Image quality has been estimated and predicted using the signal to noise ratio (SNR). The purpose of this study is to investigate the relationships between body mass index (BMI) and SNR measurements in PET imaging using patient studies with liver cancer. Three groups of 59 patients (24 males and 35 females) were divided according to BMI. After intravenous injection of 0.1 mCi of 18F-FDG per kilogram of body weight, PET emission scans were acquired for (1, 1.5, and 3) min/bed position according to the weight of patient. Because liver is an organ of homogenous metabolism, five region of interest (ROI) were made at the same location, five successive slices of the PET/CT scans to determine the mean uptake (signal) values and its standard deviation. We obtained the liver's Signal-to-Noise Ratio from the ratio of both. Weight, height, SNR, and Body Mass Index were determined using a spreadsheet, and graphs were created to show the relationship between these variables. The graphs demonstrated that SNR decreases when BMI increases and that, despite an increase in injection dose, SNR also decreases. This is because heavier individuals take higher doses and, according to reports, have lower SNR. These results show that, despite receiving larger FDG doses, heavier patients' images, as measured by SNR, are of lower quality than thinner patients' image
