Figure 5

Effects of t₁ sampling in FFT and CT based spectra. (a) FFT spectrum using 64 points along t₁ ranging TEs from 35 to 85.4 ms at 800 μs intervals, giving 1250 Hz SW. (b) FFT spectrum using first 32 t₁ points. (c) FFT spectrum using last 32 t₁ points. Both (b) and (c) reduce the spectral resolution along t₁ by half and show heavy t₁-ridging effects (arrows 1 and 2). Sampling only (d) odd t₁ points or (e) even t₁ points for 2× acceleration halves the SW along t₁ while retaining the same spectral resolution causing folding artifacts indicated by arrow 3. (f) CT spectrum using 64 points along t₁ ranging TEs from 35 to 85.4 ms at 800 μs intervals, giving 1250 Hz SW. (g) CT spectrum using first 32 t₁ points (t₁ SW = 1250 Hz). (h) CT spectrum using last 32 t₁ points (t₁ SW = 1250 Hz). Arrows 1 and 2 in (g) and (h) points out the spurious correlations appearing in the spectrum. (i) Sampling every other t₁ points starting from t₁ = 1. Effective t₁ SW = 1250 Hz. (j) Sampling every other t₁ points starting from t₁ = 2. Effective t₁ SW = 1250 Hz.