COMPARISON OF RELATIVE (18)FDG UPTAKE TO METABOLIC-RATE (MRGLUCOSE) IN THE MYOCARDIUM IN CAD, CLASSIFIED BY TC-99M MIBI

Aim: Are i) typical patterns of perfusion/metabolism (match, mismatch) , gained from relative (99)mTc-MIBI vs relative (18)FDG uptake (normal ized to the perfusion maximum) obtainable also vs absolute MRGlu and i s ii) rMRGlu in the segment of maximum perfusion (MIBI = 100%) within the normal range for all degrees of coronary artery disease (CAD)? Met hods: in 55 non-diabetic patients with CAD, relative myocardial perfus ion (Tc-99m MIBI SPECT at rest) and relative (18)FDG uptake (PET after glucose load) were used to separate for various flow/metabolism const ellations. In addition, regional glucose metabolic rate (rMRGlu in mu mol/100 g/min; dynamic-graphic analysis from Gambhir/Patlak) was deter mined in 13 segments of the left ventricle each (i. e., in a total of 715 segments). Results: rMRGlu revealed wide standard deviations (up t o 51%). It decreased from normal (52.7 +/- 27.3 mu mol/100 g/min), mis match (45.3 +/- 17.3) and intermediate (35.2 +/- 12.4) to match (''non viable'' 26.7 +/- 13.3) significantly (p <0.01). In 26% of the perfus ion maxima, MRGlu was <40 mu mol/100 g/min. Out of these, only in five patients (of 28) with 3-vessel disease, it was even smaller (<30 mu m ol). in three out of the latter, glucose blood levels were below eugly cemia. Conclusion: rMRGlu in CAD revealed an identical perfusion/metab olism pattern as relative (18)FDG uptake. Thus, the higher efforts emp loyed to compute rMRGlu do not yield diagnostic advantage. The segment al perfusion maximum, used for normalization of relative (18)FDG uptak e (100% MIBI uptake) was reliable in euglycemic patients even with 3-v essel disease.