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Optimizing variable flip angles in magnetization-prepared gradient-echo sequences for efficient 3D-T1ρ mapping

Zibetti, Marcelo V W; De Moura, Hector L; Keerthivasan, Mahesh B; Regatte, Ravinder R
PURPOSE:mapping. METHODS:mapping and evaluate their performance in model agarose phantoms (n = 4) and healthy volunteers (n = 5) for knee joint imaging. We also tested the optimization with sequence parameters targeting faster acquisitions. RESULTS:Our results show that optimized variable flip angle can improve the accuracy and the precision of the sequences, seen as a reduction of the mean of normalized absolute difference from about 5%-6% to 3%-4% in model phantoms and from 15%-16% to 11%-13% in the knee joint, and improving SNR from about 12-28 to 22-32 in agarose phantoms and about 7-14 to 13-17 in healthy volunteers. The optimization can also compensate for the loss in quality caused by making the sequence faster. This results in sequence configurations that acquire more data per unit of time with SNR and mean of normalized absolute difference measurements close to its slower versions. CONCLUSION:mapping of the knee joint.
PMID: 37288538
ISSN: 1522-2594
CID: 5559772

Low-field MRI: A report on the 2022 ISMRM workshop

Campbell-Washburn, Adrienne E; Keenan, Kathryn E; Hu, Peng; Mugler, John P; Nayak, Krishna S; Webb, Andrew G; Obungoloch, Johnes; Sheth, Kevin N; Hennig, Jürgen; Rosen, Matthew S; Salameh, Najat; Sodickson, Daniel K; Stein, Joel M; Marques, José P; Simonetti, Orlando P
In March 2022, the first ISMRM Workshop on Low-Field MRI was held virtually. The goals of this workshop were to discuss recent low field MRI technology including hardware and software developments, novel methodology, new contrast mechanisms, as well as the clinical translation and dissemination of these systems. The virtual Workshop was attended by 368 registrants from 24 countries, and included 34 invited talks, 100 abstract presentations, 2 panel discussions, and 2 live scanner demonstrations. Here, we report on the scientific content of the Workshop and identify the key themes that emerged. The subject matter of the Workshop reflected the ongoing developments of low-field MRI as an accessible imaging modality that may expand the usage of MRI through cost reduction, portability, and ease of installation. Many talks in this Workshop addressed the use of computational power, efficient acquisitions, and contemporary hardware to overcome the SNR limitations associated with low field strength. Participants discussed the selection of appropriate clinical applications that leverage the unique capabilities of low-field MRI within traditional radiology practices, other point-of-care settings, and the broader community. The notion of "image quality" versus "information content" was also discussed, as images from low-field portable systems that are purpose-built for clinical decision-making may not replicate the current standard of clinical imaging. Speakers also described technical challenges and infrastructure challenges related to portability and widespread dissemination, and speculated about future directions for the field to improve the technology and establish clinical value.
PMID: 37345725
ISSN: 1522-2594
CID: 5542822

Multisite MRI Intravoxel Incoherent Motion Repeatability and Reproducibility across 3 T Scanners in a Breast Diffusion Phantom: A BReast Intravoxel Incoherent Motion Multisite (BRIMM) Study

