Relaxation times of breast tissue at 1.5T and 3T measured using IDEAL

Department of Radiology, School of Medicine, Stanford University, Stanford, California 94305, USA.
Journal of Magnetic Resonance Imaging (Impact Factor: 3.21). 01/2006; 23(1):87-91. DOI: 10.1002/jmri.20469
Source: PubMed


To accurately measure T1 and T2 of breast fibroglandular tissue and fat at 1.5T and 3T, and note the partial volume effects of the admixture of fibroglandular tissue and fat on the relaxation rates using an approach termed iterative decomposition of water and fat with echo asymmetry and least squares estimation (IDEAL) imaging.
T1 and T2 values were measured on the right breasts of five healthy women at 1.5T and 3T. T1 data were collected using two sequences: inversion recovery without IDEAL, and inversion recovery with IDEAL. T2 data were collected using Hahn Echo scans. SNR and CNR analyses were conducted on collected data.
T1 increased for both fat (21%) and glandular tissue (17%) from 1.5T to 3T. Thus, the TR and TI of breast protocols at 3T should be lengthened accordingly. SNR more than doubled for both tissue types from 1.5T to 3T. IDEAL imaging demonstrated the partial volume effects of fat and glandular tissue on measuring relaxation rates of independent tissue types.
With separated fat and water images, more precise measurements can be made for the lipid component in fat, and the water component in fibroglandular tissue.

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    • "In order to preserve T1 contrast, a longer T1 would require longer repetition time (TR) and/or longer inversion delay values which may lead to lower temporal resolution and/or increased scan times. T1 values for both adipose and fibroglandular tissue have been shown to increase by approximately 20% in going from 1.5T to 3T [100]. This has a proportional effect on the inversion times used for fat suppression and provides a good example of sequence parameters that must change in going to 3T. "
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