Mukund Balasubramanian1,2, Robert V Mulkern1,2, Jeffrey J Neil3, Stephan E Maier1,4,5, Jonathan R Polimeni1,6,7. 1. Harvard Medical School, Boston, Massachusetts, USA. 2. Department of Radiology, Boston Children's Hospital, Boston, Massachusetts, USA. 3. Department of Neurology, Washington University School of Medicine, Saint Louis, Missouri, USA. 4. Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts, USA. 5. Institute of Clinical Sciences, Sahlgrenska University Hospital, Gothenburg, Sweden. 6. Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA. 7. Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
Abstract
PURPOSE: The goal of this study was to measure diffusion signals within the cerebral cortex using the line-scan technique to achieve extremely high resolution in the radial direction (ie, perpendicular to the cortical surface) and to demonstrate the utility of these measurements for investigating laminar architecture in the living human brain. METHODS: Line-scan diffusion data with 250-500 micron radial resolution were acquired at 7 T on 8 healthy volunteers, with each line prescribed perpendicularly to primary somatosensory cortex (S1) and primary motor cortex (M1). Apparent diffusion coefficients, fractional anisotropy values, and radiality indices were measured as a function of cortical depth. RESULTS: In the deep layers of S1, we found evidence for high anisotropy and predominantly tangential diffusion, with low anisotropy observed in superficial S1. In M1, moderate anisotropy and predominantly radial diffusion was seen at almost all cortical depths. These patterns were consistent across subjects and were conspicuous without averaging data across different locations on the cortical sheet. CONCLUSION: Our results are in accord with the myeloarchitecture of S1 and M1, known from prior histology studies: in S1, dense bands of tangential myelinated fibers run through the deep layers but not the superficial ones, and in M1, radial myelinated fibers are prominent at most cortical depths. This work therefore provides support for the idea that high-resolution diffusion signals, measured with the line-scan technique and receiving a boost in SNR at 7 T, may serve as a sensitive probe of in vivo laminar architecture.
PURPOSE: The goal of this study was to measure diffusion signals within the cerebral cortex using the line-scan technique to achieve extremely high resolution in the radial direction (ie, perpendicular to the cortical surface) and to demonstrate the utility of these measurements for investigating laminar architecture in the living human brain. METHODS: Line-scan diffusion data with 250-500 micron radial resolution were acquired at 7 T on 8 healthy volunteers, with each line prescribed perpendicularly to primary somatosensory cortex (S1) and primary motor cortex (M1). Apparent diffusion coefficients, fractional anisotropy values, and radiality indices were measured as a function of cortical depth. RESULTS: In the deep layers of S1, we found evidence for high anisotropy and predominantly tangential diffusion, with low anisotropy observed in superficial S1. In M1, moderate anisotropy and predominantly radial diffusion was seen at almost all cortical depths. These patterns were consistent across subjects and were conspicuous without averaging data across different locations on the cortical sheet. CONCLUSION: Our results are in accord with the myeloarchitecture of S1 and M1, known from prior histology studies: in S1, dense bands of tangential myelinated fibers run through the deep layers but not the superficial ones, and in M1, radial myelinated fibers are prominent at most cortical depths. This work therefore provides support for the idea that high-resolution diffusion signals, measured with the line-scan technique and receiving a boost in SNR at 7 T, may serve as a sensitive probe of in vivo laminar architecture.
Authors: R V Mulkern; H Gudbjartsson; C F Westin; H P Zengingonul; W Gartner; C R Guttmann; R L Robertson; W Kyriakos; R Schwartz; D Holtzman; F A Jolesz; S E Maier Journal: NMR Biomed Date: 1999-02 Impact factor: 4.044
Authors: Jennifer A McNab; Jonathan R Polimeni; Ruopeng Wang; Jean C Augustinack; Kyoko Fujimoto; Allison Stevens; Christina Triantafyllou; Thomas Janssens; Reza Farivar; Rebecca D Folkerth; Wim Vanduffel; Lawrence L Wald Journal: Neuroimage Date: 2012-12-16 Impact factor: 6.556
Authors: S E Maier; H Gudbjartsson; S Patz; L Hsu; K O Lovblad; R R Edelman; S Warach; F A Jolesz Journal: AJR Am J Roentgenol Date: 1998-07 Impact factor: 3.959