Volume 61, Issue 2 pp. 473-480
Note

Effect of inflow of fresh blood on vascular-space-occupancy (VASO) contrast

Manus J. Donahue

Manus J. Donahue

Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA

F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA

Oxford Centre for Functional MRI of the Brain, Department of Clinical Neurology, University of Oxford, Oxford, UK

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Jun Hua

Jun Hua

Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA

F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA

Department of Electrical and Computer Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA

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James J. Pekar

James J. Pekar

Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA

F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA

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Peter C.M. van Zijl

Corresponding Author

Peter C.M. van Zijl

Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA

F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA

Dept. of Radiology, Johns Hopkins University School of Medicine, 217 Traylor Bldg., 720 Rutland Ave., Baltimore, MD 21205===Search for more papers by this author
First published: 22 January 2009
Citations: 24

Abstract

In vascular-space-occupancy (VASO)-MRI, cerebral blood volume (CBV)-weighted contrast is generated by applying a nonselective inversion pulse followed by imaging when blood water magnetization is zero. An uncertainty in VASO relates to the completeness of blood water nulling. Specifically, radio frequency (RF) coils produce a finite inversion volume, rendering the possibility of fresh, non-nulled blood. Here, VASO-functional MRI (fMRI) was performed for varying inversion volume and TR using body coil RF transmission. For thin inversion volume thickness (δtot < 10 mm), VASO signal changes were positive (ΔS/S = 2.1–2.6%). Signal changes were negative and varied in magnitude for intermediate inversion volumes (δtot = 100–300 mm), yet did not differ significantly (P > 0.05) for δtot > 300 mm. These data suggest that blood water is in steady state for δtot > 300 mm. In this appropriate range, long-TR VASO data converged to a less negative value (ΔS/S = –1.4% ± 0.2%) than short-TR data (ΔS/S = –2.2% ± 0.2%), implying that cerebral blood flow or transit-state effects may influence VASO contrast at short TR. Magn Reson Med 61:473–480, 2009. © 2009 Wiley-Liss, Inc.

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