Contrast Media-driven Anthropogenic Gadolinium: Knowns and Unknowns.

Gadolinium-based contrast agents (GBCAs) have augmented the capabilities of MRI, which has led to their widespread and increasing use in radiology practice. GBCAs are introduced into the environment through disposal of unused product and elimination after intravenous injection, both primarily via liquid dispersion into the environment. This human introduction of gadolinium into the environment, referred to as anthropogenic gadolinium, is associated with the detection of gadolinium in water systems, raising concerns for potential adverse impact and prompting certain mitigation actions. This article summarizes the existing knowledge and problem scope, conveys the relevant underlying chemical principles of chelate dissociation, and offers an inferred perspective that the magnitude of the problem is most unlikely to cause human harm. The merits and limitations regarding possible mitigation tactics, such as collecting urine after GBCA administration, use of lower-dose high-relaxivity macrocyclic GBCAs, and the option for virtual contrast-enhanced examinations, will be discussed. Finally, the potential for monitoring gadolinium uptake in bone will be presented, and recommendations for future research will be offered. © RSNA, 2024 See also the article by Ibrahim et al in this issue. See also the article by McKee et al in this issue.

Direct MRI-guided In-Bore Targeted Biopsy of the Prostate: A Step-by-Step How To and Lessons Learned.

Multiparametric MRI-the most accurate imaging technique for detection of prostate cancer-has transformed the landscape of prostate cancer diagnosis by enabling targeted biopsies. In a targeted biopsy, tissue samples are obtained from suspicious regions identified at prebiopsy diagnostic MRI. The authors briefly compare the different strategies available for targeting an MRI-visible suspicious lesion, followed by a step-by-step description of the direct MRI-guided in-bore approach and an illustrated review of its application in challenging clinical scenarios. In this technique, direct visualization of the needle, needle guide, and needle trajectory during the procedure provides a precise and versatile strategy to accurately sample suspicious lesions, improving detection of clinically significant cancers. Published under a CC BY 4.0 license Test Your Knowledge questions for this article are available in the supplemental material.

Preoperative Multiparametric Prostate Magnetic Resonance Imaging Structured Report Informs Risk for Positive Apical Surgical Margins During Radical Prostatectomy.

BACKGROUND: The prostatic apex is the most frequent location of positive surgical margin (PSM) after surgery. Data regarding the ability of multiparametric magnetic resonance imaging (mpMRI) to prospectively identify men at risk for apical PSMs (aPSMs) using a structured report are lacking. OBJECTIVES: The aims of the study are to determine and to compare the rate of aPSM in men with versus without prospectively flagged at-risk prostate lesions during clinical mpMRI interpretation using whole-mount histopathology as the reference standard. METHODS: This single-center, retrospective study of prospectively collected data included treatment-naive men with abnormal 3T mpMRI (PI-RADS v2 score ≥3) between January 2016 and December 2018 followed by surgery. During routine clinical interpretation, radiologists flagged prostate lesions abutting the apical most gland and/or encircling the distal most prostatic urethra using standardized language available as a "pick list" option in the structured report. Logistic regression was used to compare the rate of PSM in 2 groups (flagged vs nonflagged men). Propensity score covariate adjustment corrected for potential selection bias according to age, prostate-specific antigen (PSA), PSA density, grade group, and pT stage. The estimate was further adjusted by including surgeon as a covariate. RESULTS: A total of 428 men were included. A statistically significant higher proportion of aPSMs was noted in flagged (56% [51/91]) compared with nonflagged apical lesions (31% [105/337]; adjusted odds ratio, 2.5; 95% confidence interval, 1.6-4.1; P < 0.01). The difference in aPSM between both groups also varied according to the surgeon performing the RP. Prostate-specific antigen, PSA density, lesion size, apical location, Prostate Imaging Reporting & Data System score, grade group, pT stage, and surgeon's experience were associated with higher PSM rate. Biochemical recurrence, defined as PSA greater than 0.2 ng/mL on 2 measurements after RP, was significantly associated with PSM status (propensity score adjusted odds ratio, 3.1; 95% confidence interval, 1.8-5.3; P < 0.0001); however, patients flagged by radiologists did not have a significant difference in biochemical recurrence rates as compared with nonflagged patients ( P = 0.11). CONCLUSIONS: Standard language built into structured reports for mpMRI of the prostate helps identify preoperatively patients at risk for aPSM. CLINICAL IMPACT: Multiparametric MRI is able to identify patients at increased risk for aPSM, and this information can be conveyed in a structured report to urologists, facilitating patient counseling and treatment decisions.

