Finding the anterior comissure to set origin in a SPECT image using SPM/ISAS I am learning how to use SPM and ISAS to analyze ictal and interictal SPECT. However I am stuck at a point of their tutorial. 

In the item 1.2 one has to set the origin for the SPECT image. That is, to pinpoint the anterior commissure. This is a fairly easy task in a MRI, but very hard to do in a SPECT. How am I to find a tiny anatomical area in such a blurry image (like the one below)?



Are there any anatomical references that I should be using in order to find the approximate area for the anterior commissure?

Any help would be greatly appreciated.
You can use the Whole Brain Atlas by Harvard to look at the normal brain anatomy in 3-D with MRI/PET.

Check the Anterior Commissure (AC) on the MRI and sync it with the PET or SPECT. It helps.

More specifically, select "Anterior Commissure" and T1/FDG and click sync to show all the orientations in the same modalities and anatomical structure. It helps to find the anterior commissure in a normal brain using nuclear medicine image.