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Fig 7. MR images of a normal volunteer obtained by different imaging methods
A, T1-weighted image (560/14) with ordinary setting of phase- and frequency-encoding directions.
B, T1-weighted image (560/14) in which phase- and frequency-encoding directions are swapped.
C, T1-weighted image (560/14) with fat saturation. 
= frequency-encoding direction
Despite the absence of tumor mass, the lingual cortex of the mandible is obscured in A (arrowhead). However, it is intact when phase- and frequency-directions are swapped (B) or fat signal intensity is suppressed (C). These findings confirm that the cortical defect in A is attributed to chemical shift artifact of bone marrow fat. Spatial misplacement of the fat occurs along the y axis direction in A and along the x axis direction in B.
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