NUCLEAR PERFUSION STUDY INTERPRETATION

There are several steps to follow when confronted with a nuclear perfusion study.

1. Go back to the raw data.
The very first thing to do is check the orientation that the technologist has programmed through the ventricle, and reorientate to the long axis of the image if necessary as well as match up the two orientation lines.

2. Now go to the planar data.
You are looking to see:
i) IF LIVER/BOWEL IS MASKING THE HEART (and therefore adding counts to the heart and masking a defect) OR VERY CLOSE TO THE HEART (and therefore stealing counts from the heart and creating a false defect) . IF IT IS THEN YOU HAVE TO RESCAN.
ii) IS THERE A BIG BLACK MASS of breast or pectoral over the heart? IS THE DIAPHRAGM HIGH AND THEREFORE OVER THE INFERIOR WALL?
iii) DOES THE HEART JUMP?
iv) Is there uptake in the lungs (LVF, malignancy) or in the soft tissues?

3. Lastly, you go to the SPECT images.
i) Make sure that the two sets of images have been roughly equally normalized.
ii) Make sure that the count rates are 3:1 on the stress:rest images
iii) Then look for the same artifacts you did on the planar scan - signs of horizontal and vertical motion; spill-over of extra-cardiac counts or counts that are too close for comfort.
iv) Before you go to reading the LV, make sure that the RV looks fine.

When reading the LV, the best way is to follow this system:


So, on first view, what you should be seeing is a donut and two horse-shoes. If you don't then there's something wrong.

Patterns of abnormality:
1. Severe perfusion defect that does not significantly reverse.
The options for this are that either this wall is infarcted or that it is so severely ischaemic that it is not taking up tracer. Such walls are also immobile and so are called "hibernating".
The way to differentiate these two is with a Thallium study.

In terms of the patterns seen, the though process should go as follows:
- If see anterior or anterolateral defect then the first thing to exclude is not ischaemia but breast shadowing. The only way to be absolutely certain is to rescan in the prone position because this spreads the soft tissue out and you do not get as much attenuation.

- If see inferior wall defect, then the first thing to exclude is not ischaemia but diaphragm shadowing. The only way to be certain is to rescan again in the prone position because the heart falls forward and therefore the diaphragm does not cover as much of the heart. However, it creates an anteroseptal artifact because the sternum gets in the way.

If you think that the breast may be responsible for the artifact then rescan prone because this spreads the soft tissue out.