Magnetic Resonance Imaging of Perfusion Using Spin Inversion of Arterial Water

• Published in: Proceedings of the National Academy of Sciences - PNAS 1992-01, Vol.89 (1), p.212-216
• Main Authors: Williams, Donald S., Detre, John A., Leigh, John S., Koretsky, Alan P.
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Biology; Blood; Blood flow; Blood flow velocity; Carbon Dioxide - blood; Cerebral circulation. Blood-brain barrier. Choroid plexus. Cerebrospinal fluid. Circumventricular organ. Meninges; Cerebrovascular Circulation; Flow velocity; Fundamental and applied biological sciences. Psychology; Imaging; Magnetic resonance imaging; Magnetic Resonance Imaging - methods; Magnetization; Male; Medical imaging; Perfusion; Perfusion imaging; Physics; Protons; Rats; Rats, Inbred Strains; Vertebrates: nervous system and sense organs; Water - chemistry
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.89.1.212

A technique has been developed for proton magnetic resonance imaging (MRI) of perfusion, using water as a freely diffusable tracer, and its application to the measurement of cerebral blood flow (CBF) in the rat is demonstrated. The method involves labeling the inflowing water proton spins in the arterial blood by inverting them continuously at the neck region and observing the effects of inversion on the intensity of brain MRI. Solution to the Bloch equations, modified to include the effects of flow, allows regional perfusion rates to be measured from an image with spin inversion, a control image, and a T1image. Continuous spin inversion labeling the arterial blood water was accomplished, using principles of adiabatic fast passage by applying continuous-wave radiofrequency power in the presence of a magnetic field gradient in the direction of arterial flow. In the detection slice used to measure perfusion, whole brain CBF averaged 1.39 ± 0.19 ml·g-1· min-1(mean ± SEM, n = 5). The technique's sensitivity to changes in CBF was measured by using graded hypercarbia, a condition that is known to increase brain perfusion. CBF vs. pCO2data yield a best-fit straight line described by CBF (ml·g-1·min-1) = 0.052pCO2(mm Hg) - 0.173, in excellent agreement with values in the literature. Finally, perfusion images of a freeze-injured rat brain have been obtained, demonstrating the technique's ability to detect regional abnormalities in perfusion.