Publications by authors named "Vikas Gulani"

99 Publications

MR fingerprinting of the prostate.

MAGMA 2022 Apr 13. Epub 2022 Apr 13.

Department of Radiology, University of Michigan, University of Michigan Health System, 1500 E. Medical Center Drive, Ann Arbor, MI, 48109-5030, USA.

Multiparametric magnetic resonance imaging (mpMRI) has been adopted as the key tool for detection, localization, characterization, and risk stratification of patients suspected to have prostate cancer. Despite advantages over systematic biopsy, the interpretation of prostate mpMRI has limitations including a steep learning curve, leading to considerable interobserver variation. There is growing interest in clinical translation of quantitative imaging techniques for more objective lesion assessment. However, traditional mapping techniques are slow, precluding their use in the clinic. Magnetic resonance fingerprinting (MRF) is an efficient approach for quantitative maps of multiple tissue properties simultaneously. The T and T values obtained with MRF have been validated with phantom studies as well as in normal volunteers and patients. Studies have shown that MRF-derived T and T along with ADC values are all significant independent predictors in the differentiation between normal prostate tissue and prostate cancer, and hold promise in differentiating low and intermediate/high-grade cancers. This review seeks to introduce the basics of the prostate MRF technique, discuss the potential applications of prostate MRF for the characterization of prostate cancer, and describes ongoing areas of research.
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http://dx.doi.org/10.1007/s10334-022-01012-8DOI Listing
April 2022

Feasibility of Magnetic Resonance Fingerprinting on Aging MRI Hardware.

Tomography 2021 12 23;8(1):10-21. Epub 2021 Dec 23.

Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.

The purpose of this work is to evaluate the feasibility of performing magnetic resonance fingerprinting (MRF) on older and lower-performance MRI hardware as a means to bring advanced imaging to the aging MRI install base. Phantom and in vivo experiments were performed on a 1.5T Siemens Aera (installed 2015) and 1.5T Siemens Symphony (installed 2002). A 2D spiral MRF sequence for simultaneous T/T/M mapping was implemented on both scanners with different gradient trajectories to accommodate system specifications. In phantom, for T/T values in a physiologically relevant range (T: 195-1539 ms; T: 20-267 ms), scanners had strong correlation (R > 0.999) with average absolute percent difference of 8.1% and 10.1%, respectively. Comparison of the two trajectories on the newer scanner showed differences of 2.6% (T) and 10.9% (T), suggesting a partial explanation of the observed inter-scanner bias. Inter-scanner agreement was better when the same trajectory was used, with differences of 6.0% (T) and 4.0% (T). Intra-scanner coefficient of variation (CV) of T and T estimates in phantom were <2.0% and in vivo were ≤3.5%. In vivo inter-scanner white matter CV was 4.8% (T) and 5.1% (T). White matter measurements on the aging scanner after two months were consistent, with differences of 1.9% (T) and 3.9% (T). In conclusion, MRF is feasible on an aging MRI scanner and required only changes to the gradient trajectory.
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http://dx.doi.org/10.3390/tomography8010002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8788417PMC
December 2021

A System for Real-Time, Online Mixed-Reality Visualization of Cardiac Magnetic Resonance Images.

J Imaging 2021 Dec 14;7(12). Epub 2021 Dec 14.

Department of Radiology, University of Michigan, Ann Arbor, MI 48109, USA.

Image-guided cardiovascular interventions are rapidly evolving procedures that necessitate imaging systems capable of rapid data acquisition and low-latency image reconstruction and visualization. Compared to alternative modalities, Magnetic Resonance Imaging (MRI) is attractive for guidance in complex interventional settings thanks to excellent soft tissue contrast and large fields-of-view without exposure to ionizing radiation. However, most clinically deployed MRI sequences and visualization pipelines exhibit poor latency characteristics, and spatial integration of complex anatomy and device orientation can be challenging on conventional 2D displays. This work demonstrates a proof-of-concept system linking real-time cardiac MR image acquisition, online low-latency reconstruction, and a stereoscopic display to support further development in real-time MR-guided intervention. Data are acquired using an undersampled, radial trajectory and reconstructed via parallelized through-time radial generalized autocalibrating partially parallel acquisition (GRAPPA) implemented on graphics processing units. Images are rendered for display in a stereoscopic mixed-reality head-mounted display. The system is successfully tested by imaging standard cardiac views in healthy volunteers. Datasets comprised of one slice (46 ms), two slices (92 ms), and three slices (138 ms) are collected, with the acquisition time of each listed in parentheses. Images are displayed with latencies of 42 ms/frame or less for all three conditions. Volumetric data are acquired at one volume per heartbeat with acquisition times of 467 ms and 588 ms when 8 and 12 partitions are acquired, respectively. Volumes are displayed with a latency of 286 ms or less. The faster-than-acquisition latencies for both planar and volumetric display enable real-time 3D visualization of the heart.
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http://dx.doi.org/10.3390/jimaging7120274DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8709155PMC
December 2021

Magnetic Resonance Imaging During a Pandemic: Recommendations by the ISMRM Safety Committee.

J Magn Reson Imaging 2022 May 20;55(5):1322-1339. Epub 2021 Dec 20.

CUBRIC, School of Psychology, Cardiff University, Cardiff, UK.

The COVID-19 pandemic highlighted the challenges delivering face-to-face patient care across healthcare systems. In particular the COVID-19 pandemic challenged the imaging community to provide timely access to essential diagnostic imaging modalities while ensuring appropriate safeguards were in place for both patients and personnel. With increasing vaccine availability and greater prevalence of vaccination in communities worldwide we are finally emerging on the other side of the COVID-19 pandemic. As we learned from our institutional and healthcare system responses to the pandemic, maintaining timely access to MR imaging is essential. Radiologists and other imaging providers partnered with their referring providers to ensure that timely access to advanced MR imaging was maintained. On behalf of the International Magnetic Resonance in Medicine (ISMRM) Safety Committee, this white paper is intended to serve as a guide for radiology departments, imaging centers, and other imaging specialists who perform MR imaging to refer to as we prepare for the next pandemic. Lessons learned including strategies to triage and prioritize MR imaging research during a pandemic are discussed. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 5.
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http://dx.doi.org/10.1002/jmri.28006DOI Listing
May 2022

Diagnostic Yield of Incremental Biopsy Cores and Second Lesion Sampling for In-Gantry MRI-Guided Prostate Biopsy.

AJR Am J Roentgenol 2021 10 18;217(4):908-918. Epub 2020 Dec 18.

Department of Radiology, University of Michigan Health System, UH B1G503, 1500 E Medical Center Dr, Ann Arbor, MI 48109.

