Article Figures & Data
Figures
- Fig 1.
Pulse sequence diagram for MP 3D-FLAIR imaging. Magnetization preparation is implemented during τ2 with radiofrequency pulses for 90° excitation (EX), followed by T2-preparation and −90° flip-up (FU). FLAIR inversion recovery is achieved during τ1 with radiofrequency pulses for inversion (INV), followed by spectral fat saturation (FS) and TSE readout with 90° excitation (EX), followed by a train of refocusing pulses during τ5. τ3 and τ4 are the times for gradient spoiling and to the end of the current TR period, respectively. Black shaded trapezoids represent spoiling gradients to eliminate transverse magnetization.
- Fig 2.
Flow chart for image analysis. CNR indicates contrast-to-noise ratio.
- Fig 3.
Simulation results for the evolution of steady-state magnetization for each type of tissue (WM, GM, CSF, and oxy-CSF) are presented for non-MP (A) and MP (B) FLAIR sequences. Imaging and sequence timing parameters (Table 2) and tissue relaxation constants (Table 3) were used in simulation. Sequence timing parameters (τ1 ∼ τ5) are presented along with the time axis at each figure. An inset within each figure presents a magnified segment of the evolution of magnetization around the TE (dotted black vertical line). A.U. indicates arbitrary unit.
- Fig 4.
The non-MP 3D-FLAIR sequences of a 3-year-old boy with epilepsy (upper row). CSF hyperintensity artifact scores totaled 17 (premedullary cistern, 2; prepontine cistern, 2; suprasellar cistern, 3; basal cistern, 3; ambient cistern, 3; quadrigeminal cistern, 3; sulci of cerebral convex, 1). MP 3D-FLAIR sequences of a 4-year-old boy with epilepsy (lower row). CSF hyperintensity artifact scores totaled 4 (premedullary cistern, 0; prepontine cistern, 0; suprasellar cistern, 1; basal cistern, 1; ambient cistern, 1; quadrigeminal cistern, 1; sulci of the cerebral convex, 0).
- Fig 5.
The subdural hemorrhage (solid arrow) is suspected in the non-MP 3D-FLAIR (upper row) of a 5-year-old girl after a callosotomy, which is also observed in the immediate postoperative CT scan. However, it is not clearly demarcated from CSF hyperintensity artifacts (dotted arrow). Hemorrhage (solid arrow) is clearly demarcated in the MP 3D-FLAIR (lower row) of an 8-month-old boy after lesionectomy, which is also observed in the immediate postoperative CT scan because CSF hyperintensity artifacts are suppressed.
Tables
Non-MP 3D FLAIR (n = 41) MP 3D FLAIR (n = 44) P Value Age (yr) 6.31 ± 4.9 5.18 ± 4.63 .27 Sex 17 girls (41%) 17 girls (39%) .96 MRI findings (No.) .94 Normal 23 (56%) 24 (54%) Cortical malformation 8 (19%) 11 (25%) Ischemia 3 (8%) 4 (9%) Tumor 6 (14%) 3 (7%) Metabolic disease 1 (3%) 2 (5%) Parameter Non-MP 3D FLAIR MP 3D FLAIR FOV (mm) 224 250 TR (ms) 8000 4800 TE (ms) 340 299 TE, effective (ms) 154 128 Acquisition voxel size (RO/PE/SS) (mm) 1.0/1.0/1.0 0.98/0.99/1.0 Matrix (RO/PE) 224 × 223 256 × 253 Sensitivity encoding factor (PE/SS) 2.5/2.0 2.6/2.0 Acquisition time 7 min 44 sec 6 min 10 sec No. of sections 350 360 TSE factor 110 182 NSA 1 2 Echo-train length (ms) (τ5) 626 572 Inversion time (ms) (τ1) 2400 1650 T2 preparation (ms) (τ2) N/A 125 Spoiler duration (ms) (τ3) N/A 17.23 Sequence dead timea (ms) (τ4) 4974 2435.77 Note:—RO indicates readout; PE, phase-encoding; SS, section-selection; NSA, number of signals averaged.
↵a Duration between the end of the echo-train and TR.
Non-MP 3D FLAIR (n = 41) MP 3D FLAIR (n = 44) P Value Hyperintense CSF artifact scores Premedullary cistern 1.09 ± 0.58 0.38 ± 0.49 <.01 Prepontine cistern 1.8 ± 0.55 0.77 ± 0.47 <.01 Suprasellar cistern 2.19 ± 0.74 0.86 ± 0.41 <.01 Basal cistern 2.26 ± 0.74 0.88 ± 0.38 <.01 Ambient cistern 2.29 ± 0.87 0.88 ± 0.38 <.01 Quadrigeminal cistern 2.53 ± 0.77 0.86 ± 0.41 <.01 Sulci of cerebral convex 1.19 ± 0.55 0.21 ± 0.46 <.01 CNR GM-WM 3.28 ± 1.15 4.14 ± 1.28 .02 GM-CSF 12.85 ± 2.79 16.14 ± 2.43 <.01 WM-CSF 10.67 ± 2.78 13.82 ± 3.16 <.01 Note:—CNR indicates contrast-to-noise ratio.
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