Development of an Add-on (23)Na-MRI Radiofrequency Platform for a (1)H-MRI System Using a Crossband Repeater: Proof-of-concept

(23)Na-MRI provides information on Na(+) content, and its application in the medical field has been highly anticipated. However, for existing clinical (1)H-MRI systems, its implementation requires an additional broadband RF transmitter, dedicated transceivers, and RF coils for Na(+) imaging. However, a standard medical MRI system cannot often be modified to perform (23)Na imaging. We have developed an add-on crossband RF repeater system that enables (23)Na-MRI simply by inserting it into the magnet bore of an existing (1)H MRI. The three axis gradient fields controlled by the (1)H-MRI system were directly used for (23)Na imaging without any deformation. A crossband repeater is a common technique used for amateur radio. This concept was proven by a saline solution phantom and in vivo mouse experiments. This add-on RF platform is applicable to medical (1)H MRI systems and can enhance the application of (23)Na-MRI in clinical usage.