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Effects of large vessels in functional magnetic resonance imaging at 1.5T
Author(s) -
Duyn Jeff H.,
Frank Joseph A.,
Ramsey Nick R.,
Mattay Venkata S.,
Sexton Roy H.,
Tallent Kathleen A.,
Weinberger Daniel R.,
Moonen Chrit T. W.,
Van Gelderen Peter
Publication year - 1995
Publication title -
international journal of imaging systems and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.359
H-Index - 47
eISSN - 1098-1098
pISSN - 0899-9457
DOI - 10.1002/ima.1850060216
Subject(s) - magnetic resonance imaging , nuclear magnetic resonance , materials science , flash (photography) , phase imaging , biomedical engineering , physics , optics , medicine , microscopy , radiology
To further investigate the effects of large vessels on the activation maps generated with functional magnetic resonance imaging at 1.5T, we studied activation of the human visual and motor cortex using a multitude of dedicated FLASH and echo‐planar imaging (EPI) scanning techniques. Both slice and volume scans were performed to assess relative contributions of T 2 * effects, in‐flow, and phase‐shift effects, specifically within and around the larger vessels (around 1 mm in diameter). The contrast mechanism in single‐slice FLASH studies appeared to be predominantly sensitive to in‐flow and phase effects of the blood water within these larger vessels, and their relative contributions were dependent on experimental parameters and vascular geometry. The contrast mechanism in gradient echo EPI studies was governed predominantly by T 2 * effects in tissue water (and to a lesser extent cerebrospinal fluid) surrounding the larger vessels.