Impact of dual-energy window scatter correction on technetium image quality across different energy windows in...

The digital cadmium-zinc-telluride (CZT)-based SPECT system offers good energy resolution. However, the impacts of dual-energy window scatter correction on image quality under narrower primary energy windows remain to be determined. This study aimed to assess the impacts of SC (with scatter correction) and NOSC (without scatter correction) on image quality under different primary energy windows.

We used a standard NEMA/IEC 2007 phantom containing six hollow spheres of various sizes to simulate the human body at four target-to-background ratios (T/B ratio, the ratio of the average radioactive activity concentration in the target region to that in the background region, 32:1, 16:1, 8:1, and 4:1, respectively), by filling with ^99mTcO₄^-. For clinical validation, we recruited 20 patients and analyzed their whole-body bone scan images. Phantom and patient images were acquired with the Discovery NM/CT 670 CZT with list mode. Image quality of phantom was measured by calculating indicators from the NEMA NU 2-2018 standard, including percent background variability and percent contrast. Image quality of patients was measured by calculating coefficient of variation (COV), contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR). Visual quality was evaluated by two experts.

Higher percent background variability and COV values were present when SC was applied regardless of which energy window, acquisition time, or T/B ratio used, and statistically significant differences were observed between all SC and NOSC groups for both phantoms and patients. For phantoms, percent contrast values of most SC groups were higher than those of NOSC groups. For patients, CNRs and SNRs of SC groups were higher than those of NOSC groups (all P < 0.05). Visually, SC had higher visual scores than NOSC for both phantoms and patients.

SC significantly improves image contrast while minimizing concomitant image noise to a great extent and provides good visual image quality across different primary energy windows overall.