In-gantry MRI-guided biopsy (MRGB) of the prostate has been shown to be more accurate than other targeted prostate biopsy methods. However, the optimal number of cores to obtain during in-gantry MRGB remains undetermined. The purpose of this study was to assess the diagnostic yield of obtaining an incremental number of cores from the primary lesion and of second lesion sampling during in-gantry MRGB of the prostate. This retrospective study included 128 men with 163 prostate lesions who underwent in-gantry MRGB between 2016 and 2019. The men had a total of 163 lesions sampled with two or more cores, 121 lesions sampled with three or more cores, and 52 lesions sampled with four or more cores. A total of 40 men underwent sampling of a second lesion. Upgrade on a given core was defined as a greater International Society of Urological Pathology (ISUP) grade group (GG) relative to the previously obtained cores. Clinically significant prostate cancer (csPCa) was defined as ISUP GG 2 or greater. The frequency of any upgrade was 12.9% (21/163) on core 2 versus 10.7% (13/121) on core 3 ( = .29 relative to core 2) and 1.9% (1/52) on core 4 ( = .03 relative to core 3). The frequency of upgrade to csPCa was 7.4% (12/163) on core 2 versus 4.1% (5/121) on core 3 ( = .13 relative to core 2) and 0% (0/52) on core 4 ( = .07 relative to core 3). The frequency of upgrade on core 2 was higher for anterior lesions ( < .001) and lesions with a higher PI-RADS score ( = .007); the frequency of upgrade on core 3 was higher for apical lesions ( = .01) and lesions with a higher PI-RADS score ( = .01). Sampling of a second lesion resulted in an upgrade in a single patient (2.5%; 1/40); both lesions were PI-RADS category 4 and showed csPCa. When performing in-gantry MRGB of the prostate, obtaining three cores from the primary lesion is warranted to optimize csPCa diagnosis. Obtaining a fourth core from the primary lesion or sampling a second lesion has very low yield in upgrading cancer diagnoses. To reduce patient discomfort and procedure times, operators may refrain from obtaining more than three cores or second lesion sampling.
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http://dx.doi.org/10.2214/AJR.20.24918DOI Listing
October 2021

Radiomic analysis of magnetic resonance fingerprinting in adult brain tumors.

Eur J Nucl Med Mol Imaging 2021 03 26;48(3):683-693. Epub 2020 Sep 26.

Department of Radiology, Case Western Reserve University and University Hospitals of Cleveland, 11100 Euclid Ave, Cleveland, OH, 44106, USA.

Purpose: This is a radiomics study investigating the ability of texture analysis of MRF maps to improve differentiation between intra-axial adult brain tumors and to predict survival in the glioblastoma cohort.

Methods: Magnetic resonance fingerprinting (MRF) acquisition was performed on 31 patients across 3 groups: 17 glioblastomas, 6 low-grade gliomas, and 8 metastases. Using regions of interest for the solid tumor and peritumoral white matter on T1 and T2 maps, second-order texture features were calculated from gray-level co-occurrence matrices and gray-level run length matrices. Selected features were compared across the three tumor groups using Wilcoxon rank-sum test. Receiver operating characteristic curve analysis was performed for each feature. Kaplan-Meier method was used for survival analysis with log rank tests.

Results: Low-grade gliomas and glioblastomas had significantly higher run percentage, run entropy, and information measure of correlation 1 on T1 than metastases (p < 0.017). The best separation of all three tumor types was seen utilizing inverse difference normalized and homogeneity values for peritumoral white matter in both T1 and T2 maps (p < 0.017). In solid tumor T2 maps, lower values in entropy and higher values of maximum probability and high-gray run emphasis were associated with longer survival in glioblastoma patients (p < 0.05). Several texture features were associated with longer survival in glioblastoma patients on peritumoral white matter T1 maps (p < 0.05).

Conclusion: Texture analysis of MRF-derived maps can improve our ability to differentiate common adult brain tumors by characterizing tumor heterogeneity, and may have a role in predicting outcomes in patients with glioblastoma.
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http://dx.doi.org/10.1007/s00259-020-05037-wDOI Listing
March 2021

T1 and T2 MR fingerprinting measurements of prostate cancer and prostatitis correlate with deep learning-derived estimates of epithelium, lumen, and stromal composition on corresponding whole mount histopathology.

Eur Radiol 2021 Mar 2;31(3):1336-1346. Epub 2020 Sep 2.

Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, 44106, USA.

Objectives: To explore the associations between T1 and T2 magnetic resonance fingerprinting (MRF) measurements and corresponding tissue compartment ratios (TCRs) on whole mount histopathology of prostate cancer (PCa) and prostatitis.

Materials And Methods: A retrospective, IRB-approved, HIPAA-compliant cohort consisting of 14 PCa patients who underwent 3 T multiparametric MRI along with T1 and T2 MRF maps prior to radical prostatectomy was used. Correspondences between whole mount specimens and MRI and MRF were manually established. Prostatitis, PCa, and normal peripheral zone (PZ) regions of interest (ROIs) on pathology were segmented for TCRs of epithelium, lumen, and stroma using two U-net deep learning models. Corresponding ROIs were mapped to T2-weighted MRI (T2w), apparent diffusion coefficient (ADC), and T1 and T2 MRF maps. Their correlations with TCRs were computed using Pearson's correlation coefficient (R). Statistically significant differences in means were assessed using one-way ANOVA.

Results: Statistically significant differences (p < 0.01) in means of TCRs and T1 and T2 MRF were observed between PCa, prostatitis, and normal PZ. A negative correlation was observed between T1 and T2 MRF and epithelium (R = - 0.38, - 0.44, p < 0.05) of PCa. T1 MRF was correlated in opposite directions with stroma of PCa and prostatitis (R = 0.35, - 0.44, p < 0.05). T2 MRF was positively correlated with lumen of PCa and prostatitis (R = 0.57, 0.46, p < 0.01). Mean T2 MRF showed significant differences (p < 0.01) between PCa and prostatitis across both transition zone (TZ) and PZ, while mean T1 MRF was significant (p = 0.02) in TZ.

Conclusion: Significant associations between MRF (T1 in the TZ and T2 in the PZ) and tissue compartments on corresponding histopathology were observed.

Key Points: • Mean T2 MRF measurements and ADC within cancerous regions of interest dropped with increasing ISUP prognostic groups (IPG). • Mean T1 and T2 MRF measurements were significantly different (p < 0.001) across IPGs, prostatitis, and normal peripheral zone (NPZ). • T2 MRF showed stronger correlations in the peripheral zone, while T1 MRF showed stronger correlations in the transition zone with histopathology for prostate cancer.
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http://dx.doi.org/10.1007/s00330-020-07214-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7882016PMC
March 2021

Magnetic Resonance Fingerprinting: Implications and Opportunities for PET/MR.

IEEE Trans Radiat Plasma Med Sci 2019 Jul 4;3(4):388-399. Epub 2019 Feb 4.