What the Baby Formula and Medical Contrast Material Shortages Have in Common: Insights and Recommendations for Managing the Iodinated Contrast Media Shortage.

The impact of supply chain and supply chain logistics, including personnel directly and indirectly related to the movement of supplies, has come to light in a variety of industries since the global COVID-19 pandemic. Acutely, the experience with baby formula and iodinated contrast material exposes key vulnerabilities to supply chains. The rather sudden diminished availability of iodinated contrast material has forced health care systems to engage in more judicious use of product through catalyzing the adoption of behaviors that had been recommended and deemed reasonable prior to the shortage. The authors describe efforts at a large, academic safety net county health system to conserve iodinated contrast media by optimizing contrast media use in the CT department and changing ordering patterns of referring providers. Special attention is given to opportunities to conserve contrast material in cardiothoracic imaging, including low kV and dual-energy CT techniques. A values-based leadership philosophy and collaboration with key stakeholders facilitate effective response to the critical shortage and rapid deployment of iodinated contrast media conservation strategies. Last, while the single-supplier model is efficient and cost-effective, its application to critically necessary services such as health care must be questioned considering disruptions related to the COVID-19 pandemic. Keywords: CT, Intravenous Contrast Agents, CT-Spectral Imaging (Dual Energy) ©RSNA, 2022.

Magnetic Resonance Imaging Detection of Glucose-Stimulated Zinc Secretion in the Enlarged Dog Prostate as a Potential Method for Differentiating Prostate Cancer From Benign Prostatic Hyperplasia.

OBJECTIVES: In the United States, prostate cancer (PCa) is the most common cancer in men. Multi-parametric magnetic resonance imaging (MRI) is increasingly being relied upon for the diagnosis and characterization of PCa, but differentiating malignancy from benign prostatic hyperplasia (BPH) in the transition zone using MRI can be challenging. The characteristically high levels of zinc in human prostate tissue and a close relationship between malignant proliferation and zinc homeostatic dysregulation create opportunities to visualize PCa with novel contrast media. In mouse models, glucose-stimulated zinc secretion (GSZS) can be preferentially observed in healthy prostate tissue compared with malignant tissue; in vivo, these differences can be captured with MRI by using Gdl1, a gadolinium-based zinc-responsive contrast agent. In this study, we examined whether this technology can be applied in a large animal model by imaging older dogs with clinically diagnosed BPH. MATERIALS AND METHODS: Four intact male dogs 6 years or older with enlarged prostates were imaged (T1-weighted turbo spin-echo, TE/TR, 12/400 milliseconds and T2-weighted, TE/TR, 112/5000 milliseconds) using a 3 T scanner before and at multiple time points after intravenous injection of 0.05 mmol/kg GdL1 plus either (a) 2 mL/kg of 50% dextrose in 1 session or (b) 2 mL/kg normal saline in another session. The two sessions were one week apart, and their order was randomly determined for each dog. During postprocessing, regions of interest were generated in prostate tissue and in paraspinal muscles to evaluate the contrast-to-noise ratio (CNR). The ratio of CNR at any postinjection time point compared with baseline CNR was defined as r-CNR. After the second imaging session, the dogs were euthanized, and their prostates were harvested for histopathological examination. Baseline and postintervention plasma and urine samples were analyzed for total zinc by inductively coupled plasma mass spectrometry. RESULTS: The mean ± SD r-CNR values at 13 minutes postinjection in the dextrose versus saline imaging sessions were 134% ± 10% and 127% ± 7%, respectively (P < 0.01). The histopathologic evaluation of prostate tissues confirmed BPH in all dogs. Interestingly, prostatic intraepithelial neoplasia was detected in 1 animal, and a suspicious mass was found in the same region on T2-weighted scans. The r-CNR of the mass was calculated as 113% ± 4% and 111% ± 6% in the dextrose and saline groups, respectively, with no significant differences between the 2 interventions (P = 0.54), whereas there was a statistically significant difference between the r-CNR of the whole prostate in the dextrose (130% ±11%) and saline (125% ± 9%) interventions (P = 0.03). Inductively coupled plasma mass spectrometry analyses showed a significantly higher urinary zinc in the dextrose versus saline groups, but no differences were found in plasma zinc levels. CONCLUSIONS: T1-weighted MRI of the enlarged canine prostate showed higher r-CNR after injection of GdL1 plus dextrose compared with GdL1 plus saline, consistent with GSZS from BPH tissues. One small region of neoplastic tissue was identified in a single dog on the basis of less GSZS from that region by MRI. These findings suggest a new method for the detection of PCa by MRI that could facilitate the differentiation of BPH from PCa in the transition zone.

