Decoupling of a double-row 16-element tight-fit transceiver phased array for human whole-brain imaging at 9.4 T.

One of the major challenges in constructing multi-channel and multi-row transmit (Tx) or transceiver (TxRx) arrays is the decoupling of the array's loop elements. Overlapping of the surface loops allows the decoupling of adjacent elements and also helps to improve the radiofrequency field profile by increasing the penetration depth and eliminating voids between the loops. This also simplifies the design by reducing the number of decoupling circuits.

In vivo estimation of transverse relaxation time constant (T ) of 17 human brain metabolites at 3T.

Purpose: The transverse relaxation times T of 17 metabolites in vivo at 3T is reported and region specific differences are addressed.

Methods: An echo-time series protocol was applied to one, two, or three volumes of interest with different fraction of white and gray matter including a total number of 106 healthy volunteers and acquiring a total number of 128 spectra. The data were fitted with the 2D fitting tool ProFit2, which included individual line shape modeling for all metabolites and allowed the T calculation of 28 moieties of 17 metabolites.

Novel splittable N-Tx/2N-Rx transceiver phased array to optimize both signal-to-noise ratio and transmit efficiency at 9.4T.

Purpose: The goal of this study was to optimize signal-to-noise ratio (SNR) and parallel receive (Rx) performance of ultrahigh field (UHF) (≥7T) transceiver arrays without compromising their transmit (Tx) efficiency. UHF transceiver head phased arrays with a tight fit improve Tx efficiency in comparison with Tx-only arrays, which are usually larger so that Rx-only arrays can fit inside. However, having ≥16 elements inside a head transceiver array presents decoupling problems.

Safety testing and operational procedures for self-developed radiofrequency coils.

The development of novel radiofrequency (RF) coils for human ultrahigh-field (≥7 T), non-proton and body applications is an active field of research in many MR groups. Any RF coil must meet the strict requirements for safe application on humans with respect to mechanical and electrical safety, as well as the specific absorption rate (SAR) limits. For this purpose, regulations such as the International Electrotechnical Commission (IEC) standard for medical electrical equipment, vendor-suggested test specifications for third party coils and custom-developed test procedures exist.