Noninvasive oxygen saturation estimation with quantitative MRI T2 mapping

Doctor's Name: 
Juliet Varghese
The Ohio State University

Collaboratively awarded through the CHF and AHA Congenital Heart Defect Research Awards
(Total Request = $28,080;  CHF portion = $14,040)

Congenital heart defects are characterized by reduced blood oxygen saturation due to mixing of arterial and venous blood. Increased survival into adulthood necessitates the need for non-invasive diagnostic tests that can reduce the need for invasive procedures in management of such patients. As magnetic resonance transverse relaxation time T2 is affected by hemoglobin O2 saturation, we aim to develop a rapid, novel quantitative T2 mapping method that is designed to minimize the effects and artifacts caused by flowing blood. An accurate and reliable measurement of blood T2 will enable the estimation of arterio-venous oxygen saturation in the heart and deep vessels, even in regions having limited accessibility with other techniques. The method could be easily incorporated into MRI protocols for evaluation of patients with congenital heart disease, and may also have applications in peripheral arterial and other cardiovascular diseases. The design, development and successful implementation of our proposed technique will be accomplished by: A. Optimizing and testing the technique in a flow phantom to assess and establish flow insensitivity. B. Validating and establishing the relationship between blood T2 and O2 saturation in an animal model, and empirically deriving a calibration factor. C. Evaluating feasibility in healthy volunteers by comparing SaO2-SvO2 differences with simultaneously monitored VO2 levels and cardiac output. The proposed project evolves from my current AHA project that utilizes rapid quantitative relaxometric T1, T2 and T2* mapping to characterize calf muscle response pre and post treadmill exercise. Our experiments led to the determination of normative calf muscle behavior in healthy adults, which was fundamental in understanding physiological skeletal muscle changes across age and gender. The knowledge gained helps to identify and differentiate the pathophysiological calf muscle behavior in peripheral arterial disease (PAD). As claudication in PAD is an indicator of skeletal muscle ischemia, rapid quantitative determination of oxygen consumption in the muscles would be beneficial in further characterization of PAD pathophysiology. The successful execution of the proposed project would give rise to non-invasive rapid estimation of oxygen saturation in large blood vessels; insight and knowledge gained from this research would lead to the application of this technique in quantifying microvascular oxygen consumption and ischemia in PAD.


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