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. Author manuscript; available in PMC: 2007 Aug 8.
Published in final edited form as: Neuroimage. 2006 Feb 15;31(2):627–640. doi: 10.1016/j.neuroimage.2005.12.013

Table 2.

Performance ranking of four sequences acquired using a birdcage coil with N3 correction

Permutation test (P values) Birdcage with N3 correction
SPGR MP-RAGE IR-SPGR SYN
SPGR 0.001 (SPGR) <0.0001 (SPGR) <0.0001 (SPGR)
MP-RAGE 0.264 (MP-RAGE) 0.0081 (MP-RAGE)
0.443 (IR-SPGR)
IR-SPGR 0.016 (IR-SPGR)
SYN

For all tables, sequence types are listed in the order of performance; the P values are the significance levels in favor of the alternative hypothesis that the sequence in parenthesis has a lower deviation (for example, IR-SPGR has a lower deviation than Synthetic T1 with a significant P value of 0.016). In other words, when the P value is significant, the sequence in parentheses is the one that performs best. Both P values are reported if two pulse sequences are statistically indistinguishable: so, for example, two sequences appear in the MP-RAGE vs. IR-SPGR box. This is because we tested the hypotheses both ways (that is, H1 = MP-RAGE shows less variance than IR-SPGR; and then again, H1 = IR-SPGR shows less variance than MP-RAGE). Note that SPGR in the tables actually refers to SPGR for GE acquisitions and FLASH for Siemens acquisitions.