Contrast/Bolus Ingredient Opaque (0018,9425) attribute specifies the type of relative X-Ray absorption of the contrast/bolus ingredient, compared to the X-Ray absorption of water. The the meaning for the Enumerated Values are:
YES The contrast/bolus ingredient absorbs more X-Ray photons than water;
NO The contrast/bolus ingredient absorbs less X-Ray photons than water;
Note: The Contrast/Bolus Ingredient Opaque (0018,9425) attribute determines the sign of the gradient of X-Ray beam intensity from inside to outside the injected vessel, thus allowing optimal settings of the image processing applications (e.g. vessel edge detection, etc.), see Figure C.7.6.4b-1.
The relative gray level of the injected vessel with respect to the gray level of the water of Pixel Data (7FE0,0010) is determined by the Contrast/Bolus Ingredient Opaque (0018,9425) and by the Pixel Intensity Relationship Sign (0028,1041). For example, if the contrast/bolus ingredient is more radio graphically dense than water (i.e. YES), and the Pixel Intensity Relationship Sign (0028,1041) is -1, then the contrast/bolus ingredient is represented by higher values of Pixel Data than water.
Figure C.7.6.4b-1X-Ray beam intensity vs. Contrast/Bolus Ingredient Opaque