Basukala, Dibash; Mikheev, Artem; Sevilimedu, Varadan; Gilani, Nima; Moy, Linda; Pinker, Katja; Thakur, Sunitha B; Sigmund, Eric E
BACKGROUND:Monoexponential apparent diffusion coefficient (ADC) and biexponential intravoxel incoherent motion (IVIM) analysis of diffusion-weighted imaging is helpful in the characterization of breast tumors. However, repeatability/reproducibility studies across scanners and across sites are scarce. PURPOSE/OBJECTIVE:)) within and across sites employing MRI scanners from different vendors utilizing 16-channel breast array coils in a breast diffusion phantom. STUDY TYPE/METHODS:Phantom repeatability. PHANTOM/UNASSIGNED:A breast phantom containing tubes of different polyvinylpyrrolidone (PVP) concentrations, water, fat, and sponge flow chambers, together with an MR-compatible liquid crystal (LC) thermometer. FIELD STRENGTH/SEQUENCE/UNASSIGNED:Bipolar gradient twice-refocused spin echo sequence and monopolar gradient single spin echo sequence at 3 T. ASSESSMENT/RESULTS:Studies were performed twice in each of two scanners, located at different sites, on each of 2 days, resulting in four studies per scanner. ADCs of the PVP and water were normalized to the vendor-provided calibrated values at the temperature indicated by the LC thermometer for repeatability/reproducibility comparisons. STATISTICAL TESTS/METHODS:ADC and IVIM repeatability and reproducibility within and across sites were estimated via the within-system coefficient of variation (wCV). Pearson correlation coefficient (r) was also computed between IVIM metrics and flow speed. A P value <0.05 was considered statistically significant. RESULTS:correlations with flow speed were significant at both sites. DATA CONCLUSION/CONCLUSIONS:. LEVEL OF EVIDENCE/METHODS:2 TECHNICAL EFFICACY: Stage 1.
PMID: 37702382
ISSN: 1522-2586
CID: 5558202

In-vivo measurement of radio frequency electric fields in mice brain

Yaghmazadeh, Omid; Schoenhardt, Seth; Sarabandi, Arya; Sabet, Ali; Sabet, Kazem; Safari, Fatemeh; Alon, Leeor; Buzsáki, Gyorgy
With the development of novel technologies, radio frequency (RF) energy exposure is expanding at various wavelengths and power levels. These developments necessitate updated approaches of RF measurements in complex environments, particularly in live biological tissue. Accurate dosimetry of the absorbed RF electric fields (E-Fields) by the live tissue is the keystone of environmental health considerations for this type of ever-growing non-ionizing radiation energy. In this study, we introduce a technique for direct in-vivo measurement of electric fields in living tissue. Proof of principle in-vivo electric field measurements were conducted in rodent brains using Bismuth Silicon Oxide (BSO) crystals exposed to varying levels of RF energy. Electric field measurements were calibrated and verified using in-vivo temperature measurements using optical temperature fibers alongside electromagnetic field simulations of a transverse electromagnetic (TEM) cell.
SCOPUS:85150039993
ISSN: 2590-1370
CID: 5447022

Improving measurement of blood-brain barrier permeability with reduced scan time using deep-learning-derived capillary input function

Bae, Jonghyun; Li, Chenyang; Masurkar, Arjun; Ge, Yulin; Kim, Sungheon Gene
PURPOSE/OBJECTIVE:In Dynamic contrast-enhanced MRI (DCE-MRI), Arterial Input Function (AIF) has been shown to be a significant contributor to uncertainty in the estimation of kinetic parameters. This study is to assess the feasibility of using a deep learning network to estimate local Capillary Input Function (CIF) to estimate blood-brain barrier (BBB) permeability, while reducing the required scan time. MATERIALS AND METHOD/METHODS:-10min methods in estimating the PS values. RESULTS:-10min. We found a 75% increase of BBB permeability in the gray matter and a 35% increase in the white matter, when comparing the older group to the younger group. CONCLUSIONS:We demonstrated the feasibility of estimating the capillary-level input functions using a deep learning network. We also showed that this method can be used to estimate subtle age-related changes in BBB permeability with reduced scan time, without compromising accuracy. Moreover, the trained deep learning network can automatically select CIF, reducing the potential uncertainty resulting from manual user-intervention.
PMCID:10475161
PMID: 37507078
ISSN: 1095-9572
CID: 5559022

Early adversity changes the economic conditions of mouse structural brain network organization

