Neurochemistry

Richter, Derek

doi:10.1007/978-3-642-67416-7_1

Cited by 1 publication

(2 citation statements)

References 147 publications

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“…The relative water content is higher in GM than in WM, indicating that differences in proton density outbalance the effects of relatively low T 1 weighting. The ratio of mean absolute WM to GM amplitudes for the water component is 0.96; this value is confirmed by calculations of T 1 -weighted steady-state signal levels using T 1 s 29 of 832 ms and 1331 ms and water contents 30 of 72% and 82% for WM and GM (assuming equal mass density), 31 respectively.…”

Section: F I G U R Esupporting

confidence: 59%

“…The relative amplitudes presented in Table 2 for the three signal components across WM and GM correspond well with those reported for ex vivo human brain tissue with native water content. 9 The relative water contents of both tissue types are lower than reported in literature, 30 which can be explained by differences in how the values were obtained; here, the water component amplitudes reflect the combination of water proton density and T 1 weighting, whereas literature values typically reflect mass fractions. The component amplitude maps in Figure 6 exhibit substantial differences in the non-brain tissues of the head.…”

Section: Component Amplitudesmentioning

confidence: 79%

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Myelin bilayer mapping in the human brain in vivo

Baadsvik,

Weiger,

Froidevaux

et al. 2024

Magnetic Resonance in Med

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PurposeTo quantitatively map the myelin lipid‐protein bilayer in the live human brain.MethodsThis goal was pursued by integrating a multi‐TE acquisition approach targeting ultrashort T2 signals with voxel‐wise fitting to a three‐component signal model. Imaging was performed at 3 T in two healthy volunteers using high‐performance RF and gradient hardware and the HYFI sequence. The design of a suitable imaging protocol faced substantial constraints concerning SNR, imaging volume, scan time, and RF power deposition. Model fitting to data acquired using the proposed protocol was made feasible through simulation‐based optimization, and filtering was used to condition noise presentation and overall depiction fidelity.ResultsA multi‐TE protocol (11 TEs of 20–780 μs) for in vivo brain imaging was developed in adherence with applicable safety regulations and practical scan time limits. Data acquired using this protocol produced accurate model fitting results, validating the suitability of the protocol for this purpose. Structured, grainy texture of myelin bilayer maps was observed and determined to be a manifestation of correlated image noise resulting from the employed acquisition strategy. Map quality was significantly improved by filtering to uniformize the k‐space noise distribution and simultaneously extending the k‐space support. The final myelin bilayer maps provided selective depiction of myelin, reconciling competitive resolution (1.4 mm) with adequate SNR and benign noise texture.ConclusionUsing the proposed technique, quantitative maps of the myelin bilayer can be obtained in vivo. These maps offer unique information content with potential applications in basic research, diagnosis, disease monitoring, and drug development.

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Section: F I G U R Esupporting

confidence: 59%

Section: Component Amplitudesmentioning

confidence: 79%