Silicone‐based materials with tailored MR relaxation characteristics for use in reduced coil visibility and in tissue‐mimicking phantom design

Abstract

Background:The development of materials with tailored signal intensity in MR imaging is critically important both for the reduction of signal from nontissue hardware, as well as for the construction of tissue-mimicking phantoms. Silicone-based phantoms are becoming more popular due to their structural stability, stretchability, longer shelf life, and ease of handling, as well as for their application in dynamic imaging of physiology in motion. Moreover, silicone can be also used for the design of stretchable receive radio-frequency (RF) coils. Purpose: Fabrication of materials with tailored signal intensity for MRI requires knowledge of precise T 1 and T 2 relaxation times of the materials used. In order to increase the range of possible relaxation times, silicone materials can be doped with gadolinium (Gd). In this work, we aim to systematically evaluate relaxation properties of Gd-doped silicone material at a broad range of Gd concentrations and at three clinically relevant magnetic field strengths (1.5 T, 3 T, and 7 T). We apply the findings for rendering silicone substrates of stretchable receive RF coils less visible in MRI. Moreover, we demonstrate early stage proof -of -concept applicability in tissue-mimicking phantom development. Materials and Methods: Ten samples of pure and Gd-doped Ecoflex silicone polymer samples were prepared with various Gd volume ratios ranging from 1:5000 to 1:10, and studied using 1.5 T and 3 T clinical and 7 T preclinical scanners. T 1 and T 2 relaxation times of each sample were derived by fitting the data to Bloch signal intensity equations. A receive coil made from Gd-doped Ecoflex silicone polymer was fabricated and evaluated in vitro at 3 T. Results: With the addition of a Gd-based contrast agent, it is possible to significantly change T 2 relaxation times of Ecoflex silicone polymer

Flexible array coil for cervical and extraspinal (FACE) MRI at 3.0 Tesla

“…Additionally, the 3D-printed mask substrate had noticeable MRI signal on low-echo-time gradient-recalled echo imaging. While this did not obscure interpretation, future designs could use alternate 3D materials or incorporate doping the substrate with paramagnetic materials to reduce signal from the substrate (Motovilova et al 2023).…”

Stretchable Sensor Materials Applicable to Radiofrequency Coil Design in Magnetic Resonance Imaging: A Review

“…Several research groups reported having successfully designed and developed flexible RF coils based on coaxial cables [14], screen-printed arrays [15][16][17], liquid metals [8,13,[18][19][20], and conductive polymers [21]. Major MRI vendors have also made significant efforts to produce commercially available lightweight coils that apply less pressure onto the patient compared to previous coil generations (AIR TM Coils from GE Healthcare [22], Contour Coils from Siemens [23], and Shape Coils from Canon [24]).…”

Dual-Channel Stretchable, Self-Tuning, Liquid Metal Coils and Their Fabrication Techniques

“…The DIW technique is favored due to its significantly easier fabrication as well as its reduced visibility in images-the coil array is much thinner (0.6 mm) and uses smaller amounts of polymer to produce. Anecdotally, we also propose to suppress the appearance of silicone polymer in MR images [47].…”