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. Author manuscript; available in PMC: 2015 Feb 15.
Published in final edited form as: Neuroimage. 2013 Nov 2;87:32–41. doi: 10.1016/j.neuroimage.2013.10.053

Figure 1.

Figure 1

Pulse sequence for 2D UTE imaging using half pulse excitation and radial ramp sampling with a minimal nominal TE of 8 μs (A). An adiabatic inversion recovery preparation pulse together with dual echo acquisition was used to create short T2 contrast (B). The adiabatic IR pulse provides robust inversion of the longitudinal magnetizations of gray matter (GM) and the long T2 components in white matter (WML). The ultrashort T2 components in white matter (WMS) experience significant transverse relaxation during the long adiabatic inversion process, and are not inverted but partly saturated. The UTE acquisition starts when the inverted longitudinal magnetization of WML reaches the null point, leaving signals from WMS and residual GM to be detected by the FID acquisition. The 2nd echo contains signal from GM, with near zero signal from WMS due to its short T2*. Subtraction of the 2nd echo from the FID provides selective imaging of WMS.