Fasting and nonfasting iodine-123-idophenylpentadecanoic acid myocardial SPECT imaging in coronary artery disease

Iodine-123-labeled idophenylpentadecanoic acid (IPPA) metabolic imaging has been shown to be clinically useful for the identification of myocardial viability in patients with coronary artery disease and left ventricular dysfunction. Imaging is usually performed under fasting conditions since nonfasting conditions may affect myocardial uptake of 123I-IPPA. The purpose of this study was to examine the impact of dietary condition on 123I-IPPA metabolic imaging. METHODS: Forty patients with stable coronary artery disease underwent, in randomized order and on separate days, 123I-IPPA SPECT myocardial imaging under fasting and nonfasting conditions. Patients were injected with 123I-IPPA (4-5 mCi) at rest with imaging performed at 4 (initial) and 30 (delay) min. For each image (initial and delay images), 10 segments were analyzed by three experienced observers without knowledge of patient identity or dietary condition using a 5-point grading system (O = no uptake to 4 = normal uptake). A summed global score was obtained for each image by adding the scores for all 10 segments. Image quality was assessed using a 3-point grading system. RESULTS: Visual agreement for normal and abnormal segments between fasting and nonfasting conditions was 82% (kappa = 0.63). There were no significant differences in the summed global scores for both conditions. Image quality was equivalent for both conditions in 65% of cases and superior under the nonfasting condition in 25% of cases. CONCLUSION: Image quality as well as the presence, location and severity of defects are similar under fasting and nonfasting conditions with 123I-IPPA. Therefore, fasting is not necessary before 123I-IPPA SPECT imaging for the assessment of myocardial viability.