Gleason Grade Group Concordance between Preoperative Targeted Biopsy and Radical Prostatectomy Histopathologic Analysis: A Comparison Between In-Bore MRI-guided and MRI-Transrectal US Fusion Prostate Biopsies.

Purpose: To determine and compare rates of grade group (GG) discrepancies between different targeted biopsy techniques (in-bore vs fusion) after propensity score weighting using whole-mount radical prostatectomy (RP) histopathologic analysis as the reference standard. Materials and Methods: This retrospective study evaluated men who underwent targeted (fusion or in-bore) biopsy between April 2017 and January 2019 followed by prostatectomy. The primary endpoint of the study was a change in GG from biopsy to RP at a patient level. For downgrade and upgrade analysis, men with biopsy GG1 (downgrade not possible) and GG5 (upgrade not possible) were excluded, respectively. GG upgrade, downgrade, and concordance rates of each targeting approach were compared using propensity score weighting and logistic regression with inverse probability of treatment weighting. Significance level was set at .05. Index lesion GG on RP specimen served as the reference standard. Results: A total of 191 men (90 in the in-bore [mean age, 63 years ± 7 (standard deviation)] and 101 in the fusion biopsy group [mean age, 65 years ± 7]) were eligible and included. Fewer GG upgrades were noted in the in-bore biopsy group (14%; 12 of 85) compared with the fusion plus systematic biopsy group (30%; 28 of 93) (P = .012). The incidence of GG downgrade in the in-bore group (25%; 21 of 84) was higher than in the fusion group (17%; 16 of 93); however, the difference was not statistically significant (P = .2). Of the 77 men misclassified by both biopsy techniques, the majority (56%, n = 43) had a change in GG of 2 to 3 or 3 to 2. Conclusion: Superior sampling accuracy with MRI-guided in-bore biopsies offers a lower incidence of GG upgrades compared with MRI-transrectal US fusion biopsies upon RP.Keywords: Biopsy/Needle Aspiration, MR-Imaging, Oncology, Pathology, Prostate Supplemental material is available for this article.© RSNA, 2021.

Single-shot RARE with Dixon: Application to robust abdominal imaging with uniform fat and water separation at 3T.

