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Assessment of the myocardial FDG-PET image quality with the use of maximal Standardized Uptake Value myocardial to background index. Application of the results in regard to semiquantitative assessment of myocardial viability with cardiac dedicated softwar.

BACKGROUND
The objective of this study was to semiquantitatively assess the degree of myocardial fluorodeoxyglucose (FDG) uptake in glucose-loaded myocardial viability positron emission tomography/computed tomography (PET/CT) scans, to calculate the myocardial to background index, and correlate the index with image quality assessed on the basis of visual qualitative assessment.


MATERIAL AND METHODS
The myocardial FDG-PET/CT study was carried out in 69 non-diabetic patients, who had known coronary artery disease, by intravenous injection of 250 ± 70 MBq (range: 180-320 MBq) FDG. Images were interpreted visually and patients were divided into three groups according to the grade of myocardial uptake: optimal, suboptimal, and uninterpretable. Semiquantitative analysis was performed by calculating the standardized uptake value (SUVmax) for myocardium and background (blood pool) activity, and expressed as the myocardial to background (M/B) activity ratio.


RESULTS
On the basis of visual (qualitative) analysis, 60/69 (86.96%) patients showed optimal quality of FDG cardiac uptake, 3/69 (4.35%) were suboptimal, and uninterpretable FDG PET scan results were found in 6/69 (8.70%) patients. The M/B index was found to be significantly higher in images of optimal vs. suboptimal quality (6.87 ± 3.99 vs. 1.65 ± 0.78 respectively; p < 0.0001).


CONCLUSIONS
The index ratio of 2.2, which is consistent with the upper borderline value for visually uninterpretable images, was considered the cut-off value for scans of optimal and non-optimal quality.