GuiTexture width after widthchange

I have a GuiTexture and the original size of the texture is 500x500;

After some calculations i change rescale the GuiTexture using pixelInset; myGuiTexture.pixelInset = new Rect( 0, 0, 100, 100);

Everything works like a charm.

Now i need to read the current texture width, sadly using myGuiTexture.pixelInset.width return 500 the original texture size instead of the current one at the screen.

Any advice on how to get the current width of the texture?