A novel, non-invasive, MRI based approach to the measurement of OEF, CBF and CMRO2 in the human brain.

2013 Fiscal Year Research-status Report

• Project/Area Number: 25861120
• Research Category: Grant-in-Aid for Young Scientists (B)
• Research Institution: Iwate Medical University
• Principal Investigator: ジョナサン グッドウィン 岩手医科大学, 医学部, 常任研究員 (80633156)
• Project Period (FY): 2013-04-01 – 2015-03-31
• Keywords: OEF / SWI / CBF / O2 / CMRO2

Research Abstract

The work on this project over the last 12 months has focused on development of the imaging methodology. This has focused on three areas: 1) OEF measurement with susceptibility weighted imaging
2) CBF measurement using pulsed arterial spin labelling, 3) Combined OEF and CBF measurement to quantify CMRO2.
OEF measurement has been based on our groups previous methodology with the addition of new post processing techniques, that enable resting state OEF measurement, as well as the correction of image inhomogeneity associated with high field MRI. This means, high-resolution baseline maps of OEF are now achievable without previously observed image distortions, and without the need for multiple measurements, which were previously used to measure OEF change only.
The measurement of CBF is currently the main technical issue. Due to technical limitations of the MRI scanner, the current system, including scanner head coil and MRI pulse processing techniques, have meant that CBF measurements are currently not useable, and therefore quantification of CMRO2, as described in the original Kakenhi proposal has not been resolved. To address this issue, I have currently been working on a new technique for quantification of CMRO2 without the use of CBF measurements, but instead using artificial modulation of venous oxygenation using high concentration oxygen gas and carbon dioxide gas mixture. During the ongoing months, I hope to validate this methodology in a subject group, and hopefully continue developing CBF measurement in co-operation with the MRI manufacturers. (GE)

Current Status of Research Progress

3: Progress in research has been slightly delayed.

Reason

The measurement of CBF has not been very successful. This is due to a technical issue of the manufacturer, which has prevented the successful use of pulsed arterial spin labelling at high field, and is therefore largely uncontrollable According to the manufacturer (GE), there will hopefully be some additional improvement to the sequence programming later this year. I will be working in co-operation with them on this. Also, equipment purchased for the measurement of end-tidal gases was delayed by several months due to international order. Also, methodological comparisons using 3T MRI in the hospital, have become impractical due to scanner availability and language difficulties with hospital staff. AS such, the research has been focused on 7T MRI only.

Strategy for Future Research Activity

Whilst working on obtaining improved CBF measurement using arterial spin labelling, my methodology of CMRO2 qualification using susceptibility weighted imaging with high concentration O2 and CO2 mixed gas inhalation will continue, with the aim of validating the technique in a volunteer group.
This technique is based on the modification of gas transport equations, in combination with modified bloch equations for MRI signal change. When combined with existing quantitative Susceptibility mapping theory, it represents a novel approach to CMRO2 qualification.

Expenditure Plans for the Next FY Research Funding

The quotation for gas analysis equipment was considerably lower than the actual costs due to the inflated price of the Japanese import company. Therefore, the remaining money is insufficient to attend the international conferences as originally proposed. Additional travel for meetings with collaborators is also not possible.
Therefore the remaining money, which is proportionally smaller than expected for this point in the grant, will be used for travel related expenses for the presentation of scientific results.