Gelled vs non-gelled phantom material for measurement of temperature rise by the MRI RF-magnetic field

Park, S.M.; Nyenuis, J.A.; Lim, Einly; Finelli, Daniel A.; Hrdlicka, Greg; Rezai, Ali R.; Rugieri, Paul; Shellock, Frank G.; Stypulkowski, Paul H.; Tkach, Jean A.

doi:10.1109/intmag.2003.1230558

Cited by 1 publication

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“…While paramagnetic additives can be used to shorten both T 1 and T 2 in aqueous phantoms, 17 the use of gelling agents as T 2 modifiers has the benefit of decoupling T 1 and T 2 effects, 18 enabling the construction of phantoms with tissue like T 1 and T 2 times 19 . Gelled or solid phantoms are also closer to biological tissue in terms of thermal 2,20 and mechanical properties 21 . Furthermore, gel phantoms do not require a settling time 15 and are not prone to flow 1 and less prone to vibrational effects 15 …”

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confidence: 99%

Technical Note: Human tissue‐equivalent MRI phantom preparation for 3 and 7 Tesla

et al. 2021

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While test objects (phantoms) in MRI are crucial for sequence development, protocol validation and quality control, studies on the preparation of phantoms has been scarce, particularly at fields exceeding 3 Tesla. Here we present a framework for the preparation of phantoms with well-defined T 1 and T 2 times at 3 and 7 Tesla. MethodsPhantoms with varying concentrations of agarose and Gd-DTPA were prepared and measured at 3 and 7 Tesla using T 1 and T 2 mapping techniques. An empirical, polynomial model was constructed that best represents the data at both field strengths, enabling the preparation of new phantoms with specified combinations of both T 1 and T 2 . Instructions for three different tissue types (brain grey matter, brain white matter, and renal cortex) are presented and validated. ResultsT 1 times in the samples ranged from 698ms to 2820ms and from 695ms to 2906ms, whereas T 2 times ranged from 39ms to 227ms and from 34ms to 235ms for 3 and 7 Tesla scans, respectively. Models for both relaxation times used six parameters to represent the data with an adjusted R² of 0.998 and 0.997 for T 1 and T 2 , respectively. ConclusionBased on the equations derived from the current study, it is now possible to obtain accurate weight specifications for a test object with desired T 1 and T 2 relaxation times. This will spare researchers the laborious task of trail-and-error approaches in test object preparation attempts.

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