I. Saniour, R. Aydé, AL. Perrier, G. Gaborit, L. Duvillaret, R. Sablong, O. Beuf
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 isocontour maps. Onexperimental bench, the results show an increase delay of the switching times (tuned-detuned or detuned-tuned) for optical-detuned coils of about 10 μs 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 isocontours of the different endoluminal coils prototypes are comparable.
Magnetic resonance imaging (MRI) is widely used to diagnose and analyze inflammatory bowel diseases (Geenen et al 2007) and to determine rectal cancer stages (Torkzad et al 2010, Beets-Tanet al 2013, Dewhurst and Mortele 2013). However, accurate exploration of bowel diseases and detailed information about the colon wall layers,mandatory for propermanagement and effective treatment, are still not available. Indeed, despite the huge progresses in radiofrequency (RF) coils, based on the phased array technology with increase of channels (Giusti et al 2012), the external MRI coils have remained unable to provide adequate SNR to reach required high spatial resolution images. By comparison several authors have demonstrated that internal coils significantly increase the local SNR and makes possible either to perform fast in vivo MR spectroscopy of heart tissues or to obtain high spatial resolutionMR images of colon walls in preclinical context (Kantor et al 1984, Beuf et al 2004, Pilleul et al 2005, Ramgolamet al 2011, Dorez et al 2016)…
Biomed. Phys. Eng. Express 3 (2017) 025002