Quantitative Analysis of 18F-FDG PET/CT in Patients with Diffuse Large B-Cell Lymphoma and Variable Body Mass Index

Introduction: 18F-FDG PET/CT is a non-invasive modality of imaging for the staging and pretreatment assessment in diffuse large B-cell lymphoma (DLBCL). SUVmax is a quantitative tool which is commonly used for semiquantitative analysis. SULmax is another useful parameter in semiquantitative analysis of the fluorodeoxyglucose (FDG)- avid lesions with possible difference in the estimated values when used for different body mass index (BMI) levels. Obesity is a worldwide challenge with associated comorbidities and heightened risks of multiple types of cancers, one of which is lymphoma. Special considerations were suggested to enhance the accuracy of the quantitative evaluation of metabolically active lesions in 18F-FDG PET/CT scans of obese individuals. Methods: In a random selection of 30 patients, we recorded and analyzed the estimated SUVmax and SULmax values in non-lesion areas at FDG PET/CT studies performed for patients having DLBCL and categorized at different BMI groups who met the inclusion criteria after exclusion of any other factors that might affect the metabolic activity of the patient hence the FDG readings. Results: SUVmax and SULmax values were found to be relatively higher in obese patients when compared to patients who had normal body weight and overweight individuals. However, changes of SUVmax and SULmax were comparable in different BMI groups, with constant levels of increase in both values in higher BMI groups. Discussion: Multiple studies have questioned the accuracy of SUVmax in higher BMI groups and suggested the use of SULmax, especially on follow-up studies for the same patient. Further efforts were needed to determine the significance of both with the increase of BMI and the possibility of altered diagnosis and staging efficiency. In our study, we found that both SUVmax and SULmax showed increased values in higher BMI groups. However, both were increased with the same ratio. Conclusion: Both SUVmax and SULmax are reliable semiquantitative tools and can be used in 18F-FDG PET/CT analysis in lymphoma patients with different BMI categorizations as both are increasing with a constant ratio with the increased values seen in patient with higher body weight.