Road Closure at 801 Broadway Parking Garage
Effective June 18, 2014 - Road closures will block regular access to our Broadway parking garage. Please allow more time for travel to your appointment.
Detour Route and more information.
News & Updates
Search Research Content
Resource Finder at Kennedy Krieger Institute
A free resource that provides access to information and support for individuals and families living with developmental disabilities.
Venous blood effects in spin-echo fMRI of human brain.
|Title||Venous blood effects in spin-echo fMRI of human brain.|
|Publication Type||Journal Article|
|Year of Publication||1999|
|Authors||Oja JM, Gillen J, Kauppinen RA, Kraut M, van Zijl PC|
|Journal||Magnetic resonance in medicine : official journal of the Society of Magnetic Resonance in Medicine / Society of Magnetic Resonance in Medicine|
|Date Published||1999 Oct|
The spin-echo response to visual activation was studied as a function of spatial resolution at a field of 1.5 T. The results showed that the increase in absolute T(2) upon activation was as large as 22.8 +/- 3.1% (P < 0.05) at the highest resolution (5.3 mm(3)), while it was as small as 3.5 +/- 0.2% (P < 0.05) at the lowest resolution (42.2 mm(3)). In addition, upon increasing resolution, the spin-echo signal decay as a function of echo time changed from monoexponential to nonexponential. These data indicate that, when using the standard resolution for fMRI studies at 1.5 T, the effects of spin-echo changes in the draining veins are of major contribution to the total blood oxygenation level-dependent (BOLD) signal changes measured in voxels encompassing the activated brain areas. The data can be quantitatively accounted for using a model based on the intravascular origin of the spin-echo effect including both macrovascular and microvascular effects. Existing theories for the spin-echo BOLD effect based on diffusion through field gradients predict negligible spin-echo effects inside the large vessels and are therefore incompatible with the data. Magn Reson Med 42:617-626, 1999.
|Alternate Journal||Magn Reson Med|