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Objectives: To develop an automated pipeline for extracting prostate cancer-related information from clinical notes., Materials and Methods: This retrospective study included 23,225 patients who underwent prostate MRI between 2017 and 2022. Cancer risk factors (family history of cancer and digital rectal exam findings), pre-MRI prostate pathology, and treatment history of prostate cancer were extracted from free-text clinical notes in English as binary or multi-class classification tasks. Any sentence containing pre-defined keywords was extracted from clinical notes within one year before the MRI. After manually creating sentence-level datasets with ground truth, Bidirectional Encoder Representations from Transformers (BERT)-based sentence-level models were fine-tuned using the extracted sentence as input and the category as output. The patient-level output was determined by compilation of multiple sentence-level outputs using tree-based models. Sentence-level classification performance was evaluated using the area under the receiver operating characteristic curve (AUC) on 15% of the sentence-level dataset (sentence-level test set). The patient-level classification performance was evaluated on the patient-level test set created by radiologists by reviewing the clinical notes of 603 patients. Accuracy and sensitivity were compared between the pipeline and radiologists., Results: Sentence-level AUCs were ≥ 0.94. The pipeline showed higher patient-level sensitivity for extracting cancer risk factors (e.g., family history of prostate cancer, 96.5% vs. 77.9%, p < 0.001), but lower accuracy in classifying pre-MRI prostate pathology (92.5% vs. 95.9%, p = 0.002) and treatment history of prostate cancer (95.5% vs. 97.7%, p = 0.03) than radiologists, respectively., Conclusion: The proposed pipeline showed promising performance, especially for extracting cancer risk factors from patient's clinical notes., Clinical Relevance Statement: The natural language processing pipeline showed a higher sensitivity for extracting prostate cancer risk factors than radiologists and may help efficiently gather relevant text information when interpreting prostate MRI., Key Points: When interpreting prostate MRI, it is necessary to extract prostate cancer-related information from clinical notes. This pipeline extracted the presence of prostate cancer risk factors with higher sensitivity than radiologists. Natural language processing may help radiologists efficiently gather relevant prostate cancer-related text information., Competing Interests: Compliance with ethical standards Guarantor The scientific guarantor of this publication Naoki Takahashi. Conflict of interest The authors of this manuscript declare no relationships with any companies, whose products or services may be related to the subject matter of the article. Statistics and biometry No complex statistical methods were necessary for this paper. Informed consent Written informed consent was waived by the Institutional Review Board. “The Reviewer approved waiver of the requirement to obtain informed consent in accordance with 45 CFR 46.116 as justified by the Investigator, and waiver of HIPAA authorization in accordance with applicable HIPAA regulations”. Ethical approval Institutional Review Board approval was obtained. (#23-008038). “IRB Application #: 23-008038. Title: Development of Machine Learning Model of Prostate Cancer Using Prostate MRI and Clinical Data. IRB Approval Date: 8/30/2023. IRB Expiration Date: The above referenced application was reviewed by expedited review procedures and is determined to be exempt from the requirement for IRB approval (45 CFR 46.104d, category 4). Continued IRB review of this study is not required as it is currently written. However, requests for modifications to the study design or procedures must be submitted to the IRB to determine whether the study continues to be exempt. The Reviewer approved waiver of HIPAA authorization in accordance with applicable HIPAA regulations. As the principal investigator of this project, you are responsible for the following relating to this study. (1) When applicable, use only IRB approved materials which are located under the documents tab of the IRBe workspace. Materials include consent forms, HIPAA, questionnaires, contact letters, advertisements, etc. (2) Submission to the IRB of any modifications to approved research along with any supporting documents for review and approval prior to initiation of the changes. (3) Submission to the IRB of all Unanticipated Problems Involving Risks to Subjects or Others (UPIRTSO) and major protocol violations/deviations within five working days of becoming aware of the occurrence. (4) Compliance with applicable regulations for the protection of human subjects and with Mayo Clinic Institutional Policies. Mayo Clinic Institutional Reviewer”. Study subjects or cohorts overlap Thousands of patients included in this study overlapped with previously published works that evaluated cancer detection rates of prostate MRI in various different populations and a study that developed deep learning models for detecting clinically significant prostate cancer.1.Nagayama H, Nakai H, Takahashi H, et al Cancer detection rate and abnormal interpretation rate of prostate MRI performed for clinical suspicion of prostate cancer. J Am Coll Radiol. 2023; https://doi.org/10.1016/j.jacr.2023.07.031.2.Nakai H, Nagayama H, Takahashi H, et al Cancer detection rate and abnormal interpretation rate of prostate MRI in patients with low-grade cancer. J Am Coll Radiol. 2023; https://doi.org/10.1016/j.jacr.2023.07.030.3.3.Nakai H, Takahashi H, Adamo DA, et al Decreased cancer detection rate of the prostate MRI in patients with moderate to severe susceptibility artifacts from hip prosthesis. Eur Radiol. 2023; https://doi.org/10.1007/s00330-023-10345-4.4.Cai JC, Nakai H, Kuanar S, et al A fully automated deep learning model to detect clinically significant prostate cancer on multiparametric MRI. (Manuscript under review). Methodology RetrospectiveDiagnostic or prognostic studyPerformed at one institution, (© 2024. The Author(s), under exclusive licence to European Society of Radiology.)

The PRESERVE study (NCT04972097) aims to evaluate the safety and effectiveness of the NanoKnife System to ablate prostate tissue in patients with intermediate-risk prostate cancer (PCa). The NanoKnife uses irreversible electroporation (IRE) to deliver high-voltage electrical pulses to change the permeability of cell membranes, leading to cell death. A total of 121 subjects with organ-confined PCa ≤ T2c, prostate-specific antigens (PSAs) ≤ 15 ng/mL, and a Gleason score of 3 + 4 or 4 + 3 underwent focal ablation of the index lesion. The primary endpoints included negative in-field biopsy and adverse event incidence, type, and severity through 12 months. At the time of analysis, the trial had completed accrual with preliminary follow-up available. Demographics, disease characteristics, procedural details, PSA responses, and adverse events (AEs) are presented. The median (IQR) age at screening was 67.0 (61.0-72.0) years and Gleason distribution 3 + 4 (80.2%) and 4 + 3 (19.8%). At 6 months, all patients with available data (n = 74) experienced a median (IQR) percent reduction in PSA of 67.6% (52.3-82.2%). Only ten subjects (8.3%) experienced a Grade 3 adverse event; five were procedure-related. No Grade ≥ 4 AEs were reported. This study supports prior findings that IRE prostate ablation with the NanoKnife System can be performed safely. Final results are required to fully assess oncological, functional, and safety outcomes.

Objectives: To evaluate the impact of susceptibility artifacts from hip prosthesis on cancer detection rate (CDR) in prostate MRI., Materials and Methods: This three-center retrospective study included prostate MRI studies for patients without known prostate cancer between 2017 and 2021. Exams with hip prosthesis were searched on MRI reports. The degree of susceptibility artifact on diffusion-weighted images was retrospectively categorized into mild, moderate, and severe (> 66%, 33-66%, and < 33% of the prostate volume are evaluable) by blind reviewers. CDR was defined as the number of exams with Gleason score ≥7 detected by MRI (PI-RADS ≥3) divided by the total number of exams. For each artifact grade, control exams without hip prosthesis were matched (1:6 match), and CDR was compared. The degree of CDR reduction was evaluated with ratio, and influential factors were evaluated by expanding the equation., Results: Hip arthroplasty was present in 548 (4.8%) of the 11,319 MRI exams. CDR of the cases and matched control exams for each artifact grade were as follows: mild (n = 238), 0.27 vs 0.25, CDR ratio = 1.09 [95% CI: 0.87-1.37]; moderate (n = 143), 0.18 vs 0.27, CDR ratio = 0.67 [95% CI: 0.46-0.96]; severe (n = 167), 0.22 vs 0.28, CDR ratio = 0.80 [95% CI: 0.59-1.08]. When moderate and severe artifact grades were combined, CDR ratio was 0.74 [95% CI: 0.58-0.93]. CDR reduction was mostly attributed to the increased frequency of PI-RADS 1-2., Conclusion: With moderate to severe susceptibility artifacts from hip prosthesis, CDR was decreased to 74% compared to the matched control., Clinical Relevance Statement: Moderate to severe susceptibility artifacts from hip prosthesis may cause a non-negligible CDR reduction in prostate MRI. Expanding indications for systematic prostate biopsy may be considered when PI-RADS 1-2 was assigned., Key Points: • We proposed cancer detection rate as a diagnostic performance metric in prostate MRI. • With moderate to severe susceptibility artifacts secondary to hip arthroplasty, cancer detection rate decreased to 74% compared to the matched control. • Expanding indications for systematic prostate biopsy may be considered when PI-RADS 1-2 is assigned., (© 2023. The Author(s), under exclusive licence to European Society of Radiology.)

