Purpose:Widely used MRI methods show brain morphology both in vivo and ex vivo at very high resolution. Many of these methods (e.g., T2*‐weighted imaging, phase‐sensitive imaging, or susceptibility‐weighted imaging) are sensitive to local magnetic susceptibility gradients produced by subtle variations in tissue composition. However, the spectral resolution of commonly used methods is limited to maintain reasonable run‐time combined with very high spatial resolution. Here, the authors report on data acquisition at increased spectral resolution, with 3‐dimensional high spectral and spatial resolution MRI, in order to analyze subtle variations in water proton resonance frequency and lineshape that reflect local anatomy. The resulting information compliments previous studies based on T2* and resonance frequency.Methods:The proton free induction decay was sampled at high resolution and Fourier transformed to produce a high‐resolution water spectrum for each image voxel in a 3D volume. Data were acquired using a multigradient echo pulse sequence (i.e., echo‐planar spectroscopic imaging) with a spatial resolution of 50 × 50 × 70 μm3 and spectral resolution of 3.5 Hz. Data were analyzed in
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