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Analysis of magnetization transfer effects on T1‐weighted spin‐echo scans using a simple tissue phantom simulating gadolinium‐enhanced brain lesions
Author(s) -
Finelli Daniel A.,
Hurst Gregory C.,
Frank Holly A.,
Gullapali Rao P.,
Apicella Anthony
Publication year - 1997
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.1880070420
Subject(s) - gadolinium , imaging phantom , magnetization transfer , flip angle , nuclear magnetic resonance , pulse sequence , nuclear medicine , magnetic resonance imaging , materials science , pulse (music) , contrast (vision) , medicine , physics , radiology , optics , detector , metallurgy
The purpose of this study was to analyze the effect of several magnetization transfer (MT) pulse and T1‐weighted spin‐echo (SE) sequence parameters on lesion‐to‐background contrast, using a simple tissue phantom emulating the T1 relaxation and MT properties of gadolinium‐enhanced brain lesions. Eggbeaters (Nabisco Inc., East Hanover, NJ) liquid egg product was doped with gadolinium in six concentrations from .0 to 1.0 mmol and cooked. The gadolinium‐doped egg phantom and normal volunteer brains were studied using an SE sequence with TE = 20 msec and high power, pulsed, off‐resonance MT saturation. The effects of MT pulse frequency offset (1,000–6,000 Hz), sequence repetition time (TR = 500–1,000 msec, with MT power held constant), and slice‐select flip angle (60–120 degrees) on the magnetization transfer ratio (MTR) and the simulated lesion‐to‐background contrast were determined at the different “Intralesion” gadolinium concentrations. The MTR and lesion‐to‐background contrast of all materials were greatest at narrow MT pulse frequency offsets. There was an inverse relationship between gadolinium concentration and MTR and a positive correlation between the gadolinium concentration and lesion‐to‐background (L/B) contrast, a weak negative correlation between slice‐select flip angle and L/B, and a negative correlation between TR and L/B. The relaxation properties and MT behavior of the egg phantom are close to that expected for enhancing brain lesions, allowing a rigorous analysis of several variables affecting lesion‐to‐background contrast for high MT power, T1‐weighted SE sequences.