Department of Radiology, Case Western Reserve University, Cleveland, OH 44106 USA.

Magnetic Resonance Imaging (MRI) can be used to assess anatomical structure, and its sensitivity to a variety of tissue properties enables superb contrast between tissues as well as the ability to characterize these tissues. However, despite vast potential for quantitative and functional evaluation, MRI is typically used qualitatively, in which the underlying tissue properties are not measured, and thus the brightness of each pixel is not quantitatively meaningful. Positron Emission Tomography (PET) is an inherently quantitative imaging modality that interrogates functional activity within a tissue, probed by a molecule of interest coupled with an appropriate tracer. These modalities can complement one another to provide clinical information regarding both structure and function, but there are still technical and practical hurdles in the way of the integrated use of both modalities. Recent advances in MRI have moved the field in an increasingly quantitative direction, which is complementary to PET, and could also potentially help solve some of the challenges in PET/MR. Magnetic Resonance Fingerprinting (MRF) is a recently described MRI-based technique which can efficiently and simultaneously quantitatively map several tissue properties in a single exam. Here, the basic principles behind the quantitative approach of MRF are laid out, and the potential implications for combined PET/MR are discussed.
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http://dx.doi.org/10.1109/trpms.2019.2897425DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7454032PMC
July 2019

Recommendations for Imaging Patients With Cardiac Implantable Electronic Devices (CIEDs).

J Magn Reson Imaging 2021 05 17;53(5):1311-1317. Epub 2020 Aug 17.

Department of Radiology, University of Michigan, Ann Arbor, Michigan, USA.

Historically, the presence of cardiac implantable electronic devices (CIEDs), including pacemakers and implantable cardioverter defibrillators (ICDs), was widely considered an absolute contraindication to magnetic resonance imaging (MRI). The recent development of CIEDs with MR Conditional labeling, as well as encouraging results from retrospective studies and a prospective trial on the safety of MRI performed in patients with CIEDs without MR Conditional labeling, have led to a reevaluation of this practice. The purpose of this report is to provide a concise summary of recent developments, including practical guidelines that an institution could adopt for radiologists who choose to image patients with CIEDs that do not have MR Conditional labeling. This report was written on behalf of and approved by the International Society for Magnetic Resonance in Medicine (ISMRM) Safety Committee. LEVEL OF EVIDENCE: 3. TECHNICAL EFFICACY STAGE: 1.
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http://dx.doi.org/10.1002/jmri.27320DOI Listing
May 2021

Quantifying Perfusion Properties with DCE-MRI Using a Dictionary Matching Approach.

Sci Rep 2020 06 23;10(1):10210. Epub 2020 Jun 23.

Department of Radiology, University of Michigan, Ann Arbor, Michigan, USA.

Perfusion properties can be estimated from pharmacokinetic models applied to DCE-MRI data using curve fitting algorithms; however, these suffer from drawbacks including the local minimum problem and substantial computational time. Here, a dictionary matching approach is proposed as an alternative. Curve fitting and dictionary matching were applied to simulated data using the dual-input single-compartment model with known perfusion property values and 5 in vivo DCE-MRI datasets. In simulation at SNR 60 dB, the dictionary estimate had a mean percent error of 0.4-1.0% for arterial fraction, 0.5-1.4% for distribution volume, and 0.0% for mean transit time. The curve fitting estimate had a mean percent error of 1.1-2.1% for arterial fraction, 0.5-1.3% for distribution volume, and 0.2-1.8% for mean transit time. In vivo, dictionary matching and curve fitting showed no statistically significant differences in any of the perfusion property measurements in any of the 10 ROIs between the methods. In vivo, the dictionary method performed over 140-fold faster than curve fitting, obtaining whole volume perfusion maps in just over 10 s. This study establishes the feasibility of using a dictionary matching approach as a new and faster way of estimating perfusion properties from pharmacokinetic models in DCE-MRI.
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http://dx.doi.org/10.1038/s41598-020-66985-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7311534PMC
June 2020

Simultaneous Mapping of T and T Using Cardiac Magnetic Resonance Fingerprinting in a Cohort of Healthy Subjects at 1.5T.

J Magn Reson Imaging 2020 10 28;52(4):1044-1052. Epub 2020 Mar 28.

Department of Radiology, University of Michigan, Ann Arbor, Michigan, USA.

Background: Cardiac MR fingerprinting (cMRF) is a novel technique for simultaneous T and T mapping.

Purpose: To compare T /T measurements, repeatability, and map quality between cMRF and standard mapping techniques in healthy subjects.

Study Type: Prospective.

Population: In all, 58 subjects (ages 18-60). FIELD STRENGTH/SEQUENCE: cMRF, modified Look-Locker inversion recovery (MOLLI), and T -prepared balanced steady-state free precession (bSSFP) at 1.5T.

Assessment: T /T values were measured in 16 myocardial segments at apical, medial, and basal slice positions. Test-retest and intrareader repeatability were assessed for the medial slice. cMRF and conventional mapping sequences were compared using ordinal and two alternative forced choice (2AFC) ratings.

Statistical Tests: Paired t-tests, Bland-Altman analyses, intraclass correlation coefficient (ICC), linear regression, one-way analysis of variance (ANOVA), and binomial tests.

Results: Average T measurements were: basal 1007.4±96.5 msec (cMRF), 990.0±45.3 msec (MOLLI); medial 995.0±101.7 msec (cMRF), 995.6±59.7 msec (MOLLI); apical 1006.6±111.2 msec (cMRF); and 981.6±87.6 msec (MOLLI). Average T measurements were: basal 40.9±7.0 msec (cMRF), 46.1±3.5 msec (bSSFP); medial 41.0±6.4 msec (cMRF), 47.4±4.1 msec (bSSFP); apical 43.5±6.7 msec (cMRF), 48.0±4.0 msec (bSSFP). A statistically significant bias (cMRF T larger than MOLLI T ) was observed in basal (17.4 msec) and apical (25.0 msec) slices. For T , a statistically significant bias (cMRF lower than bSSFP) was observed for basal (-5.2 msec), medial (-6.3 msec), and apical (-4.5 msec) slices. Precision was lower for cMRF-the average of the standard deviation measured within each slice was 102 msec for cMRF vs. 61 msec for MOLLI T , and 6.4 msec for cMRF vs. 4.0 msec for bSSFP T . cMRF and conventional techniques had similar test-retest repeatability as quantified by ICC (0.87 cMRF vs. 0.84 MOLLI for T ; 0.85 cMRF vs. 0.85 bSSFP for T ). In the ordinal image quality comparison, cMRF maps scored higher than conventional sequences for both T (all five features) and T (four features).

