Device localization and dynamic scan plane selection using a wireless magnetic resonance imaging detector array

Abstract

Purpose A prototype wireless guidance device using single sideband amplitude modulation (SSB) is presented for a 1.5T MRI system. Methods The device contained three fiducial markers each mounted to an independent receiver coil equipped with wireless SSB technology. Acquiring orthogonal projections of these markers determined the position and orientation of the device, which was used to define the scan plane for a subsequent image acquisition. Device localization and scan plane update required approximately 30 ms, so it could be interleaved with high temporal resolution imaging. Since the wireless device is used for localization and doesn’t require full imaging capability, the design of the SSB wireless system was simplified by allowing an asynchronous clock between the transmitter and receiver. Results When coupled to a high readout bandwidth, the error caused by the lack of a shared frequency reference was quantified to be less than one pixel (0.78 mm) in the projection acquisitions. Image-guidance with the prototype was demonstrated with a phantom where a needle was successfully guided to a target and contrast was delivered. Conclusion The feasibility of active tracking with a wireless detector array is demonstrated. Wireless arrays could be incorporated into devices to assist in image-guided procedures.

Wireless Reconfigurable RF Detector Array for Focal and Multiregional Signal Enhancement

“…Unlike passive inductive arrays [28,29] whose individual detector elements cannot be wirelessly controlled, our reconfigurable array can conveniently switch between selective and simultaneous activation to highlight multiple detection regions in real time, enabling convenient multiplexing [30][31][32] of a single-channel MRI scanner without the need for expensive console upgrade. Unlike several other active arrays [33][34][35][36][37] that require at least 100 mW of DC power to operate complicated on-board microcontrollers, our reconfigurable array relies on simple nonlinear circuits that can operate by less than 10 mW of wireless power, thus creating a wireless signal link between internal detectors (that are optimized for focal tissues) and the generic detector (that is commonly available on standard MRI scanners). Besides sensitivity enhancement for multimodal imaging of rodent brains, this wireless reconfigurable detector array will also be useful to improve the operation flexibility of clinical MRI, e.g.…”

Magnetic Resonance Fingerprinting

“…For DESPOT1 this was 1.27 s and for DESPOT2 it was 2.29 s (which includes the time for the required DESPOT1 acquisition.) Statistical Analysis-Quantitative estimates of the errors and efficiencies of MRF, DESPOT1 and DESPOT2 were calculated pixel-wise using a bootstrapped Monte Carlo method as in Riffe et al 51 . Two sets of raw data were acquired for each sequence: the encoded signal and a separate acquisition that only contained noise.…”

Enabling Technology for MRI-Guided Intervention

“…The most recent generation of devices have been optimized for high field strength closed bore magnets, resulting in predictable susceptibility pattern and allowing for visual visualization of the device without obscuring nearby anatomic structures (21). Additionally, new techniques, including passive tracking using applied electric currents (22) and active wireless tracking (23) have shown promise in aiding device localization.…”