PURPOSE: To develop a true single shot turbo spin echo (SShTSE) acquisition with Dixon for robust T2 -weighted abdominal imaging with uniform fat and water separation at 3T. METHODS: The in-phase (IP) and out-of-phase (OP) echoes for Dixon processing were acquired in the same repetition time of a SShTSE using partial echoes. A phase-preserved bi-directional homodyne reconstruction was developed to compensate the partial echo and the partial phase encoding of SShTSE. With IRB approval, the SShTSE-Dixon was compared against standard SShTSE, without and with fat suppression using spectral adiabatic inversion recovery (SPAIR) in 5 healthy volunteers and 5 patients. The SNR and contrast ratio (CR) of spleen to liver were compared among different acquisitions. RESULTS: The bi-directional homodyne reconstruction successfully minimized ringing artifacts because of partial acquisitions. SShTSE-Dixon achieved uniform fat suppression compared to SShTSE-SPAIR with fat suppression failures of 1/10 versus 10/10 in the axial plane and 0/5 versus 5/5 in the coronal plane, respectively. The SNRs of the liver (12.2 ± 4.9 vs. 11.7 ± 5.2; P = .76) and spleen (25.9 ± 11.6 vs. 23.7 ± 9.7; P = .14) were equivalent between fat-suppressed images (SShTSE-Dixon water-only and SShTSE-SPAIR). The SNRs of liver (14.4 ± 5.7 vs. 13.4 ± 5.0; P = .60) and spleen (26.5 ± 10.1 vs. 25.7 ± 8.5; P = .56) were equivalent between non-fat-suppressed images (SShTSE-Dixon IP and SShTSE). The CRs of spleen to liver were also similar between fat-suppressed images (2.6 ± 0.4 vs. 2.5 ± 0.5; P =.92) and non-fat-suppressed images (2.3 ± 0.6 vs. 2.2 ± 0.4; P =.84). CONCLUSION: SShTSE-Dixon generates robust abdominal T2 -weighted images at 3T with and without uniform fat suppression, along with perfectly co-registered fat-only images in a single acquisition.

Prospective PI-RADS v2.1 Atypical Benign Prostatic Hyperplasia Nodules With Marked Restricted Diffusion: Detection of Clinically Significant Prostate Cancer on Multiparametric MRI.

BACKGROUND. On the basis of expert consensus, PI-RADS version 2.1 (v2.1) introduced the transition zone (TZ) atypical benign prostatic hyperplasia (BPH) nodule, defined as a TZ lesion with an incomplete or absent capsule (T2 score, 2). PI-RADS v2.1 also included a revised scoring pathway whereby such nodules, if exhibiting marked restricted diffusion (DWI score, 4-5), are upgraded from overall PI-RADS category 2 to category 3 (2 + 1 TZ lesions). OBJECTIVE. The purpose of this study was to compare the rates of detection of clinically significant prostate cancer (csPCa) in prospectively reported 2 + 1 TZ lesions, as defined by PI-RADS v2.1, and conventional 3 + 0 TZ lesions with targeted biopsy as the reference standard. METHODS. This retrospective study included men with no known PCa or with treatment-naïve grade group (GG) 1 PCa who underwent 3-T multiparametric MRI of the prostate with prospective reporting by means of PI-RADS v2.1. Patients with at least one PI-RADS category 3 TZ lesion who underwent targeted biopsy formed the final sample. Biopsy results were summarized descriptively for 2 + 1 and 3 + 0 lesions. Generalized estimating equations were used to compare csPCa detection rates between groups. Associations between csPCa in 2 + 1 lesions and patient age, PSA level, prostate volume, PSA density, biopsy history, lesion size, and lesion ADC were tested with Kruskal-Wallis and Fisher exact tests. RESULTS. Among 1238 eligible patients who underwent MRI reported with PI-RADS v2.1, 2 + 1 lesions were reported in 6% (n = 69) and 3 + 0 TZ lesions in 7% (n = 87) of patients. No PCa, GG1 PCa, or csPCa was found in 84% (n = 41), 10% (n = 5), and 6% (n = 3) of 49 patients with 2 + 1 lesions who underwent targeted biopsy. Nor were they found in 74% (n = 45), 15% (n = 9), and 11% (n = 7) of 61 patients with 3 + 0 lesions who underwent targeted biopsy. The csPCa detection rate was not significantly different between 2 + 1 and 3 + 0 lesions (p = .31). All cases of csPCa were GG2, except for one 3 + 0 lesion with a GG3 tumor. No clinical or imaging variable was associated with csPCa in 2 + 1 lesions. CONCLUSION. The rate of csPCa in atypical BPH nodules with marked restricted diffusion was low (6%) and not significantly different from that of conventional 3 + 0 TZ lesions (11%). CLINICAL IMPACT. The results provide prospective clinical data about the revised TZ scoring criterion and pathway in PI-RADS v2.1 for atypical BPH nodules with marked restricted diffusion.