Objective: Automated surgical step recognition (SSR) using AI has been a catalyst in the "digitization" of surgery. However, progress has been limited to laparoscopy, with relatively few SSR tools in endoscopic surgery. This study aimed to create a SSR model for transurethral resection of bladder tumors (TURBT), leveraging a novel application of transfer learning to reduce video dataset requirements., Materials and Methods: Retrospective surgical videos of TURBT were manually annotated with the following steps of surgery: primary endoscopic evaluation, resection of bladder tumor, and surface coagulation. Manually annotated videos were then utilized to train a novel AI computer vision algorithm to perform automated video annotation of TURBT surgical video, utilizing a transfer-learning technique to pre-train on laparoscopic procedures. Accuracy of AI SSR was determined by comparison to human annotations as the reference standard., Results: A total of 300 full-length TURBT videos (median 23.96 min; IQR 14.13-41.31 min) were manually annotated with sequential steps of surgery. One hundred and seventy-nine videos served as a training dataset for algorithm development, 44 for internal validation, and 77 as a separate test cohort for evaluating algorithm accuracy. Overall accuracy of AI video analysis was 89.6%. Model accuracy was highest for the primary endoscopic evaluation step (98.2%) and lowest for the surface coagulation step (82.7%)., Conclusion: We developed a fully automated computer vision algorithm for high-accuracy annotation of TURBT surgical videos. This represents the first application of transfer-learning from laparoscopy-based computer vision models into surgical endoscopy, demonstrating the promise of this approach in adapting to new procedure types., Competing Interests: AA, MZ, OB, TW, and DA were employed by Theator Inc. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Deol, Tollefson, Antolin, Zohar, Bar, Ben-Ayoun, Mynderse, Lomas, Avant, Miller, Elliott, Boorjian, Wolf, Asselmann and Khanna.)

Purpose: The aim of this study was to evaluate the utility of cancer detection rate (CDR) and abnormal interpretation rate (AIR) in prostate MRI for patients with low-grade prostate cancer (PCa)., Methods: This three-center retrospective study included patients who underwent prostate MRI from 2017 to 2021 with known low-grade PCa (Gleason score 6) without prior treatment. Patient-level highest Prostate Imaging Reporting & Data System (PI-RADS®) score and pathologic diagnosis within 1 year after MRI were used to evaluate the diagnostic performance of prostate MRI in detecting clinically significant PCa (csPCa; Gleason score ≥ 7). The metrics AIR, CDR, and CDR adjusted for pathologic confirmation rate were calculated. Radiologist-level AIR-CDR plots were shown. Simulation AIR-CDR lines were created to assess the effects of different diagnostic performances of prostate MRI and the prevalence of csPCa., Results: A total of 3,207 examinations were interpreted by 33 radiologists. Overall AIR, CDR, and CDR adjusted for pathologic confirmation rate at PI-RADS 3 to 5 (PI-RADS 4 and 5) were 51.7% (36.5%), 22.1% (18.8%), and 30.7% (24.6%), respectively. Radiologist-level AIR and CDR at PI-RADS 3 to 5 (PI-RADS 4 and 5) were in the 36.8% to 75.6% (21.9%-57.5%) range and the 16.3%-28.7% (10.9%-26.5%) range, respectively. In the simulation, changing parameters of diagnostic performance or csPCa prevalence shifted the AIR-CDR line., Conclusions: The authors propose CDR and AIR as performance metrics in prostate MRI and report reference performance values in patients with known low-grade PCa. There was variability in radiologist-level AIR and CDR. Combined use of AIR and CDR could provide meaningful feedback for radiologists to improve their performance by showing relative performance to other radiologists., (Copyright © 2023 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

Purpose: To report cancer detection rate (CDR) and abnormal interpretation rate (AIR) in prostate MRI performed for clinical suspicion of prostate cancer (PCa)., Materials and Methods: This retrospective single-institution, three-center study included patients who underwent MRI for clinical suspicion of PCa between 2017 and 2021. Patients with known PCa were excluded. Patient-level Prostate Imaging-Reporting and Data System (PI-RADS) score was extracted from the radiology report. AIR was defined as number of abnormal MRI (PI-RADS score 3-5) / total number of MRIs. CDR was defined as number of clinically significant PCa (csPCa: Gleason score ≥7) detected at abnormal MRI / total number of MRI. AIR, CDR, and CDR adjusted for pathology confirmation rate were calculated for each of three centers and pre-MRI biopsy status (biopsy-naive and previous negative biopsy)., Results: A total of 9,686 examinations (8,643 unique patients) were included. AIR, CDR, and CDR adjusted for pathology confirmation rate were 45.4%, 23.8%, and 27.6% for center I; 47.2%, 20.0%, and 22.8% for center II; and 42.3%, 27.2%, and 30.1% for center III, respectively. Pathology confirmation rate ranged from 81.6% to 88.0% across three centers. AIR and CDR for biopsy-naive patients were 45.5% to 52.6% and 24.2% to 33.5% across three centers, respectively, and those for previous negative biopsy were 27.2% to 39.8% and 11.7% to 14.2% across three centers, respectively., Conclusion: We reported CDR and AIR in prostate MRI for clinical suspicion of PCa. CDR needs to be adjusted for pathology confirmation rate and pre-MRI biopsy status for interfacility comparison., (Copyright © 2023 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

Introduction: The primary objective of the ReIMAGINE Prostate Cancer Screening Study is to explore the uptake of an invitation to prostate cancer screening using MRI., Methods and Analysis: The ReIMAGINE Prostate Cancer Screening Study is a prospective single-centre feasibility study. Eligible men aged 50-75 years with no prior prostate cancer diagnosis or treatment will be identified through general practitioner practices and randomly selected for invitation. Those invited will be offered an MRI scan and a prostate-specific antigen (PSA) blood test. The screening MRI scan consists of T2-weighted, diffusion-weighted and research-specific sequences, without the use of intravenous contrast agents. Men who screen positive on either MRI or PSA density will be recommended to have standard of care (National Health Service) tests for prostate cancer assessment, which includes multiparametric MRI. The study will assess the acceptability of an MRI-based prostate screening assessment and the prevalence of cancer detected in MRI-screened men. Summary statistics will be used to explore baseline characteristics in relation to acceptance rates and prevalence of cancer., Ethics and Dissemination: ReIMAGINE Prostate Cancer Screening is a single-site screening study to assess the feasibility of MRI as a screening tool for prostate cancer. Ethical approval was granted by London-Stanmore Research Ethics Committee Heath Research Authority (reference 19/LO/1129). Study results will be published in peer-reviewed journals after completion of data analysis and used to inform the design of a multicentre screening study in the UK., Trial Registration Number: ClinicalTrials.gov Registry (NCT04063566)., Competing Interests: Competing interests: CMM receives funding from the Prostate Cancer UK, Movember, the Medical Research Council, Cancer Research UK and the NIHR. She receives fees for HIFU proctoring from SonaCare. She has received speaker fees from Astellas and Jannsen. She carries out research into photodynamic therapy supported by Spectracure. ME serves as a consultant/educator/trainer to Sonacare, Exact Imaging, Angiodynamics and Profound Medical., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY. Published by BMJ.)

Purpose: To develop an improved reconstruction method, k-space subtraction with phase and intensity correction (KSPIC), for highly accelerated, subtractive, non-contrast-enhanced MRA., Methods: The KSPIC method is based on k-space subtraction of complex raw data. It applies a phase-correction procedure to restore the polarity of negative signals caused by subtraction and an intensity-correction procedure to improve background suppression and thereby sparsity. Ten retrospectively undersampled data sets and 10 groups of prospectively undersampled data sets were acquired in 12 healthy volunteers. The performance of KSPIC was compared with another improved reconstruction based on combined magnitude subtraction, as well as with conventional k-space subtraction reconstruction and magnitude subtraction reconstruction, both using quantitative metrics and using subjective quality scoring., Results: In the quantitative evaluation, KSPIC had the best performance in terms of peak SNR, structural similarity index measure, contrast-to-noise ratio of artery-to-background and sharpness, especially at high acceleration factors. The KSPIC method also had the highest subjective scores for all acceleration factors in terms of vessel delineation, image noise and artifact, and background contamination. The acquisition can be accelerated by a factor of 20 without significant decreases of subjective scores. The optimal size of the phase-correction region was found to be 12-20 pixels in this study., Conclusion: Compared with combined magnitude subtraction and conventional reconstructions, KSPIC has the best performance in all of the quantitative and qualitative measurements, permitting good image quality to be maintained up to higher accelerations. The KSPIC method has the potential to further reduce the acquisition time of subtractive MRA for clinical examinations., (© 2021 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.)

