Can nuclear medicine technologists assess whether a myocardial perfusion rest study is required?

Both stress and rest imaging are usually performed to diagnose ischemia or infarction in the left ventricle. If the stress study is performed first and the images indicate normal findings, it might be unnecessary to perform the rest study. The current study determines whether nuclear medicine technologists can assess the necessity of a rest study.

The results of gated SPECT performed using a 2-d nongated stress and gated rest (99m)Tc-sestamibi protocol for 532 consecutive patients were studied. Myocardial perfusion imaging was performed for diagnosing coronary artery disease (CAD) in 421 patients and for managing known CAD in 107 patients; 4 patients were examined for other reasons. Seventy-nine patients had previous myocardial infarction. Visual interpretation by 1 experienced physician at the time of clinical reporting was used as the gold standard for determining the scintigraphic presence of myocardial infarction or ischemia; rest, stress, and gated rest images and clinical information were available to this physician. All cases categorized as infarction or ischemia present or probably present were categorized as the group requiring a rest study (i.e., the "rest-study-required group"), whereas all other cases were categorized as the group not requiring a rest study (i.e., the "no-rest-study-required group"). A total of 3 physicians and 3 technologists independently interpreted the nongated stress images (slice images and polar plots) and decided whether a rest study was required.

In the rest-study-required group, the 3 technologists correctly classified on average 171 of the 172 cases, and the 3 physicians correctly classified 169 (a difference that was not statistically significant). In the no-rest-study-required group, the physicians correctly classified 32% and the technologists 21% of the cases (P = 0.001). The risk that a patient sent home without a rest study would have been diagnosed with infarction or ischemia using the combined stress-rest interpretation was 1.3% (1/75) for the technologists and 2.6% (3/115) for the physicians.

The nuclear medicine technologists were able to assess whether a rest study was needed; the risk that this assessment would be incorrect was not higher for the technologists than it was for the physicians. This type of assessment by a nuclear medicine technologist could be of value in efforts to improve effectiveness at a nuclear medicine clinic.