Inferring diameters of spheres and cylinders using interstitial water
| Autor: | Melanie Martin, Sheryl L. Herrera, Richard Buist, Morgan E. Mercredi |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Materials science
Tube diameter Diffusion Biophysics Analytical chemistry Spectral line 030218 nuclear medicine & medical imaging 03 medical and health sciences 0302 clinical medicine Oscillometry Image Processing Computer-Assisted Effective diffusion coefficient Animals Humans Radiology Nuclear Medicine and imaging Computer Simulation Spectroscopy Interstitial water Models Statistical Radiological and Ultrasound Technology Phantoms Imaging Water Axons Diffusion Magnetic Resonance Imaging Spin echo Polystyrenes SPHERES Monte Carlo Method 030217 neurology & neurosurgery |
| Zdroj: | Magma (New York, N.Y.). 31(5) |
| ISSN: | 1352-8661 |
| Popis: | Most early methods to infer axon diameter distributions using magnetic resonance imaging (MRI) used single diffusion encoding sequences such as pulsed gradient spin echo (SE) and are thus sensitive to axons of diameters > 5 μm. We previously simulated oscillating gradient (OG) SE sequences for diffusion spectroscopy to study smaller axons including the majority constituting cortical connections. That study suggested the model of constant extra-axonal diffusion breaks down at OG accessible frequencies. In this study we present data from phantoms to test a time-varying interstitial apparent diffusion coefficient. Diffusion spectra were measured in four samples from water packed around beads of diameters 3, 6 and 10 μm; and 151 μm diameter tubes. Surface-to-volume ratios, and diameters were inferred. The bead pore radii estimates were 0.60±0.08 μm, 0.54±0.06 μm and 1.0±0.1 μm corresponding to bead diameters ranging from 2.9±0.4 μm to 5.3±0.7 μm, 2.6±0.3 μm to 4.8±0.6 μm, and 4.9±0.7 μm to 9±1 μm. The tube surface-to-volume ratio estimate was 0.06±0.02 μm−1 corresponding to a tube diameter of 180±70 μm. Interstitial models with OG inferred 3-10 μm bead diameters from 0.54±0.06 μm to 1.0±0.1 μm pore radii and 151 μm tube diameters from 0.06±0.02 μm−1 surface-to-volume ratios. |
| Databáze: | OpenAIRE |
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