Purpose of Review: This review aims to summarize the latest evidence for the use of salvage ablation of localized prostate cancer recurrences after primary therapy radiotherapy or prostatectomy., Recent Findings: Savage ablation represents a treatment option in select patients with localized recurrences following primary therapy of prostate cancer. Following radiotherapy, salvage cryotherapy and high-intensity focused ultrasound (HIFU) demonstrate encouraging oncologic outcomes. Biochemical recurrence-free survival ranged from 71% at 2 years to 44.2% at 10 years for cryotherapy and from 51% at 5 years to 28.7% at 10 years for HIFU. Rates of adverse effects appear to be more favorable with ablation compared to salvage surgery. Focal salvage ablation may offer a further balance between oncologic control and adverse effects. Following radical prostatectomy, recent data on the use of salvage ablation of local recurrences are less robust with only a few small studies published in the last 2 years., Summary: Salvage ablation is an option for localized disease recurrences following primary treatment. Its role is most established for postradiation recurrence. It can also be utilized in postprostatectomy recurrence, although published data is more limited. Future studies are needed to further explore the role of ablation in both cohorts., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose: To correct the intensity difference of static background signal between bright blood images and dark blood images in subtractive non-contrast-enhanced MR angiography using robust regression, thereby improving static background signal suppression on subtracted angiograms., Methods: Robust regression (RR), using iteratively reweighted least squares, is used to calculate the regression coefficient of background tissues from a scatter plot showing the voxel intensity of bright blood images versus dark blood images. The weighting function is based on either the Euclidean distance from the estimated regression line or the deviation angle. Results from RR using the deviation angle (RRDA), conventional RR using the Euclidean distance, and ordinary leastsquares regression were compared with reference values determined manually by two observers. Performance was evaluated over studies using different sequences, including 36 thoracic flow-sensitive dephasing data sets, 13 iliac flow-sensitive dephasing data sets, and 26 femoral fresh blood imaging data sets., Results: RR deviation angle achieved robust and accurate performance in all types of images, with small bias, small mean absolute error, and high-correlation coefficients with reference values. Background tissues, such as muscle, veins, and bladder, were suppressed while the vascular signal was preserved. Euclidean distance gave good performance for thoracic and iliac flow-sensitive dephasing, but could not suppress background tissues in femoral fresh blood imaging. Ordinary least squares regression was sensitive to outliers and overestimated regression coefficients in thoracic flow-sensitive dephasing., Conclusion: Weighted subtraction using RR was able to acquire the regression coefficients of background signal and improve background suppression of subtractive non-contrast-enhanced MR angiography techniques. RR deviation angle has the most robust and accurate overall performance among three regression methods., (© 2020 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.)

Following detection of high levels of serum prostate-specific antigen, many men are advised to have transrectal ultrasound-guided biopsy in an attempt to locate a cancer. This nontargeted approach lacks accuracy and carries a small risk of potentially life-threatening sepsis. Worse still, it can detect clinically insignificant cancer cells, which are unlikely to be the origin of advanced-stage disease. The detection of these indolent cancer cells has led to overdiagnosis, one of the major problems of contemporary medicine, whereby many men with clinically insignificant disease are advised to undergo unnecessary radical surgery or radiotherapy. Advances in imaging and biomarker discovery have led to a revolution in prostate cancer diagnosis, and nontargeted prostate biopsies should become obsolete. In this Perspective article, we describe the current diagnostic pathway for prostate cancer, which relies on nontargeted biopsies, and the problems linked to this pathway. We then discuss the utility of prebiopsy multiparametric MRI and novel tumour markers. Finally, we comment on how the incorporation of these advances into a new diagnostic pathway will affect the current risk-stratification system and explore future challenges.

Purpose: To describe safety, efficacy, and added oncologic margin of saline displacement of the rectal wall during MRI-guided cryoablation of primary and recurrent prostate cancer., Methods: A retrospective review was conducted for patients who underwent MRI-guided cryoablation with saline displacement of the rectal wall for treatment of primary and recurrent prostate cancer over a 2-year period. Saline displacement was used when the distance from the edge of the ablation area to the rectal wall was insufficient to provide at least a 5-mm treatment margin. Pre- and post-ablation rectal wall displacement distances as well as ablative zone margins were assessed with MRI. Saline displacement distance was measured from the rectal wall to the edge of the lesion for focal lesion ablation and from the edge of the prostate for hemi-gland ablation. Immediate and intermediate-term complications were assessed., Results: Saline displacement was used in 25 patients undergoing MRI-guided cryoablation. Twenty-one patients underwent salvage cryoablation, while four patients had it as primary treatment for prostate cancer. Median pre- and post- saline displacement rectal wall displacement distances were 6.0 and 11.2 mm, respectively (P < 0.0001). Median-added oncologic margin achieved by saline displacement was 4.6 mm (range 0.6-26.5). Median follow-up was 14 months (range 5-29). There were no intra-procedural complications and 3 patients experienced minor (Clavien-Dindo grade I) complications. One rectal complication occurred in a patient undergoing salvage cryotherapy with a history of extensive pelvic surgery and radiation., Conclusions: Saline infusion at the time of MRI- guided cryoablation for prostate cancer resulted in increased distances between the target lesion and rectum. This is a useful technique in providing an added oncologic margin when treating lesions close to the rectal wall.

Our purpose is to investigate the feasibility of imaging tumor metabolism in breast cancer patients using 13 C magnetic resonance spectroscopic imaging (MRSI) of hyperpolarized 13 C label exchange between injected [1- 13 C]pyruvate and the endogenous tumor lactate pool. Treatment-naïve breast cancer patients were recruited: four triple-negative grade 3 cancers; two invasive ductal carcinomas that were estrogen and progesterone receptor-positive (ER/PR+) and HER2/neu-negative (HER2-), one grade 2 and one grade 3; and one grade 2 ER/PR+ HER2- invasive lobular carcinoma (ILC). Dynamic 13 C MRSI was performed following injection of hyperpolarized [1- 13 C]pyruvate. Expression of lactate dehydrogenase A (LDHA), which catalyzes 13 C label exchange between pyruvate and lactate, hypoxia-inducible factor-1 (HIF1α), and the monocarboxylate transporters MCT1 and MCT4 were quantified using immunohistochemistry and RNA sequencing. We have demonstrated the feasibility and safety of hyperpolarized 13 C MRI in early breast cancer. Both intertumoral and intratumoral heterogeneity of the hyperpolarized pyruvate and lactate signals were observed. The lactate-to-pyruvate signal ratio (LAC/PYR) ranged from 0.021 to 0.473 across the tumor subtypes (mean ± SD: 0.145 ± 0.164), and a lactate signal was observed in all of the grade 3 tumors. The LAC/PYR was significantly correlated with tumor volume ( R = 0.903, P = 0.005) and MCT 1 ( R = 0.85, P = 0.032) and HIF1α expression ( R = 0.83, P = 0.043). Imaging of hyperpolarized [1- 13 C]pyruvate metabolism in breast cancer is feasible and demonstrated significant intertumoral and intratumoral metabolic heterogeneity, where lactate labeling correlated with MCT1 expression and hypoxia., Competing Interests: Competing interest statement: A research agreement is in place between GE Healthcare and K.M.B. and F.A.G., (Copyright © 2020 the Author(s). Published by PNAS.)

Hyperpolarized 13 C Magnetic Resonance Imaging ( 13 C-MRI) provides a highly sensitive tool to probe tissue metabolism in vivo and has recently been translated into clinical studies. We report the cerebral metabolism of intravenously injected hyperpolarized [1- 13 C]pyruvate in the brain of healthy human volunteers for the first time. Dynamic acquisition of 13 C images demonstrated 13 C-labeling of both lactate and bicarbonate, catalyzed by cytosolic lactate dehydrogenase and mitochondrial pyruvate dehydrogenase respectively. This demonstrates that both enzymes can be probed in vivo in the presence of an intact blood-brain barrier: the measured apparent exchange rate constant (k PL ) for exchange of the hyperpolarized 13 C label between [1- 13 C]pyruvate and the endogenous lactate pool was 0.012 ± 0.006 s -1 and the apparent rate constant (k PB ) for the irreversible flux of [1- 13 C]pyruvate to [ 13 C]bicarbonate was 0.002 ± 0.002 s -1 . Imaging also revealed that [1- 13 C]pyruvate, [1- 13 C]lactate and [ 13 C]bicarbonate were significantly higher in gray matter compared to white matter. Imaging normal brain metabolism with hyperpolarized [1- 13 C]pyruvate and subsequent quantification, have important implications for interpreting pathological cerebral metabolism in future studies., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate the performance of acceleration-dependent vascular anatomy for non-contrast-enhanced MR venography (ADVANCE-MRV) in femoral veins and to investigate whether venous signal uniformity can be improved by applying multiple acquisitions with different flow suppressions or multiple flow suppressions in 1 acquisition., Methods: The ADVANCE-MRV method uses flow-sensitized modules to acquire a dark-artery image set and a dark-artery vein set, which are subsequently subtracted. Ten healthy volunteers were imaged using the ADVANCE-MRV sequence with improved venous suppression uniformity in the dark-artery vein images achieved by applying multiple flow suppressions in the same acquisition or by combining multiple images acquired with different flow suppressions. The performance of the improved technique was also evaluated in 13 patients with lower-limb deep venous thrombosis., Results: Multiple-preparation and multiple-acquisition approaches all improved venous signal uniformity and reduced the signal void artifacts observed in the original ADVANCE-MRV images. The multiple-acquisition approaches achieved excellent blood signal uniformity and intensity, albeit at the cost of an increase in the total acquisition time. The double-preparation approach demonstrated good performance in all measurements, providing a good compromise between signal uniformity and acquisition time. The blood signal spatial variation and its variation using different gradient amplitudes were reduced by 20% and 29%. All patient images showed uniform and bright venous signal in nonoccluded sections of vein., Conclusion: The enhanced ADVANCE-MRV methods substantially improved signal uniformity in healthy volunteers and patients with known deep venous thrombosis. The double-preparation approach gave good-quality femoral vein images, providing improved venous signal uniformity without increasing acquisition time in comparison to the original sequence., (© 2018 International Society for Magnetic Resonance in Medicine.)