Impact of the Number of Cores on the Prostate Cancer Detection Rate in Men Undergoing in-Bore Magnetic Resonance Imaging-Guided Targeted Biopsies.

OBJECTIVE: To determine the incremental detection rate of clinically significant prostate cancer (csPCa) provided by sequential cores during in-bore magnetic resonance imaging (MRI)-guided prostate biopsies. METHODS: Single-center, retrospective interpretation of prospectively acquired data in men without previous diagnosis of csPCa who underwent in-bore MRI-guided prostate biopsy between May 2017 and December 2019. Endpoints included detection of csPCa (grade group [GG] ≥ 2) and rate of GG upgrade provided by additional cores. Descriptive statistics presented as mean and standard deviation for the continuous variables, and frequency and percentage for the categorical variables. RESULTS: Four hundred and forty-three men with 747 lesions met eligibility criteria. Clinically significant prostate cancer was detected in 43.1% (322/747) of the biopsied lesions and GG 2 PCa or greater was identified by the first core in 78.3% (252/322) of them. On a per-core basis, cores 2, 3, 4, and 5 found new csPCa in 6% (42/744), 4% (26/719), 1% (2/137), and 0% (0/11) of the cases. Core biopsy 2, 3, 4, and 5 resulted in GG upgrade in 12% (91/744), 7% (49/719), 7% (9/137), and 0% (0/11) of the lesions, respectively. Each additional core was associated with a mean increase of 5 minutes in the duration of the biopsy. CONCLUSIONS: In men undergoing in-bore MRI-guided prostate biopsies, 3 targeted cores per lesion provide an optimal trade-off between detection of clinically significant tumors and biopsy duration.

Preparing and Promoting Women for Leadership Positions in Radiology and the Imaging Industry.

A dearth of women leaders in the field of radiology and affiliated industries persists despite a recognition of the importance, value, and impact that would derive from its rectification. A targeted educational collaboration, described herein, was established between academia and industry to address this deficit and to facilitate the placement of highly qualified women into leadership positions. The actionable platform offered has the potential to narrow the gap for underrepresented groups in professional leadership positions.

Response to COVID-19: Minimizing Risks, Addressing Challenges and Maintaining Operations in a Complex Academic Radiology Department.

The coronavirus disease 2019 (COVID-19) pandemic has necessitated rapid response plans to minimize risks of infection in the workforce while ensuring maintenance of essential functions of radiology departments. Plan adoption is, however, challenged by the need to coordinate with institutional efforts, a rapidly expanding number of patients, and the diversity of clinical and administrative functions in the department. Here, we describe the implementation of a response plan in an academic radiology department, challenges encountered, and tactics used to address these challenges.

Comparing radiomic classifiers and classifier ensembles for detection of peripheral zone prostate tumors on T2-weighted MRI: a multi-site study.

