Combining Navigator and Optical Prospective Motion Correction for High-Quality 500 μm Resolution Quantitative Multi-Parameter Mapping at 7T

AbstractPURPOSEHigh-resolution quantitative multi-parameter mapping shows promise for non-invasively characterizing human brain microstructure but is limited by physiological artifacts. We implemented corrections for rigid head movement and respiration-related B0-fluctuations and evaluated them in healthy volunteers and dementia patients.METHODSCamera-based optical prospective motion correction (PMC) and free-induction decay (FID) navigator correction were implemented in a gradient and RF-spoiled multi-echo 3D gradient echo sequence for mapping proton density (PD), longitudinal relaxation rate (R1) and effective transverse relaxation rate (R2*). We studied their effectiveness separately and in concert in young volunteers and then evaluated the navigator correction (NAVcor) with PMC in a group of elderly volunteers and dementia patients. We used spatial homogeneity within white matter (WM) and gray matter (GM) and scan-rescan measures as quality metrics.RESULTSNAVcor and PMC reduced artifacts and improved the homogeneity and reproducibility of parameter maps. In elderly participants, NAVcor improved scan-rescan reproducibility of parameter maps (coefficient of variation decreased by 14.7% and 11.9% within WM and GM respectively). Spurious inhomogeneities within WM were reduced more in the elderly than in the young cohort (by 9% vs 2%). PMC increased regional GM/WM contrast and was especially important in the elderly cohort, which moved twice as much as the young cohort. We did not find a significant interaction between the two corrections.CONCLUSIONNavigator correction and PMC significantly improved the quality of PD, R1 and R2* maps, particularly in less compliant elderly volunteers and dementia patients.

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Multiparameter quantitative histological MRI values in high-grade gliomas: a potential biomarker of tumor progression

Neuro-Oncology Practice ◽

10.1093/nop/npaa047 ◽

2020 ◽

Vol 7 (6) ◽

pp. 646-655

Author(s):

Gilles Reuter ◽

Emilie Lommers ◽

Evelyne Balteau ◽

Jessica Simon ◽

Christophe Phillips ◽

...

Keyword(s):

Tumor Progression ◽

Relaxation Rate ◽

Proton Density ◽

Normal Brain ◽

Transverse Relaxation Rate ◽

High Grade ◽

Conventional Mri ◽

Initial Surgery ◽

Potential Biomarker ◽

High Grade Gliomas

Abstract Background Conventional MRI poorly distinguishes brain parenchyma microscopically invaded by high-grade gliomas (HGGs) from the normal brain. By contrast, quantitative histological MRI (hMRI) measures brain microstructure in terms of physical MR parameters influenced by histochemical tissue composition. We aimed to determine the relationship between hMRI parameters in the area surrounding the surgical cavity and the presence of HGG recurrence. Methods Patients were scanned after surgery with an hMRI multiparameter protocol that allowed for estimations of longitudinal relaxation rate (R1) = 1/T1, effective transverse relaxation rate (R2)*=1/T2*, magnetization transfer saturation (MTsat), and proton density. The initial perioperative zone (IPZ) was segmented on the postoperative MRI. Once recurrence appeared on conventional MRI, the area of relapsing disease was delineated (extension zone, EZ). Conventional MRI showing recurrence and hMRI were coregistered, allowing for the extraction of parameters R1, R2*, MTsat, and PD in 3 areas: the overlap area between the IPZ and EZ (OZ), the peritumoral brain zone, PBZ (PBZ = IPZ – OZ), and the area of recurrence (RZ = EZ – OZ). Results Thirty-one patients with HGG who underwent gross-total resection were enrolled. MTsat and R1 were the most strongly associated with tumor progression. MTsat was significantly lower in the OZ and RZ, compared to PBZ. R1 was significantly lower in RZ compared to PBZ. PD was significantly higher in OZ compared to PBZ, and R2* was higher in OZ compared to PBZ or RZ. These changes were detected 4 to 120 weeks before recurrence recognition on conventional MRI. Conclusions HGG recurrence was associated with hMRI parameters’ variation after initial surgery, weeks to months before overt recurrence.