Objective: To evaluate patient's recall of pretreatment counseling for radical prostatectomy and radiation therapy for the treatment of prostate cancer., Material and Methods: A retrospective review of all patients presenting to our reconstructive urology clinic for the management of the complications of prostate cancer treatment was conducted over 24 months. Patients treated with only surgery or radiotherapy were included in the study. Patients were asked a standard series of questions to assess their recall of their pre-prostate cancer treatment counseling., Results: We identified 206 patients that met inclusion criteria. Of those, 153 underwent radical prostatectomy and 53 patients received radiation therapy. Median age at presentation was 72 years in the surgery group and 75 in the radiation therapy group. Mean time since treatment was 8.8 years in those that recalled being counseled and 9.9 years in those who did not (p=0.21). In the surgery group, the adverse effects experienced by 119 (77.8%) patients recalled, and counselled were related to the risk of treatment. In the surgical patients that had records with documentation of pretreatment counseling, 41/48 (85.4%) endorsed recall. In the surgery group, 117 (76.5%) stated that their treating physician was aware of their complication. In the radiation group, 5 patients (9.4%) endorsed recall (p<0.0001). In the subgroup of radiation patients with documentation of pre-treatment counseling, no patients endorsed recall. In the surgery group, 117 (76.5%) patients stated that their treating physicians were aware of their complication, while in the radiation group, only 16 (30.2%) of treating physicians were aware of the complications (p<0.0001)., Conclusion: Patient recall of potential complications of prostate cancer treatment is poor. It's unclear if this is secondary to poor recall, selective memory loss or inadequate counseling.

Inflatable penile prosthesis (IPP) is the gold standard for medically refractory erectile dysfunction. Infectious complications remain a significant concern in IPP revision surgery. We sought to evaluate the impact of number of IPP surgeries on subsequent infection rates. A retrospective analysis was performed on all new patients (self or outside provider referred) presenting for consideration of IPP revision or salvage surgery between 2013 and 2015. Histories were reviewed including number of prior IPPs, reason for evaluation, and rate, number, and timing of prior IPP infections. No patients were operated on by the primary investigator prior to data acquisition. We identified 44 patients with at least one prior IPP presenting for consultation regarding IPP revision/salvage. There were 88 IPPs placed by 28 different surgeons. In patients with two or more devices, 55% had at least two different surgeons. The most common reason for presentation was malfunction (52%). The risk of specific device infection was strongly correlated and increased based on number of prior IPPs: 1st (6.8%; 3/44), 2nd (18.2%; 4/22), 3rd (33.3%; 4/12), 4th (50%; 4/8), and 5th (100%; 2/2) (R 2  = 0.90, p = 0.01). Similarly, overall rates of infection positively correlated with number of prior IPP-related surgeries performed (R 2  = 0.97, p < 0.01). The median time to development of infection after most recent IPP surgery was 2 months (IQR 1-3.3 months). Infection rates of revision/salvage IPP surgery increase with each subsequent IPP placement or following IPP-related surgeries. The majority of patients referred for penile implant surgery can expect to have experienced at least one infection by their 4th device. These data represent a change in paradigm on revision prosthetic surgery.

Background Dedicated blood-pool contrast agents combined with optimal angiographic protocols could improve the diagnostic accuracy of thoracic magnetic resonance angiography (MRA). Purpose To assess the clinical utility of Gadofesveset-enhanced imaging and compare an optimized steady-state (SS) sequence against conventional first-pass dynamic multi-phase (DMP) imaging. Material and Methods Twenty-nine patients (17 men, 12 women; mean age = 42.7, age range = 18-72 years) referred for MR thoracic venography were recruited. Imaging was performed on a 1.5T MRI system. A blood-pool contrast agent (Gadofesveset) was administered intravenously. Thirty temporal phases were acquired using DMP. This was immediately followed by a high-resolution SS sequence. Three radiologists in consensus reviewed seven thoracic vascular segments after randomizing the acquisition order. Image quality, stenoses, thromboses, and artifacts were graded using a categorical scoring system. The image quality for both approaches was compared using Wilcoxon's signed-rank test. McNemar's test was used to compare the proportions of stenosis grades, thrombus and artifacts. Results SS had significantly better image quality than DMP (3.14 ± 0.73 and 2.92 ± 0.60, respectively; P < 0.001). SS identified fewer stenoses (>50%) than DMP; the differences in stenosis categorizations was statistically significant ( P = 0.013). There was no significant difference in the proportions of vessels with thromboses ( P = 0.617). DMP produced more artifacts than SS (101 versus 85); however, the difference was not statistically significant ( P = 0.073). Conclusion Gadofesveset-enhanced thoracic angiography is clinically feasible. SS imaging produces better image quality and fewer artifacts than conventional DMP imaging.

Introduction: Hepatic morphology changes are well described in Primary Sclerosing Cholangitis and characterised by a combination of atrophy and hypertrophy changes. This study investigates the relationship between progression of these changes over time and clinical outcome in patients with PSC., Methods: Fifty-three patients with PSC (mean age 44, 28 males and 25 females) who underwent serial MRI liver studies at least one year apart were identified. The first and the last MRI studies were selected for the retrospective analysis. Three radiologists reviewed and compared both studies for changes in hepatic morphology, specifically atrophy and/or hypertrophy. The imaging findings were correlated with adverse clinical outcomes defined as death or liver transplantation and with serum bilirubin., Results: There was a mean interval of 60 months between MRI examinations and a mean clinical follow-up period thereafter of 22 months. Thirty-three (62.3%) patients had stable hepatic morphology, whilst 20 (37.7%) patients showed hepatic morphology changes (atrophy: 13 patients, 24%; hypertrophy: 16 patients, 30%). Eleven patients (21%) died or underwent liver transplantation. There was a significant correlation between interval hepatic atrophy and adverse clinical outcomes (P = 0.001). Significant correlations were found between increasing serum bilirubin level and interval hepatic atrophy, hepatic hypertrophy and combined changes (P = 0.025, P = 0.022, P = 0.027, respectively)., Conclusion: Hepatic morphology changes over time in patients with PSC are heterogeneous with some patients developing atrophy and/or hypertrophy whilst other patients remain stable. In this retrospective study, progressive hepatic atrophy showed significant association with adverse clinical outcome defined by either death or liver transplantation., (© 2017 The Royal Australian and New Zealand College of Radiologists.)

Objective: To aid the extraction of the portal venous input function (PVIF) from axial dynamic contrast-enhanced CT images of the liver, eliminating the need for full manual outlining of the vessel across time points., Methods: A cohort of 20 patients undergoing perfusion CT imaging of the liver was examined. Dynamic images of the liver were reformatted into contiguous thin slices. A region of interest was defined within a transverse section of the portal vein on a single contrast-enhanced image. This region of interest was then computationally projected across all thin slices for all time points to yield a semi-automated PVIF curve. This was compared against the "gold-standard" PVIF curve obtained by conventional manual outlining., Results: Bland-Altman plots of curve characteristics indicated no substantial difference between automated and manual PVIF curves [concordance correlation coefficient in the range (0.66, 0.98)]. No substantial differences were shown by Bland-Altman plots of derived pharmacokinetic parameters when a suitable kinetic model was applied in each case [concordance correlation coefficient in range (0.92, 0.95)]., Conclusion: This semi-automated method of extracting the PVIF performed equivalently to a "gold-standard" manual method for assessing liver function. Advances in knowledge: This technique provides a quick, simple and effective solution to the problems incurred by respiration motion and partial volume factors in the determination of the PVIF in liver dynamic contrast-enhanced CT.

