Active optical-based detuning circuit for receiver endoluminal coil

In this paper we demonstrate the effectiveness of an active optical detuning circuit for magnetic resonance imaging endoluminal receiver coil. Three endoluminal coils prototypes were built: a coil without any detuning circuit, a coil with a galvanic (classic) detuning circuit using a PIN diode, and a coil with an optical detuning circuit using two photodiodes in parallel with a PIN diode. These coils were built and characterized on a laboratory experimental bench. Then, an in vitro experiment was performed with a 3.0 TMR system to evaluate the impact of the endoluminal receiver coils in detuned phase on the image uniformity distribution measured using the body coil. Next, the endoluminal coil was used as a receiver coil to compare the signal-to-noise ratio (SNR) distribution based on iso-contour maps. On experimental bench, the results show an increase delay of the switching times (tuned-detuned or detuned-tuned) for optical-detuned coils of about 10 mu s due to the electro-optical circuits, delay still compatible with requirements. When the body coil is used as a transceiver, the SNR uniformity is similar whether the galvanic or the optical detuning circuit is used. Finally, the SNR iso-contours of the different endoluminal coils prototypes are comparable.