BACKGROUND: For most computer-aided diagnosis (CAD) problems involving prostate cancer detection via medical imaging data, the choice of classifier has been largely ad hoc, or been motivated by classifier comparison studies that have involved large synthetic datasets. More significantly, it is currently unknown how classifier choices and trends generalize across multiple institutions, due to heterogeneous acquisition and intensity characteristics (especially when considering MR imaging data). In this work, we empirically evaluate and compare a number of different classifiers and classifier ensembles in a multi-site setting, for voxel-wise detection of prostate cancer (PCa) using radiomic texture features derived from high-resolution in vivo T2-weighted (T2w) MRI. METHODS: Twelve different supervised classifier schemes: Quadratic Discriminant Analysis (QDA), Support Vector Machines (SVMs), naïve Bayes, Decision Trees (DTs), and their ensemble variants (bagging, boosting), were compared in terms of classification accuracy as well as execution time. Our study utilized 85 prostate cancer T2w MRI datasets acquired from across 3 different institutions (1 for discovery, 2 for independent validation), from patients who later underwent radical prostatectomy. Surrogate ground truth for disease extent on MRI was established by expert annotation of pre-operative MRI through spatial correlation with corresponding ex vivo whole-mount histology sections. Classifier accuracy in detecting PCa extent on MRI on a per-voxel basis was evaluated via area under the ROC curve. RESULTS: The boosted DT classifier yielded the highest cross-validated AUC (= 0.744) for detecting PCa in the discovery cohort. However, in independent validation, the boosted QDA classifier was identified as the most accurate and robust for voxel-wise detection of PCa extent (AUCs of 0.735, 0.683, 0.768 across the 3 sites). The next most accurate and robust classifier was the single QDA classifier, which also enjoyed the advantage of significantly lower computation times compared to any of the other methods. CONCLUSIONS: Our results therefore suggest that simpler classifiers (such as QDA and its ensemble variants) may be more robust, accurate, and efficient for prostate cancer CAD problems, especially in the context of multi-site validation.

Diagnostic Utility of a Likert Scale Versus Qualitative Descriptors and Length of Capsular Contact for Determining Extraprostatic Tumor Extension at Multiparametric Prostate MRI.

OBJECTIVE: The purpose of this study is to determine the reproducibility and diagnostic performance of a Likert scale in comparison with the European Society of Urogenital Radiology (ESUR) criteria and tumor-pseudocapsule contact length (TCL) for the detection of extraprostatic extension (EPE) at multiparametric MRI. MATERIALS AND METHODS: This was a retrospective review of all men who underwent multiparametric MRI followed by prostatectomy between November 2015 and July 2016. Multiparametric 3-T MRI studies with an endorectal coil were independently reviewed by five readers who assigned the likelihood of EPE using a 1-5 Likert score, ESUR criteria, and TCL (> 10 mm). EPE outcome (absent or present) for the index lesion at whole-mount histopathologic analysis was the standard of reference. Odds ratios (ORs) and areas under the ROC curve (Az) were used for diagnostic accuracy. The interreader agreement was determined using a weighted kappa coefficient. A p < 0.05 was considered significant. RESULTS: Eighty men met the eligibility criteria. At univariate analysis, the Likert score showed the strongest association (OR, 1.8) with EPE, followed by prostate-specific antigen level (OR, 1.7), ESUR score (OR, 1.6), and index lesion size (OR, 1.2). At multivariable analysis, higher Likert score (OR, 1.8) and prostate-specific antigen level (OR, 1.6-1.7) were independent predictors of EPE. The Az value for Likert scores was statistically significantly higher (0.79) than that for TCL (0.74; p < 0.01), but not statistically significantly higher than the value for ESUR scores (0.77; p = 0.17). Interreader agreement with Likert (κ = 0.52) and ESUR scores (κ = 0.55) was moderate and slightly superior to that for TCL (κ = 0.43). Except for TCL among inexperienced readers (κ = 0.34), reader experience did not affect interreader agreement. CONCLUSION: A Likert score conveying the degree of suspicion at multiparametric MRI is a stronger predictor of EPE than is either ESUR score or TCL and may facilitate informed decision making, patient counseling, and treatment planning.

Whole-body MRI for metastatic cancer detection using T2 -weighted imaging with fat and fluid suppression.

