Integrated active tracking detector for MRI‐guided interventions

Abstract

We present a fully integrated detector suitable for active tracking of interventional devices in MR-guided interventions. The single-chip microsystem consists of a detection coil, a tuning capacitor, an intermediate frequency downconversion receiver, and a phase-locked-loop-based frequency synthesizer. Thanks to the integrated mixer, the chip output stage delivers an analog frequency-downconverted NMR signal in the frequency range from 0 to 200 kHz. The microchip, realized in a standard complementary metal oxide semiconductor technology, has a size of 1 3 2 3 0.74 mm 3 and operates at a frequency of 63 MHz (i.e., in 1.5 T clinical scanners). Tests in a standard clinical scanner demonstrate the compatibility of the complementary metal oxide semiconductor microchip with clinical MRI systems. Using a solid sample of cis-polyisoprene having a size of 1 3 1.9 3 0.8 mm 3 as internal signal source, the detector achieves a three-dimensional isotropic spatial resolution of 0.15 mm in a measuring time of 100 ms. Magn Reson Med 67:290-296,

Using a low-amplitude RF pulse at echo time (LARFET) for device localization in MRI

“…In this sense, the technique proposed here performs at least comparably well. The demonstrated performance together with the absence of electrical connections, we believe, paves the way for this technique to be directly applied to systems that are based on the combined nearby placement of the tip coil and circuitry for amplification and electro-optical signal conversion [1,13,14,33,35]. On the other hand, the frequency down-conversion not only simplifies the design of the stages after the LNA but also decreases the power necessary to drive the LED at the end, which is basically the electro-optical signal converter.…”

“…This would increase the complexity at the distal end. A second alternative is an oscillator placed at the catheter tip next to the low-noise amplifier (LNA), and mixer [1]. But for on-chip oscillators a decrease in accuracy is expected over time due to temperature or bias voltage variations.…”

“…Amplifying [27] and frequency down-converting [1,33] the MR signal at the catheter tip could minimize signal losses and thus provide higher SNR. The mixing signal could be provided from an outside generator, necessitating an additional cable to transmit this signal to the catheter tip.…”

Active Integrated Tracking Detectors for MRI-Guided Interventions

“…We have presented and previously published [1] a fully-integrated tracking detector with a state-of-the-art performance in terms of spatial resolution. Currently, we are designing an updated version of the previous chip with a reduced size to make it suitable with the use in smaller size catheters.…”

A fully-integrated detector for NMR microscopy in 0.13μm CMOS

“…This improved spin sensitivity can then be used in life science experiments to analyze highly mass-limited samples or in the field of NMR microscopy to obtain images with aggressively scaled voxel sizes in the micron range. In the past ten years, several research groups have launched activities to exploit the capabilities of modern IC technologies for NMR applications [3]- [8]. Examples of these activities include the realization of portable NMR relaxometers for biomolecule sensing [3], [4] and the design of arrays of NMR detectors for high-resolution magnetic resonance imaging (MRI) with large field-of-views (FOVs) [6].…”