Retrospective correction of false data entry on the PET/CT Imaging

Aim: One of the advantages of PET imaging is its ability to accurately quantify the distribution of the injected tracer. This accuracy relies on several corrections during the image acquisition and reconstruction process, but also depends on the accurate knowledge of the amount of injected activity. Case: A 88 kg female with gastric cancer was injected with 406 MBq of FDG at 11:30. Approximately 60 min later, a PET/CT examination was obtained from mid thigh to skull base with a Truflight Select PET/CT system (Philips Medical Systems). After the scan was completed, the technologist noticed that the information about injected PET dose was incorrect and reconstructed of images by correcting the injected dose information in order to make sure that the images showed the right activity concentrations. A repeat PET/CT was performed by for same patient two days later. Patient preparation, acquisition parameters and reconstruction protocols for same patient was standardized. Two-dimensional circular region of interest was placed on the blood pool in the aortic arch, the right lobe of the liver, the heart and the tumor lesion on the lung. Measured SUVmax data in these 4 regions of interest was recorded for each scan. The data were transferred into SPSS statistical analysis software (version 11.0). The SUV max measurements depending on false injected dose were determined as 3.5, 5.7, 3.7, and 17.5 for these 4 region, respectively. The SUVmax measurements depending on retrospective correction were found as 2.9, 3.5, 3.1 and 12.8. The SUV max measurements depending on repeat PET/CT were found as 2.7, 3.1, 2.6, and 10.9. The average SUV max correction with retrospective change was determined as 85%. Conclusion: Errors in patient data entry may alter patient management. Extreme care should be taken when retrospectively changing or correcting scan entries.