PURPOSE: To develop a whole-body MRI technique at 3T with improved lesion conspicuity for metastatic cancer detection using fast, high-resolution and high SNR T2 -weighted (T2 W) imaging with simultaneous fat and fluid suppression. THEORY AND METHODS: The proposed dual-echo T2 -weighted acquisition for enhanced conspicuity of tumors (DETECT) acquires 4 images, in-phase (IP) and out-of-phase (OP) at a short and a long TE using single-shot turbo spin echo. The IP/OP images at the short and long TEs are reconstructed using the standard Dixon and shared-field-map Dixon reconstruction respectively, for robust fat-water separation. An adaptive complex subtraction between the 2 TE water-only images achieves fluid attenuation. DETECT imaging was optimized and evaluated in whole-body imaging of 5 healthy volunteers, and compared against diffusion-weighted imaging with background suppression (DWIBS) in 5 patients with known metastatic renal cell carcinoma. RESULTS: Robust fat-water separation and fluid attenuation were achieved using the shared-field-map Dixon reconstruction and adaptive complex subtraction, respectively. DETECT imaging technique generated co-registered T2 W images with and without fat suppression, heavily T2 W, and fat and fluid suppressed T2 W whole-body images in <7 min. Compared to DWIBS acquired in 17 min, the DETECT imaging achieved better detection and localization of lesions in patients with metastatic cancer. CONCLUSION: DETECT imaging technique generates T2 W images with high resolution, high SNR, minimal geometric distortions, and provides good lesion conspicuity with robust fat and fluid suppression in <7 min for whole-body imaging, demonstrating efficient and reliable metastatic cancer detection at 3T.

Improved Magnetic Resonance Imaging-Pathology Correlation With Imaging-Derived, 3D-Printed, Patient-Specific Whole-Mount Molds of the Prostate.

OBJECTIVES: The aim of this study was to compare the anatomical registration of preoperative magnetic resonance imaging (MRI) and prostate whole-mount obtained with 3D-printed, patient-specific, MRI-derived molds (PSM) versus conventional whole-mount sectioning (WMS). MATERIALS AND METHODS: Based on an a priori power analysis, this institutional review board-approved study prospectively included 50 consecutive men who underwent 3 T multiparametric prostate MRI followed by radical prostatectomy. Two blinded and independent readers (R1 and R2) outlined the contours of the prostate, tumor, peripheral, and transition zones in the MRI scans using regions of interest. These were compared with the corresponding regions of interest from the whole-mounted histopathology, the reference standard, using PSM whole-mount results obtained in the study group (n = 25) or conventional WMS in the control group (n = 25). The spatial overlap across the MRI and histology data sets was calculated using the Dice similarity coefficient (DSC) for the prostate overall (DSCprostate), tumor (DSCtumor), peripheral (DSCPZ), and transition (DSCTZ) zone. Results in the study and control groups were compared using Wilcoxon rank sum test. RESULTS: The MRI histopathology anatomical registration for the prostate gland overall, tumor, peripheral, and transition zones were significantly superior with the use of PSMs (DSCs for R1: 0.95, 0.86, 0.84, and 0.89; for R2: 0.93, 0.75, 0.78, and 0.85, respectively) than with the use of standard WMS (R1: 0.85, 0.46, 0.66, and 0.69; R2: 0.85, 0.46, 0.66, and 0.69) (P < 0.0001). CONCLUSIONS: The use of PSMs for prostate specimen whole-mount sectioning provides significantly superior anatomical registration of in vivo multiparametric MRI and ex vivo prostate whole-mounts than conventional WMS.

An initial negative round of targeted biopsies in men with highly suspicious multiparametric magnetic resonance findings does not exclude clinically significant prostate cancer-Preliminary experience.

