Combining Dipole and Loop Coil Elements for 7 T Magnetic Resonance Studies of the Human Calf Muscle.

Combining proton and phosphorus magnetic resonance spectroscopy offers a unique opportunity to study the oxidative and glycolytic components of metabolism in working muscle. This paper presents a 7 T proton calf coil design that combines dipole and loop elements to achieve the high performance necessary for detecting metabolites with low abundance and restricted visibility, specifically lactate, while including the option of adding a phosphorus array. We investigated the transmit, receive, and parallel imaging performance of three transceiver dipoles with six pair-wise overlap-decoupled standard or twisted pair receive-only coils. With a higher SNR and more efficient transmission decoupling, standard loops outperformed twisted pair coils. The dipoles with standard loops provided a four-fold-higher image SNR than a multinuclear reference coil comprising two proton channels and 32% more than a commercially available 28-channel proton knee coil. The setup enabled up to three-fold acceleration in the right-left direction, with acceptable g-factors and no visible aliasing artefacts. Spectroscopic phantom measurements revealed a higher spectral SNR for lactate with the developed setup than with either reference coil and fewer restrictions in voxel placement due to improved transmit homogeneity. This paper presents a new use case for dipoles and highlights their advantages for the integration in multinuclear calf coils.

Novel time-domain NMR-based traits for rapid, label-free Olive oils profiling.

Olive oil is one of the oldest and essential edible oils in the market. The classification of olive oils (e.g. extra virgin, virgin, refined) is often influenced by factors ranging from its complex inherent physiochemical properties (e.g. fatty acid profiles) to the undisclosed manufacturing processes. Therefore, olive oils have been the target of adulteration due to its profitable margin. In this work, we demonstrate that multi-parametric time-domain NMR relaxometry can be used to rapidly (in minutes) identify and classify olive oils in label-free and non-destructive manner. The subtle differences in molecular microenvironment of the olive oils induce substantial changes in the relaxation mechanism in the time-domain NMR regime. We demonstrated that the proposed NMR-relaxation based detection (AUC = 0.95) is far more sensitive and specific than the current gold-standards in the field i.e. near-infrared spectroscopy (AUC = 0.84) and Ultraviolet-visible spectroscopy (AUC = 0.73), respectively. We further show that, albeit the inherent complexity of olive plant natural phenotypic variations, the proposed NMR-relaxation based traits may be a viable mean (AUC = 0.71) in tracing the regions of origin for olive trees, in agreement with their geographical orientation.

Neurocognitive Deficits and Effects of Cognitive Reserve in Mild Cognitive Impairment.

BACKGROUND/AIMS: Mild cognitive impairment (MCI) is a frequent syndrome in the older population, which involves an increased risk to develop Alzheimer's disease (AD). The latter can be modified by the cognitive reserve, which can be operationalized by the length of school education. MCI can be differentiated into four subtypes according to the cognitive domains involved: amnestic MCI, multiple-domain amnestic MCI, non-amnestic MCI and multiple-domain non-amnestic MCI. While neurocognitive deficits are a constituent of the diagnosis of these subtypes, the question of how they refer to the cognitive reserve still needs to be clarified. METHODS: We examined neuropsychological deficits in healthy controls, patients with MCI and patients with mild AD (n = 485) derived from a memory clinic. To reduce the number of neuropsychological variables, a factor analysis with varimax rotation was calculated. In a second step, diagnostic groups including MCI subtypes were compared with respect to their clinical and neuropsychological characteristics including cognitive reserve. RESULTS: Most MCI patients showed the amnestic multiple-domain subtype followed by the pure amnestic subtype, while the non-amnestic subtypes were rare. The amnestic subtype displayed a significantly higher level of cognitive reserve and higher MMSE scores than the amnestic multiple-domain subtype, which was in most cases characterized by additional psychomotor and executive deficits. CONCLUSIONS: These findings confirm earlier reports revealing that the amnestic multiple-domain subtype is the most frequent one and indicating that a high cognitive reserve may primarily prevent psychomotor and executive deficits in MCI.

Morphological cerebral correlates of CERAD test performance in mild cognitive impairment and Alzheimer's disease.

The objective of this study was to investigate the association between structural cerebral changes and neuropsychological deficits in mild cognitive impairment (MCI) and Alzheimer's disease (AD). Sixty patients with MCI, 34 patients with mild to moderate AD, and 32 healthy controls underwent both extensive neuropsychological assessment (CERAD test battery) and high-resolution structural magnetic resonance imaging. We used optimized voxel based morphometry to investigate (i) differences in gray matter density between the three aforementioned groups and (ii) the putative relations of CERAD test performance with atrophic brain changes. When compared to the healthy controls, the AD patients and, to a lesser extent, patients with MCI showed significant density losses predominantly in the medial temporal lobe. Deficits in verbal fluency and word finding were significantly correlated with left fronto-temporal and left temporal (including hippocampal) changes, respectively. Decreased scores in immediate and delayed recall and in delayed recognition were associated with several cortical and subcortical sites including the parahippocampal and posterior cinguli gyri, the right thalamus, and the right hippocampus, whereas deficits in constructional praxis and constructional praxis recall referred to sites in the left thalamus and cerebellum, and the temporal cortices (bilaterally), respectively. Our findings lend further support for medial temporal lobe degeneration in MCI and AD and demonstrate that cognitive deficits as assessed on the CERAD do not simply refer to specific changes in discrete cerebral sites but rather reflect morphological alterations in widespread networks.

MRI-derived atrophy of the olfactory bulb and tract in mild cognitive impairment and Alzheimer's disease.

