An approach for comparative quantification of myocardial blood flow (O-15-H2O-PET), perfusion (Tc-99m-tetrofosmin-SPECT), and metabolism (F-18-FDG-PET)

Aim: In the present study a new approach has been developed for comparative quantification of absolute myocardial blood flow (MBF), myocardial perfusi on, and myocardial metabolism in short-axis sl ices. Methods: 42 patients w ith severe CAD, referred for myocardial viability diagnostics, were studied consecutively with 0-1 5-H2O PET (H2O-PET) (twice), Tc-99m-Tetrofosmin SPE CT (TT-SPECT) and F-18-FDG PET (FDG-PET). All data sets were reconstructed using attenuation correction and reoriented into short axis slices. Each he art was divided into three representative slices (base, midventricular, ape x) and 18 ROIs were defined on the FDG PET images and transferred to the co rresponding H2O-PET and TT-SPECT slices. TT-SPECT and FDG-PET data were nor malized to the ROI showing maximum perfusion. MBF was calculated for all le ft-ventricular ROIs using a single-comportment-model fitting the dynamic H2 O-PET studies. Microsphere equivalent MBF (MBF_micr) was calculated by mult iplying MBF and tissue-fraction, a parameter which was obtained by fitting the dynamic H2O-PET studies. To reduce influence of viability only well per fused areas (> 70% TT-SPECT) were used for comparative quantification. Resu lts: First and second mean global MBF values were 0.85 ml x min(-1) x g(-1) and 0.84 ml x min(-1) x g(-1), respectively, with a repeatability coeffici ent of 0.30 ml x min(-1) x g(-1). After sectorization mean MBF micr was bet ween 0.58 ml x min(-1) x ml(-1) and 0.68 ml x min(-1) X ml(-1) in well perf used areas. Corresponding TT-SPECT values ranged from 83% to 91%, and FDG-P ET values from 91% to 103%. All procedures yielded higher values for the la teral than the septal regions. Conclusion: Comparative quantification of MB F, MBF micr, TT-SPECT perfusion and FDG-PET metabolism con-be done with the introduced method in short axis slices. The obtained values agree well wit h experimentally validated values of MBF and MBF_micr.