Stress Attenuation Study

I wanted to record some notes for what was done in this study, so why not put it in HTML?

We know that the heart moves down relative to the chest cavity during stress. We suspected that other organs were also moving during stress. I think we found proof of this in one patient.

This type of movement can cause artifacts in 2 situations that I can think of:

1. When the attenuation study is acquired simultaneously with the emission study.
   (As in our PET stress perfusion studies)
2. When the liver or diaphragm attenuates emission data from the heart (creating a shadow) on non-attenuation corrected rest and stress scans.
   (as in Rest-Stress SPECT studies)

patient_2095 -- 2/27/96

Here are the lowest 5 slices from the Attenuation, Rest, and Stress transaxials:

Notice the 2 slice shift on the Stress scan and the resulting hot inferior wall. After reconstructing the Stress scan with an attenuation correction that was shifted up by 2 slices (the wrong way to do it, I maintain), I made this transaxial:

These are the 3 Rb bullseyes:

Rest	Stress	Stress Shifted

patient_2264 -- 4/23/96

This is an overlay of the Rest Attenuation (in the red scale) on top of the Stress Attenuation study (in the green scale):

Notice the perfect alignment of the outer body contour. The patient was absolutely still during and between the two attenuation studies.

Here are the transaxials of the Rest Attenuation study:

And here are the transaxials of the Stress Attenuation study:

Notice that the liver/diaphragm has moved out of the field of view!

Here are the transaxials of the Stress Emission scan reconstructed using attenuation correction factors from the Rest Attenuation scan:

And here are the transaxials of the Stress Emission scan reconstructed using attenuation correction factors from the Stress Attenuation scan:

Notice the difference in the slices that contained liver on the Rest Attenuation scan. The slices reconstructed using the Rest Attenuation are being over-corrected in these areas.

These are the bullseyes:

Rest	Stress (using Rest Atten)	Stress (using Stress Atten)

I expected more change between the stress bullseyes of this scan (since we saw a significant change in the inferior wall of the stress bullseyes of the 2/27/96 study). Perhaps an explanation of why the inferior wall is hot in the 2/27 scan and is not in the 4/23 scan can be found by comparing overlays of the stress scans from the 2 studies on top of their respective (resting) attenuation scans.
Here are overlays of the rest scans (just for a reference).