Double-tuned 31 P/ 1 H human head array with high performance at both frequencies for spectroscopic imaging at 9.4T

• Published in: Magnetic resonance in medicine Vol. 84; no. 2; pp. 1076 - 1089
• Main Authors: Avdievich, Nikolai I, Ruhm, Loreen, Dorst, Johanna, Scheffler, Klaus, Korzowski, Andreas, Henning, Anke
• Format: Journal Article
• Language: English
• Published: United States 01-08-2020
• Subjects: Brain - diagnostic imaging; Equipment Design; Head - diagnostic imaging; Humans; Magnetic Resonance Imaging; Phantoms, Imaging; Signal-To-Noise Ratio; double-tuned arrays; central SNR; RF human head coil; ultra-high field MRI; MRSI
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/mrm.28176

To develop a robust design of a human head double-tuned
P/
H array, which provides good performance at both
P and
H frequencies for MR spectroscopic imaging at 9.4T.
Increasing the number of surface loops in a human head array improves the peripheral signal-to-noise ratio (SNR), while the central SNR doesn't substantially change. High peripheral SNR can contaminate MR spectroscopic imaging data at both
H and
P frequency. To minimize this effect, we limited the number of elements in the
P array to 10, i.e., 8 transceiver surface loops circumscribing the head and 2 receive "vertical" loops placed at the superior location. The
H-portion of the array also consists of 10 elements, i.e., 8 transceiver surface loops circumscribing the head and 2 transceiver "vertical" loops at the superior location of the head. Both the
P array and
H array are placed in a single layer at the same distance to the head, which provides high loading and, thus, a good performance for both arrays.
Transmit efficiency of the
H-portion of the double-tuned array was very similar to that of the single-tuned arrays of similar size. Also, addition of the cross-loops substantially improved the brain coverage.
We developed a novel
P/
H double-tuned array for MR spectroscopic imaging of a human brain at 9.4T. Placing both
P and
H loops in a single layer provides for high transmit efficiency at both frequencies without compromising SNR near the brain center at the
P-frequency. Addition of the cross-loops at the superior location improves the brain coverage.