How does gated SPET alter reporting of myocardial perfusion studies?

Gated single photon emission tomography (SPET) during myocardial perfusion scintigraphy has been proposed as a method for distinguishing artefact from myocardial infarction and for assessing myocardial viability. This study describes the alterations in the specialist report produced when gated SPET was included in 50 consecutive myocardial perfusion studies. Diagnostic confidence was scored following an initial assessment using non-gated images alone and then re-scored after a review of the gated SPET data. The change in diagnostic confidence and the presence of additional information about myocardial viability were recorded. These were correlated with various clinical parameters, including a subjective assessment of the likelihood of an attenuation artefact as determined by clinical examination prior to imaging. Diagnostic confidence was altered by identification of attenuation artefacts in 11 (22%) patients, moving towards normality in all cases. In three of these (6%), the change was sufficient to make coronary angiography potentially unnecessary. Attenuation artefacts were equally common in men and women. Whereas breast attenuation artefacts could be anticipated from clinical examination, this was not so far diaphragmatic attenuation artefacts, which occurred most commonly in men under 55 years of age. The gated study provided additional information about myocardial viability in 13 (26%) patients, most commonly those referred following myocardial infarction. In view of the frequent alterations in the specialist's final report and the difficulties in pre-selecting patients likely to benefit from the technique, the use of gated SPET can be justified for all patients undergoing sestamibi myocardial perfusion imaging.