Room: AAPM ePoster Library
Purpose: To investigate using a PRESS (Point RESolved Spectroscopy) magnetic resonance spectroscopy (MRS) sequence with an inversion recovery (IR) pulse to suppress the water signal (about 4.8 ppm) that obstructs the fat olefinic resonance (about 5.3 ppm) in spectra acquired with short TE (echo time) from tissues containing both fat and water, such as breast. The olefinic resonance yields measures of fat unsaturation, which is relevant to disease, including breast cancer. Olefinic signal yield from the short-TE IR method is compared to that obtained with a previously optimized PRESS long-TE (TE = 200 ms) that exploits the shorter T2 (transverse relaxation) time of water.
Methods: PRESS spectra (TE = 40 ms) were acquired from the breast of a female volunteer using a 3T Philips whole-body MRI scanner. Spectra were acquired from a water region of the breast with several IR times to determine a delay that minimizes water signal (null time). Spectra were then obtained from a voxel that contained both fat and water, using PRESS with TE = 40 ms and no IR pulse, PRESS with TE = 40 ms with an IR delay equal to the estimated null time, and PRESS with TE = 200 ms with no IR. Olefinic peak signal to noise ratios (SNR) were compared between the latter two spectra.
Results: Olefinic signal was not resolved from water using short-TE PRESS with no IR. The SNR of the olefinic resonance with short-TE PRESS with the estimated IR null time (650 ms) is about three times higher than that obtained with PRESS with TE of 200 ms and no IR.
Conclusion: Fat olefinic signal is resolved from water at 3T in breast tissue using a short-TE PRESS sequence preceded by a water IR. Olefinic peak SNR is higher than that obtained with optimized long-TE PRESS.