Analytical corrections of banding artifacts in driven equilibrium single pulse observation of T2 (DESPOT2)

DESPOT2 is a single-component T₂ mapping technique based on bSSFP imaging. It has seen limited application because of banding artifacts and magnetization transfer (MT) effects. In this work, acquisitions are optimized to minimize MT effects, while exact and approximate analytical equations enable automatic correction of banding artifacts within the T₂ maps in mere seconds.

The technique was verified on an agar phantom at 3 tesla. The T₂ resulting from four different data combination techniques was compared with the T₂ from CPMG. Two comparable DESPOT2 scan protocols (short vs. long TR/T_RF ) designed to minimize MT effects, were tested both in the phantom and in vivo. A third protocol was tested in the brain of 8 volunteers and analytical correction schemes were compared with DESPOT2-FM.

The T₂ measurements in agar agree with CPMG within ∼7% and in vivo results agree with values reported in the literature. The approximate analytical solutions provide increased robustness to hardware imperfections and higher T₂ -to-noise ratio than the exact solutions.

New analytical solutions enable fast and accurate whole-brain T₂ mapping from previously measured T₁ and B₁ maps, and bSSFP images with at least two phase offsets and two flip angles (=4 datasets, 8 min scan). Magn Reson Med 76:1790-1804, 2016. © 2015 International Society for Magnetic Resonance in Medicine.