Design and fabrication of a realistic anthropomorphic heterogeneous head phantom for MR purposes

Abstract

ObjectiveThe purpose of this study is to design an anthropomorphic heterogeneous head phantom that can be used for MRI and other electromagnetic applications.Materials and methodsAn eight compartment, physical anthropomorphic head phantom was developed from a 3T MRI dataset of a healthy male. The designed phantom was successfully built and preliminarily evaluated through an application that involves electromagnetic-tissue interactions: MRI (due to it being an available resource). The developed phantom was filled with media possessing electromagnetic constitutive parameters that correspond to biological tissues at ~297 MHz. A preliminary comparison between an in-vivo human volunteer (based on whom the anthropomorphic head phantom was created) and various phantoms types, one being the anthropomorphic heterogeneous head phantom, were performed using a 7 Tesla human MRI scanner.ResultsEcho planar imaging was performed and minimal ghosting and fluctuations were observed using the proposed anthropomorphic phantom. The magnetic field distributions (during MRI experiments at 7 Tesla) and the scattering parameter (measured using a network analyzer) were most comparable between the anthropomorphic heterogeneous head phantom and an in-vivo human volunteer.ConclusionThe developed anthropomorphic heterogeneous head phantom can be used as a resource to various researchers in applications that involve electromagnetic-biological tissue interactions such as MRI.

A simple head‐sized phantom for realistic static and radiofrequency characterization at high fields

“…A limitation of the simplified two‐compartment phantom design is that the impact of tissue heterogeneities on local RF heating cannot be captured. For this purpose, multi‐compartment designs would be desirable, however, these are difficult to implement . Finally, we note that, although the phantom has been shown to be suitable for guiding the validation of simulated RF coils, the measured temperature increases should not be taken as a surrogate measure for in vivo tissue heating that requires heterogeneous body models as well as the incorporation of thermoregulatory response mechanisms …”

“…These phantom recipes typically incorporate salt as an additive to control electrical conductivity and also gelling agents to reduce thermal convection . Advanced 3D‐printed anthropomorphic phantoms with multiple compartments have also been proposed to better reproduce the dielectric heterogeneity of the human head . Despite these efforts, the correspondence of the RF fields obtained in these advanced phantom designs with those obtained in vivo is still rather weak.…”

“…[17][18][19] Given such considerations, there is a growing interest in head-mimicking phantoms with increasing complexity to reproduce these sensitivities in a realistic manner. [20][21][22][23] Several materials such as aqueous solutions of polyethylene powder, 21,24 sugar, 22,25 or ethanol 23 are known to allow for appropriate tuning of their dielectric properties to reach values similar to those of human tissues. These phantom recipes typically incorporate salt as an additive to control electrical conductivity and also gelling agents to reduce thermal convection.…”

Recent advances on the development of phantoms using 3D printing for imaging with CT, MRI, PET, SPECT, and ultrasound

“…The resolution is expressed in dots per inch (dpi) or micrometers (lm) and assessed by comparing the dimensions of the produced physical phantom with the original dimensions provided to the printer. Among the papers used, 10 have assessed the resolution or accuracy of the printer by quantitative (numerical) comparison, [26][27][28][29][30][31][32][33][34][35] 10 by qualitative (figural) comparison, 22,[36][37][38][39][40][41][42][43][44] and 14 by both quantitative and qualitative comparison. 10,21,[45][46][47][48][49][50][51][52][53][54][55][56] Sixteen of the research articles do not include a verification of the printers' resolutions.…”

A new RF transmit coil for foot and ankle imaging at 7T MRI

“…1f) and in-vivo. The phantom is composed of 80% of denatured ethanol, 20% of water, and 9.85 g/L of sodium chloride [38]. The in-vivo scans were conducted under a study approved by the University of Pittsburgh Institutional Review Board.…”