[Exercise-nitroglycerine technetium-99m-2-methoxy isobutyl isonitrile tomoscintigraphic imaging for identifying...

A same-day double injection protocol employing 99mTc-methoxy isobutyl isonitrile (MIBI) and myocardial single-photon emission computed tomography (SPECT) for detecting coronary heart disease (CAD) was assessed in 21 patients. Our exercise-nitroglycerin (NTG) MIBI study was performed as follows: 150 MBq 99mTc-MIBI was injected at peak exercise, and after 5 minutes 0.3 mg of NTG was sublingually administered. Then, SPECT was performed 1 hour later. Immediately after the 1st imaging, patients were injected of 750 MBq 99mTc-MIBI and were reimaged 1 hour later. Within 1 month, all patients were underwent standard exercise redistribution SPECT thallium (Tl) study. Of the 126 myocardial segments evaluated, 81 were judged as normal by both techniques, while the presence of stress defects were demonstrated in 37 segments (Agreement: 94%). Vessel sensitivities were 75% by MIBI and 67% by Tl. Specificities were 90% by MIBI and 93% by Tl. For the pattern of reversibility in myocardial segments with stress defects, the agreement was 73%. In conclusion, our exercise-NTG MIBI may be safely performed, giving results equivalent to those of standard stress-redistribution thallium studies.