Dataset Information

Time-harmonic magnetic resonance elastography of the normal feline brain.

ABSTRACT: Imaging of the mechanical properties of in vivo brain tissue could eventually lead to non-invasive diagnosis of hydrocephalus, Alzheimer's disease and other pathologies known to alter the intracranial environment. The purpose of this work is to (1) use time-harmonic magnetic resonance elastography (MRE) to estimate the mechanical property distribution of cerebral tissue in the normal feline brain and (2) compare the recovered properties of grey and white matter. Various in vivo and ex vivo brain tissue property measurement strategies have led to the highly variable results that have been reported in the literature. MR elastography is an imaging technique that can estimate mechanical properties of tissue non-invasively and in vivo. Data was acquired in 14 felines and elastic parameters were estimated using a globo-regional nonlinear image reconstruction algorithm. Results fell within the range of values reported in the literature and showed a mean shear modulus across the subject group of 7-8 kPa with all but one animal falling within 5-15 kPa. White matter was statistically stiffer (p<0.01) than grey matter by about 1 kPa on a per subject basis. To the best of our knowledge, the results reported represent the most extensive set of estimates in the in vivo brain which have been based on MRE acquisition of the three-dimensional displacement field coupled to volumetric shear modulus image reconstruction achieved through nonlinear parameter estimation. However, the inter-subject variation in mean shear modulus indicates the need for further study, including the possibility of applying more advanced models to estimate the relevant tissue mechanical properties from the data.

SUBMITTER: Pattison AJ

PROVIDER: S-EPMC2963725 | biostudies-literature | 2010 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Time-harmonic magnetic resonance elastography of the normal feline brain.

Pattison A J AJ Lollis S S SS Perriñez P R PR Perreard I M IM McGarry M D J MD Weaver J B JB Paulsen K D KD

Journal of biomechanics 20100723 14

Imaging of the mechanical properties of in vivo brain tissue could eventually lead to non-invasive diagnosis of hydrocephalus, Alzheimer's disease and other pathologies known to alter the intracranial environment. The purpose of this work is to (1) use time-harmonic magnetic resonance elastography (MRE) to estimate the mechanical property distribution of cerebral tissue in the normal feline brain and (2) compare the recovered properties of grey and white matter. Various in vivo and ex vivo brain ...[more]

PMID: 20655045

Similar Datasets

Project description:BackgroundIdiopathic normal pressure hydrocephalus (iNPH) is a ventriculomegaly syndrome characterized by dementia, urinary incontinence, and gait disturbance, which is potentially reversible after ventriculoperitoneal shunting (VPS). Magnetic resonance elastography (MRE) is an evolving imaging technology that noninvasively measures tissue viscoelasticity. We studied iNPH patients using MRE prior to shunting, compared them with normal controls, and analyzed associations between MRE findings and clinical features, as a pilot assessment of MRE in iNPH.MethodsStiffness values were measured on preoperative MRE in 10 iNPH patients scheduled for VPS and compared with those in 20 age- and sex-matched controls. Stiffness results were correlated with clinical iNPH symptoms.ResultsMRE demonstrated significantly increased stiffness in iNPH in cerebrum (P = 0.04), occipital (P = 0.002), and parietal (P = 0.01) regions of interest (ROIs) and significantly decreased stiffness in periventricular ROIs (P < 0.0001). Stiffness was not significantly different in frontal (P = 0.1) and deep gray ROIs (P = 0.4). Univariate analysis showed associations between preoperative iNPH symptoms and abnormally increased stiffness, including urinary incontinence with cerebrum (P = 0.005), frontal (P = 0.04), and cerebellum (P = 0.03) ROIs, and Parkinsonism with occipital ROI (P = 0.04). Postoperative improvement was associated with increased deep gray stiffness (P = 0.01); failure was associated with increased temporal (P = 0.0002) stiffness.ConclusionsBased on the preliminary results of this small, limited analysis, brain stiffness may be altered in iNPH, and these alterations in parenchymal viscoelastic properties may be correlated with clinical symptoms. Increased temporal stiffness may predict surgical failure and potentially suggest an alternative dementing pathology underlying the iNPH-like symptoms. These findings highlight the potential future utility of MRE in iNPH management.

