Skip to main content
. Author manuscript; available in PMC: 2020 May 1.
Published in final edited form as: J Magn Reson Imaging. 2018 Oct 25;49(5):1475–1488. doi: 10.1002/jmri.26325

FIG. 7.

FIG. 7.

Mean R2* values calculated with different fits by varying UTE-A parameters for in vivo data. For each fit, the mean R2* values calculated by varying SNR (top row), ∆TE (middle row), and TEmax (bottom row) were compared with those obtained using the 3-average UTE-A acquisition as reference. SNR was compared by varying the number of averages (NA). All models produced similar R2* values for different NA and shorter ∆TEs (0.25, 0.5 ms), but underestimated or overestimated R2* for longer ∆TEs (≥1ms) in cases of high iron overload (R2*>1000 s−1). By using shorter TEmax (2.1, 4.7ms), the constant offset and quadratic models overestimated R2* in cases of mild iron overload (R2*<250 s−1) whereas the noise subtraction model still produced accurate results. Results of linear regression analysis (slope, intercept, and R2) between calculated and reference R2* values for each fit are shown in Table 2.