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. 2024 Jun 19;45(9):e26761. doi: 10.1002/hbm.26761

FIGURE 1.

FIGURE 1

Diagram illustrating the mcDESPOT (multicomponent driven equilibrium single pulse observation of T1/T2) technique. McDESPOT combines DESPOT1 and DESPOT2 methods with a multicomponent, multi‐compartment model of water relaxation. Quantitative maps of T1 and T2 are derived, respectively, by fitting spoiled‐gradient echo (SPGR) and balanced steady‐state free precession (bSSFP) signal intensities to varying flip angles (α1… αn, differing between DESPOT1 and DESPOT2). In DESPOT1, an inversion‐recovery SPGR (IR‐SPGR) is used for correction of B1 inhomogeneities (Deoni, 2007); in DESPOT2, the effect of B0 inhomogeneities is mitigated by the use of RF‐phase cycling (Deoni et al., 2004). A three‐pool model including a fast, slow and very slow relaxing water (attributed to myelin, intra‐extra axonal and bulk, non‐exchanging water, respectively) is used to describe water relaxation. A map of the fraction of free water is shown on the right.