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Nuclear magnetic resonance surface relaxation mechanisms of kerogen

Geophysics ◽

10.1190/geo2016-0350.1 ◽

2017 ◽

Vol 82 (6) ◽

pp. JM15-JM22 ◽

Cited By ~ 8

Author(s):

Boyang Zhang ◽

Hugh Daigle

Keyword(s):

Nuclear Magnetic Resonance ◽

Hydrogen Bonding ◽

Magnetic Resonance ◽

Relaxation Rate ◽

Dipolar Coupling ◽

Surface Relaxation ◽

Proton Density ◽

Transverse Relaxation Rate ◽

Pore Fluids ◽

Transverse Relaxation

Nuclear magnetic resonance (NMR) relaxometry is an excellent tool for probing the interactions between solid pore surface and pore fluids in porous media. Surface relaxation is a key component of NMR relaxation. It is well-known that in conventional rocks, paramagnetic centers contribute most to the surface relaxation phenomenon. However, the interactions between organic pore surfaces and pore fluids, and the mechanism of surface relaxation in organic shale pores, are not well-understood. We tackle the issue using deuterated compounds to adjust the proton density in the liquid phase and monitoring the transverse relaxation rate changes of kerogen-fluid mixtures. With the Barnett and Eagle Ford kerogen isolates, we found that for alkanes, it is intramolecular dipolar coupling that dominates among the magnetic interactions. As a result, the transverse relaxation rate of alkane proton spins is more likely to be dependent on the concentration of active adsorption sites on the kerogen surface, rather than the kerogen proton density. For water inside organic pores, surface relaxation most likely originates from hydrogen bonding and intermolecular dipolar coupling. We also examined the temperature effect on kerogen surface relaxation and found temperature-dependent behavior that is consistent with surface relaxation by hydrogen bonding and homonuclear dipolar coupling interactions.

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DOP57 Vedolizumab has similar efficacy rates in young and elderly patients: A binational, multicentre, retrospective case–control study

Journal of Crohn s and Colitis ◽

10.1093/ecco-jcc/jjz203.096 ◽

2020 ◽

Vol 14 (Supplement_1) ◽

pp. S095-S097

Author(s):

N A Cohen ◽

N Plevris ◽

U Kopylov ◽

A Grinman ◽

B Ungar ◽

...

Keyword(s):

Adverse Events ◽

Elderly Patients ◽

Case Control Study ◽

The Elderly ◽

Case Control ◽

Young Cohort ◽

Retrospective Case ◽

Remission Rates ◽

Elderly Cohort ◽

Control Study

Abstract Background Treatment of inflammatory bowel diseases (IBD) is associated with multiple side effects, such as malignancies and infections, that may be more common in the elderly population. The aim of this study was to compare the safety and efficacy of vedolizumab (VDZ) in young and elderly patients. Methods This is a binational, multicentre, retrospective, case–control study consisting of patients from multiple centres in Israel and from Edinburgh, UK. IBD patients in whom VDZ treatment was initiated during 2015–2019, and were followed for at least 14 weeks, were included in the study according to their age groups: ≤40 years or ≥60 years. Patients were matched for disease duration, classification and severity. Results We recruited 144 patients (82 CD and 62 UC) to the elderly cohort and 140 patients (83 CD and 57 UC) to the young cohort. The respective average age was 70.2 ± 7.3 years and 29.6 ± 5.7 years. Elderly patients had significantly more cardiovascular, metabolic and respiratory co-morbidities and had less prior exposure to anti-TNF agents compared with the young cohort (CD: 51% vs. 88%, p < 0.001; UC: 47% vs. 70%, p = 0.03). Clinical and endoscopic responses were comparable between the groups at Weeks 14 and 52 among elderly and young (Week 52 remission: CD: 40% vs. 35%, p = 0.7; UC: 48% vs. 51%, p = 0.84) (Figure 1). However, the use of more than one anti-TNF agent was an independent predictor of poor response and remission rates to VDZ at all time points among the elderly (OR 0.13; 95% CI 0.03–0.69). A total of 49 adverse events were documented, 23 (16%) in the young cohort and 26 (18%) in the elderly cohort (p = 0.5). Overall there were significantly more infections in the elderly cohort (3 (2%) vs. 17 (12%), p = 0.002) and included nasopharyngeal, urinary, skin and Clostridium difficile infections. None of them was fatal but one patient stopped treatment due to urinary sepsis. There were significantly more non-specific adverse events such as headache and myalgia in the young cohort (8% vs. 2%, p = 0.03). Six patients (4%) in the young cohort required drug discontinuation due to adverse events compared with 4 patients (3%) in the elderly cohort (p = 0.5). The reasons for discontinuation were similar between the groups. Conclusion VDZ is equally effective in elderly and young IBD patients. This study shows an increased risk of overall infections in the elderly cohort, it is unclear whether these are related to VDZ treatment or the age and background diseases of these patients. In elderly patients, the use of VDZ before anti-TNF therapy may improve response and remission rates.

