Objective: to evaluate the importance of patient preparation for diagnostic quality of PET-CT images.
Methods: prospective study of 188 patients‘ who underwent PET-CT examination at our Nuclear medicine department has been carried out. Patients were asked to fill in questionnaire about preparation for PET-CT. Then PET-CT images were analysed and attributed to one of the five quality categories, assigning score from 1 to 5. Additionally, average and maximum standardized uptake values (SUV) were calculated in the standard size (200cm3) region of interest (ROI) placed on the left ventricle of the heart. P<0.05 was considered statistically significant.
Results: diabetes was found in 14 (7.5%), obesity in 44 (23.4%) patients. Mean patients’ glycaemia prior 18F-FDG injection – 5.42±1.02 mmol/l. Most of the patients’ (n=186; 98.9%; p<0.001) had their last meal more than 6 hours before PET-CT. One hundred sixteen (61.7%; p<0.001) patients consumed 3-4 glasses (0.75-1 litre) of water during last 6 hours. Patients have followed low carbohydrates low fat containing products diet (n=97; 51.6%), low carbohydrates diet – 32 (17.0%), high proteins diet – 15 (8.0%), high fat diet – 2 (1.1%). SUVmax – 2.78±1.36, SUVav – 1.63±0.79. Most of the PET-CT images were considered as high quality (p<0.05): 82 (43.6 %) images were assigned for 4 points, 48 (25.5%) – 5 points. PET-CT images of diabetic patients‘ were significantly lower quality compared with non-diabetic patients (p<0.001) and in obese patients compared with non-obese (p<0.001). Mean quality of PET-CT images was associated with glycaemia (r=-0.29; p<0.001), SUVav (r=-0.38; p<0.001). SUVmax (r=0.2; p=0.006) and SUVav (r=0.19; p=0.01) were associated with glycaemia.
Conclusions: Eighty percent of the patients‘ have followed the instructions of preparation for PET-CT examination. Quality of PET-CT images was lower in patients‘ with diabetes, obesity and higher pre-test glycaemia. Higher glycaemia levels were associated with higher SUVmax and SUVav in the left ventricle of the heart.
Key words: patient‘s preparation, positron emission tomography – computed tomography, quality of images.