NMR in biomedicine
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There is a need to obtain higher specificity in the detection of breast lesions using MRI. To address this need, Dynamic Contrast-Enhanced (DCE) MRI has been combined with other structural and functional MRI techniques. Unfortunately, owing to time constraints structural images at ultra-high spatial resolution can generally not be obtained during contrast uptake, whereas the relatively low spatial resolution of functional imaging (e.g. diffusion and perfusion) limits the detection of small lesions. ⋯ To test the feasibility of this concept, we developed a unilateral breast coil for 7T. It comprises a volume optimized dual-channel transmit coil combined with a 30-channel receive array coil. The high density of small coil elements enabled efficient acceleration in any direction to acquire ultra high spatial resolution MRI of close to 0.6 mm isotropic detail within a temporal resolution of 69 s, high spatial resolution MRI of 1.5 mm isotropic within an ultra high temporal resolution of 6.7 s and low distortion DWI at 7T, all validated in phantoms, healthy volunteers and a patient with a lesion in the right breast classified as Breast Imaging Reporting and Data System (BI-RADS) IV.
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Childhood status epilepticus (SE) initiates an epileptogenic process that leads to spontaneous seizures and hippocampal pathology characterized by neuronal loss, gliosis and an imbalance between excitatory and inhibitory neurotransmission. It remains unclear whether these changes are a cause or consequence of chronic epilepsy. In this study, in vivo MRS was used in a post-SE juvenile rat model of temporal lobe epilepsy (TLE) to establish the temporal evolution of hippocampal injury and neurotransmitter imbalance. ⋯ This may reflect glutamine synthase downregulation in order to normalize Gln levels. These changes occurred before spontaneous recurrent seizures were present but, by creating a pre-epileptic state, may play a role in epileptogenesis. MRS can be applied in a clinical setting and may be used as a noninvasive tool to monitor the development of TLE.
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Separate quantification of glutamate (Glu) and glutamine (Gln) using conventional MRS on clinical scanners is challenging. In previous work, constant-time point-resolved spectroscopy (CT-PRESS) was optimized at 3 T to detect Glu, but did not resolve Gln. To quantify Glu and Gln, a time-domain basis set was constructed taking into account metabolite T(2) relaxation times and dephasing from B(0) inhomogeneity. ⋯ This method was first validated using seven custom-built phantoms containing variable metabolite concentrations, and then applied to in vivo data acquired in rats exposed to vaporized ethanol and controls. Separate metabolite quantification revealed increased Gln after 16 weeks and increased Glu after 24 weeks of vaporized ethanol exposure in ethanol-treated compared with control rats. Without separate quantification, the signal from the combined resonances of Glu and Gln (Glx) showed an increase at both 16 and 24 weeks in ethanol-exposed rats, precluding the determination of the independent and differential contribution of each metabolite at each time.
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Migraine is a primary headache disorder characterized by recurrent attacks of throbbing pain associated with neurological, gastrointestinal and autonomic symptoms. Previous studies have detected structural deficits and functional impairments in migraine patients. However, researchers have failed to investigate the functional connectivity alterations of regions with structural deficits during the resting state. ⋯ Furthermore, the functional connectivity between the dACC and two regions (i.e. DLPFC and OFC) was correlated with the duration of disease in migraine patients. We suggest that frequent nociceptive input has modified the structural and functional patterns of the frontal cortex, and these changes may explain the functional impairments in migraine patients.
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In this preliminary study, we aimed to investigate the abnormalities of water diffusion in children with temporal lobe epilepsy (TLE). Eight children with unilateral TLE (according to electroencephalography, EEG) and eight age- and sex-matched controls were recruited. Diffusion tensor imaging (DTI)/diffusional kurtosis imaging (DKI) acquisitions were performed. ⋯ No significant difference was observed between EEG-abnormal and EEG-normal sides in cases. These preliminary results indicate that DKI is more sensitive than DTI for the detection of diffusion abnormalities in the temporal lobes of children with TLE, even when EEG signals are normal. These findings pave the way for the application of DKI for in-depth studies on TLE in children.