Purpose: To evaluate the diagnostic performance of velocity- and acceleration-sensitized noncontrast-enhanced magnetic resonance angiography (NCE-MRA) of the infrageniculate arteries using contrast-enhanced MRA (CE-MRA) as a reference standard., Materials and Methods: Twenty-four patients with symptoms of peripheral arterial disease were recruited. Each patient's infrageniculate arterial tree was examined using a velocity-dependent flow-sensitized dephasing (VEL-FSD) technique, an acceleration-dependent (ACC-FSD) technique, and our conventional CE-MRA technique performed at 1.5T. The images were independently reviewed by two experienced vascular radiologists, who evaluated each vessel segment to assess visibility, diagnostic confidence, venous contamination, and detection of pathology., Results: In all, 432 segments were evaluated by each of the three techniques by each reader in total. Overall diagnostic confidence was rated as moderate or high in 98.5% of segments with CE-MRA, 92.1% with VEL-FSD, and 79.9% with ACC-FSD. No venous contamination was seen in 96% of segments with CE-MRA, 72.2% with VEL-FSD, and 85.8% with ACC-FSD. Per-segment, per-limb, and per-patient sensitivities for detecting significant stenotic disease were 63.4%, 73%, and 92%, respectively, for ACC-FSD, and 65.3%, 87.2%, and 96% for VEL-FSD, and as such no significant statistical change was detected using McNemar's chi-squared test with P-values of 1.00, 0.13, and 0.77 obtained, respectively., Conclusion: Flow-dependent NCE-MRA techniques may have a role to play in evaluation of patients with peripheral vascular disease. Increased sensitivity of a velocity-based technique compared to an acceleration-based technique comes at the expense of greater venous contamination., Level of Evidence: 2J. Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;45:1846-1853., (© 2016 International Society for Magnetic Resonance in Medicine.)

Objectives: Lower limb deep venous thrombosis (DVT) is a common condition with high morbidity and mortality. The aim of the study was to investigate the temporal evolution of the acute thrombus by magnetic resonance imaging (MRI) and its relationship to venous recanalization in patients with recurrent DVTs., Methods: Thirteen patients with newly diagnosed lower limb DVTs underwent MRI with non-contrast MR venography (NC-MRV) and MR direct thrombus imaging (MR-DTI), an inversion-recovery water-selective fast gradient-echo acquisition. Imaging was performed within 7 days of the acute thrombotic event, then at 3 and 6 months., Results: By 3 months from the thrombotic event a third of the thrombi had resolved and by 6 months about half of the cases had resolved on the basis of vein recanalisation using NC-MRV. On the initial MR-DTI acute thrombus was clearly depicted by hyperintense signal, while the remaining thrombi were predominantly low signal at 3 and 6 months. Some residual thrombi contained small and fragmented persisting hyperintense areas at 3 months, clearing almost completely by 6 months., Conclusions: Our study suggests that synergistic venous assessment with combined NC-MRV and MR-DTI is able to distinguish acute venous thrombosis from the established (old) or evolving DVT detected by ultrasound., Key Points: • MRI can distinguish between acute and evolving or chronic lower limb DVT • Two advanced MRI techniques can follow the evolution of lower limb DVT • MRI could be used to avoid an incorrect diagnosis of recurrent DVT • MRI could help avoid the risks and complications of lifelong anticoagulation therapy.

Purpose: Hepatic magnetic resonance elastography (MRE) is currently a breath-hold imaging technique. Patients with chronic liver disease can have comorbidities that limit their ability to breath-hold (BH) for the required acquisition time. Our aim was to evaluate whether stiffness measurements obtained from a navigator-triggered MRE acquisition are comparable to standard expiratory breath-hold, inspiratory breath-hold or free-breathing in healthy participants., Materials and Methods: Twelve healthy participants were imaged using the four methods on a clinical 1.5T MR system equipped with a product MRE system. Mean liver stiffness, and measurable area of stiffness (with a confidence threshold >95%) were compared between sequences using the concordance correlation coefficient. Repeatability of each sequence between two acquisitions was also assessed., Results: The standard BH expiratory technique had high concordance with the navigated technique (r=0.716), and low concordance with the BH inspiration (r=0.165) and free-breathing (r=0.105) techniques. The navigator-triggered technique showed no statistical difference in measurable area of liver or in repeatability compared with the standard expiratory acquisition (p=0.997 and p=0.407 respectively). The free-breathing technique produced less measurable liver area and was less repeatable than the alternative techniques. The increase in acquisition time for navigator techniques was 3min 6s compared to standard expiratory breath-hold., Conclusion: Navigator-based hepatic MRE measurements are comparable to the reference standard expiratory breath-hold acquisition in healthy participants., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Objective: To evaluate and profile ammonium acid urate (AAU) stone formers utilizing a large contemporary cohort., Materials and Methods: A retrospective review of all patients with documented AAU urolithiasis on stone analysis was performed from 1995 to 2013. A stone was considered AAU if it contained at least 10% of the total composition on stone analysis., Results: Of 12,421 stones, a total of 111 AAU stones were identified in 89 patients. Seventy-two patients (81%) had mixed composition stones. Of the 89 AAU patients, 10 (11%) had chronic kidney disease, 12 (13%) had recurrent urinary tract infections, 8 (9%) had diabetes mellitus, 25 (28%) had a history of ileostomy or bowel resection, and 11 (12%) had significant diarrhea or inflammatory bowel disease. Additionally, 20 (22%) had prior prostate surgery with bladder neck contracture and 8 (9%) were managed with a chronic indwelling catheter. Surgical intervention was required in 74 patients (83%). At the median follow-up of 4.9 years, 19 patients (21%) had stone recurrence with a median time to recurrence of 22 months (interquartile range: 10.5-42.0)., Conclusion: AAU stones are rare. In addition to previously described risk factors for AAU stone formation, patients with prior prostate surgery and bladder neck contracture or a surgically altered bladder may be at increased risk for formation. Furthermore, the long-term follow-up provided by this large AAU cohort demonstrates a significant risk for stone recurrence., (Copyright © 2016 Elsevier Inc. All rights reserved.)

This short commentary provides the MRI community in the UK with practical advice on the impact of the Control of Electromagnetic Fields at Work Regulations 2016 in clinical and research settings. The regulations are the UK implementation of the European Union Physical Agents (Electromagnetic Fields) Directive, which has been the subject of much discussion and concern over the past 13 years. However, thanks to concessions achieved through negotiation, and sensible and proportionate transposition into UK law by the Health and Safety Executive, the negative consequences that were foreseen have been averted. MRI activities are exempt from the occupational exposure limits contained in the regulations, subject to meeting certain conditions. The commentary gives advice on compliance with these conditions and on how to satisfy the other requirements of the regulations, all of which are either already required under existing legislation or represent good MR safety practice.

Objective: To evaluate long-term outcomes for men with benign prostatic obstruction (BPO) and concurrent detrusor underactivity (DUA) or acontractility following holmium laser enucleation of the prostate (HoLEP)., Methods: A retrospective chart review was performed on all patients with BPO and urodynamic evidence of DUA or acontractility secondary to a nonneurogenic etiology that underwent HoLEP at our institution over a 4-year period. Patients were included if they had at least 24 months of follow-up., Results: We identified 9 patients with DUA and 8 patients with acontractility who met inclusion criteria with median ages of 76 and 75 years, respectively. Preoperatively, 7 (77.8%) men with DUA and 8 (100%) men with acontractility had catheter-dependent urinary retention for a median of 2 and 5 months, respectively. Postoperatively, 8 (88.9%) men with DUA and 5 (62.5%) men with acontractility were catheter free, with a median follow-up of 50.9 and 38.6 months, respectively. All the men requiring catheterization were voiding spontaneously, but used intermittent catheterization for elevated postvoid residuals., Conclusion: HoLEP appears to be an effective surgical option for patients with BPO and detrusor hypocontractility or acontractility, with durable results at follow-up greater than 24 months. However, patients with acontractile bladders should be counseled on possible need to for intermittent catheterization that may be needed for high postvoid residuals., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Objectives: This work evaluates rapid magnetic resonance projection hydrography (PH) based amniotic fluid volume (AFV) estimates against established routine ultrasound single deepest vertical pocket (SDVP) and amniotic fluid index (AFI) measurements, in utero at 28-32 weeks gestation. Manual multi-section planimetry (MSP) based measurement of AFV is used as a proxy reference standard., Methods: Thirty-five women with a healthy singleton pregnancy (20-41 years) attending routine antenatal ultrasound were recruited. SDVP and AFI were measured using ultrasound, with same day MRI assessing AFV with PH and MSP. The relationships between the respective techniques were assessed using linear regression analysis and Bland-Altman method comparison statistics., Results: When comparing estimated AFV, a highly significant relationship was observed between PH and the reference standard MSP (R(2) = 0.802, p < 0.001). For the US measurements, SDVP measurement related most closely to amniotic fluid volume, (R(2) = 0.470, p < 0.001), with AFI demonstrating a weaker relationship (R(2) = 0.208, p = 0.007)., Conclusion: This study shows that rapid MRI based PH measurement is a better predictor of AFV, relating more closely to our proxy standard than established US techniques. Although larger validation studies across a range of gestational ages are required this approach could form part of MR fetal assessment, particularly where poly- or oligohydramnios is suspected., Key Points: • MR projection hydrography can be used to estimate amniotic fluid volume. • MR projection hydrography relies on the T2w signal from amniotic fluid. • Amniotic fluid volume (AFV) is more accurately assessed than with ultrasound.

