Trabecular spacing

[Frank Acquaah]

Dear Dr Doube,

I am taking measurements of trabecular spacing of my sample. From
reading the website I am under the impression that on a binerized
thersholded image, trabecular spacing is a measurement of the black
voxels (black spaces/ background). What I wanted to know is if this is
the case, does this measurement include the black area around the side
of my image (I have used a spherical ROI) or just the spaces within
the boundries of my sphere?

Kind regards,

Frank Acquaah

[Michael Doube]

Hi Frank

> I am taking measurements of trabecular spacing of my sample. From
> reading the website I am under the impression that on a binerized
> thersholded image, trabecular spacing is a measurement of the black

Be careful you don't confuse 'black' as you see it on the screen with
'background' as the computer sees it. In ImageJ, foreground is normally
255 and background 0, but these values can be displayed in any colour
depending on the LUT applied. The inverting LUT makes the foreground
(255) appear black. BoneJ assumes that trabeculae are in the foreground
and have a pixel value of 255.

> voxels (black spaces/ background). What I wanted to know is if this is
> the case, does this measurement include the black area around the side
> of my image (I have used a spherical ROI) or just the spaces within
> the boundries of my sphere?

If your ROIs are in the ROI Manager and you chose to use ROI Manager in
the Thickness options, then the measurements are restricted to your
ROIs. If you cut the sphere out with the sphere fitter, then Tb.Th
doesn't need ROIs, but Tb.Sp does - if no ROIs are specified it will
measure the space all around the sphere and maybe take a very long time
to finish.

Michael