Uniform prostate imaging and spectroscopy at 7 T: comparison between a microstrip array and an endorectal coil

Abstract

An endorectal coil and an eight-element microstrip array were compared for prostate imaging at 7 T. An extensive radiofrequency safety assessment was performed with the use of finite difference time domain simulations to determine safe scan parameters. These simulations showed that the endorectal coil can deliver substantially more B(1)(+) to the prostate than can the microstrip array within the specific absorption rate safety guidelines. However, the B(1)(+) field of the endorectal coil is very inhomogeneous, which makes the use of adiabatic pulses compulsory for T(1) - or T(2) -weighted imaging. As a consequence, a full prostate examination is only possible in a feasible amount of time when the microstrip array is used for T(1) - and T(2) -weighted imaging, whereas the endorectal coil is required for spectroscopic imaging. The pulse parameters were optimised within the specific absorption rate guidelines and thereafter used to provide a good illustration of the possibilities of prostate imaging at 7 T.

Improving SNR and B1 transmit field for an endorectal coil in 7 T MRI and MRS of prostate cancer

“…Finite difference time domain (FDTD) calculations were performed using a home‐built software package developed based on methods explained in the study of van den Bergen et al (14). The simulations were performed to calculate B 1 + and B 1 − fields in a uniform phantom as well as in a realistic model of the human prostate (7, 14) for both the loop and the stripline elements. The electrical and magnetic radiofrequency fields were calculated, from which the SAR distribution and B 1 + fields were derived.…”

7 Tesla MR Imaging: Opportunities and Challenges

“…They applied an endorectal transceiver coil system and a pulse sequence with slice selective adiabatic refocusing pulses [63]. Recent publications have mainly focused on the optimization of coil systems for ultra-high-field prostate imaging, as deeply localized organs are known to be challenging with respect to spin excitation and signal reception [64,65]. Van den Bergen et al proposed the application of a microstrip array for structural prostate imaging and an endorectal coil for spectroscopy for a full anatomical and functional prostate examination at 7 T [65].…”

“…Recent publications have mainly focused on the optimization of coil systems for ultra-high-field prostate imaging, as deeply localized organs are known to be challenging with respect to spin excitation and signal reception [64,65]. Van den Bergen et al proposed the application of a microstrip array for structural prostate imaging and an endorectal coil for spectroscopy for a full anatomical and functional prostate examination at 7 T [65]. Ipek et al recently published their results on two different radiative antenna designs employing relative permittivities of 37 and 90 for the antenna substrate.…”

Myocardial T2* Mapping with Ultrahigh Field Magnetic Resonance: Physics and Frontier Applications

“…Local transceiver (TX/RX) and multi-channel transmission arrays in conjunction with multi-channel local receive arrays have been suggested as possible solutions. Eminent developments put building blocks to use consisting of stripline elements [41][42][43][44][45], electrical dipoles [45][46][47][48][49][50][51], dielectric resonant antennas [52], slot antennas [53], and loop elements [54][55][56][57][58][59]. Rigid, flexible and modular configurations have been exploited.…”