Data Conclusion: This work reports on myocardial T /T measurements in healthy subjects using cMRF and standard mapping sequences. cMRF had slightly lower precision, similar test-retest and intrareader repeatability, and higher scores for map quality.

Evidence Level: 2 TECHNICAL EFFICACY: Stage 1 J. Magn. Reson. Imaging 2020;52:1044-1052.
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http://dx.doi.org/10.1002/jmri.27155DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7772954PMC
October 2020

Non-invasive tumor decoding and phenotyping of cerebral gliomas utilizing multiparametric F-FET PET-MRI and MR Fingerprinting.

Eur J Nucl Med Mol Imaging 2020 06 6;47(6):1435-1445. Epub 2019 Dec 6.

Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Hufelandstraße 55, 45147, Essen, Germany.

Objectives: The introduction of the 2016 WHO classification of CNS tumors has made the combined molecular and histopathological characterization of tumors a pivotal part of glioma patient management. Recent publications on radiogenomics-based prediction of the mutational status have demonstrated the predictive potential of imaging-based, non-invasive tissue characterization algorithms. Hence, the aim of this study was to assess the potential of multiparametric F-FET PET-MRI including MR fingerprinting accelerated with machine learning and radiomic algorithms to predict tumor grading and mutational status of patients with cerebral gliomas.

Materials And Methods: 42 patients with suspected primary brain tumor without prior surgical or systemic treatment or biopsy underwent an F-FET PET-MRI examination. To differentiate the mutational status and the WHO grade of the cerebral tumors, support vector machine and random forest were trained with the radiomics signature of the multiparametric PET-MRI data including MR fingerprinting. Surgical sampling served as a gold standard for histopathological reference and assessment of mutational status.

Results: The 5-fold cross-validated area under the curve in predicting the ATRX mutation was 85.1%, MGMT mutation was 75.7%, IDH1 was 88.7%, and 1p19q was 97.8%. The area under the curve of differentiating low-grade glioma vs. high-grade glioma was 85.2%.

Conclusion: F-FET PET-MRI and MR fingerprinting enable high-quality imaging-based tumor decoding and phenotyping for differentiation of low-grade vs. high-grade gliomas and for prediction of the mutational status of ATRX, IDH1, and 1p19q. These initial results underline the potential of F-FET PET-MRI to serve as an alternative to invasive tissue characterization.
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http://dx.doi.org/10.1007/s00259-019-04602-2DOI Listing
June 2020

Editorial on "ACR Guidance Document on MR Safe Practices: Updates and Critical Information 2019".

J Magn Reson Imaging 2020 02 25;51(2):339-340. Epub 2019 Nov 25.

Department of Radiology, University of Michigan, Ann Arbor, Michigan, USA.

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http://dx.doi.org/10.1002/jmri.26990DOI Listing
February 2020

Magnetic Resonance Fingerprinting to Characterize Childhood and Young Adult Brain Tumors.

Pediatr Neurosurg 2019 15;54(5):310-318. Epub 2019 Aug 15.

Department of Radiology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA.

Object: Magnetic resonance fingerprinting (MRF) allows rapid, simultaneous mapping of T1 and T2 relaxation times and may be an important diagnostic tool to measure tissue characteristics in pediatric brain tumors. We examined children and young adults with primary brain tumors to determine whether MRF can discriminate tumor from normal-appearing white matter and distinguish tumor grade.

Methods: MRF was performed in 23 patients (14 children and 9 young adults) with brain tumors (19 low-grade glioma, 4 high-grade tumors). T1 and T2 values were recorded in regions of solid tumor (ST), peritumoral white matter (PWM), and contralateral white matter (CWM). Nonparametric tests were used for comparison between groups and regions.

Results: Median scan time for MRF and a sequence for tumor localization was 11 min. MRF-derived T1 and T2 values distinguished ST from CWM (T1: 1,444 ± 254 ms vs. 938 ± 96 ms, p = 0.0002; T2: 61 ± 22 ms vs. 38 ± 9 ms, p = 0.0003) and separated high-grade tumors from low-grade tumors (T1: 1,863 ± 70 ms vs. 1,355 ± 187 ms, p = 0.007; T2: 90 ± 13 ms vs. 56 ± 19 ms, p = 0.013). PWM was distinct from CWM (T1: 1,261 ± 359 ms vs. 933 ± 104 ms, p = 0.0008; T2: 65 ± 51 ms vs. 38 ± 8 ms, p = 0.008), as well as from tumor (T1: 1,261 ± 371 ms vs. 1,462 ± 248 ms, p = 0.047).

Conclusions: MRF is a fast sequence that can rapidly distinguish important tissue components in pediatric brain tumor patients. MRF-derived T1 and T2 distinguished tumor from normal-appearing white matter, differentiated tumor grade, and found abnormalities in peritumoral regions. MRF may be useful for rapid quantitative measurement of tissue characteristics and distinguish tumor grade in children and young adults with brain tumors.
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http://dx.doi.org/10.1159/000501696DOI Listing
March 2020

Magnetic resonance fingerprinting review part 2: Technique and directions.

J Magn Reson Imaging 2020 04 25;51(4):993-1007. Epub 2019 Jul 25.

Department of Radiology, Case Western Reserve University, Cleveland, Ohio, USA.

Magnetic resonance fingerprinting (MRF) is a general framework to quantify multiple MR-sensitive tissue properties with a single acquisition. There have been numerous advances in MRF in the years since its inception. In this work we highlight some of the recent technical developments in MRF, focusing on sequence optimization, modifications for reconstruction and pattern matching, new methods for partial volume analysis, and applications of machine and deep learning. Level of Evidence: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:993-1007.
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http://dx.doi.org/10.1002/jmri.26877DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6980890PMC
April 2020

MR Fingerprinting and ADC Mapping for Characterization of Lesions in the Transition Zone of the Prostate Gland.

Radiology 2019 09 23;292(3):685-694. Epub 2019 Jul 23.

From the Department of Radiology, Mayo Clinic, Rochester, Minn (A.P.); Department of Diagnostic, Interventional and Pediatric Radiology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland (V.C.O.); Departments of Biomedical Engineering (W.C.L., M.A.G.), Epidemiology and Biostatistics (S.M., M.S.), and Radiology (Y.J., C.B., M.A.G., V.G.), Case Western Reserve University, Cleveland, Ohio; Department of Radiology, University of Michigan, UH B1 G503, 1500 E. Medical Center Drive, SPC 5030, Ann Arbor, MI 48109-5030 (Y.J., V.G.); Department of Radiology, Mayo Clinic, Phoenix, Az (I.J.P.); Departments of Radiology (I.J.P., D.N., C.B., M.A.G.) and Urology (I.J., L.E.P.), University Hospitals Cleveland Medical Center, Cleveland, Ohio.

