Quantitative measurements of proton spin‐lattice (T1) and spin–spin (T2) relaxation times in the mouse brain at 7.0 T

Guilfoyle, David N.; Dyakin, Victor V.; O'Shea, Jacqueline; Pell, Gaby S.; Helpern, Joseph A.

doi:10.1002/mrm.10371

Cited by 50 publications

(43 citation statements)

References 17 publications

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“…Our experience has indicated that T 1 relaxography is not as sensitive to this type of pathology in mice. Therefore, we have attempted to obtain the highest resolution data via T 2 relaxography because of the specificity to pathology this measure has provided in our previous studies of mouse models of AD [25,32]. In Ts65Dn mice, but not Ts1Cje mice or disomic (2N) controls, MRI revealed changes likely involved in the damage to cholinergic circuits and the atrophy of BFCNs and their hippocampal and cortical targets, which we confirmed by immunohistochemical and biochemical analyses.…”

Section: Introductionsupporting

confidence: 52%

In vivo MRI identifies cholinergic circuitry deficits in a Down syndrome model

Chen

Dyakin

Branch

et al. 2009

Neurobiology of Aging

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In vivo quantitative magnetic resonance imaging (MRI) was employed to detect brain pathology and map its distribution within control, disomic mice (2N) and in Ts65Dn and Ts1Cje trisomy mice with features of human Down syndrome (DS). In Ts65Dn, but not Ts1Cje mice, transverse proton spinspin (T 2 ) relaxation time was selectively reduced in the medial septal nucleus (MSN) and in brain regions that receive cholinergic innervation from the MSN, including the hippocampus, cingulate cortex, and retrosplenial cortex. Basal forebrain cholinergic neurons (BFCNs) in the MSN, identified by choline acetyltransferase (ChAT) and nerve growth factor receptors p75 NTR and TrkA immunolabeling were reduced in Ts65Dn brains and in situ acetylcholinesterase (AChE) activity was depleted distally along projecting cholinergic fibers, and selectively on pre-and post-synaptic profiles in these target areas. T 2 effects were negligible in Ts1Cje mice that are diploid for APP and lack BFCN neuropathology, consistent with the suspected relationship of this pathology to increased App dosage. These results establish the utility of quantitative MRI in vivo for identifying Alzheimer's disease-relevant cholinergic changes in animal models of DS and the selective vulnerability of cholinergic neuron subpopulations.

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Section: Introductionsupporting

confidence: 52%

In vivo MRI identifies cholinergic circuitry deficits in a Down syndrome model

Chen

Dyakin

Branch

et al. 2009

Neurobiology of Aging

Self Cite

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“…This minor discrepancy could be due to different imaging parameters. By comparison, rat brain T 1 is 1.6-1.8 s at 7 T (Guilfoyle et al, 2003;Barbier et al, 2005). B. T 2 .…”

Section: Discussionmentioning

confidence: 98%

Relaxation time constants and apparent diffusion coefficients of rat retina at 7 Tesla

Nair

Shen

Duong

2010

Int J Imaging Syst Tech

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MRI has recently been applied to study the retina in vivo. Measurements of relaxation time constants (T 1 , T 2 , and T 2 *) and the apparent diffusion coefficient (ADC) of the retina would be useful to systemically optimize structural, physiological, and functional MRI contrasts. MRI studies were performed on 12 anesthetized and paralyzed rats. High-resolution T 1 , T 2 , T 2 * and ADC of the rat eyes were measured at 50 3 50 3 800 lm at 7 Tesla. Profiles of T 1 , T 2 , T 2 * and ADC across the retinal thickness were analyzed. Region of interests of three layers across the retinal thickness were tabulated. This study demonstrated that high resolution T 1 , T 2 , T 2 * and ADC of the rat retina could be imaged. Profile analysis of T 1 , T 2 , T 2 * and ADC across the retinal thickness were helpful to minimize partial volume effects. T 1 , T 2 , T 2 * and ADC of the rat retina were overall similar to those of the brain. Quantitative T 1 , T 2 , T 2 * and ADC may change in retinal diseases and their measurements could help to stage retinal disease progression and monitor therapeutic intervention.

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“…Because Gd‐DOTA has a short plasma half‐life (approximately ~ 30 minutes) and a significantly low R 2 relaxivity (4.17 mmol/L/s) compared with our SPION (40 mmol/L/s),9 residual gadolinium after DCE‐MRI examination would not affect SPION‐induced ΔR 2 * and ΔR 2 measurements 10. Thus, SPION‐induced ΔR 2 *and ΔR 2 were measured after DCE MRI examinations.…”

Section: Methodsmentioning

confidence: 99%

Spatiotemporal heterogeneity of tumor vasculature during tumor growth and antiangiogenic treatment: MRI assessment using permeability and blood volume parameters

et al. 2018

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Tumor heterogeneity is an important concept when assessing intratumoral variety in vascular phenotypes and responses to antiangiogenic treatment. This study explored spatiotemporal heterogeneity of vascular alterations in C6 glioma mice during tumor growth and antiangiogenic treatment on serial MR examinations (days 0, 4, and 7 from initiation of vehicle or multireceptor tyrosine kinase inhibitor administration). Transvascular permeability (TP) was quantified on dynamic‐contrast‐enhanced MRI (DCE‐MRI) using extravascular extracellular agent (Gd‐DOTA); blood volume (BV) was estimated using intravascular T2 agent (SPION). With regard to region‐dependent variability in vascular phenotypes, the control group demonstrated higher TP in the tumor center than in the periphery, and greater BV in the tumor periphery than in the center. This distribution pattern became more apparent with tumor growth. Antiangiogenic treatment effect was regionally heterogeneous: in the tumor center, treatment significantly suppressed the increase in TP and decrease in BV (ie, typical temporal change in the control group); in the tumor periphery, treatment‐induced vascular alterations were insignificant and BV remained high. On histopathological examination, the control group showed greater CD31, VEGFR2, Ki67, and NG2 expression in the tumor periphery than in the center. After treatment, CD31 and Ki67 expression was significantly suppressed only in the tumor center, whereas VEGFR2 and α‐caspase 3 expression was decreased and NG2 expression was increased in the entire tumor. These results demonstrate that MRI can reliably depict spatial heterogeneity in tumor vascular phenotypes and antiangiogenic treatment effects. Preserved angiogenic activity (high BV on MRI and high CD31) and proliferation (high Ki67) in the tumor periphery after treatment may provide insights into the mechanism of tumor resistance to antiangiogenic treatment.

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Quantitative measurements of proton spin‐lattice (T₁) and spin–spin (T₂) relaxation times in the mouse brain at 7.0 T

Cited by 50 publications

References 17 publications

In vivo MRI identifies cholinergic circuitry deficits in a Down syndrome model

In vivo MRI identifies cholinergic circuitry deficits in a Down syndrome model

Relaxation time constants and apparent diffusion coefficients of rat retina at 7 Tesla

Spatiotemporal heterogeneity of tumor vasculature during tumor growth and antiangiogenic treatment: MRI assessment using permeability and blood volume parameters

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