Handheld Analyzer Improves MRI Performance

Handheld Analyzer Improves MRI Performance

Magnetic Resonance Imaging (MRI) helps healthcare professionals quickly uncover problems inside a patient’s body through use of high-power magnetic fields. To produce these large magnetic fields, the MRI coils are driven using high voltage (several kilovolts) and high current (hundreds of amps) requiring regular maintenance. Specifically, the RF coil inside the MRI must be tuned for impedance matching and RF leakage. If this step is not done, or done improperly, the result is often noisy scanned images with poor contrast. One Japanese medical equipment company found itself regularly confronting the challenge of servicing its MRI machines. To do that, its technicians had to drag a benchtop vector network analyzer (VNA) into hospitals to conduct the needed MRI RF coil tuning process. Without a power socket in the MRI room, the only way to perform that process was to have the instrument powered through a power socket in another room and a coaxial BNC cable connected to the back of the MRI machine. It was complicated and limited by the reach of the benchtop machine. For every maintenance cycle, the technician would set this up then go back and forth between the instrument and the MRI machine to adjust the coils, because the instrument had to be far enough away from the MRI machine’s magnetic field when measurements were made. To solve these challenges, the company found a solution with Keysight’s FieldFox handheld RF and microwave analyzer. In high-power RF environments such as a hospital, analyzer equipment needs to provide some basic critical features, such as:

• Interference and signal monitoring With the number of connected devices in a hospital environment on the rise, interference problems have become increasingly severe. For example, consumer products like cellphones or tablets can cause wireless interference with medical equipment, such as MRI machine, CT machines, and other physiological monitoring devices. The Real Time Spectrum Analysis (RTSA) software found in the FieldFox is an effective tool for interference hunting and signal monitoring. Interference detection and signal monitoring is accomplished using a fast Fourier transform (FFT) analyzer without dead time. The measurement system needs to have sufficient capture bandwidth to detects transient signals, dynamic signals, and RF pulses (Figure 1). A high-speed, gap-free measurement capability to detect, locate and fix interference problems is critical in the field.
• Wireless signal coverage monitoring All hospitals have different layout and are built with numerous specialized construction materials. This makes it extremely difficult to provide good wireless signal coverage throughout the hospital building. The Fieldfox is able to show channel power measurements to verify signal coverage, identify potential interference issues, and optimize network performance (Figure 2). Each channel can be custom set with different frequencies and bandwidths for multiple signal analysis. This capability is useful for technicians performing wireless signal network coverage test and interference analysis.