BackgroundPreliminary studies have shown that MR fingerprinting-based relaxometry combined with apparent diffusion coefficient (ADC) mapping can be used to differentiate normal peripheral zone from prostate cancer and prostatitis. The utility of relaxometry and ADC mapping for the transition zone (TZ) is unknown.PurposeTo evaluate the utility of MR fingerprinting combined with ADC mapping for characterizing TZ lesions.Materials and MethodsTZ lesions that were suspicious for cancer in men who underwent MRI with T2-weighted imaging and ADC mapping ( values, 50-1400 sec/mm), MR fingerprinting with steady-state free precession, and targeted biopsy (60 in-gantry and 15 cognitive targeting) between September 2014 and August 2018 in a single university hospital were retrospectively analyzed. Two radiologists blinded to Prostate Imaging Reporting and Data System (PI-RADS) scores and pathologic diagnosis drew regions of interest on cancer-suspicious lesions and contralateral visually normal TZs (NTZs) on MR fingerprinting and ADC maps. Linear mixed models compared two-reader means of T1, T2, and ADC. Generalized estimating equations logistic regression analysis was used to evaluate both MR fingerprinting and ADC in differentiating NTZ, cancers and noncancers, clinically significant (Gleason score ≥ 7) cancers from clinically insignificant lesions (noncancers and Gleason 6 cancers), and characterizing PI-RADS version 2 category 3 lesions.ResultsIn 67 men (mean age, 66 years ± 8 [standard deviation]) with 75 lesions, targeted biopsy revealed 37 cancers (six PI-RADS category 3 cancers and 31 PI-RADS category 4 or 5 cancers) and 38 noncancers (31 PI-RADS category 3 lesions and seven PI-RADS category 4 or 5 lesions). The T1, T2, and ADC of NTZ (1800 msec ± 150, 65 msec ± 22, and [1.13 ± 0.19] × 10 mm/sec, respectively) were higher than those in cancers (1450 msec ± 110, 36 msec ± 11, and [0.57 ± 0.13] × 10 mm/sec, respectively; < .001 for all). The T1, T2, and ADC in cancers were lower than those in noncancers (1620 msec ± 120, 47 msec ± 16, and [0.82 ± 0.13] × 10 mm/sec, respectively; = .001 for T1 and ADC and = .03 for T2). The area under the receiver operating characteristic curve (AUC) for T1 plus ADC was 0.94 for separation. T1 and ADC in clinically significant cancers (1440 msec ± 140 and [0.58 ± 0.14] × 10 mm/sec, respectively) were lower than those in clinically insignificant lesions (1580 msec ± 120 and [0.75 ± 0.17] × 10 mm/sec, respectively; = .001 for all). The AUC for T1 plus ADC was 0.81 for separation. Within PI-RADS category 3 lesions, T1 and ADC of cancers (1430 msec ± 220 and [0.60 ± 0.17] × 10 mm/sec, respectively) were lower than those of noncancers (1630 msec ± 120 and [0.81 ± 0.13] × 10 mm/sec, respectively; = .006 for T1 and = .004 for ADC). The AUC for T1 was 0.79 for differentiating category 3 lesions.ConclusionMR fingerprinting-based relaxometry combined with apparent diffusion coefficient mapping may improve transition zone lesion characterization.© RSNA, 2019
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http://dx.doi.org/10.1148/radiol.2019181705DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6716564PMC
September 2019

Magnetic resonance fingerprinting Part 1: Potential uses, current challenges, and recommendations.

J Magn Reson Imaging 2020 03 2;51(3):675-692. Epub 2019 Jul 2.

Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado, USA.

Magnetic resonance fingerprinting (MRF) is a powerful quantitative MRI technique capable of acquiring multiple property maps simultaneously in a short timeframe. The MRF framework has been adapted to a wide variety of clinical applications, but faces challenges in technical development, and to date has only demonstrated repeatability and reproducibility in small studies. In this review, we discuss the current implementations of MRF and their use in a clinical setting. Based on this analysis, we highlight areas of need that must be addressed before MRF can be fully adopted into the clinic and make recommendations to the MRF community on standardization and validation strategies of MRF techniques. Level of Evidence: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:675-692.
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http://dx.doi.org/10.1002/jmri.26836DOI Listing
March 2020

Reproducibility and Repeatability of MR Fingerprinting Relaxometry in the Human Brain.

Radiology 2019 08 18;292(2):429-437. Epub 2019 Jun 18.

From Siemens Healthcare, Allee am Roethelheimpark 2, 91052 Erlangen, Germany (G.K., R.K., J.P., M.N.); Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany (G.K., B.H.); Siemens Medical Solutions USA, Malvern, Pa (K.L.); Departments of Biomedical Engineering (Y.J., D.M., M. Griswold, V.G.) and Radiology (M. Griswold, V.G.), Case Western Reserve University, Cleveland, Ohio; Department of High Field and Hybrid MR Imaging, University Hospital Essen, Essen, Germany (M. Gratz); Erwin L. Hahn Institute for MRI, University Duisburg-Essen, Essen, Germany (M. Gratz); Department of Biomedical Imaging and Image-guided Therapy, High Field Magnetic Resonance Center, Medical University of Vienna, Vienna, Austria (P.B., W.B., E.S., P.L.C., S.T.); Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany (L.U.); and Christian Doppler Laboratory for Clinical Molecular MR Imaging, MOLIMA, Vienna, Austria (W.B., S.T.).

Background Only sparse literature investigates the reproducibility and repeatability of relaxometry methods in MRI. However, statistical data on reproducibility and repeatability of any quantitative method is essential for clinical application. Purpose To evaluate the reproducibility and repeatability of two-dimensional fast imaging with steady-state free precession MR fingerprinting in vivo in human brains. Materials and Methods Two-dimensional section-selective MR fingerprinting based on a steady-state free precession sequence with an external radiofrequency transmit field, or , correction was used to generate T1 and T2 maps. This prospective study was conducted between July 2017 and January 2018 with 10 scanners from a single manufacturer, including different models, at four different sites. T1 and T2 relaxation times and their variation across scanners (reproducibility) as well as across repetitions on a scanner (repeatability) were analyzed. The relative deviations of T1 and T2 to the average (95% confidence interval) were calculated for several brain compartments. Results Ten healthy volunteers (mean age ± standard deviation, 28.5 years ± 6.9; eight men, two women) participated in this study. Reproducibility and repeatability of T1 and T2 measures in the human brain varied across brain compartments (1.8%-20.9%) and were higher in solid tissues than in the cerebrospinal fluid. T1 measures in solid tissue brain compartments were more stable compared with T2 measures. The half-widths of the confidence intervals for relative deviations were 3.4% for mean T1 and 8.0% for mean T2 values across scanners. Intrascanner repeatability half-widths of the confidence intervals for relative deviations were in the range of 2.0%-3.1% for T1 and 3.1%-7.9% for T2. Conclusion This study provides values on reproducibility and repeatability of T1 and T2 relaxometry measured with fast imaging with steady-state free precession MR fingerprinting in brain tissues of healthy volunteers. Reproducibility and repeatability are considerably higher in solid brain compartments than in cerebrospinal fluid and are higher for T1 than for T2. © RSNA, 2019 See also the editorial by Barkhof and Parker in this issue.
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http://dx.doi.org/10.1148/radiol.2019182360DOI Listing
August 2019

Observed racial disparity in the negative predictive value of multi-parametric MRI for the diagnosis for prostate cancer.