Carozza, Sofia; Holmes, Joni; Vértes, Petra E; Bullmore, Ed; Arefin, Tanzil M; Pugliese, Alexa; Zhang, Jiangyang; Kaffman, Arie; Akarca, Danyal; Astle, Duncan E
Early adversity can change educational, cognitive, and mental health outcomes. However, the neural processes through which early adversity exerts these effects remain largely unknown. We used generative network modeling of the mouse connectome to test whether unpredictable postnatal stress shifts the constraints that govern the organization of the structural connectome. A model that trades off the wiring cost of long-distance connections with topological homophily (i.e., links between regions with shared neighbors) generated simulations that successfully replicate the rodent connectome. The imposition of early life adversity shifted the best-performing parameter combinations toward zero, heightening the stochastic nature of the generative process. Put simply, unpredictable postnatal stress changes the economic constraints that reproduce rodent connectome organization, introducing greater randomness into the development of the simulations. While this change may constrain the development of cognitive abilities, it could also reflect an adaptive mechanism that facilitates effective responses to future challenges.
PMCID:10505050
PMID: 37607894
ISSN: 1098-2302
CID: 5563592

Characterization of Age-Related and Sex-Related Differences of Relaxation Parameters in the Intervertebral Disc Using MR-Fingerprinting

Menon, Rajiv G; Monga, Anmol; Kijowski, Richard; Regatte, Ravinder R
BACKGROUND:Multiparameter characterization using MR fingerprinting (MRF) can quantify multiple relaxation parameters of intervertebral disc (IVD) simultaneously. These parameters may vary by age and sex. PURPOSE/OBJECTIVE:To investigate age- and sex-related differences in the relaxation parameters of the IVD of the lumbar spine using a multiparameter MRF technique. STUDY TYPE/METHODS:Prospective. SUBJECTS/METHODS:17 healthy subjects (8 male; mean age = 34 ± 10 years, range 20-60 years). FIELD STRENGTH/SEQUENCE/UNASSIGNED:maps at 3.0T. ASSESSMENT/RESULTS:maps. STATISTICAL TESTS/METHODS:of IVD. Statistical significance was defined as P-value <0.05. RESULTS:contrast (R = 0.709). CONCLUSION/CONCLUSIONS:of IVD in healthy subjects. LEVEL OF EVIDENCE/METHODS:2 TECHNICAL EFFICACY: Stage 1.
PMID: 37610269
ISSN: 1522-2586
CID: 5563682

Co-use of MDMA with psilocybin/LSD may buffer against challenging experiences and enhance positive experiences

Zeifman, Richard J; Kettner, Hannes; Pagni, Broc A; Mallard, Austin; Roberts, Daniel E; Erritzoe, David; Ross, Stephen; Carhart-Harris, Robin L
Psilocybin and lysergic acid diethylamide (LSD) experiences can range from very positive to highly challenging (e.g., fear, grief, and paranoia). These challenging experiences contribute to hesitancy toward psychedelic-assisted psychotherapy among health care providers and patients. Co-use of 3,4-Methylenedioxy methamphetamine (MDMA) with psilocybin/LSD anecdotally reduces challenging experiences and enhances positive experiences associated with psilocybin/LSD. However, limited research has investigated the acute effects of co-use of MDMA and psilocybin/LSD. In a prospective convenience sample (N = 698) of individuals with plans to use psilocybin/LSD, we examined whether co-use of MDMA with psilocybin/LSD (n = 27) is associated with differences in challenging or positive experiences. Challenging experiences were measured using the Challenging Experiences Questionnaire and positive experiences were measured using the Mystical Experience Questionnaire and single-item measures of self-compassion, compassion, love, and gratitude. Potentially confounding variables were identified and included as covariates. Relative to psilocybin/LSD alone, co-use of psilocybin/LSD with a self-reported low (but not medium-high) dose of MDMA was associated with significantly less intense total challenging experiences, grief, and fear, as well as increased self-compassion, love and gratitude. Co-use of psilocybin/LSD and MDMA was not associated with differences in mystical-type experiences or compassion. Findings suggest co-use of MDMA with psilocybin/LSD may buffer against some aspects of challenging experiences and enhance certain positive experiences. Limitations include use of a convenience sample, small sample size, and non-experimental design. Additional studies (including controlled dose-response studies) that examine the effects and safety of co-administering MDMA with psilocybin/LSD (in healthy controls and clinical samples) are warranted and may assist the development of personalized treatments.
PMCID:10444769
PMID: 37608057
ISSN: 2045-2322
CID: 5561742

