First In Vivo Potassium-39 $(^{ bf 39}$K) MRI at 9.4 T Using Conventional Copper Radio Frequency Surface Coil Cooled to 77 K. - Ibrahim A. Elabyad; Raffi Kalayciyan; Nagesh C. Shanbhag; Lothar R. Schad (IEEE Trans. Biomed. Eng., 2014)