Radiofrequency Coil Design for in vivo Sodium Magnetic Resonance Imaging of Mouse Kidney at 9.4T

Abstract

The objective of this study was to describe a radiofrequency (RF) coil design for in vivo sodium magnetic resonance imaging (MRI) for use in small animals. Accumulating evidence has indicated the importance and potential of sodium imaging with improved magnet strength (> 7T), faster gradient, better hardware, multi-nucleus imaging methods, and optimal coil design for patient and animal studies. Thus, we developed a saddle-shaped sodium volume coil with a diameter/ length of 30/30 mm. To evaluate the efficiency of this coil, bench-level measurement was performed. Unloaded Q value, loaded Q value, and ratio of these two values were estimated to be 352.8, 211.18, and 1.67, respectively. Thereafter, in vivo acquisition of sodium images was performed using normal mice (12 weeks old; n = 5) with a twodimensional gradient echo sequence and minimized echo time to increase spatial resolution of images. Sodium signal-to-noise ratio in mouse kidneys (renal cortex, medulla, and pelvis) was measured. We successfully acquired sodium MR images of the mouse kidney with high spatial resolution (approximately 0.625 mm) through a combination of sodium-proton coils.

Sodium Magnetic Resonance Imaging Shows Impairment of the Counter-current Multiplication System in Diabetic Mice Kidney

“…Sample sizes were selected to provide 80% power for a significant difference of 0.05 and were based on a previous study investigating changes in the tissue sodium concentration (TSC) in rats before and after furosemide administration. 10 …”

“…[6][7][8] Previous reports on kidney 23 Na MR images have studied humans and animals, such as rodents and pigs. [9][10][11] The sodium signal intensity changed in the medulla after diuretic administration in hydronephrosis and in acute tubular necrosis. [11][12][13] After administration of furosemide, an NKCC2 inhibitor, the high-intensity sodium signal in the renal medulla decreased in rats and humans.…”