Performance evaluation of quantitative SPECT/CT using NEMA NU 2 PET methodology.

In this study, the quantitative performance of the Symbia Intevo SPECT/CT was evaluated for two common isotopes (99mTc, 177Lu) and benchmarked against the performance of a PET/CT. A further aim was to demonstrate the utility of adapting NEMA NU2 PET measurements to SPECT. In addition, dead-time and resolution recovery were evaluated to provide more complete system evaluations. Spatial resolution of the SPECT system at 1 cm from the center in the transverse direction was 13.1 mm and 22.4 mm for 99mTc and 177Lu respectively, compared with 4.3 mm (18F) and 5.8 mm (68Ga) for PET. Sensitivity at the center of the FoV was 119 cps/MBq and 48 cps/MBq (99mTc, 177Lu) for SPECT and 9,632 cps/MBq and 8,216 cps/MBq (18F, 68Ga) for PET. Scatter fraction was 0.25 and 0.36 (99mTc, 77Lu) for SPECT and 0.32 and 0.29 (18F, 68Ga) for PET. Contrast recovery coefficient in the largest spheres was 0.79 and 0.65 (99mTc, 177Lu) for SPECT, 1.00 and 0.97 (18F, 68Ga) for PET and the background variability was 2.7%, 6.5% (99mTc, 177Lu), 1.5% and 1.6% (18F, 68Ga), respectively. Partial volume effect was evaluated using the NEMA IQ phantom with six sphere inserts (diameter: 37 mm, 28 mm, 22 mm, 17 mm, 13 mm and 10 mm). Full contrast recovery was reached with the 17 mm for 18F, while SPECT did not reach full recovery for any sphere. Count rate losses were 2% for 99mTc at 1 GBq and 11% for 177Lu at 8.5 GBq which are well below the typical activities for clinical applications. We concluded NEMA NU2 methodolog...

Source: Physics in Medicine and Biology - June 16, 2019 Category: Physics Authors: Ryu H, Meikle SR, Willowson K, Eslick EM, Bailey DL Tags: Phys Med Biol Source Type: research