BACKGROUND: Targeted prostate biopsies are changing the landscape of prostate cancer (PCa) diagnosis with the degree of suspicion on multiparametric magnetic resonance imaging (mpMRI) being a strong predictor of targeted biopsy outcome. Data regarding the rate and potential causes of false-negative magnetic resonance imaging-transrectal ultrasound (MRI-TRUS) fusion-targeted biopsy in patients with highly suspicious mpMRI findings are lacking. OBJECTIVES: To determine the rate of clinically significant PCa detection in repeat targeted biopsy or surgery in patients with highly suspicious mpMRI findings and in an initial negative MRI-TRUS fusion-targeted biopsy. MATERIALS AND METHODS: In this single-center, retrospective study of prospectively generated data, men with highly suspicious lesions (Likert 5 score) on mpMRI and an initial negative MRI-TRUS fusion-targeted biopsy were reviewed. The rate of PCa detection in a subsequent MRI-TRUS fusion-targeted biopsy or radical prostatectomy was determined. Tumors in the intermediate- and high-risk groups according to the National Comprehensive Cancer Network criteria were considered clinically significant. RESULTS: A total of 32 men with 38 Likert 5 lesions were identified. Repeat targeted biopsy or surgery detected cancer in 42% (16/38) of the Likert 5 lesions with initial negative targeted biopsy. Most of these cancers were intermediate- (69%; 11/16) or high-risk (25%; 4/16) tumors. CONCLUSION: A negative round of targeted biopsies does not exclude clinically significant PCa in men with highly suspicious mpMRI findings. Patients with imaging-pathology disagreement should be carefully reviewed and considered for repeat biopsy or for strict surveillance.

White Paper of the Society of Computed Body Tomography and Magnetic Resonance on Dual-Energy CT, Part 4: Abdominal and Pelvic Applications.

This is the fourth of a series of 4 white papers that represent expert consensus documents developed by the Society of Computed Body Tomography and Magnetic Resonance through its task force on dual-energy computed tomography. This article, part 4, discusses DECT for abdominal and pelvic applications and, at the end of each, will offer our consensus opinions on the current clinical utility of the application and opportunities for further research.

Quantitative diffusion-weighted imaging and dynamic contrast-enhanced characterization of the index lesion with multiparametric MRI in prostate cancer patients.

PURPOSE: To compare a simplified intravoxel incoherent motion (sIVIM) model to commonly used monoexponential and biexponential models in the characterization of prostate cancer (PCa) and noncancerous prostate tissues, and to investigate combinations of diffusion-weighted imaging (DWI) measures with dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI)-derived parameters in MRI-visible index lesions, to facilitate PCa risk stratification. MATERIALS AND METHODS: In this retrospective, Institutional Review Board (IRB)-approved study, 43 consecutive patients with PCa who had 3T MRI exams followed by radical prostatectomy were included. DWI and DCE parameters were measured from one index lesion per patient, and noncancerous central gland and peripheral zone. Logistic regression modeling was performed to select the optimal combination of DWI and DCE measurements for tumor risk assessment. RESULTS: All diffusion models showed the lowest diffusion coefficients in tumors, intermediate values in noncancerous central gland, and highest values in noncancerous peripheral zone (all P < 0.001). Ktrans and kep were higher in tumors compared to central gland (P < 0.005) and peripheral zone (P < 0.001). The initial area under the contrast concentration curve was higher in tumor than the peripheral zone (P < 0.001). The area under the receiver operating characteristic curve of the combined DWI and DCE parameters (0.78) was higher than its individual components (0.73 and 0.63, respectively) for discriminating low- and intermediate-to-high-risk tumors. CONCLUSION: The sIVIM model provided comparable results with fewer b-values and shorter image acquisition time. The combination of DWI and DCE measurements of MRI-visible index lesions improved the preoperative prostate cancer risk characterization compared to the individual parameters from either technique alone. LEVEL OF EVIDENCE: 3 J. Magn. Reson. Imaging 2017;45:908-916.

White Paper of the Society of Computed Body Tomography and Magnetic Resonance on Dual-Energy CT, Part 1: Technology and Terminology.

This is the first of a series of 4 white papers that represent Expert Consensus Documents developed by the Society of Computed Body Tomography and Magnetic Resonance through its task force on dual-energy computed tomography (DECT). This article, part 1, describes the fundamentals of the physical basis for DECT and the technology of DECT and proposes uniform nomenclature to account for differences in proprietary terms among manufacturers.