arXiv subjects

Caglar Ataman

Publications and source records attributed to Caglar Ataman.

3 recordsLinked to original sources

arXiv2026

Optically-powered Low Power Low Noise Amplifiers for MRI

Purpose: Fully optical receive coils can potentially allow dense receiver arrays with a large channel count, reduced channel crosstalk, and less cable clutter. The power requirements of conventional low-noise amplifiers (LNAs) are prohibitive for simultaneously driving many coils through optical means, as opto-electric power conversion efficiencies can only reach about 50%. The goal is to develop low-power LNAs (LPLNA) with substantially lower power consumption without compromising noise figure (NF) and gain. Methods: A LPLNA was designed as a two-stage cascaded amplifier using an MR-compatible E-pHEMT (Enhancement-mode Pseudomorphic High Electron Mobility Transistor) transistor. The design was implemented on a single-sided printed circuit board (PCB), and its performance was compared with a commercial LNA. A four-channel shielded loop resonator array was constructed, and the signal-to-noise ratio (SNR), noise covariance, and preamplifier decoupling performance were evaluated. Results: The LPLNA had a five-fold lower electrical power consumption (40 mW) than the commercial LNA and provided comparable SNR in phantom measurements. In vivo experiments further confirmed that the LPLNA operates reliably under realistic MRI conditions. Additionally, four-channel receiver array measurements demonstrated comparable SNR within 2% of the commercial LNA and lower inter-channel noise correlation with 0.26 vs 0.3 on average. Conclusion: This study demonstrates the feasibility of LPLNAs for optically-powered RF receiver coil arrays. The LPLNA could also be applied in power-constrained or remote MRI environments.

physics.med-ph↗

arXiv2026

Optical Detuning Strategies for Shielded Loop Resonators

Purpose: To compare detuning performance and evaluate the power requirements of optical detuning methods, and to demonstrate the feasibility of an optically detuned four-channel receive array. Methods: Four optical detuning methods were compared in simulations, bench tests, and phantom measurements at 3T against conventional galvanic detuning. Passive detuning was also tested as an additional wireless detuning option. Optical power requirements for the detuning networks were investigated, and a flexible, optically detuned 4-channel shielded-loop resonator (SLR) array was constructed and tested in vivo. Results: A photodiode-PIN diode combination exhibited the highest unloaded Q (68.6) and Q ratio (1.9), with detuning performance and signal-to-noise ratio comparable to that of galvanic detuning at an optical power of 10 mW. Using this detuning strategy, in vivo images of the knee and brain were successfully acquired with a 4-channel flexible array. Conclusion: Optical detuning is a practical alternative to conventional galvanic detuning in flexible SLR arrays. With advances in optical signal and power transmission, optimizing optical detuning while meeting manageable power requirements is an important step toward fully optical receive-coil arrays. This study provides a baseline for the total optical power required for active detuning in such optical coil systems.

eess.SY↗

arXiv2026

Light Coils: MRI with Fully Optical Data and Power Transmission

In MRI, dense receiver coil arrays with a high number of coil elements are used to efficiently detect and encode the signal. Further increasing the number of coils is hampered by electrical cabling and massive electronics that introduce electromagnetic coupling, integration complexity and even safety constraints. Here we introduce the novel Light Coils concept, a fully optical MRI receive architecture in which data transmission, front-end power delivery, and coil detuning are all implemented optically, thereby reducing the massive galvanic cabling to a few optical fibers. For signal encoding, Mach-Zehnder modulators (MZM) are used to convert the MR signal from each coil onto a C-band optical carrier. The preamplifiers are driven via a power-over-fiber (PoF) system that uses a high-efficiency photovoltaic (PV) cell for optical-to-electrical power conversion. A pulse-sequence-triggered optical path controls active detuning. Jointly optimizing modulator bias, optical power and front-end gain under realistic receiver chain conditions, Light Coils can match the signal-to-noise ratio (SNR) of conventional RF coil systems with galvanic cables at MZM input powers of 5-10mW and photonic power converter inputs of 80-100mW. At a clinical 3T MRI system, we show in vivo human brain imaging with a single-channel Light Coil element with an image quality and SNR comparable to a conventional coaxial readout using the identical coil element. Extending the concept to a four-channel array using dense wavelength-division multiplexing over a single fiber, we demonstrate wavelength-selective routing with inter-channel optical isolation exceeding 28dB, reduced noise correlation compared with the galvanic reference, and parallel imaging. These results establish a scalable route towards lightweight, modular, and potentially ultra-dense MRI receive arrays based on integrated photonics and power-over-fiber.

eess.SP↗