Introduction: High submuscular ectopic placement of inflatable penile prosthesis (IPP) reservoirs via the inguinal canal has been popularized as an alternative to the retropubic (orthotopic) location, particularly among men with prior pelvic surgery. Published results suggest minimal complications and high patient satisfaction. However, in our practice, we identified several patients presenting for IPP revision after high submuscular placement who were found to have reservoirs within the peritoneal cavity., Aim: Given the potential for complications, we performed a cadaveric study to define the anatomic location of reservoirs placed using this technique., Methods: We utilized 10 fresh male cadavers without embalming. Bilateral ectopic reservoir placement (10 AMS Conceal [Boston Scientific, Marlborough, MA] and 10 Coloplast Cloverleaf [Coloplast Corp, Humlebaek, Denmark]) was performed using the high submuscular technique via a penoscrotal incision. Strict adherence to published reports detailing the technique was emphasized to assure reliability of findings., Main Outcome Measures: Anatomic dissection was performed to identify reservoir location within the abdominal wall layers., Results: Twenty IPP reservoirs were placed without difficulty or concern for inadvertent malpositioning. Sixteen reservoirs (80%) were found anterior to the transversalis fascia, including 7 (35%) deep to the rectus muscle and 9 (45%) deep to the external oblique fascia and lateral to the rectus muscle belly. Two reservoirs (10%) were identified in the retroperitoneal space, while 1 (5%) was preperitoneal (deep to transversalis fascia) and 1 (5%) was intraperitoneal., Conclusion: Placement of IPP reservoirs using the high submuscular technique results in variable anatomic locations, including within or immediately superficial to the peritoneal cavity. Given the lack of immediate recognition and risk of delayed complications with suboptimal reservoir placement, further studies are mandated to assess the long-term safety of the technique., (Copyright © 2016 International Society for Sexual Medicine. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate the utility of oxygen challenge and report on temporal changes in blood oxygenation level-dependent (BOLD) contrast in normal liver, hepatocellular carcinoma (HCC) and background fibrosis., Materials and Methods: Eleven volunteers (nine male and two female, mean age 33.5, range 27-41 years) and 10 patients (nine male and one female, mean age 68.9, range 56-87 years) with hepatocellular carcinoma on a background of diffuse liver disease were recruited. Imaging was performed on a 3T system using a multiphase, multiecho, fast gradient echo sequence. Oxygen was administered via a Hudson mask after 2 minutes of free-breathing. Paired t-tests were performed to determine if the mean pre- and post-O2 differences were statistically significant., Results: In patients with liver fibrosis (n = 8) the change in T2* following O2 administration was elevated (0.88 ± 0.582 msec, range 0.03-1.69 msec) and the difference was significant (P = 0.004). The magnitude of the BOLD response in patients with HCC (n = 10) was larger, however the response was more variable (1.07 ± 1.458 msec, range -0.93-3.26 msec), and the difference was borderline significant (P = 0.046). The BOLD response in the volunteer cohort was not significant (P = 0.121, 0.59 ± 1.162 msec, range -0.81-2.44 msec)., Conclusion: This work demonstrates that the BOLD response following oxygen challenge within cirrhotic liver is consistent with a breakdown in vascular autoregulatory mechanisms. Similarly, the elevated BOLD response within HCC is consistent with the abnormal capillary vasculature within tumors and the arterialization of the blood supply. Our results suggest that oxygen challenge may prove a viable BOLD contrast mechanism in the liver. J. Magn. Reson. Imaging 2016;44:739-744., (© 2016 The Authors Journal of Magnetic Resonance Imaging published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.)

Objective: The aim of this work was to evaluate whether the uterine arteries (UtA) could be identified and their flow profiles measured during a fetal MRI examination. A comparison was performed against same day sonographic Doppler assessment., Methods: 35 normal, healthy, singleton pregnancies at 28-32 weeks gestation underwent routine Doppler examination, followed by MRI examination. The resistivity index (RI) and pulsatility index (PI) of the left and right UtA were measured using phase contrast MRI. Bland Altman statistics were used to compare MRI and ultrasound results., Results: Sixty-nine comparable vessels were analysed. Six vessels were excluded due to artefact or technical error. Bland-Altman analysis demonstrated the ultrasound indices were comparable, although systematically lower than the MRI indices; Right UtA RI bias -0.03 (95% limits of agreement (LOA) -0.27 to +0.20), and left UtA RI bias -0.06 (95% LOA -0.26 to +0.14); Right UtA PI bias -0.06 (95% LOA -0.50 to +0.38), Left UtA PI bias -0.11 (95% LOA -0.54 to +0.32). The inter-rater agreement for the MRI derived PI and RI analysis was good., Conclusion: This study demonstrates that in the majority of early third trimester pregnancies, the uterine arteries can be identified, and their flow profiles measured using MRI, and that the derived PI and RI values are comparable with Doppler ultrasound values., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Objectives: We conducted an individual participant data (IPD) pooled analysis on diagnostic accuracy of MRE to detect fibrosis stage in patients with non-alcoholic fatty liver disease (NAFLD)., Methods: Through a systematic literature search, we identified studies of MRE (at 60-62.5 Hz) for staging fibrosis in patients with NAFLD, using liver biopsy as gold standard, and contacted study authors for IPD. Through pooled analysis, we calculated the cluster-adjusted AUROC, sensitivity and specificity of MRE for any (≥stage 1), significant (≥stage 2) and advanced (≥stage 3) fibrosis and cirrhosis (stage 4)., Results: We included nine studies with 232 patients with NAFLD (mean age, 51 ± 13 years; 37.5% males; mean BMI, 33.5 ± 6.7 kg/m(2); interval between MRE and biopsy <1 year, 98.3%). Fibrosis stage distribution (stage 0/1/2/3/4) was 33.6, 32.3, 10.8, 12.9 and 10.4%, respectively. Mean AUROC (and 95% CIs) for diagnosis of any, significant or advanced fibrosis and cirrhosis was 0.86 (0.82-0.90), 0.87 (0.82-0.93), 0.90 (0.84-0.94) and 0.91 (0.76-0.95), respectively. Similar diagnostic performance was observed in stratified analysis based on sex, obesity and degree of inflammation., Conclusions: MRE has high diagnostic accuracy for detection of fibrosis in NAFLD, independent of BMI and degree of inflammation., Key Points: • MRE has high diagnostic accuracy for detection of fibrosis in NAFLD. • BMI does not significantly affect accuracy of MRE in NAFLD. • Inflammation had no significant influence on MRE performance in NAFLD for fibrosis., Competing Interests: This research has been reviewed by the Mayo Clinic Conflict of Interest Review Board and is being conducted in compliance with Mayo Clinic Conflict of Interest policies. None of the other authors have any disclosures.

Background and Aims: We conducted an individual participant data (IPD) pooled analysis on the diagnostic accuracy of magnetic resonance elastography (MRE) to detect fibrosis stage in liver transplant recipients., Material and Methods: Through a systematic literature search, we identified studies on diagnostic performance of MRE for staging liver fibrosis, using liver biopsy as gold standard. We contacted study authors for published and unpublished IPD on age, sex, body mass index, liver stiffness, fibrosis stage, degree of inflammation and interval between MRE and biopsy; from these we limited analysis to patients who had undergone liver transplantation. Through pooled analysis using nonparametric two-stage receiver-operating curve (ROC) regression models, we calculated the cluster-adjusted AUROC, sensitivity and specificity of MRE for any (≥ stage 1), significant (≥ stage 2) and advanced fibrosis (≥ stage 3) and cirrhosis (stage 4)., Results: We included 6 cohorts (4 published and 2 unpublished series) reporting on 141 liver transplant recipients (mean age, 57 years; 75.2% male; mean BMI, 27.1 kg/m2). Fibrosis stage distribution stage 0, 1, 2, 3, or 4, was 37.6%, 23.4%, 24.8%, 12% and 2.2%, respectively. Mean AUROC values (and 95% confidence intervals) for diagnosis of any (≥ stage 1), significant (≥ stage 2), or advanced fibrosis (≥ stage 3) and cirrhosis were 0.73 (0.66-0.81), 0.69 (0.62-0.74), 0.83 (0.61-0.88) and 0.96 (0.93-0.98), respectively. Similar diagnostic performance was observed in stratified analysis based on sex, obesity and inflammation grade., Conclusions: In conclusion, MRE has high diagnostic accuracy for detection of advanced fibrosis and cirrhosis in liver transplant recipients, independent of BMI and degree of inflammation., Competing Interests: This research has been reviewed by the Mayo Clinic Conflict of Interest Review Board and is being conducted in compliance with Mayo Clinic Conflict of Interest policies.