Int Urol Nephrol 2019 Aug 2;51(8):1343-1348. Epub 2019 May 2.

Division of Urologic Oncology, Urology Institute, University Hospitals Cleveland Medical Center, 11100 Euclid Avenue, Lakeside Building Suite 4954, Mailstop LKS 5046, Cleveland, OH, 44106, USA.

Objective: To evaluate the trend that despite recent advances in the screening, diagnosis, and management of prostate cancer (PCa), African-Americans (AAs) continue to have poorer outcomes compared to their Caucasian (CAU) counterparts. The reason for this may be rooted in biological differences in the cancer between the two groups; however, there may be some inherent disparities within the efficacy of the screening modalities. In this study, we aim to evaluate the negative predictive value (NPV) of multi-parametric MRI (mpMRI) between AA compared to CAUs.

Methods: All mpMRI between January 2014 and June 2017 were evaluated. The MRIs were read by dedicated genitourinary radiologists. Subsequently, the readings were correlated to final pathology after the patients underwent radical prostatectomy. The NPV and negative likelihood ratios (-LR) of mpMRI were evaluated in AAs versus CAUs based on four cutoffs (≥ Grade I, ≥ Grade II, ≥ Grade III and ≥ Grade IV).

Results: The mpMRI was almost equally as effective between AAs and CAUs in excluding Grade III (NPV = 89 and 94, respectively), and Grade IV or above (NPV = 96 and 98, respectively) PCa; however, the NPV of mpMRI was significantly lower for Grade I (NPV = 32 and 52, respectively) and Grade II (NPV = 50 and 79, respectively) PCa.

Conclusion: Despite advances in the screening for PCa, there are disparities noted in the efficacy of screening tools between AAs and CAUs. For this reason, patients should be risk stratified and their screening results should be evaluated with consideration given to their baseline risk.
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http://dx.doi.org/10.1007/s11255-019-02158-6DOI Listing
August 2019

Targeted Biopsy Validation of Peripheral Zone Prostate Cancer Characterization With Magnetic Resonance Fingerprinting and Diffusion Mapping.

Invest Radiol 2019 08;54(8):485-493

Case Western University School of Medicine, Departments of.

Objective: This study aims for targeted biopsy validation of magnetic resonance fingerprinting (MRF) and diffusion mapping for characterizing peripheral zone (PZ) prostate cancer and noncancers.

Materials And Methods: One hundred four PZ lesions in 85 patients who underwent magnetic resonance imaging were retrospectively analyzed with apparent diffusion coefficient (ADC) mapping, MRF, and targeted biopsy (cognitive or in-gantry). A radiologist blinded to pathology drew regions of interest on targeted lesions and visually normal peripheral zone on MRF and ADC maps. Mean T1, T2, and ADC were analyzed using linear mixed models. Generalized estimating equations logistic regression analyses were used to evaluate T1 and T2 relaxometry combined with ADC in differentiating pathologic groups.

Results: Targeted biopsy revealed 63 cancers (low-grade cancer/Gleason score 6 = 10, clinically significant cancer/Gleason score ≥7 = 53), 15 prostatitis, and 26 negative biopsies. Prostate cancer T1, T2, and ADC (mean ± SD, 1660 ± 270 milliseconds, 56 ± 20 milliseconds, 0.70 × 10 ± 0.24 × 10 mm/s) were significantly lower than prostatitis (mean ± SD, 1730 ± 350 milliseconds, 77 ± 36 milliseconds, 1.00 × 10 ± 0.30 × 10 mm/s) and negative biopsies (mean ± SD, 1810 ± 250 milliseconds, 71 ± 37 milliseconds, 1.00 × 10 ± 0.33 × 10 mm/s). For cancer versus prostatitis, ADC was sensitive and T2 specific with comparable area under curve (AUC; (AUCT2 = 0.71, AUCADC = 0.79, difference between AUCs not significant P = 0.37). T1 + ADC (AUCT1 + ADC = 0.83) provided the best separation between cancer and negative biopsies. Low-grade cancer T2 and ADC (mean ± SD, 75 ± 29 milliseconds, 0.96 × 10 ± 0.34 × 10 mm/s) were significantly higher than clinically significant cancers (mean ± SD, 52 ± 16 milliseconds, 0.65 ± 0.18 × 10 mm/s), and T2 + ADC (AUCT2 + ADC = 0.91) provided the best separation.

Conclusions: T1 and T2 relaxometry combined with ADC mapping may be useful for quantitative characterization of prostate cancer grades and differentiating cancer from noncancers for PZ lesions seen on T2-weighted images.
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http://dx.doi.org/10.1097/RLI.0000000000000569DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6602844PMC
August 2019

Repeatability and reproducibility of 3D MR fingerprinting relaxometry measurements in normal breast tissue.

J Magn Reson Imaging 2019 10 20;50(4):1133-1143. Epub 2019 Mar 20.

Department of Radiology, Case Western Reserve University, Cleveland, Ohio, USA.

Background: The 3D breast magnetic resonance fingerprinting (MRF) technique enables T and T mapping in breast tissues. Combined repeatability and reproducibility studies on breast T and T relaxometry are lacking.

Purpose: To assess test-retest and two-visit repeatability and interscanner reproducibility of the 3D breast MRF technique in a single-institution setting.

Study Type: Prospective.

Subjects: Eighteen women (median age 29 years, range, 22-33 years) underwent Visit 1 scans on scanner 1. Ten of these women underwent test-retest scan repositioning after a 10-minute interval. Thirteen women had Visit 2 scans within 7-15 days in same menstrual cycle. The remaining five women had Visit 2 scans in the same menstrual phase in next menstrual cycle. Five women were also scanned on scanner 2 at both visits for interscanner reproducibility.

Field Strength/sequence: Two 3T MR scanners with the 3D breast MRF technique.

Assessment: T and T MRF maps of both breasts.

Statistical Tests: Mean T and T values for normal fibroglandular tissues were quantified at all scans. For variability, between and within-subjects coefficients of variation (bCV and wCV, respectively) were assessed. Repeatability was assessed with Bland-Altman analysis and coefficient of repeatability (CR). Reproducibility was assessed with interscanner coefficient of variation (CoV) and Wilcoxon signed-rank test.

