Table of Contents
Advertisement
10. Appendices > 10.3. Comparing thermal dose volumes and non-perfused volumes
10.3.2. Calculating non-perfused volumes (NPV)
A non-perfused volume indicates cells with no blood flow and therefore no contrast agent.
1.
Open the DICOM image set containing the day-0 post-treatment C+ images using the DICOM
viewer on the MR console.
2.
Create difference images with the Image Algebra function using the precontrast and post-
contrast images. If difference images are not available or usable, use the post-contrast images,
analyzing the pre-contrast images to exclude any pre-existing NPV.
3.
To estimate non-perfused volume assuming an ellipsoid shape:
-
Measure the length a of the NPV using the centermost (longest) SAG (or COR) image.
-
Measure the two diameters b and c of the NPV (ellipsoid) using the centermost (largest
diameter) COR (or SAG) image.
-
Calculate volume as
V = a × b × c × π ⁄ 6.
Tip
If the centermost image is a poor estimate of the NPV due to e.g. an irregular shape of the
NPV, try to fit in multiple ellipsoids and choose the slices that are the most representative.
Alternative step 3: Manual contour segmentation method:
Contour each non-merged NPV using 2D modeling tools and let the tool calculate the total area
in each slice.
The volume is the total area multiplied by the slice thickness.
Repeat steps 2 and 3 for all the NPVs and sum the NPVs together.
Instructions for Use
109745C2 / 02-2022
162 (192)
Advertisement
Table of Contents
