Biology subjects

Lattanzi, R.

Publications and source records attributed to Lattanzi, R..

4 recordsLinked to original sources

bioRxiv2025

Rational MRI Coil Design: An Optimization Framework for the Design of Radiofrequency Coils for Magnetic Resonance Imaging

The radiative characteristics of the radiofrequency receive coils dictate the signal-to-noise ratio (SNR) of magnetic resonance images. Despite the crucial importance of RF coils, the practical coil design process has remained a largely empirical one. This work introduces a novel optimization framework for rational coil design, which relies on a fully automated pipeline that combines rapid electromagnetic simulations, shape optimization and coil meshing. The objective function iteratively maximizes SNR performance in a target region of interest with respect to the ultimate intrinsic SNR, which is the theoretically highest SNR independent from any particular coil design. The forward simulation employs a fast electromagnetic solver based on coupled surface and volume integral equations. The coils are represented as B-spline curves with an associated width, and automatically meshed for EM simulation. We implemented a new method to tune and decouple coils at each iteration without manual user intervention. The algorithm optimizes the size and position of a given number of coils with a combination of grid search and a line search. We demonstrated the framework by designing receive arrays of increasing complexity that yield optimal SNR for different target regions inside a numerical head model. SNR simulation time ranged from 15 s for a 3-coil configuration to 32 s for a 12-coil array, constrained to a helmet-like surface, including tuning and decoupling. The optimized 12-coil geometry yielded 9% higher average SNR performance in the brain at 3 T. This work represents the first automated coil optimization framework that uses full-wave electromagnetic simulations and ultimate performance benchmarks. This novel approach enables the systematic design of coils for magnetic resonance imaging with significantly improved SNR performance, potentially transforming coil development from empirical design to physics-driven optimization.

bioengineering↗

bioRxiv2024

A 128-channel receive array with enhanced SNR performance for 10.5 tesla brain imaging

PurposeTo develop and characterize the performance of a 128-channel head array for brain imaging at 10.5 tesla and evaluate the potential of brain imaging at this unique, >10 tesla magnetic field. MethodsThe coil is composed of a 16-channel self-decoupled loop transmit/receive array with a 112-loop receive-only (Rx) insert. Interactions between the outer transmitter and the inner 112Rx insert were mitigated using coaxial cable traps placed every 1/16 of a wavelength on each feed cable, locating most preamplifier boards outside the transmitter field and miniaturizing those placed directly on individual coils. ResultsThe 128-channel array described herein achieved 77% of ultimate intrinsic SNR in the center of the brain. Transmit field maps obtained experimentally on a phantom with and without the receive array were similar and matched EM simulations, leading to FDA approval for human imaging. Anatomical and functional data, including with power demanding sequences, were acquired successfully on human volunteers. ConclusionsCounterintuitive to expectations based on magnetic fields [≤]7T, the higher channel counts provided SNR gains centrally, capturing [~]80% uiSNR. Fraction of uiSNR achieved centrally in 64Rx, 80Rx, and 128Rx arrays suggested that a plateau was being reached at 80%. At this plateau, linear to approximately quadratic B0 dependent SNR gains for the periphery and the center, respectively, were observed for 10.5T relative 7T.

neuroscience↗

bioRxiv2024

Translating human drug use patterns into rat models: exploring spontaneous interindividual differences via refined drug self-administration procedures

Heroin and cocaine users tailor their dosage and frequency of use, as well as their method of administration, to maximize the drugs pleasurable effects and prevent withdrawal symptoms. On the other hand, many preclinical self-administration and choice experiments employ fixed unit doses and mandatory timeouts after doses (known as discrete dimension procedures). These restrictions fail to consider the distinct pharmacokinetic properties of heroin and cocaine, leading to uniform and comparable behaviors (including drug-taking patterns). This uniformity contrasts sharply with the significantly different ways humans use heroin and cocaine, which are characterized by highly individualized drug use behaviors. Here, we introduce a no-timeout procedure that overcomes this limitation (continuous dimension procedure). We analyzed the heroin and cocaine taking- and seeking-patterns and estimated drug-brain levels in the presence or absence of timeout between drug injections. We further assessed how absence of timeout and the availability of drug or social peer (access time to the two rewards) affect drug preference. Removing the timeout had a profound effect on pattern of heroin taking and seeking, promoting the emergence of burst-like drug intake and social withdrawal as revealed by a discrete choice procedure. On the other hand, timeout removal had a lesser impact on cocaine taking and seeking and did not impact social preference. By removing timeout during self-administration and increasing the access time during choice resulted in a self-administration procedure that more closely mimic human heroin intake, offering a platform to identify novel medications.

neuroscience↗

bioRxiv2024

RF coil design strategies for improving SNR at theultrahigh magnetic field of 10.5 Tesla

PurposeTo develop multichannel transmit and receive arrays towards capturing the ultimate-intrinsic-SNR (uiSNR) at 10.5 Tesla (T) and to demonstrate the feasibility and potential of whole-brain, high-resolution human brain imaging at this high field strength. MethodsA dual row 16-channel self-decoupled transmit (Tx) array was converted to a 16Tx/Rx transceiver using custom transmit/receive switches. A 64-channel receive-only (64Rx) array was built to fit into the 16Tx/Rx array. Electromagnetic modeling and experiments were employed to define safe operation limits of the resulting 16Tx/80Rx array and obtain FDA approval for human use. ResultsThe 64Rx array alone captured approximately 50% of the central uiSNR at 10.5T while the identical 7T 64Rx array captured [~]76% of uiSNR at this lower field strength. The 16Tx/80Rx configuration brought the fraction of uiSNR captured at 10.5T to levels comparable to the performance of the 64Rx array at 7T. SNR data obtained at the two field strengths with these arrays displayed [Formula] dependent increases over a large central region. Whole-brain high resolution T2* and T1 weighted anatomical and gradient-recalled echo EPI BOLD fMRI images were obtained at 10.5T for the first time with such an advanced array, illustrating the promise of >10T fields in studying the human brain. ConclusionWe demonstrated the ability to approach the uiSNR at 10.5T over the human brain with a novel, high channel count array, achieving large SNR gains over 7T, currently the most commonly employed ultrahigh field platform, and demonstrate high resolution and high contrast anatomical and functional imaging at 10.5T.

neuroscience↗