Cyclic variation of myocardial signal intensity in real-time myocardial perfusion imaging

Background: The presence of cyclic intensity variation during real-time myocardial perfusion imaging (RTPI) has been controversially discussed. We investigated whether cyclic intensity variation is systematically found during RTPI and whether such variations are related to regional functional parameters. Methods. Intraoperative RTPI were obtained in 12 pigs before, during, and after left descending coronary artery occlusion with 60 mL/h SonoVue infusion. Furthermore, RTPI was performed in 14 patients after slow bolus injection of 0.7 mL of Optison. Instantaneous regional systolic to diastolic (S/D) myocardial intensity ratios were calculated after high mechanical index bubble destruction. S/D ratios were correlated with A- and beta-values, and fractional area shortening. Results. Systematic cyclic S/D changes were present in both experimental settings showing significantly higher systolic values (animals, S/D 1.28 +/- 0.44; patients, S/D 1.25 +/- 0.7). Cyclic S/D variation was not related to fractional area shortening, or A- or beta-values (all r < 0.3, not significant). Conclusion: Consistent cyclic changes in myocardial contrast intensity can be measured both in intraoperative animals and in patients, showing higher systolic values. S/D ratios are not related to regional functional parameters.