Karin Shmueli1, 2, Peter van Gelderen1, Jozef H. Duyn1
1Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States; 2Department of Medical Physics and Bioengineering, University College London, London, United Kingdom
It is unknown which molecules are primarily responsible for tissue exchange-induced frequency contrast (fe). So far, fe measurements have relied on internal frequency reference chemicals but these interact, causing confounding frequency shifts. Therefore, we developed a reference-chemical-free phantom-based method to measure fe and applied it to cerebrosides. The phantom is an interchangeable cylindrical tube inside a saline-filled sphere. Frequency images were acquired with the (cerebroside- or saline-filled) tube parallel and perpendicular to B0 to separate orientation-dependent susceptibility-induced contributions from fe. Precise cerebroside susceptibility and fe values were obtained at 7 Tesla and the phantom could be filled with different chemicals.