PET spots functional signs of early coronary artery disease in diabetes patients

Molecular imaging researchers have shown that coronary vascular dysfunction uncovered with PET may be diagnostically more powerful than vascular ultrasound or CT calcium tests for identifying early coronary artery disease in type 2 diabetes patients.

Dr. Thomas Schindler, chief of nuclear cardiology at the University Hospital of Geneva in Switzerland, evaluated 23 diabetes patients with normal blood pressure, 13 patients with hypertensive diabetes, and 32 normal controls.

Myocardial blood flow indicative of coronary endothelium dysfunction was measured with nitrogen-13 ammonia PET and rest-stress PET. The amount of vascular resistance in the coronary arteries was significantly higher in the diabetes patients with normal or elevated blood pressure than in the normal controls. No significant differences appeared when PET data for the two diabetes groups were evaluated.

These results were then compared with high-resolution vascular ultrasound and multislice CT coronary calcium tests performed on the subjects. Abnormal thickening of the subintimal space of the carotid artery detected with vascular ultrasound or the presence of coronary artery calcium measured with multislice CT are known indicators of coronary artery disease.

Schindler's trial, conducted in collaboration with Dr. Henrick Schelbert at the University of California, Los Angeles, suggested that coronary endothelial dysfunction diagnosed with PET is more sensitive to early coronary diseases than the other two surrogate markers.

Schindler found that 44% of the type 2 diabetes patients with coronary endothelial dysfunction identified with PET imaging had a normal carotid intima-media thickness based on intravascular ultrasound. About 34% of these patients had no evidence of coronary artery calcium measured with CT.

"PET assessment of functional abnormalities of coronary circulation may allow the earliest identification of developing heart vessel disease," Schindler said before presenting the results at the 2008 SNM meeting. "This could lead to an optimized identification of the very early state of coronary artery disease, allowing physicians to initiate or reinforce preventive medical therapy strategies."

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