Abstract #0810

Quantitative Study of TX/RX-efficiency of X-Nuclear MRS/MRI at High/Ultrahigh Field

Hannes M. Wiesner ¹ , Wei Luo ² , Qing X. Yang ³ , Xiao-Hong Zhu ¹ , Scott Schillak ¹ , and Wei Chen ¹

¹ Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, Minneapolis, Minnesota, United States, ² Department of Engineering Science and Mechanics, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States, ³ Center for NMR Research, Department of Radiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, United States

In vivo MRS and MRI can benefit significantly from high/ultrahigh field in improving detection sensitivity and spectral resolution. However, the RF wave property can behave substantially differently at high field and influence both B ₁ ⁺ and B ₁ ^- fields, thus, affect the transmission and reception efficiencies as well as RF power transmission and SAR. This study aims to quantitatively investigate and compare the transmission and reception efficiencies of ¹ H and common X-nuclei ³¹ P, ²³ Na and ¹⁷ O at 7T. The results indicate that low- lower case Greek gamma

nuclei require a large RF pulse voltage (or power) to achieve the same flip angle as compared to ¹ H spin, nevertheless, their relative RF power demand is significantly reduced due to a higher B ₁ ⁺ transmission efficiency at high field. Moreover, low- lower case Greek gamma

nuclei exhibit much better reception efficiencies than that of ¹ H, leading to superior detection sensitivity at high/ultrahigh field.

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