Ground Truth Tracing and Data Collection

Figures 9.5-9.9 show abnormal images of the left and right carotid arteries overlayed with the ground truth tracing. In each pair of rows, the top row is the left carotid arteries and the bottom row is the right carotid arteries. The ground truth tracing is the boundary of the inner lumen wall. Figure 9.9 shows the normal images of the same left and right carotid arteries. The normal images show

M

lo

r0

S5

►o

cl o

o*

M

1 o

O

o

of

B

H

o

m

0

'O

ñ

o

n

0

4

Figure 9.6: Abnormal ground truth overlays. The top row in each row pair is the left carotid artery overlayed with the ground truth tracing of the inner lumen wall, and the bottom row is the corresponding image of the right carotid artery. Some lumens have a circular shape, while others have an elliptical shape.

lumens that are more circular than those of the abnormal images, and there is no constriction of the arteries. Ground truth tracing was done using the MATLAB program MRI GUI ver 1.2. For each lumen boundary the image was zoomed in and points were plotted by the user around the inner wall boundary. The points were spline-fitted to 20 points.

The imaging parameters (TR/TE/TI/NEX/thickness/FOV/ETL) are as following: T1W:1R-R/7.1 ms/500 ms/2/3 mm/12-14 cm/21; PDW: 2R-R/7.1 ms/600 ms/

o

Q

o

o

o

o

o

o

1

ro

r o

9

Fi y

0

o

k

Figure 9.7: Abnormal ground truth overlays. The top row in each row pair is the left carotid artery overlayed with the ground truth tracing of the inner lumen wall, and the bottom row is the corresponding image of the right carotid artery. Some lumens have a circular shape, while others have an elliptical shape.

2/3 mm/12-14 cm/31; T2W: 2R-R/68 ms/600 ms/2/3 mm/12-14 cm/31. Matrix for all images were 256 x 192. Voxel size was 0.5 x 0.5 x 3 mm3. For bright blood 3D TOF images: TR/TE/flip angle/thickness/FOV = 20 ms/3.4 ms/25/2.0 mm/18. Zero-filled Fourier transform was used to create voxels of 0.35 x 0.35 x 1 mm3 for 3-D TOF imaging. The factors which affect MR plaque quality are (a) random patient motion, including (b) obese patients who may have deeper carotid arteries, (c) incomplete flow suppression, and (d) artery wall pulsation.

Figure 9.8: Abnormal ground truth overlays. The top row in each row pair is the left carotid artery overlayed with the ground truth tracing of the inner lumen wall, and the bottom row is the corresponding image of the right carotid artery. Some lumens have a circular shape, while others have an elliptical shape.

Figure 9.8: Abnormal ground truth overlays. The top row in each row pair is the left carotid artery overlayed with the ground truth tracing of the inner lumen wall, and the bottom row is the corresponding image of the right carotid artery. Some lumens have a circular shape, while others have an elliptical shape.

0 0

Post a comment