-targeted biopsy, and it was agreed that a new definition of clinical significance in this setting needed to be derived in future studies. Conclusions Use of the START checklist would improve the quality of reporting in MRI-targeted biopsy studies and facilitate a comparison between standard and MRI-targeted approaches.
Time-Dependent Diffusion in Prostate Cancer Lemberskiy, Gregory; Rosenkrantz, Andrew B; Veraart, Jelle ...
Investigative radiology,
07/2017, Letnik:
52, Številka:
7
Journal Article
Recenzirano
Prior studies in prostate diffusion-weighted magnetic resonance imaging (MRI) have largely explored the impact of b-value and diffusion directions on estimated diffusion coefficient D. Here we ...suggest varying diffusion time, t, to study time-dependent D(t) in prostate cancer, thereby adding an extra dimension in the development of prostate cancer biomarkers.
Thirty-eight patients with peripheral zone prostate cancer underwent 3-T MRI using an external-array coil and a diffusion-weighted image sequence acquired for b = 0, as well as along 12 noncollinear gradient directions for b = 500 s/mm using stimulated echo acquisition mode (STEAM) diffusion tensor imaging (DTI). For this sequence, 6 diffusion times ranging from 20.8 to 350 milliseconds were acquired. Tumors were classified as low-grade (Gleason score GS 3 + 3; n = 11), intermediate-grade (GS 3 + 4; n = 16), and high-grade (GS ≥4 + 3; n = 11). Benign peripheral zone and transition zone were also studied.
Apparent diffusion coefficient (ADC) D(t) decreased with increasing t in all zones of the prostate, though the rate of decay in D(t) was different between sampled zones. Analysis of variance and area under the curve analyses suggested better differentiation of tumor grades at shorter t. Fractional anisotropy (FA) increased with t for all regions of interest. On average, highest FA was observed within GS 3 + 3 tumors.
There is a measurable time dependence of ADC in prostate cancer, which is dependent on the underlying tissue and Gleason score. Therefore, there may be an optimal selection of t for prediction of tumor grade using ADC. Controlling t should allow ADC to achieve greater reproducibility between different sites and vendors. Intentionally varying t enables targeted exploration of D(t), a previously overlooked biophysical phenomenon in the prostate. Its further microstructural understanding and modeling may lead to novel diffusion-derived biomarkers.
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