Manyetik rezonans görüntüleme sinyalleri için minyatür fiber çelik iletim sistemi

In conventional Magnetic Resonance Imaging (MRI) instruments, after echo sig-nals are received by an MRI coil, they are transmitted through an ultra low noisetransmission system consisting of electrical cables. Although this design provedto be effective over the years, there are recent developments in the MRI tech-nology which require a better, more sophisticated design. One of these emergingtechnologies is ?parallel imaging?, where total size of interconnections is the pri-mary problem, and the other is ?interventional MRI?, where safety needs to beimproved. The Miniature Fiber Optic Transmission System was developed toserve these needs. The system consists of a receiver MRI coil with passive de-tuning, a two-stage low-noise preamplifier and a low-noise laser diode connectedto a photodetector with fiber optic cable in between. The overall noise figureof the system is measured to be lower than 1 dB which guarantees that totalsignal-to-noise ratio (SNR) reduction in the images due to optical MRI signaltransmission system is less than 15%. Total power consumption is 50mW andthe device is switchable by another fiber optic line, which can also control activedetuning circuit if it is present. A prototype device was tested in a GE 1.5 TeslaMRI instrument and several images were acquired with a slight SNR drop, dueto problems with passive detuning. We believe that this design will significantlyreduce the size of parallel imaging arrays and enable placement of internal coilsinto body cavities without providing any safety hazard to the patient, such aselectrical shock or burns.Keywords: Magnetic Resonance Imaging, Fiber Optics, Laser, InterventionalImaging, Parallel Imaging, Ultra Low Noise System.iv