Second, gradient-echo imaging, using an echo time in which fat and water are in opposed phases, can demonstrate fat water interfaces and mixtures of fat and water [19].
Using an echo time of 135 ms, as will be referred to in this paper, has an additional advantage in that the lactate peak at 1.33 ppm is inverted and can more easily be discriminated from a lipid resonance in the same range [ 1].
A slice thickness of 4 mm and slice gap of 0.4 mm was used with an echo time of 0.1 s and relaxation time of 3.0 s.
Resting-state fMRI data were acquired using an echo-planar imaging sequence (repetition time = 2 s; echo time = 29 ms; flip angle = 80°; in plane spatial resolution = 3 × 3 mm; field of view = 240 × 240 mm; slice thickness = 4 mm; number of slices = 32; number of volumes = 240; acquisition time = 8 min).
Resting-state blood oxygen level-dependent data were acquired using an echo-planar imaging sequence (repetition time = 2 s; echo time = 29 ms; flip angle = 80°; in plane spatial resolution = 3 × 3 mm; field of view = 240 × 240 mm; slice thickness = 4 mm; number of slices = 32; number of volumes = 240; acquisition time = 8 min).
Functional images were collected using an echo-planar pulse sequence (parameters: repetition time (TR) = 2 sec, echo time (TE) = 25 msec, flip angle = 60°, field of view = 220 mm, matrix = 64, voxel size = 3.4 × 3.4 × 4 mm, 34 slices).
In each case, parameters were selected to maximise image contrast between thermal lesions and un-sonicated regions, e.g. using a short echo time of 40 60 ms in the T2-weighted sequences, for an expected muscle T2 value of approximately 50 ms [22].
Using a typical echo time TE of 20 ms, the intensity is maximum at a volumetric swelling ratio Q ∼15, and MRI is suitable to study the drying of hydrogels at lower Q values.
Another quantitative MRS study using a short echo time (TE), revealed decreases in the concentrations of NAA and glutamate/glutamine, and Lact concentration increases in infants with perinatal asphyxia compared to non-asphyxiated babies [ 18].
Data were acquired using a standard PRESS sequence with an echo time of 30 ms, a relaxation delay of 2,000 ms and 176 transients.
DTI images were acquired using a echo-planar sequence (repetition time = 8500 ms, echo time = 81.9, 25 directions, b = 1000 s/mm).