Results: The bCV at test-retest scans was 9-12% for T , 7-17% for T , wCV was <4% for T , and <7% for T . For two visits in same menstrual cycle, bCV was 10-15% for T , 13-17% for T , wCV was <7% for T and <5% for T . For two visits in the same menstrual phase, bCV was 6-14% for T , 15-18% for T , wCV was <7% for T , and <9% for T . For test-retest scans, CR for T and T were 130 msec and 11 msec. For two visit scans, CR was <290 msec for T and 10-14 msec for T . Interscanner CoV was 3.3-3.6% for T and 5.1-6.6% for T , with no differences between interscanner measurements (P = 1.00 for T , P = 0.344 for T ).

Data Conclusion: 3D breast MRF measurements are repeatable across scan timings and scanners and may be useful in clinical applications in breast imaging.

Level Of Evidence: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:1133-1143.
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http://dx.doi.org/10.1002/jmri.26717DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6750981PMC
October 2019

Partial volume mapping using magnetic resonance fingerprinting.

NMR Biomed 2019 05 1;32(5):e4082. Epub 2019 Mar 1.

Radiology, Case Western Reserve University, Cleveland, OH, USA.

Magnetic resonance fingerprinting (MRF) is a quantitative imaging technique that maps multiple tissue properties through pseudorandom signal excitation and dictionary-based reconstruction. The aim of this study is to estimate and validate partial volumes from MRF signal evolutions (PV-MRF), and to characterize possible sources of error. Partial volume model inversion (pseudoinverse) and dictionary-matching approaches to calculate brain tissue fractions (cerebrospinal fluid, gray matter, white matter) were compared in a numerical phantom and seven healthy subjects scanned at 3 T. Results were validated by comparison with ground truth in simulations and ROI analysis in vivo. Simulations investigated tissue fraction errors arising from noise, undersampling artifacts, and model errors. An expanded partial volume model was investigated in a brain tumor patient. PV-MRF with dictionary matching is robust to noise, and estimated tissue fractions are sensitive to model errors. A 6% error in pure tissue T resulted in average absolute tissue fraction error of 4% or less. A partial volume model within these accuracy limits could be semi-automatically constructed in vivo using k-means clustering of MRF-mapped relaxation times. Dictionary-based PV-MRF robustly identifies pure white matter, gray matter and cerebrospinal fluid, and partial volumes in subcortical structures. PV-MRF could also estimate partial volumes of solid tumor and peritumoral edema. We conclude that PV-MRF can attribute subtle changes in relaxation times to altered tissue composition, allowing for quantification of specific tissues which occupy a fraction of a voxel.
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http://dx.doi.org/10.1002/nbm.4082DOI Listing
May 2019

Development of high-resolution 3D MR fingerprinting for detection and characterization of epileptic lesions.

J Magn Reson Imaging 2019 05 23;49(5):1333-1346. Epub 2018 Dec 23.

Epilepsy Center, Cleveland Clinic, Cleveland, Ohio, USA.

Background: Conventional MRI can be limited in detecting subtle epileptic lesions or identifying active/epileptic lesions among widespread, multifocal lesions.

Purpose: We developed a high-resolution 3D MR fingerprinting (MRF) protocol to simultaneously provide quantitative T , T , proton density, and tissue fraction maps for detection and characterization of epileptic lesions.

Study Type: Prospective.

Population: National Institute of Standards and Technology (NIST) / International Society for Magnetic Resonance in Medicine (ISMRM) phantom, five healthy volunteers and 15 patients with medically intractable epilepsy undergoing presurgical evaluation with noninvasive or invasive electroclinical data.

Field Strength/sequence: 3D MRF scans and routine clinical epilepsy MR protocols were acquired at 3 T.

Assessment: The accuracy of the T and T values were first evaluated using the NIST/ISMRM phantom. The repeatability was then estimated with both phantom and volunteers based on the coefficient of variance (CV). For epilepsy patients, all the maps were qualitatively reviewed for lesion detection by three independent reviewers (S.E.J., M.L., I.N.) blinded to clinical data. Region of interest (ROI) analysis was performed on T and T maps to quantify the multiparametric signal differences between lesion and normal tissues. Findings from qualitative review and quantitative ROI analysis were compared with patients' electroclinical data to assess concordance.

Statistical Tests: Phantom results were compared using R-squared, and patient results were compared using linear regression models.

Results: The phantom study showed high accuracy with the standard values, with an R of 0.99. The volunteer study showed high repeatability, with an average CV of 4.3% for T and T in various tissue regions. For the 15 patients, MRF showed additional findings in four patients, with the remaining 11 patients showing findings consistent with conventional MRI. The additional MRF findings were highly concordant with patients' electroclinical presentation.

Data Conclusion: The 3D MRF protocol showed potential to identify otherwise inconspicuous epileptogenic lesions from the patients with negative conventional MRI diagnosis, as well as to correlate with different levels of epileptogenicity when widespread lesions were present.

Level Of Evidence: 3. Technical Efficacy Stage: 3. J. Magn. Reson. Imaging 2019;49:1333-1346.
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http://dx.doi.org/10.1002/jmri.26319DOI Listing
May 2019

Realistic 4D MRI abdominal phantom for the evaluation and comparison of acquisition and reconstruction techniques.

Magn Reson Med 2019 03 5;81(3):1863-1875. Epub 2018 Nov 5.

Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio.

Purpose: This work presents a 4D numerical abdominal phantom, which includes T and T relaxation times, proton density fat fraction, perfusion, and diffusion, as well as respiratory motion for the evaluation and comparison of acquisition and reconstruction techniques.

Methods: The 3D anatomical mesh models were non-rigidly scaled and shifted by respiratory motion derived from an in vivo scan. A time series of voxelized 3D abdominal phantom images were obtained with contrast determined by the tissue properties and pulse sequence parameters. Two example simulations: (1) 3D T mapping under breath-hold and free-breathing acquisition conditions and (2) two different reconstruction techniques for accelerated 3D dynamic contrast-enhanced MRI, are presented. The source codes can be found at https://github.com/SeiberlichLab/Abdominal_MR_Phantom.

Results: The proposed 4D abdominal phantom can successfully simulate images and MRI data with nonrigid respiratory motion and specific contrast settings and data sampling schemes. In example 1, the use of a numerical 4D abdominal phantom was demonstrated to aid in the comparison between different approaches for volumetric T mapping. In example 2, the average arterial fraction over the healthy hepatic parenchyma as calculated with spiral generalized autocalibrating partial parallel acquisition was closer to that from the fully sampled data than the arterial fraction from conjugate gradient sensitivity encoding, although both are elevated compared to the gold-standard reference.

