Effect of blood glucose on myocardium FDG uptake

PET with FDG has become the gold standard for myocardium viability. However, myocardial FDG uptake is too low or non-existent in some patients, preventing adequate imaging. We studied the frequency of this phenomenon in 225 oncologic patients referred for PET (112 male, 113 female). All patients were asked to fast for at least 4 hours and known diabetic subjects were not included. Blood glucose was measured in all patients prior to the FDG injection. Emission scans acquired on a GE Advance scanner (2-D mode) starting 50-60 minutes p.i. were corrected for attenuation. The images were qualitatively classified as adequate or very poor/non-existent heart visualization. In 68 patients (30.2%) a substantial number, the left myocardium was not well identified (26.8% male and 33.6% female, p<0.05). Blood glucose was 91.2 mg/dL±29.2 (SD) in the 68 patients and 88.2±16.0 in those with adequate heart visualization (p<0.05). We concluded that poor/nonvisualization of the heart with FDG is common. Glycemic levels do not correlate with FDG myocardial uptake, not predicting the heart visualization. We are using these results for the development of new protocols to improve the visualization of the heart