Magnetization transfer enhanced vascular-space-occupancy (MT-VASO) functional MRI.

Mark McIntosh,'s picture
PubMed URL:
van Zijl PC
Author List: 
Hua J
Donahue MJ
Zhao JM
Grgac K
Huang AJ
Zhou J
van Zijl PC
Magn Reson Med
PubMed ID: 
Vascular-space-occupancy (VASO) MRI is a novel technique that uses blood signal nulling to detect blood volume alterations through changes in tissue signal. VASO has relatively low signal to noise ratio (SNR) because only 10-20% of tissue signal remain at the time of blood nulling. Here, it is shown that by adding a magnetization transfer (MT) prepulse it is possible to increase SNR either by attenuating the initial tissue magnetization when the MT pulse is placed before inversion, or, accelerating the recovery process when the pulse is applied after the inversion. To test whether the MT pulse would affect the blood nulling time in VASO, MT effects in blood were measured both ex vivo in a bovine blood phantom and in vivo in human brain. Such effects were found to be sufficiently small (<2.5%) under a saturation power <or= 3 microT, length=500 ms, and frequency offset >or=40 ppm to allow use of the same nulling time. Subsequently, functional MRI experiments using MT-VASO were performed in human visual cortex at 3 Tesla. The relative signal changes in MT-VASO were of the same magnitude as in VASO, while the contrast to noise ratio (CNR) was enhanced by 44+/-12% and 36+/-11% respectively. Therefore, MT-VASO should provide a means for increasing inherently low CNR in VASO experiments while preserving the CBV sensitivity.
Published Date: 
April, 2009

Bradley L. Schlaggar, M.D., Ph.D., Named President and CEO of Kennedy Krieger Institute

We’re thrilled to welcome Bradley L. Schlaggar, M.D., Ph.D., to the Kennedy Krieger family as our next President and CEO.

Learn more.

Appointments & Referrals



Read inspiring stories, news and updates about the Institute's patient care, research, special education, professional training, and community programs.


Resource Finder


A free resource that provides access to information and support for individuals and families living with developmental disabilities.