TY - JOUR
T1 - Anatomic localization and quantitative analysis of gradient refocused echo-planar fMRI susceptibility artifacts
AU - Ojemann, Jeffrey G.
AU - Akbudak, Erbil
AU - Snyder, Abraham Z.
AU - McKinstry, Robert C.
AU - Raichle, Marcus E.
AU - Conturo, Thomas E.
N1 - Funding Information:
This research was supported by NIH Grants NS 06833, NS 01783, an HL13851, by The Charles A. Dana Foundation, by the McDonnell Center for Higher Brain Function, and by the Whitaker Foundation Biomedical Engineering Research Grant Program. J.G.O. received additional support from NIH Training Grant NS 07205. We also thank Dr. Tong-Zeng Yang for assistance with software.
PY - 1997/10
Y1 - 1997/10
N2 - Functional magnetic resonance imaging (fMRI) techniques, such as echo- planar imaging, can permit rapid, sensitive, whole-brain measurements of local blood flow-induced MR signal changes seen during cognitive paradigms. Changes in blood oxygenation due to mismatch of flow and oxygen metabolism cause dynamic variations in microscopic susceptibility effects, leading to the blood oxygenation level-dependent (BOLD) signal measured by fMRI techniques. A related static macroscopic susceptibility effect is known to cause artifacts that attenuate the MR signal, leading to 'blind spots' in some regions of brain adjacent to bone and air sinuses. The anatomical location, spatial extent, and magnitude of signal loss artifact are quantitated for a common whole-brain fMRI technique. Resting gradient-echo EPI studies were obtained in four healthy volunteers. Signal loss was primarily localized to inferior frontal regions (medial orbital gyri and gyrus rectus) and to inferior lateral temporal lobe (including part of fusiform gyrus) bilaterally. Increased echo time (TE) uniformly produced larger artifacts. The orientation of acquired slices and choice of phase- encoding direction influenced the location, shape, and extent of the artifacts. Regions of the brain with severe artifact may have attenuated activation signal, with potential implications for the design and interpretation of fMRI studies targeting activations in these areas.
AB - Functional magnetic resonance imaging (fMRI) techniques, such as echo- planar imaging, can permit rapid, sensitive, whole-brain measurements of local blood flow-induced MR signal changes seen during cognitive paradigms. Changes in blood oxygenation due to mismatch of flow and oxygen metabolism cause dynamic variations in microscopic susceptibility effects, leading to the blood oxygenation level-dependent (BOLD) signal measured by fMRI techniques. A related static macroscopic susceptibility effect is known to cause artifacts that attenuate the MR signal, leading to 'blind spots' in some regions of brain adjacent to bone and air sinuses. The anatomical location, spatial extent, and magnitude of signal loss artifact are quantitated for a common whole-brain fMRI technique. Resting gradient-echo EPI studies were obtained in four healthy volunteers. Signal loss was primarily localized to inferior frontal regions (medial orbital gyri and gyrus rectus) and to inferior lateral temporal lobe (including part of fusiform gyrus) bilaterally. Increased echo time (TE) uniformly produced larger artifacts. The orientation of acquired slices and choice of phase- encoding direction influenced the location, shape, and extent of the artifacts. Regions of the brain with severe artifact may have attenuated activation signal, with potential implications for the design and interpretation of fMRI studies targeting activations in these areas.
UR - http://www.scopus.com/inward/record.url?scp=0030714180&partnerID=8YFLogxK
U2 - 10.1006/nimg.1997.0289
DO - 10.1006/nimg.1997.0289
M3 - Article
C2 - 9344820
AN - SCOPUS:0030714180
SN - 1053-8119
VL - 6
SP - 156
EP - 167
JO - NeuroImage
JF - NeuroImage
IS - 3
ER -