Retrospective Analysis of Scintimetric Characterization of Primary Tumors by Dual Phase PETCT Study

Aim: This retrospective analysis of the scintimetric characterization of the primary tumors of various cancers using the dual phase PETCT scans thrives to establish the utility of the Rong's Retention ratio and the Dr. V. Siva's modification of RRI. Methods: In the proven cases of various cancers the SUV max values were obtained in the Early and Delayed PETCT scans using the ROI method over the FDG avid primary sites. The PETCT scans were done using the GE Discovery IQ unit one and 4 hours after the I.V injection of 5 to 10 mCi of F18- FDG after overnight Fasting. The image analysis and the SUV were calculated using the Advantage 4.7 software provided by GE. Total of 19 primary sites at various locations were included and the calculated SUV max were used to arrive at the Rongs Retention Index (RRI) and Dr. V. Siva's modification of RRI. The values were tabulated and analyzed. Results: The Rong's retention ratio had a very narrow range with wide overlapping. However the Dr. V. Siva's modification of RRI showed much wider values with a definite cut off level. The statistical evaluation of the data confirm that the Dr. V. Siva's modification of RRI significantly correlates well with the Rong's Retention Index (RRI). Conclusion: It can be concluded that the scintimetric characterization of the primary tumors of various cancers is possible and might be useful in the identification of the primary malignancies.