Project description:BackgroundPostmortem magnetic resonance imaging (MRI) has been used to investigate the cause of death, but due to time constraints, it is not widely applied to the heart. Therefore, MRI analysis of the heart after formalin fixation was previously performed. However, the changes in MRI signal values based on the fixation time of formalin were not investigated. The objective was to investigate changes over time in the T1- and T2-values of MRI signals in normal areas of hearts removed during autopsy, hearts subsequently fixed in formalin, and heart specimens sliced for the preparation of pathological specimens.MethodsThe study subjects were 21 autopsy cases in our hospital between May 26, 2019 and February 16, 2020 whose hearts were removed and scanned by MRI. The male:female ratio was 14:7, and their ages at death ranged from 9 to 92 years (mean age 65.0 ± 19.7 years). Postmortem (PM)-MRI was conducted with a 0.3-Tesla (0.3-T) scanner containing a permanent magnet. A 4-channel QD head coil was used as the receiver coil. Scans were performed immediately after removal, post-formalin fixation, and after slicing; 7 cases were scanned at all three time points.ResultsThe T1- and T2-values were calculated from the MRI signals of each sample organ at each scanning stage. Specimens were sliced from removed organs after formalin fixation, and the changes in T1- and T2-values over time were graphed to obtain an approximate curve. The median T1-values at each measurement time point tended to decrease from immediately after removal. The T2-values showed the same tendency to decrease, but this tendency was more pronounced for the T1-values.ConclusionMRI signal changes in images of heart specimens were investigated. Formalin fixation shortened both T1- and T2-values over time, and approximation formulae were derived to show these decreases over time. The shortening of T1- and T2-values can be understood as commensurate with the reduction in the water content (water molecules) of the formalin-fixed heart.

Project description:BACKGROUND AND OBJECTIVES:Fibrosis is a major cause of kidney allograft injury. Currently, the only means of assessing allograft fibrosis is by biopsy, an invasive procedure that samples <1% of the kidney. We examined whether magnetic resonance elastography, an imaging-based measure of organ stiffness, could noninvasively estimate allograft fibrosis and predict progression of allograft dysfunction. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS:Kidney allograft recipients >1 year post-transplant undergoing an allograft biopsy first underwent free-breathing, flow-compensated magnetic resonance elastography on a 3.0-T magnetic resonance imaging scanner. Each patient had serial eGFR measurements after the elastography scan for a follow-up period of up to 1 year. The mean stiffness value of the kidney allograft was compared with both the histopathologic Banff fibrosis score and the rate of eGFR change during the follow-up period. RESULTS:Sixteen patients who underwent magnetic resonance elastography and biopsy were studied (mean age: 54±9 years old). Whole-kidney mean stiffness ranged between 3.5 and 7.3 kPa. Whole-kidney stiffness correlated with biopsy-derived Banff fibrosis score (Spearman rho =0.67; P<0.01). Stiffness was heterogeneously distributed within each kidney, providing a possible explanation for the lack of a stronger stiffness-fibrosis correlation. We also found negative correlations between whole-kidney stiffness and both baseline eGFR (Spearman rho =-0.65; P<0.01) and eGFR change over time (Spearman rho =-0.70; P<0.01). Irrespective of the baseline eGFR, increased kidney stiffness was associated with a greater eGFR decline (regression r2=0.48; P=0.03). CONCLUSIONS:Given the limitations of allograft biopsy, our pilot study suggests the potential for magnetic resonance elastography as a novel noninvasive measure of whole-allograft fibrosis burden that may predict future changes in kidney function. Future studies exploring the utility and accuracy of magnetic resonance elastography are needed.

Dataset Information

Time-harmonic magnetic resonance elastography of the normal feline brain.

Publications

Time-harmonic magnetic resonance elastography of the normal feline brain.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets