Assessment of dual-time-point 18F-FDG-PET imaging for pulmonary lesions

The objective of this study was to assess suitability of dual-time-point 18F-FDG [(18F)-fluoro-2-deoxyglucose]-PET imaging for differentiating between malignant and benign pulmonary lesions, whose size and maximal standardized uptake values (SUVs) are greater than 10 mm and 2.5, respectively.

A total of 38 patients, 27 with malignant lesions (n = 30), and 11 with benign lesions (n = 22), were investigated by performing two static acquisitions started at mean times t = 79 and t = 158 min after the tracer injection. A model analysis involving tissue 18F-FDG uptake and release has been developed and applied.

Malignant lesions showed a SUV increase between the two acquisitions for 27 of 30 lesions, and a SUV decrease or constancy for the other three. Benign lesions showed a SUV increase in 19 of 22 lesions, and a SUV decrease in three (both increase and decrease were observed for multiple benign lesions in two patients).

It is recommended that dual-time-point 18F-FDG-PET imaging is not indicated to differentiate between malignant and benign pulmonary lesions, whose size and maximal SUV are greater than 10 mm and 2.5, respectively. Furthermore, a model analysis suggests that the variation in SUV observed between early and delayed scans may be explained by different values of the 18F-FDG release/uptake ratio.