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Quantitative Multi-Parameter Mapping Optimized for the Clinical Routine

Frontiers in Neuroscience ◽

10.3389/fnins.2020.611194 ◽

2020 ◽

Vol 14 ◽

Author(s):

Graham Cooper ◽

Sebastian Hirsch ◽

Michael Scheel ◽

Alexander U. Brandt ◽

Friedemann Paul ◽

...

Keyword(s):

White Matter ◽

Relaxation Rate ◽

Bias Field ◽

Brain Atlas ◽

Transverse Relaxation Rate ◽

Post Processing ◽

Clinical Routine ◽

Parameter Mapping ◽

Bias Field Correction ◽

Subject Variability

Using quantitative multi-parameter mapping (MPM), studies can investigate clinically relevant microstructural changes with high reliability over time and across subjects and sites. However, long acquisition times (20 min for the standard 1-mm isotropic protocol) limit its translational potential. This study aimed to evaluate the sensitivity gain of a fast 1.6-mm isotropic MPM protocol including post-processing optimized for longitudinal clinical studies. 6 healthy volunteers (35±7 years old; 3 female) were scanned at 3T to acquire the following whole-brain MPM maps with 1.6 mm isotropic resolution: proton density (PD), magnetization transfer saturation (MT), longitudinal relaxation rate (R1), and transverse relaxation rate (R2*). MPM maps were generated using two RF transmit field (B1+) correction methods: (1) using an acquired B1+ map and (2) using a data-driven approach. Maps were generated with and without Gibb's ringing correction. The intra-/inter-subject coefficient of variation (CoV) of all maps in the gray and white matter, as well as in all anatomical regions of a fine-grained brain atlas, were compared between the different post-processing methods using Student's t-test. The intra-subject stability of the 1.6-mm MPM protocol is 2–3 times higher than for the standard 1-mm sequence and can be achieved in less than half the scan duration. Intra-subject variability for all four maps in white matter ranged from 1.2–5.3% and in gray matter from 1.8 to 9.2%. Bias-field correction using an acquired B1+ map significantly improved intra-subject variability of PD and R1 in the gray (42%) and white matter (54%) and correcting the raw images for the effect of Gibb's ringing further improved intra-subject variability in all maps in the gray (11%) and white matter (10%). Combining Gibb's ringing correction and bias field correction using acquired B1+ maps provides excellent stability of the 7-min MPM sequence with 1.6 mm resolution suitable for the clinical routine.

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Reliability of quantitative multiparameter maps is high for MT and PD but attenuated for R1 and R2* in healthy young adults

10.1101/2021.11.10.467254 ◽

2021 ◽

Author(s):

Elisabeth Wenger ◽

Sarah E Polk ◽

Maike M Kleemeyer ◽

Nikolaus Weiskopf ◽

Nils C Bodammer ◽

...

Keyword(s):

Young Adults ◽

Measurement Error ◽

Relaxation Rate ◽

Structural Equation ◽

High Reliability ◽

Brain Regions ◽

Proton Density ◽

Specific Information ◽

Transverse Relaxation Rate ◽

Intra Class Correlation

We investigate the reliability of individual differences of four quantities measured by magnetic resonance imaging based multiparameter mapping (MPM): magnetization transfer (MT), proton density (PD), longitudinal relaxation rate (R1), and effective transverse relaxation rate (R2*). A total of four MPM datasets, two on each of two consecutive days, were acquired in healthy young adults. On Day 1, no repositioning occurred; on Day 2, participants were repositioned between MPM datasets. Using intra-class correlation effect decomposition (ICED), we assessed the contributions of session-specific, day-specific, and residual sources of measurement error. For whole-brain gray and white matter, all four MPM parameters showed high reproducibility and high reliability, as indexed by the coefficient of variation (CoV) and the intra-class correlation (ICC). However, MT, PD, R1, and R2* differed markedly in the extent to which reliability varied across brain regions. MT and PD showed high reliability in almost all regions. In contrast, R1 and R2* showed low reliability in some regions outside the basal ganglia, such that the sum of the measurement error estimates in our structural equation model was higher than estimates of between-person differences. In sum, in this sample of healthy young adults, the four MPM parameters showed very little variability over four measurements over two days but differed in how well they could assess between-person differences. We conclude that R1 and R2* might carry only limited person-specific information in samples of healthy young adults, and, by implication, might be of restricted utility for studying associations to between-person differences in behavior.

