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Conventional diffusion imaging uses pulsed gradient spin echo (PGSE) waveforms with diffusion times of tens of milliseconds (ms) to infer differences of white matter microstructure. The combined use of these long diffusion times with short diffusion times (<10 ms) enabled by oscillating gradient spin echo (OGSE) waveforms can enable more sensitivity to changes of restrictive boundaries on the scale of white matter microstructure (e.g. membranes reflecting the axon diameters). Here, PGSE and OGSE images were acquired at 4.7 T from 20 healthy volunteers aged 20-73 years (10 males). Mean, radial, and axial diffusivity, as well as fractional anisotropy were calculated in the genu, body and splenium of the corpus callosum (CC). Monte Carlo simulations were also conducted to examine the relationship of intra- and extra-axonal radial diffusivity with diffusion time over a range of axon diameters and distributions. The results showed elevated diffusivities with OGSE relative to PGSE in the genu and splenium (but not the body) in both males and females, but the OGSE-PGSE difference was greater in the genu for males. Females showed positive correlations OGSE-PGSE diffusivity difference with age across the CC, whereas there were no such age correlations in males. Simulations of radial diffusion demonstrated that for axon sizes in human brain both OGSE and PGSE diffusivities were dominated by extra-axonal water, but the OGSE-PGSE difference nonetheless increased with area-weighted outer-axon diameter. Therefore, the lack of OGSE-PGSE difference in the body is not entirely consistent with literature that suggests it is composed predominantly of axons with large diameter. The greater OGSE-PGSE difference in the genu of males could reflect larger axon diameters than females. The OGSE-PGSE difference correlation with age in females could reflect loss of smaller axons at older ages. The use of OGSE with short diffusion times to sample the microstructural scale of restriction implies regional differences of axon diameters along the corpus callosum with preliminary results suggesting a dependence on age and sex.
This article was published in the following journal.
To demonstrate that oscillating gradient spin-echo sequences can be combined with diffusion-weighted magnetic resonance spectroscopy even on clinical MR systems to study human brain at short diffusion...
Diffusion times longer than 50 ms are typically probed with stimulated-echo sequences. Varying the diffusion time in stimulated-echo sequences affects the T weighting of subcompartments, complicating ...
An improved version of the integrative optical imaging method has been developed that substantially increases the time resolution of diffusion measurements. We present a theory for time-resolved integ...
Recent experimental data reveals the complexity of diffusion dynamics beyond the scope of classical Brownian dynamics. The particles exhibit diverse diffusive motions from the anoma-lous towards class...
The purpose of this study is to assess the neurological development at three years of age of children born after prenatal diagnosis of "isolated" agenesis of the corpus callosum.
Agenesis of the corpus callosum (ACC) is one of the most frequent cerebral malformations and is now diagnosed prenatally in most cases. Prenatal counseling is then challenging because of u...
Corpus callosum malformation (CCM) is the most frequently detected cerebral defect diagnosed in the prenatal setting. The most common CCM is corpus callosum agenesis (CCA) which is found i...
This study aims to determine size of corpus callosum on midsagittal MR scan in patients with a pineal cyst and to compare it with the control group without a pineal cyst.
To investigate the relationship between the integrity of the white matter, including the corticospinal tracts and the corpus callosum, with the recovery of lower extremity function in pati...
Birth defect that results in a partial or complete absence of the CORPUS CALLOSUM. It may be isolated or a part of a syndrome (e.g., AICARDI'S SYNDROME; ACROCALLOSAL SYNDROME; ANDERMANN SYNDROME; and HOLOPROSENCEPHALY). Clinical manifestations include neuromotor skill impairment and INTELLECTUAL DISABILITY of variable severity.
A diagnostic technique that incorporates the measurement of molecular diffusion (such as water or metabolites) for tissue assessment by MRI. The degree of molecular movement can be measured by changes of apparent diffusion coefficient (ADC) with time, as reflected by tissue microstructure. Diffusion MRI has been used to study BRAIN ISCHEMIA and tumor response to treatment.
Set of nerve fibers that cross the midline of the TELENCEPHALON. They include the ANTERIOR COMMISSURE; the CORPUS CALLOSUM; and the HIPPOCAMPAL COMMISSURE of the fornix.
A rare genetic disorder characterized by partial or complete absence of the CORPUS CALLOSUM, resulting in infantile spasms, MENTAL RETARDATION, and lesions of the RETINA or OPTIC NERVE.
Complete severing of the CORPUS CALLOSUM. In humans it is usually performed to treat medically intractable, multifocal EPILEPSY. EXPERIMENTAL ANIMAL MODELS of split brain preparations are used in research.
Multiple Sclerosis MS
Multiple sclerosis (MS) is the most common disabling neurological condition affecting 100,000 young adults in the UK. The condition results from autoimmune damage to myelin, causing interference in nerve signaling. Symptoms experienced depend on the pa...