Conclusion: This realistic abdominal MR phantom can be used to simulate different pulse sequences and data sampling schemes for the comparison of acquisition and reconstruction methods under controlled conditions that are impossible or prohibitively difficult to perform in vivo.
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http://dx.doi.org/10.1002/mrm.27545DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7728431PMC
March 2019

Three-dimensional MR Fingerprinting for Quantitative Breast Imaging.

Radiology 2019 01 30;290(1):33-40. Epub 2018 Oct 30.

From the Departments of Radiology (Y.C., A.P., S.P., S.D., D.F.M., D.M., J.B., N.S., M.A.G., D.P., V.G.) and Biomedical Engineering (J.I.H., N.S., M.A.G., V.G.), Case Western Reserve University, 11100 Euclid Ave, Cleveland, OH 44106; and Department of Radiology, University Hospitals Cleveland Medical Center, Cleveland, Ohio (Y.C., A.P., S.P., S.D., D.F.M., D.M., J.B., M.A.G., D.P., V.G.).

Purpose To develop a fast three-dimensional method for simultaneous T1 and T2 quantification for breast imaging by using MR fingerprinting. Materials and Methods In this prospective study, variable flip angles and magnetization preparation modules were applied to acquire MR fingerprinting data for each partition of a three-dimensional data set. A fast postprocessing method was implemented by using singular value decomposition. The proposed technique was first validated in phantoms and then applied to 15 healthy female participants (mean age, 24.2 years ± 5.1 [standard deviation]; range, 18-35 years) and 14 female participants with breast cancer (mean age, 55.4 years ± 8.8; range, 39-66 years) between March 2016 and April 2018. The sensitivity of the method to B field inhomogeneity was also evaluated by using the Bloch-Siegert method. Results Phantom results showed that accurate and volumetric T1 and T2 quantification was achieved by using the proposed technique. The acquisition time for three-dimensional quantitative maps with a spatial resolution of 1.6 × 1.6 × 3 mm was approximately 6 minutes. For healthy participants, averaged T1 and T2 relaxation times for fibroglandular tissues at 3.0 T were 1256 msec ± 171 and 46 msec ± 7, respectively. Compared with normal breast tissues, higher T2 relaxation time (68 msec ± 13) was observed in invasive ductal carcinoma (P < .001), whereas no statistical difference was found in T1 relaxation time (1183 msec ± 256; P = .37). Conclusion A method was developed for breast imaging by using the MR fingerprinting technique, which allows simultaneous and volumetric quantification of T1 and T2 relaxation times for breast tissues. © RSNA, 2018 Online supplemental material is available for this article.
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http://dx.doi.org/10.1148/radiol.2018180836DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6312432PMC
January 2019

Magnetic resonance field fingerprinting.

Magn Reson Med 2019 04 15;81(4):2347-2359. Epub 2018 Oct 15.

Siemens Healthcare GmbH, Erlangen, Germany.

Purpose: To develop and evaluate the magnetic resonance field fingerprinting method that simultaneously generates T , T , B , and maps from a single continuous measurement.

Methods: An encoding pattern was designed to integrate true fast imaging with steady-state precession (TrueFISP), fast imaging with steady-state precession (FISP), and fast low-angle shot (FLASH) sequence segments with varying flip angles, radio frequency (RF) phases, TEs, and gradient moments in a continuous acquisition. A multistep matching process was introduced that includes steps for integrated spiral deblurring and the correction of intravoxel phase dispersion. The method was evaluated in phantoms as well as in vivo studies in brain and lower abdomen.

Results: Simultaneous measurement of T , T , B , and is achieved with T and T subsequently being less afflicted by B and variations. Phantom results demonstrate the stability of generated parameter maps. Higher undersampling factors and spatial resolution can be achieved with the proposed method as compared with solely FISP-based magnetic resonance fingerprinting. High-resolution B maps can potentially be further used as diagnostic information.

Conclusion: The proposed magnetic resonance field fingerprinting method can estimate T , T , B , and maps accurately in phantoms, in the brain, and in the lower abdomen.
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http://dx.doi.org/10.1002/mrm.27558DOI Listing
April 2019

Magnetic resonance fingerprinting: a technical review.

Magn Reson Med 2019 01 14;81(1):25-46. Epub 2018 Sep 14.

Department of Radiology, Case Western Reserve Universityand University Hospitals Cleveland Medical Center, Cleveland, Ohio.

Multiparametric quantitative imaging is gaining increasing interest due to its widespread advantages in clinical applications. Magnetic resonance fingerprinting is a recently introduced approach of fast multiparametric quantitative imaging. In this article, magnetic resonance fingerprinting acquisition, dictionary generation, reconstruction, and validation are reviewed.
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http://dx.doi.org/10.1002/mrm.27403DOI Listing
January 2019

Diagnostic Accuracy of a Rapid Biparametric MRI Protocol for Detection of Histologically Proven Prostate Cancer.

Urology 2018 Dec 7;122:133-138. Epub 2018 Sep 7.

Department of Radiology, Case Western Reserve University, Cleveland, OH; Department of Radiology, University Hospitals Cleveland Medical Center, Cleveland, OH; Department of Urology, Case Western Reserve University and University Hospitals Cleveland Medical Center, Cleveland, OH; Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH. Electronic address:

Objective: To evaluate the performance of a rapid, low cost, noncontrast MRI examination as a secondary screening tool in detection of clinically significant prostate cancer.

Methods: In this prospective single institution study, 129 patients with elevated prostate-specific antigen levels or abnormal digital rectal examination findings underwent MRI with an abbreviated biparamatric MRI protocol consisting of high-resolution axial T2- and diffusion-weighted images. Index lesions were classified according to modified Prostate Imaging - Reporting and Data System (mPI-RADS) version 2.0. All patients underwent standard transrectal ultrasound-guided biopsy after MRI with the urologist being blinded to MRI results. Subsequently, all patients with suspicious lesions (mPI-RADS 3, 4, or 5) underwent cognitively guided targeted biopsy after discussion of MRI results with the urologist. Sensitivity and negative predictive value for identification of clinically significant prostate cancer (Gleason score 3+4 and above) were determined.

Results: Rapid biparametric MRI discovered 176 lesions identified in 129 patients. Rapid MRI detected clinically significant cancers with a sensitivity of 95.1% with a negative predictive value of 95.1% and positive predictive value of 53.2%, leading to a change in management in 10.8% of the patients. False negative rate of biparametric (bp) MRI was 4.7%.

Conclusion: We found that a bp-MRI examination can detect clinically significant lesions and changed patient management in 10.8% of the patients. A rapid MRI protocol can be used as a useful secondary screening tool in men presenting with suspicion of prostate cancer.
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http://dx.doi.org/10.1016/j.urology.2018.08.032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6295224PMC
December 2018
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