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Magnetic resonance image attributes of the bovine ovarian follicle antrum during development and regression

Reproduction ◽

10.1530/reprod/120.2.311 ◽

2000 ◽

pp. 311-323 ◽

Cited By ~ 3

Author(s):

JL Hilton ◽

GE Sarty ◽

GP Adams ◽

RA Pierson

Keyword(s):

Magnetic Resonance ◽

Relaxation Rate ◽

Follicular Fluid ◽

Magnetic Resonance Image ◽

Follicular Development ◽

Physiological Status ◽

Proton Density ◽

Dominant Follicle ◽

Rate Heterogeneity ◽

Pixel Value

The magnetic resonance images and maps of bovine ovaries acquired at defined phases of follicular development and regression were studied to determine whether magnetic resonance image attributes of the follicular antrum reflect the physiological status of dominant and subordinate ovarian follicles. Ovariectomies were performed at day 3 of wave one, day 6 of wave one, day 1 of wave two and at >/= day 17 after ovulation. The timings of ovariectomies were selected to acquire growing, early static, late static and regressing follicles of the first wave and preovulatory follicles of the ovulatory wave. Pre-selection and subordinate follicles were also available for analysis. Serum samples were taken on the day of ovariectomy and follicular fluid samples were taken after imaging. Numerical pixel value and pixel heterogeneity in a spot representing approximately 95% of the follicular antrum were quantified in T(1)- and T(2)-weighted images. T(1) and T(2) relaxation rates (T(1) and T(2)), proton density, apparent diffusion coefficients and their heterogeneities were determined from the computed magnetic resonance maps. The antra of early atretic dominant follicles showed higher T(2)-weighted mean pixel value (P < 0.008) and heterogeneity (P < 0. 01) and lower T(2) heterogeneity (P < 0.008) than growing follicles. Subordinate follicles in the presence of a preovulatory dominant follicle had higher T(1), T(1) heterogeneity, proton density, proton density heterogeneity, and lower mean pixel value in T(1)-weighted images than subordinate follicles of the anovulatory wave (P < 0.04). T(1) relaxation rate heterogeneity and proton density heterogeneity were positively correlated with follicular fluid oestradiol concentration (r = 0.4 and 0.3; P < 0.04). T(2) relaxation rate heterogeneity was positively correlated with follicular fluid progesterone concentration (r = 0.4; P < 0.008). Quantitative differences in magnetic resonance image attributes of the antrum observed among phases of follicular development and regression coincided with changes in the ability of the dominant follicle to produce steroid hormones and ovulate, and thus were indicative of physiological status and follicular health.

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Neuropsychiatric Symptoms and Antipsychotic Therapy in the Elderly Patients with Dementia

Psychiatry ◽

10.30629/2618-6667-2020-18-4-6-15 ◽

2020 ◽

Vol 18 (4) ◽

pp. 6-15

Author(s):

I. V. Kolykhalov

Keyword(s):

Neuropsychiatric Symptoms ◽

The Elderly ◽

Psychotic Symptoms ◽

Mixed Dementia ◽

Short Term ◽

Antipsychotic Therapy ◽

Dementia Patients ◽

Frequency Of Use ◽

Number Of Patients ◽

High Incidence

The objective of the study was to investigate syndromal-nosological specificities of neuropsychiatric symptoms (NPS) and the frequency of use of antipsychotics in patients with various types of dementias, institutionalized to geriatric units of mental hospitals.Patients and methods: a total of 106 in-patients of three psychogeriatric units were examined. The median age of patients is 75 years [69; 80].The diagnostic distribution of patients at the time of the examination was as follows: in 33 subjects (31.1%) Alzheimer’s disease (AD) was diagnosed, in 25 (23.6%) - mixed dementia (MD), in 32 (30.2%) - vascular dementia (VD) and in 16 (15.1%) patients had dementia of complex origin (DCO).Results: a high incidence (54.7%) of NPS was found in patients with dementia of various origins. The greatest number of patients with behavioral and psychotic symptoms was found in AD and MD. The proportion of dementia patients with such disorders in each of these types of dementia is about 70%, while in CGD and VD, the proportion of patients with NPS is noticeably smaller (30% and 40%, respectively). For the treatment of NPS, antipsychotics were most often prescribed, but their use caused adverse events (AEs) in 1/3 of cases. Patients with VD are most susceptible to the development of AE, and AD patients are the least susceptible.Conclusion: the study showed that NPS are one of the important components of dementia, regardless of the nosology and stage of the disease. The treatment of NPS in dementia is particularly challenging because, although the symptoms cause significant distress, there are currently no effective alternative therapies. The risk of AE can be minimized by carefully considering the indications for prescribing antipsychotics and their short-term use, regular monitoring of the patient’s condition, and educating caregivers.

