Objective: A time normalisation method of tumour SUVs in (18) F-FDG PET imaging is proposed that has been verified in lung cancer patients.
Methods: A two-compartment model analysis showed that, when SUV is not corrected for (18) F physical decay (SUV(uncorr)), its value is within 5% of its peak value (t = 79 min) between 55 and 110 min after injection, in each individual patient. In 10 patients, each with 1 or more malignant lesions (n = 15), two PET acquisitions were performed within this time delay, and the maximal SUV of each lesion, both corrected and uncorrected, was assessed.
Results: No significant difference was found between the two uncorrected SUVs, whereas there was a significant difference between the two corrected ones: mean differences were 0.04 ± 0.22 and 3.24 ± 0.75 g.ml(-1), respectively (95% confidence intervals). Therefore, a simple normalisation of decay-corrected SUV for time differences after injection is proposed: SUV(N) = 1.66 SUV(uncorr), where the factor 1.66 arises from decay correction at t = 79 min.
Conclusions: When (18) F-FDG PET imaging is performed within the range 55-110 min after injection, a simple SUV normalisation for time differences after injection has been verified in patients with lung cancer, with a ±2.5% relative measurement uncertainty.