Dissolution dynamic nuclear polarization (DNP) enables the metabolism of hyperpolarized (13)C-labelled molecules, such as the conversion of [1-(13)C]pyruvate to [1-(13)C]lactate, to be dynamically and non-invasively imaged in tissue. Imaging of this exchange reaction in animal models has been shown to detect early treatment response and correlate with tumour grade. The first human DNP study has recently been completed, and, for widespread clinical translation, simple and reliable methods are necessary to accurately probe the reaction in patients. However, there is currently no consensus on the most appropriate method to quantify this exchange reaction. In this study, an in vitro system was used to compare several kinetic models, as well as simple model-free methods. Experiments were performed using a clinical hyperpolarizer, a human 3 T MR system, and spectroscopic imaging sequences. The quantitative methods were compared in vivo by using subcutaneous breast tumours in rats to examine the effect of pyruvate inflow. The two-way kinetic model was the most accurate method for characterizing the exchange reaction in vitro, and the incorporation of a Heaviside step inflow profile was best able to describe the in vivo data. The lactate time-to-peak and the lactate-to-pyruvate area under the curve ratio were simple model-free approaches that accurately represented the full reaction, with the time-to-peak method performing indistinguishably from the best kinetic model. Finally, extracting data from a single pixel was a robust and reliable surrogate of the whole region of interest. This work has identified appropriate quantitative methods for future work in the analysis of human hyperpolarized (13)C data., (© 2016 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.)

Magnetic resonance elastography (MRE) is an innovative imaging technique for the non-invasive quantification of the biomechanical properties of soft tissues via the direct visualization of propagating shear waves in vivo using a modified phase-contrast magnetic resonance imaging (MRI) sequence. Fundamentally, MRE employs the same physical property that physicians utilize when performing manual palpation - that healthy and diseased tissues can be differentiated on the basis of widely differing mechanical stiffness. By performing "virtual palpation", MRE is able to provide information that is beyond the capabilities of conventional morphologic imaging modalities. In an era of increasing adoption of multi-parametric imaging approaches for solving complex problems, MRE can be seamlessly incorporated into a standard MRI examination to provide a rapid, reliable and comprehensive imaging evaluation at a single patient appointment. Originally described by the Mayo Clinic in 1995, the technique represents the most accurate non-invasive method for the detection and staging of liver fibrosis and is currently performed in more than 100 centers worldwide. In this general review, the mechanical properties of soft tissues, principles of MRE, clinical applications of MRE in the liver and beyond, and limitations and future directions of this discipline -are discussed. Selected diagrams and images are provided for illustration.

Objective: Hepatorenal syndrome (HRS) is the most lethal cause of renal impairment in cirrhosis. Magnetic resonance elastography (MRE) is a diagnostic test that characterises tissues based on their biomechanical properties. The aim of this study was to assess the feasibility of MRE for detecting HRS in cirrhotic patients., Methods: A prospective diagnostic investigation was performed. Renal MRE was performed on 21 hospitalised patients with cirrhosis and ascites. Six patients had HRS, one patient had non-HRS renal impairment, and 14 patients had normal renal function. The MRE-measured renal stiffness was compared against the clinical diagnosis as determined by clinical review alongside laboratory and radiologic results., Results: The MRE-measured renal stiffness was significantly lower in patients with HRS (median stiffness of 3.30 kPa at 90 Hz and 2.62 kPa at 60 Hz) compared with patients with normal renal function (median stiffness of 5.08 kPa at 90 Hz and 3.41 kPa at 60 Hz) (P ≤ 0.014). For the detection of HRS, MRE had an area under the receiver operating characteristic curve of 0.94 at 90 Hz and 0.89 at 60 Hz. MRE had excellent inter-rater agreement, as assessed by Bland-Altman and intraclass correlation coefficient (> 0.9)., Conclusion: MRE shows potential in the detection of HRS., Key Points: • Magnetic resonance elastography (MRE) shows promise in the detection of hepatorenal syndrome. • MRE has the potential to track renal disease in a clinical population. • MRE is a reliable diagnostic test with excellent inter-rater agreement.

Background: The detection of occult bone metastases is a key factor in determining the management of patients with renal cell carcinoma (RCC), especially when curative surgery is considered. This prospective study assessed the sensitivity of (18)F-labelled sodium fluoride in conjunction with positron emission tomography/computed tomography ((18)F-NaF PET/CT) for detecting RCC bone metastases, compared with conventional imaging by bone scintigraphy or CT., Patients and Methods: An adaptive two-stage trial design was utilized, which was stopped after the first stage due to statistical efficacy. Ten patients with stage IV RCC and bone metastases were imaged with (18)F-NaF PET/CT and (99m)Tc-labelled methylene diphosphonate ((99m)Tc-MDP) bone scintigraphy including pelvic single photon emission computed tomography (SPECT). Images were reported independently by experienced radiologists and nuclear medicine physicians using a 5-point scoring system., Results: Seventy-seven lesions were diagnosed as malignant: 100% were identified by (18)F-NaF PET/CT, 46% by CT and 29% by bone scintigraphy/SPECT. Standard-of-care imaging with CT and bone scintigraphy identified 65% of the metastases reported by (18)F-NaF PET/CT. On an individual patient basis, (18)F-NaF PET/CT detected more RCC metastases than (99m)Tc-MDP bone scintigraphy/SPECT or CT alone (P = 0.007). The metabolic volumes, mean and maximum standardized uptake values (SUV mean and SUV max) of the malignant lesions were significantly greater than those of the benign lesions (P < 0.001)., Conclusions: (18)F-NaF PET/CT is significantly more sensitive at detecting RCC skeletal metastases than conventional bone scintigraphy or CT. The detection of occult bone metastases could greatly alter patient management, particularly in the context when standard-of-care imaging is negative for skeletal metastases., (© The Author 2015. Published by Oxford University Press on behalf of the European Society for Medical Oncology.)

Background: To evaluate the reliability of MRE using a spin-echo echo-planar imaging (SE-EPI) renal MRE technique in healthy volunteers., Methods: Institutional review board approved prospective study in which all participants provided written informed consent. Sixteen healthy volunteers comprising seven males and nine females with a median age of 35 years (age range: 23 to 59 years) were included. Coronal 90 Hz and 60 Hz MRE acquisitions were performed twice within a 30-min interval between examinations. Renal MRE reliability was assessed by (i) test-retest repeatability, and (ii) inter-rater agreement between two independent readers. The MRE-measured averaged renal stiffness values were evaluated using: intraclass correlation coefficient (ICC), Bland-Altman and the within-subject coefficient of variation (COV)., Results: For test-retest repeatability, Bland-Altman showed a mean stiffness difference between examinations of 0.07 kPa (95% limits of agreement: -1.41, 1.54) at 90 Hz and 0.01 kPa (95% limits of agreement: -0.51, 0.53) at 60 Hz. Coefficient of repeatability was 1.47 kPa and 0.52 kPa at 90 Hz and 60 Hz, respectively. The within-subject COV was 13.6% and 7.7% at 90 Hz and 60 Hz, respectively. ICC values were 0.922 and 0.907 for test-retest repeatability and 0.998 and 0.989 for inter-rater agreement, respectively (P < 0.001)., Conclusion: SE-EPI renal MRE is a reliable technique., (© 2014 Wiley Periodicals, Inc.)

A variety of transplants have been performed in the abdomen including liver, kidney, pancreas and islet, bowel, and multivisceral transplants. Imaging plays an important role in graft surveillance particularly to exclude post-transplant complications. When complications occur, therapeutic image-guided interventions are invaluable as these may be graft-saving and even life-saving. Vascular complications following transplantation have been extensively reported in recent reviews. The focus of this review is to discuss post-transplant complications that are primarily extravascular in location. This includes biliary, urological, intestinal, malignancy, infections, and miscellaneous complications. Familiarity with the imaging appearances of these complications is helpful for radiologists as accurate diagnosis and expedient treatment has an impact on graft and patient survival., (Copyright © 2015 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Renal impairment is common in liver disease and may occur as a consequence of the pathophysiological changes that underpin cirrhosis or secondary to a pre-existing unrelated insult. Nevertheless, the onset of renal impairment often portends a worsening prognosis. Hepatorenal syndrome remains one of the most recognized and reported causes of renal impairment in cirrhosis. However, other causes of renal impairment occur and can be classified into prerenal, intrinsic or postrenal, which are the subjects of the present review.

