Objectives: With the latest SPECT scanners, it is possible to quantitate radioisotope activity precisely. We aimed at reporting the values of SUVmax and SUVmean from first data from quantitative In-111 Octreoscan scintigraphy using x-SPECT quantification technique.
Methods: We measured mean±SD and 95% confidence interval (95%CI) of SUVmax and SUVmean in nine patients undergoing quantitative In-111 Octreoscan scintigraphy for neuroendocrine tumor assessment with xSPECT (Intevo, Siemens). ROIs of non-tumoral abdominal organs, primary and metastatic sites were calculated on both 2-hour and 24-hour acquisitions. ROIs of hepatic, splenic and digestive organs were at least 3cm3; pancreas was divided into head and body-tail regions.
Results: SUVmax and SUVmean (g/mL) measured at 2- and 24-hour post-tracer injection acquisitions were, respectively: liver (3.4±1; 2.2±0.7; 3.3±1.2; 1.9±0.7), spleen (11.5±4.6; 8.1±3.3; 9±4.7; 6.3±3.2), digestive tract (2.0±0.9; 1.1 ± 0.5; 2.8 ± 1.8; 1.7 ± 1.1), pancreatic head (2.1±0.6; 1.4±0.5; 2±1.4; 1.3±0.9), pancreatic body-tail (1.8±0.7; 1.2±0.5; 1.5±0.6; 1.0±0.4), primary site (9.6±5.7; 6±3.7; 5.8±3.4 ; 3.6±2.0), metastases (18.3±12; 11.2±7.9; 10.3±3.2; 6.1±2.1).
Conclusion: We found a clear difference in the measured activity of tumoral and non-tumoral tissue. Both SUV max and SUVmean of primary and metastatic sites halved 24-hours after tracer injection but remained higher than mean splenic uptake. Digestive activity increased with time, but remained lower than normal hepatic uptake. The knowledge of SUV range and time variation might help understanding the nature of SPECT abnormalities. Research Support: none