Article Figures & Data
Figures
- FIG 1.
A, Boxplots of image-quality evaluation. The median values are connected with dotted lines. dDLR generally improved the image quality. Even images of inferior quality were retrieved to moderate quality. B, Representative reconstructed axial slices of the different FLAIR acquisitions without (upper row) and with dDLR (lower row). The amount of noise and the progressive shadowing of lesions when the scan time decreased can be appreciated. One, 2, and 3 asterisks indicate P < .05, P < .01, and P < .001, respectively.
- FIG 2.
Boxplots of quantitative metrics to evaluate the manual and automatic segmentation. The median values are connected with dotted lines. One, 2, and 3 asterisks indicate P < .05, P < .01, and P < .001, respectively, for post hoc paired comparisons with Wilcoxon signed-rank test after 2-way ANOVA with the aligned rank transform procedure. † indicates voxelwise metric; §, lesion-wise metric.
- FIG 3.
Illustrative axial slices of ultrafast FLAIR without and with dDLR. Standard FLAIR without dDLR is also shown for reference. The red mask represents the criterion standard that comes from the delineation of standard FLAIR by 2 expert readers; the blue mask is the manual delineation from a third reader; and the green mask is the automatic segmentation from volBrain software. After we applied dDLR, some lesions showed contours closer to the criterion standard (black arrows). dDLR also retrieved lesions that were missed on the original image (white arrows and arrowhead).
Tables
Parameters of MR imaging acquisitions
3D FLAIR MPRAGE Standard Fast Ultrafast Shortest TR (ms) 7000 5000 4000 3000 6.3 TE (ms)/effective TE (ms) 445.5/145.0 445.5/145.0 445.5/145.0 445.5/145.0 2.8 TI (ms) 2070 1580 1270 910 950 BW (Hz) 558 558 558 558 279 Echo space (ms) 4.5 4.5 4.5 4.5 FOV (mm) 230 × 230 230 × 230 230 × 230 230 × 230 230 × 230 Matrix 224 × 224 224 × 224 224 × 224 224 × 224 224 × 224 Thickness (mm) 1 1 1 1 1 Parallel imaging 2.0 × 3.0 2.0 × 3.0 2.0 × 3.0 2.0 × 3.0 1.8 × 1.5 Frequency oversampling 1.4 1.2 1.2 1.2 1.2 Half Fourier 85% 70% 70% Flip angle 90° 90° 90° 90° 9° Refocus angle VFA VFA VFA VFA Shot interval (ms) 2500 Recovery time (ms) 744 Scan time (minute : second) 4:54 2:35 1:40 1:15 6:18 Note:—VFA indicates variable flip angle; BW, Bandwidth.