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Proton magnetic relaxation of water sorbed by methaemoglobin crystals

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1973.0002 ◽

1973 ◽

Vol 331 (1587) ◽

pp. 457-468 ◽

Cited By ~ 1

Keyword(s):

Relaxation Rate ◽

Relaxation Times ◽

Transverse Relaxation Rate ◽

Ferric Ions ◽

Transverse Relaxation ◽

Water Binding ◽

Adsorption Sites ◽

Protein Molecules ◽

Proton Magnetic Relaxation ◽

Limiting Value

P. m. r. relaxation times ( T 1 and T 2 ) have been measured as a function of regain and temperature for water sorbed by lyophilized methaemoglobin. The purpose of the work was to gain information regarding the nature and extent of water binding by the protein molecules. The T 1 results are interpreted in terms of an exchange between the sixth ligand position of the Fe (III) and other adsorption sites on the protein. At high temperatures the relaxation rate at a given regain reaches a limiting value which allows the fraction of ferric ions hydrated to be calculated. Above 16% regain all the Fe (III) is hydrated. At 21 and 35% regains a maximum appears in the relaxation rate at about -46 °C indicating a contribution from a more mobile phase which produces a T 1 minimum at that temperature. The T 2 data are consistent with a model in which the main contribution to the transverse relaxation rate comes from a tightly bound fraction of the water with ω 0 Ƭ c ≫1. The temperature dependence of T 2 exhibits three different regions: ( a ) a low temperature region where lg T 2 ∝ T -1 ; ( b ) an intermediate region with a steeper increase of T 2 with temperature; and ( c ) a high temperature where T 2 levels off.

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Apparent transverse relaxation rate in human brain varies linearly with tissue iron concentration at 4.7 T

Magnetic Resonance in Medicine ◽

10.1002/mrm.21373 ◽

2007 ◽

Vol 58 (5) ◽

pp. 1054-1060 ◽

Cited By ~ 20

Author(s):

Fumiyuki Mitsumori ◽

Hidehiro Watanabe ◽

Nobuhiro Takaya ◽

Michael Garwood

Keyword(s):

Human Brain ◽

Relaxation Rate ◽

Iron Concentration ◽

Transverse Relaxation Rate ◽

Transverse Relaxation ◽

Tissue Iron

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Design of a seniors and Alzheimer's disease caring service platform

BMC Medical Informatics and Decision Making ◽

10.1186/s12911-021-01626-3 ◽

2021 ◽

Vol 21 (S10) ◽

Author(s):

Cheng-Wen Lee ◽

Hsiu-Mang Chuang

Keyword(s):

Care Service ◽

Fall Detection ◽

The Elderly ◽

Service Platform ◽

Care Services ◽

Basic Model ◽

Dementia Patients ◽

Mobile Phone Applications ◽

Iot Devices ◽

And Behavior

Abstract Background To meet the needs of aging and dementia patients in Taiwan, this study designed a nursing system that includes communication, location tracking, and fall detection, and early warning services. The main purpose of this research is to provide timely services to the elderly and patients and hope to reduce the burden when the number of nursing staff decreases. This article is a remote disease care service platform with the Internet of Things (IoT) devices to monitor the location of the elderly and whether they have dropped warning alerts. Results The device is connected to the patient's waist and chest, monitors the patient's movement and behavior, and transmits messages to the back-end system, and informs caregivers through mobile phone applications when unexpected or shocking events occur. The system can identify whether the patient has fallen, accidentally, or long-term inactivity. The device is equipped with sensors that enable it to monitor the patient's location and behavior data through Bluetooth and GPS technology. Finally, we proposed a basic model and an integrated model that will industrialize the system and is expected to play a role in a larger patient population. Conclusions The system developed in this research has passed the Activities of Daily Living (ADL) test and verification, and is expected to provide appropriate safety care services for nursing homes and elderly residences.

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