Dataset Information

Measurement of Hypothalamic Glucose Under Euglycemia and Hyperglycemia by MRI at 3T.

ABSTRACT: To evaluate the feasibility of using a clinical magnetic resonance (MR) system and MR spectroscopy (MRS) to measure glucose concentration changes in the human hypothalamus, a structure central to whole-body glucose regulation.A time series of MR spectra (semi-LASER, TE = 28 msec), localized to the bilateral hypothalamus (?1.6 ml) were obtained at 3T in six healthy subjects at baseline (euglycemia) and during a ?65-70-minute-long hyperglycemic clamp in 11-minute blocks with interleaved T1 FLASH images to retrospectively assess head motion, and track changes in cerebrospinal fluid (CSF) partial volume. The LCModel was used to quantify the sum of glucose and taurine concentrations, [Glc+Tau], along with their associated Cramér-Rao lower bounds (CRLB).Spectral quality allowed quantification of [Glc+Tau] (sum reported due to high negative correlation between these metabolites) with CRLB <25% in 35/36 timepoints during hyperglycemia. Increased [Glc+Tau] was observed with hyperglycemia in all subjects, but most reliably in those with plasma glucose targets ?300 mg/dl. For these subjects, [Glc+Tau]baseline (n = 4) was 1.5 (±0.3, SD) mM, and increased to 4.5 (±1.1) mM (n = 16) for timepoints acquired ?25 minutes after onset of the clamp, with 15/16 timepoints having no overlap of 95% confidence intervals (CIs) between baseline and hyperglycemia. Preliminary analysis revealed a linear (1:5) relationship between hypothalamus-blood glucose concentrations.It is feasible to measure glucose concentration changes in the human hypothalamus using a standard 3T scanner and a short-echo semi-LASER sequence by utilizing retrospective motion tracking, CSF correction, predetermined quality acceptance criteria, and hyperglycemic blood glucose levels ?300 mg/dl.2 J. Magn. Reson. Imaging 2017;45:681-691.

SUBMITTER: Joers JM

PROVIDER: S-EPMC5575789 | biostudies-other | 2017 Mar

REPOSITORIES: biostudies-other

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Measurement of Hypothalamic Glucose Under Euglycemia and Hyperglycemia by MRI at 3T.

Joers James M JM Deelchand Dinesh K DK Kumar Anjali A Moheet Amir A Seaquist Elizabeth E Henry Pierre-Gilles PG Öz Gülin G

Journal of magnetic resonance imaging : JMRI 20160712 3

<h4>Purpose</h4>To evaluate the feasibility of using a clinical magnetic resonance (MR) system and MR spectroscopy (MRS) to measure glucose concentration changes in the human hypothalamus, a structure central to whole-body glucose regulation.<h4>Subjects and methods</h4>A time series of MR spectra (semi-LASER, TE = 28 msec), localized to the bilateral hypothalamus (∼1.6 ml) were obtained at 3T in six healthy subjects at baseline (euglycemia) and during a ∼65-70-minute-long hyperglycemic clamp in ...[more]

PMID: 27402249

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Project description:In the recent MRI scanning, ultra-high-field (7T) MR imaging provides higher resolution and better tissue contrast compared to routine 3T MRI, which may help in more accurate and early brain diseases diagnosis. However, currently, 7T MRI scanners are more expensive and less available at clinical and research centers. These motivate us to propose a method for the reconstruction of images close to the quality of 7T MRI, called 7T-like images, from 3T MRI, to improve the quality in terms of resolution and contrast. By doing so, the post-processing tasks, such as tissue segmentation, can be done more accurately and brain tissues details can be seen with higher resolution and contrast. To do this, we have acquired a unique dataset which includes paired 3T and 7T images scanned from same subjects, and then propose a hierarchical reconstruction based on group sparsity in a novel multi-level Canonical Correlation Analysis (CCA) space, to improve the quality of 3T MR image to be 7T-like MRI. First, overlapping patches are extracted from the input 3T MR image. Then, by extracting the most similar patches from all the aligned 3T and 7T images in the training set, the paired 3T and 7T dictionaries are constructed for each patch. It is worth noting that, for the training, we use pairs of 3T and 7T MR images from each training subject. Then, we propose multi-level CCA to map the paired 3T and 7T patch sets to a common space to increase their correlations. In such space, each input 3T MRI patch is sparsely represented by the 3T dictionary and then the obtained sparse coefficients are used together with the corresponding 7T dictionary to reconstruct the 7T-like patch. Also, to have the structural consistency between adjacent patches, the group sparsity is employed. This reconstruction is performed with changing patch sizes in a hierarchical framework. Experiments have been done using 13 subjects with both 3T and 7T MR images. The results show that our method outperforms previous methods and is able to recover better structural details. Also, to place our proposed method in a medical application context, we evaluated the influence of post-processing methods such as brain tissue segmentation on the reconstructed 7T-like MR images. Results show that our 7T-like images lead to higher accuracy in segmentation of white matter (WM), gray matter (GM), cerebrospinal fluid (CSF), and skull, compared to segmentation of 3T MR images.

Dataset Information

Measurement of Hypothalamic Glucose Under Euglycemia and Hyperglycemia by MRI at 3T.

Publications

Measurement of Hypothalamic Glucose Under Euglycemia and Hyperglycemia by MRI at 3T.

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