Tumor metabolism measured by partial volume corrected standardized uptake value varies considerably in primary and metastatic sites in patients with lung cancer. A new observation.

Fluorine-18 fluorodeoxyglycose -position emission tomography ((18)F-FDG-PET) as an efficient staging tool for lung carcinoma; allows description and characterization of the primary tumor and of local and distant metastases in a single examination. One of the important limiting factors in quantification of metabolic parameters with PET is the partial volume effect. Our aim for this study was to delineate tumor (size) both in the primary and metastatic lesions in patients with lung cancer by using partial volume correction techniques. Thirty two patients with proven lung cancer who had (18)F-FDG-PET and computerized tomography (CT) within the last 80 days were involved in this study. They were 18 women and 14 men, with age range 43-83 years. Maximum standardized uptake values (SUVmax) in primary and metastatic lesions for all patients were measured. The lesions were categorized into 4 different Groups according to their site. Partial volume corrections were applied using the CT sizes of lesions to obtain corrected SUVmax values. Average corrected SUVmax in each lesion site was calculated and compared between the 4 Groups. A total of 81 primary and metastatic lesions were included in this analysis. They were 28 mediastinal-hilar lymph node lesions, 26 lung lesions, 11 solid organ lesions, and 16 bone marrow lesions. The average uncorrected SUVmax for the primary lung lesions, mediastinal-hilar lymph node lesions, solid organ lesions, and the bone marrow lesions before application of partial volume correction formula were 7.2+/-3.2; 7.0+/-2.7; 6.3+/-3.4 and 7.0+/-3.4, respectively. The average corrected SUVmax for the lesions in the above mentioned regions were 11+/-6, 10+/-4, 13+/-7, and 18+/-13, respectively. A statistically significant difference was observed in the average SUVmax values between lung lesions and nodal lesions compared to the bone marrow lesions. In conclusion, our findings indicate that metabolic activities of lung cancer lesions vary depending on the sites of metastatic disease.