Background & Aims: Magnetic resonance elastography (MRE) is a noninvasive tool for staging liver fibrosis. We conducted a meta-analysis of individual participant data collected from published studies to assess the diagnostic accuracy of MRE for staging liver fibrosis in patients with chronic liver diseases (CLD)., Methods: Through a systematic literature search of multiple databases (2003-2013), we identified studies on diagnostic performance of MRE for staging liver fibrosis in patients with CLD with native anatomy, using liver biopsy as the standard. We contacted study authors to collect data on each participant's age, sex, body mass index (BMI), liver stiffness (measured by MRE), fibrosis stage, staging system used, degree of inflammation, etiology of CLD, and interval between MRE and biopsy. Through a pooled analysis, we calculated cluster-adjusted area under the receiver-operating curve, sensitivity, and specificity of MRE for any fibrosis (≥stage 1), significant fibrosis (≥stage 2), advanced fibrosis (≥stage 3), and cirrhosis (stage 4)., Results: We analyzed data from 12 retrospective studies, comprising 697 patients (mean age, 55 ± 13 y; 59.4% male; mean BMI, 26.9 ± 6.7 kg/m(2); 92.1% with <1 year interval between MRE and biopsy; and 47.1% with hepatitis C). Overall, 19.5%, 19.4%, 15.5%, 15.9%, and 29.7% patients had stage 0, 1, 2, 3, and 4 fibrosis, respectively. The mean area under the receiver-operating curve values (and 95% confidence intervals) for the diagnosis of any (≥stage 1), significant (≥stage 2), advanced fibrosis (≥stage 3), and cirrhosis, were as follows: 0.84 (0.76-0.92), 0.88 (0.84-0.91), 0.93 (0.90-0.95), and 0.92 (0.90-0.94), respectively. A similar diagnostic performance was observed in stratified analysis based on sex, obesity, and etiology of CLD. The overall rate of failure of MRE was 4.3%., Conclusions: Based on a pooled analysis of data from individual participants, MRE has a high accuracy for the diagnosis of significant or advanced fibrosis and cirrhosis, independent of BMI and etiology of CLD. Prospective studies are warranted to better understand the diagnostic performance of MRE., (Copyright © 2015 AGA Institute. Published by Elsevier Inc. All rights reserved.)

This study introduces the use of 'error-category mapping' in the interpretation of pharmacokinetic (PK) model parameter results derived from dynamic contrast-enhanced (DCE-) MRI data. Eleven patients with metastatic renal cell carcinoma were enrolled in a multiparametric study of the treatment effects of bevacizumab. For the purposes of the present analysis, DCE-MRI data from two identical pre-treatment examinations were analysed by application of the extended Tofts model (eTM), using in turn a model arterial input function (AIF), an individually-measured AIF and a sample-average AIF. PK model parameter maps were calculated. Errors in the signal-to-gadolinium concentration ([Gd]) conversion process and the model-fitting process itself were assigned to category codes on a voxel-by-voxel basis, thereby forming a colour-coded 'error-category map' for each imaged slice. These maps were found to be repeatable between patient visits and showed that the eTM converged adequately in the majority of voxels in all the tumours studied. However, the maps also clearly indicated sub-regions of low Gd uptake and of non-convergence of the model in nearly all tumours. The non-physical condition ve ≥ 1 was the most frequently indicated error category and appeared sensitive to the form of AIF used. This simple method for visualisation of errors in DCE-MRI could be used as a routine quality-control technique and also has the potential to reveal otherwise hidden patterns of failure in PK model applications., (Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.)

Acute renal impairment is common in patients with chronic liver disease, occurring in approximately 19% of hospitalised patients with cirrhosis. A variety of types of renal impairment are recognised. The most important of these is the hepatorenal syndrome, a functional renal impairment due to circulatory and neurohormonal abnormalities that underpin cirrhosis. It is one of the most severe complications of cirrhosis with survival often measured in weeks to months. A variety of treatment options exist with early diagnosis and appropriate treatment providing the best hope for cure. This paper provides a comprehensive and up-to-date review of hepatorenal syndrome and lays out the topic according to the following sections: pathophysiology, historical developments, diagnostic criteria and limitations, epidemiology, precipitating factors, predictors, clinical and laboratory findings, prognosis, treatment options, prophylaxis, and conclusion.

Objectives: We have developed a new grading system for hip osteoarthritis using clinical computed tomography (CT). This technique was compared with Kellgren and Lawrence (K&L) grading and minimum joint space width (JSW) measurement in digitally reconstructed radiographs (DRRs) from the same CT data. In this paper we evaluate and compare the accuracy and reliability of these measures in the assessment of radiological disease., Design: CT imaging of hips from 30 female volunteers aged 66 ± 17 years were used in two reproducibility studies, one testing the reliability of the new system, the other testing K&L grading and minimum JSW measurement in DRRs., Results: Intra- and inter-observer reliability was substantial for CT grading according to weighted kappa (0.74 and 0.75 respectively), while intra- and inter-observer reliability was at worst moderate (0.57) and substantial (0.63) respectively for DRR K&L grading. Bland-Altman analysis showed a systematic difference in minimum JSW measurement of 0.82 mm between reviewers, with a least detectable difference of 1.06 mm. The area under the curve from ROC analysis was 0.91 for our CT composite score., Conclusions: CT grading of hip osteoarthritis (categorised as none, developing and established) has substantial reliability. Sensitivity was increased when CT features of osteoarthritis were assigned a composite score (0 = none to 7 = severest) that also performed well as a diagnostic test, but at the cost of reliability. Having established feasibility and reliability for this new CT system, sensitivity testing and validation against clinical measures of hip osteoarthritis will now be performed., (Copyright © 2014 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)

Objective: Plain radiography has been the mainstay of imaging assessment in osteoarthritis for over 50 years, but it does have limitations. Here we present the methodology and results of a new technique for identifying, grading, and mapping the severity and spatial distribution of osteoarthritic disease features at the hip in 3D with clinical computed tomography (CT)., Design: CT imaging of 456 hips from 230 adult female volunteers (mean age 66 ± 17 years) was reviewed using 3D multiplanar reformatting to identify bone-related radiological features of osteoarthritis, namely osteophytes, subchondral cysts and joint space narrowing. Scoresheets dividing up the femoral head, head-neck region and the joint space were used to register the location and severity of each feature (scored from 0 to 3). Novel 3D cumulative feature severity maps were then created to display where the most severe disease features from each individual were anatomically located across the cohort., Results: Feature severity maps showed a propensity for osteophytes at the inferoposterior and superolateral femoral head-neck junction. Subchondral cysts were a less common and less localised phenomenon. Joint space narrowing <1.5 mm was recorded in at least one sector of 83% of hips, but most frequently in the posterolateral joint space., Conclusions: This is the first description of hip osteoarthritis using unenhanced clinical CT in which we describe the co-localisation of posterior osteophytes and joint space narrowing for the first time. We believe this technique can perform several important roles in future osteoarthritis research, including phenotyping and sensitive disease assessment in 3D., (Copyright © 2014 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)

Background: The objective was to evaluate the use of fruit juice with an interactive inversion recovery (IR) MR pulse sequence to visualise the gastrointestinal tract., Methods: We investigated the relaxation properties of 12 different natural fruit juices in vitro, to identify which could be used as oral contrast. We then describe our initial experience using an interactive MR pulse sequence to allow optimal visualisation after administering pineapple juice orally, and suppressing pre-existing bowel fluid contents, with variable TI in three adult and one child volunteer., Results: Pineapple juice (PJ) had both the shortest T1 (243 ms) and shortest T2 (48 ms) of the fruit juices tested. Optimal signal differentiation between pre-existing bowel contents and oral PJ administration was obtained with TIs of between 900 and 1100 ms., Conclusion: The use of an inversion recovery preparation allowed long T1 pre-existing bowel contents to be suppressed whilst the short T1 of fruit juice acts as a positive contrast medium. Pineapple juice could be used as oral contrast agent for neonatal gastrointestinal magnetic resonance imaging.

Purpose: To compare the use of acceleration-dependent and velocity-dependent flow-preparation for non-contrast-enhanced magnetic resonance angiography (NCE-MRA), investigating both image quality and the ability to discriminate between arteries and veins. We develop an acceleration-dependent NCE-MRA method known as acceleration dependent vascular anatomy for non-contrast-enhanced MRA (ADVANCE-MRA)., Methods: Acceleration-dependent and velocity-dependent images were acquired using a constant and pulsatile flow-phantom and from the lower legs of six healthy volunteers and one patient with peripheral vascular disease. The volunteer images were assessed both by quantitative signal measurements and qualitative scoring by a radiologist., Results: In the phantom, acceleration-dependent preparation depicted pulsatile but not constant flow, while velocity-dependent preparation depicted both. In the volunteers and the patient, the velocity-dependent preparation was unable to separate the arterial and venous signals completely, with some overlap of arterial and venous signals for all acquired flow sensitizations whereas the acceleration-dependent preparation gave complete artery-vein separation over a wide range of flow sensitizations. Acceleration-dependent preparation received the best overall qualitative scores for arterial image quality and venous contamination., Conclusion: Acceleration-dependent NCE-MRA improves arterial image quality and reduces venous contamination, compared with velocity-dependent NCE-MRA, and warrants further investigation in patients., (Copyright © 2013 Wiley Periodicals, Inc.)