There is increasing histopathological evidence that the olfactory bulb and tract (OBT) is a primary focus of neurodegenerative changes in Alzheimer's disease (AD). Correspondingly, high-resolution magnetic resonance imaging revealed significant atrophy of the OBT in manifest AD. Whether these alterations are already present in mild cognitive impairment, the assumed preclinical stage of AD, has not been investigated yet. OBT volumes were assessed by manual tracing in 29 patients with mild cognitive impairment, 27 patients with probable AD, and 30 healthy controls. In a second step, voxel based morphometry was used to investigate the potential association between OBT atrophy and morphological changes in other brain regions. Patients had significantly lower OBT volumes when compared to controls, with atrophy being most prominent in the AD group. In addition, OBT atrophy was associated with a decreased medial temporal lobe (MTL) gray matter density bilaterally. Our findings indicate that neurodegeneration in OBT and MTL regions is linked and suggest that OBT volume might be a surrogate marker in AD.

Cerebellar substructures and neurological soft signs in first-episode schizophrenia.

A subtle impairment of motor coordination and sensory integration functions is frequently found in schizophrenia. Clinically these deficits present as neurological soft signs (NSS). Because of its crucial role in motor function, control of muscle tone and equilibrium, the cerebellum is likely to be involved in the appearance of NSS. Magnetic resonance imaging (MRI) was performed in 30 patients with first-episode schizophrenia - all treated with atypical neuroleptics - and 21 healthy controls. NSS were rated on the Heidelberg Scale. By manual tracing, the cerebellum was divided into the following subregions bilaterally: anterior lobe, superior posterior lobe, inferior posterior lobe, and corpus medullare, respectively. Volumetric measures were compared between the two groups and related to NSS scores. NSS scores were significantly higher in patients than in controls. Cerebella of patients were significantly smaller with atrophy pronounced in the corpus medullare bilaterally. In the patients' group, higher NSS scores were found to be related to reduced volumes of the posterior lobes of the cerebellum. In contrast, no significant associations between NSS scores and cerebellar subregions in healthy subjects arose. Our findings support the hypothesis of cerebellar involvement in schizophrenia and indicate that alterations in distinct cerebellar regions are related to NSS.

Reduced olfactory bulb and tract volume in early Alzheimer's disease--a MRI study.

Olfactory dysfunction has been reported to occur already in the early stages of Alzheimer's disease (AD) and to increase with disease severity. In neuropathological research, the deposition of neurofibrillary tangles and neuritic plaques in the olfactory bulb and tract (OBT) of AD patients has been consistently demonstrated. We used high-resolution magnetic resonance imaging (MRI) to determine the volume of the OBT in 21 patients with early AD and in 21 healthy comparison subjects. The OBT was manually traced on consecutive coronal slices. When compared to healthy controls, right, left and mean OBT volumes were significantly reduced in patients with AD (p<0.01). In AD patients, the mean OBT volume was significantly correlated with global cognitive performance as determined by the mini-mental state examination (r=0.605; p=0.004). Manual tracing on MRI images revealed OBT atrophy to be present early in the course of AD. Since the respective findings were associated with cognitive impairment, they may contribute to early recognition and diagnosis of the disease.

Apolipoprotein E polymorphism and brain morphology in mild cognitive impairment.

BACKGROUND: The apolipoprotein E (ApoE) genotype has been confirmed as the major genetic risk factor for late-onset Alzheimer's disease (AD). How the ApoE genotype and brain morphology relate to each other is only partly understood, particularly in mild cognitive impairment, the assumed prestage of AD. METHODS: A total of 83 subjects with mild cognitive impairment (aging-associated cognitive decline criteria) were investigated with optimized voxel-based morphometry (VBM). We tested for differences in gray and white matter densities between groups according to their ApoE status, i.e. epsilon4 allele noncarriers (n = 42), subjects with one epsilon4 allele (n = 27) and subjects with two epsilon4 alleles (n = 14). RESULTS: In individuals carrying two epsilon4 alleles, VBM revealed a decline in gray matter density predominantly in the medial temporal lobe region. Subjects with a single copy of the epsilon4 allele exhibited gray matter atrophy in the right inferior frontal gyrus. With respect to white matter changes, atrophy was only found in subjects homozygous for epsilon4 and confined to the right superior and middle temporal gyrus. CONCLUSION: Our findings support the hypothesis that the ApoE genotype in mild cognitive impairment might be associated with structural changes typically found in the early stages of AD.

Clock drawing performance and brain morphology in mild cognitive impairment and Alzheimer's disease.

The Clock Drawing Test (CDT) is a widely used instrument in the neuropsychological assessment of Alzheimer's disease (AD). As CDT performance necessitates several cognitive functions (e.g., visuospatial and constructional abilities, executive functioning), an interaction of multiple brain regions is likely. Fifty-one subjects with mild cognitive impairment, 23 with AD and 15 healthy controls underwent high-resolution magnetic resonance imaging. Optimized voxel-based morphometry (VBM) was performed to investigate the putative association between CDT performance and gray matter (GM) density throughout the entire brain. In the first step of analysis (p<.001, uncorrected), VBM revealed a reduced GM density in numerous cortical (temporal lobe, frontal lobe, parietal lobe, cerebellum) and subcortical (thalamus, basal ganglia) brain regions to be associated with poorer CDT performance. When corrected for multiple comparisons (p<.01), the associations remained significant predominantly in the left temporal and--less pronounced--the right temporal lobe. VBM demonstrated CDT performance to depend on the integrity of widely distributed cortical and subcortical areas in both brain hemispheres with accentuation in the left-sided temporal lobe region.