Observation of magnetic structural universality and jamming transition with NMR

Ruh, Alexander; Emerich, Philipp; Scherer, Harald; Novikov, Dmitry S.; Kiselev, Valerij G.
Nuclear magnetic resonance (NMR) has been instrumental in deciphering the structure of proteins. Here we show that transverse NMR relaxation, through its time-dependent relaxation rate, is distinctly sensitive to the structure of complex materials or biological tissues at the mesoscopic scale, from micrometers to tens of micrometers. Based on the ideas of universality, we show analytically and numerically that the time-dependent transverse relaxation rate approaches its long-time limit in a power-law fashion, with the dynamical exponent reflecting the universality class of mesoscopic magnetic structure. The spectral line shape acquires the corresponding non-analytic power law singularity at zero frequency. We experimentally detect the change in the dynamical exponent as a result of the transition into maximally random jammed state characterized by hyperuniform correlations. The relation between relaxational dynamics and magnetic structure opens the way for noninvasive characterization of porous media, complex materials and biological tissues
SCOPUS:85164669020
ISSN: 1090-7807
CID: 5548382

Deep-Learning-Based Contrast Synthesis From MRF Parameter Maps in the Knee Joint

Nykänen, Olli; Nevalainen, Mika; Casula, Victor; Isosalo, Antti; Inkinen, Satu I; Nikki, Marko; Lattanzi, Riccardo; Cloos, Martijn A; Nissi, Mikko J; Nieminen, Miika T
BACKGROUND:Magnetic resonance fingerprinting (MRF) is a method to speed up acquisition of quantitative MRI data. However, MRF does not usually produce contrast-weighted images that are required by radiologists, limiting reachable total scan time improvement. Contrast synthesis from MRF could significantly decrease the imaging time. PURPOSE/OBJECTIVE:To improve clinical utility of MRF by synthesizing contrast-weighted MR images from the quantitative data provided by MRF, using U-nets that were trained for the synthesis task utilizing L1- and perceptual loss functions, and their combinations. STUDY TYPE/METHODS:Retrospective. POPULATION/METHODS:Knee joint MRI data from 184 subjects from Northern Finland 1986 Birth Cohort (ages 33-35, gender distribution not available). FIELD STRENGTH AND SEQUENCE/UNASSIGNED:A 3 T, multislice-MRF, proton density (PD)-weighted 3D-SPACE (sampling perfection with application optimized contrasts using different flip angle evolution), fat-saturated T2-weighted 3D-space, water-excited double echo steady state (DESS). ASSESSMENT/RESULTS:Data were divided into training, validation, test, and radiologist's assessment sets in the following way: 136 subjects to training, 3 for validation, 3 for testing, and 42 for radiologist's assessment. The synthetic and target images were evaluated using 5-point Likert scale by two musculoskeletal radiologists blinded and with quantitative error metrics. STATISTICAL TESTS/METHODS:Friedman's test accompanied with post hoc Wilcoxon signed-rank test and intraclass correlation coefficient. The statistical cutoff P <0.05 adjusted by Bonferroni correction as necessary was utilized. RESULTS:The networks trained in the study could synthesize conventional images with high image quality (Likert scores 3-4 on a 5-point scale). Qualitatively, the best synthetic images were produced with combination of L1- and perceptual loss functions and perceptual loss alone, while L1-loss alone led to significantly poorer image quality (Likert scores below 3). The interreader and intrareader agreement were high (0.80 and 0.92, respectively) and significant. However, quantitative image quality metrics indicated best performance for the pure L1-loss. DATA CONCLUSION/CONCLUSIONS:Synthesizing high-quality contrast-weighted images from MRF data using deep learning is feasible. However, more studies are needed to validate the diagnostic accuracy of these synthetic images. EVIDENCE LEVEL/METHODS:4. TECHNICAL EFFICACY/UNASSIGNED:Stage 1.
PMID: 36562500
ISSN: 1522-2586
CID: 5409352