[Myocardial scintigraphy with 99mTc MIBI. The use of a single-day protocol in a multiregional center: a comparison between planar and tomographic imaging]

The use of a single-day protocol for 99mTc MIBI myocardial scintigraphy is particularly well-suited for the nuclear medicine departments that are the referral centres for the cardiology departments of several community hospitals. The aim of the study was to compare, in the same patient population, the diagnostic accuracy of planar and SPECT imaging with 99mTc MIBI using a single-day protocol. Thirty-nine patients (31 males and 8 females, age range 32-69 years) were studied because of effort chest pain. Of them, 7 had a pre-test probability of coronary artery disease less than 2.5%; coronary angiography demonstrated significant coronary obstructions in the remaining 32 subjects and 21 of them also had a history of previous myocardial infarction. All patients underwent 99mTc MIBI myocardial scintigraphy with acquisition of planar and SPECT images after injection of a low dose (370 MBq) at rest and after a second higher dose (1110 MBq), injected approximately four hours later during exercise stress testing. The normalcy rate in the 7 patients with low pre-test probability was 100% using both imaging techniques. For the diagnosis of previous infarction, the sensitivities of planar and SPECT images were 71% and 96% respectively. For the diagnosis of effort ischemia the sensitivity values were 34% and 88%, respectively, using planar and SPECT imaging. With regard to the classification of the diseased coronary arteries, the sensitivities of planar and SPECT studies were 42% and 79% respectively, and the related specificities were 91% and 77%. We may conclude that using a single-day protocol planar imaging seems to allow lower levels of diagnostic accuracy both for the diagnosis of effort ischemia and the classification of the diseased vessels as compared to SPECT, which appears therefore in a similar setting the imaging technique of choice.