Is stress-only imaging practical when a 1-day stress-rest 99mTc-tetrofosmin protocol is used?

Objectives: To investigate whether a significant number of normal 1-day stress-rest 99mTc-tetrofosmin myocardial perfusion scintigraphy (MPS) studies can be identified from the low-dose stress acquisition alone, and whether technical staff can find such studies reliably.

Methods: The supervising consultant and four technologists independently graded the stress acquisitions from 200 consecutive MPS studies using a five-point scale. Studies were classified as normal or abnormal according to the final clinical report based on the completed stress-rest protocol.

Results: Between 31 and 62 studies (16-31%) were classified as definitely normal from the stress acquisition alone, of which 0-4 (0-9%) proved abnormal on the final report. Of stress studies graded definitely normal by each technologist, the consultant disagreed in 13-34% of cases. Of 78 stress studies graded definitely normal by at least one technologist, 6% turned out to be abnormal and the consultant disagreed in 33%. When there was agreement between at least two technologists (57 studies), the rates fell to 4% and 21% respectively.

Conclusions: Technologists could make the decision to avoid a resting study in up to 30% of patients following a normal low-dose stress acquisition. The supervising nuclear cardiologist would disagree in perhaps one in five cases, even when there was consensus between two or more technologists. These patients would suffer minor inconvenience by being recalled for a rest acquisition on a second day, but there would be important savings in time and radiation exposure for the majority.