An Active Intravascular MR-Device in Micro System Technology

Abstract

Minimally invasive interventions have spread in the last few years. In many of these procedures, a catheter is applied to treat vascular diseases. In clinical practice x-ray fluoroscopy is mostly used as image guiding modality for intravascular interventions, but this modality is harmful for the patient due to the radiation exposure. The use of real-time Magnetic Resonance Imaging in minimally invasive interventions has recently gained much interest because it avoids radiation and provides high soft tissue contrast. However, due to RF resonance effects that can cause tissue RF heating, long electrical conductors must be avoided in respective devices. Based on a former research an optical active intravascular MR-device is proposed that allows tracking and imaging with the full functionality of a common MR-coil. Only optical connections are used to make this active intravascular device inherently RFsafe. Therefore a miniature optical modulator is presented which uses an optical fiber for signal transmission. Furthermore, power is supplied optically to the transmitter as well. To allow the full functionality of a MR-coil the active detuning of the coil will be provided by a special optical MNOS-varactor. The active MR-device is designed to fit into a 5 F (1,67 mm diameter) catheter tube.