Article

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: 2.79). 01/2006; 23(1):87-91. DOI: 10.1002/jmri.20469
Source: PubMed

ABSTRACT 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.

2 Followers
 · 
236 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Purpose To evaluate the image quality, robustness, and diagnostic performance of submillimeter in-plane resolution diffusion-weighted ( DW diffusion-weighted ) magnetic resonance (MR) imaging at 7 T in the assessment of breast tumors. Materials and Methods Institutional review board approval and written informed consent of five volunteers and 33 patients with 33 breast lesions (31 with histopathologic confirmation, two with confirmation at follow-up) were obtained. Image quality optimization and comparisons of readout-segmented echo-planar imaging ( rs-EPI readout-segmented echo-planar imaging ) and single-shot echo-planar imaging ( ss-EPI single-shot echo-planar imaging ) with or without parallel imaging were performed in volunteers. In all patients, bilateral DW diffusion-weighted imaging was performed in 3 minutes 35 seconds by using combined rs-EPI readout-segmented echo-planar imaging and parallel imaging with 0.9 × 0.9 mm in-plane resolution with a 7-T whole-body MR imager. Image quality, lesion conspicuity, and image properties (ie, signal-to-noise ratio, contrast-to-noise ratio) were assessed. Regions of interest were drawn in the largest lesion in each patient (23 malignant lesions, 10 benign lesions) by two independent readers. Apparent diffusion coefficient ( ADC apparent diffusion coefficient ) values were used to differentiate between benign and malignant breast tumors. Results DW diffusion-weighted imaging with combined parallel imaging and rs-EPI readout-segmented echo-planar imaging reduced artifacts (ie, blurring and geometric distortions) by a calculated factor of seven when compared with DW diffusion-weighted imaging with ss-EPI single-shot echo-planar imaging , and it improved image quality from a score of 1 of 10 to a score of 8 of 10. The rs-EPI readout-segmented echo-planar imaging sequence with a b value of 0 sec/mm(2) yielded high-spatial-resolution T2-weighted MR images. An ADC apparent diffusion coefficient threshold of 1.275 × 10(-3) mm(2)/sec enabled differentiation between benign and malignant breast lesions, with sensitivity and specificity of 96% and 100%, respectively, for both independent readers. Conclusion At 7 T, one DW diffusion-weighted imaging examination of less than 4 minutes yielded high-quality ADC apparent diffusion coefficient maps and high-spatial-resolution T2-weighted MR images that were used to assess tumor and breast morphology. ADC apparent diffusion coefficient quantification alone enabled excellent differentiation of benign and malignant breast lesions. © RSNA, 2014 Online supplemental material is available for this article.
    Radiology 10/2014; DOI:10.1148/radiol.14132340 · 6.21 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To quantitatively evaluate temporal blurring of dynamic contrast-enhanced MRI data generated using a k-space weighted image contrast (KWIC) image reconstruction technique with golden-angle view-ordering.
    Magnetic Resonance Imaging 09/2014; DOI:10.1016/j.mri.2014.09.003 · 2.02 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: PurposeTo develop a three-dimensional (3D) balanced steady-state free-precession (bSSFP) two-point Dixon method with banding-artifact suppression to offer robust high-resolution 3D bright-fluid imaging.MethodsA complex sum reconstruction that combines phase-cycled bSSFP images acquired at specific echo times for robust fat/water separation without banding was investigated and compared with a magnitude-based method. Bloch simulations using both single-peak and multiple-peak fat models were performed to predict the performance of these methods for a wide range of echo times and repetition times. The quality and degree of fat/water separation was evaluated in both simulations and using in vivo imaging.ResultsSimulations predicted that both effective banding-artifact suppression and substantial improvements in fat/water separation are possible at echo times that are different from conventional echo times, enabling improved spatial resolution. Comparisons between various echo times and repetition times in vivo validated the improved fat/water separation and effective banding-artifact removal predicted by the simulations.Conclusion The proposed complex sum Dixon 3D bSSFP method is able to effectively separate fat and water at different sets of echo times, while removing banding-artifacts, providing a fast, high-resolution, T2-like sequence without blurring. Magn Reson Med, 2014. © 2014 Wiley Periodicals, Inc.
    Magnetic Resonance in Medicine 09/2014; DOI:10.1002/mrm.25449 · 3.40 Impact Factor

Preview

Download
9 Downloads
Available from