Multiple echo frequency-domain image contrast: improved signal-to-noise ratio and T2 (T2*) weighting.

Conventional T2- and T2*-weighted image contrasts are produced by waiting a TE period for the transverse magnetic resonance (MR) signals to decay to differentiate tissue types with distinct relaxation rates. Significant image signal-to-noise ratio (SNR) is compromised by this contrast-producing process. In this report, a multiple echo frequency-domain image contrast (MEFIC) method is presented. During the conventional TE period, a multiple echo train modulated by T2 or T2* decay is acquired. A third Fourier transform along the echo direction produces an image set with pixel signal intensity modulated by the spectrum of the decay curve. This method simultaneously enhances image contrast with a large increase in SNR. Experimental studies of cerebral vasogenic edema in immature rats and functional MR imaging studies of the human motor cortex have demonstrated that the MEFIC method produces superior image quality over conventional methods for generating T2- and T2* weighted images.