Reduced administered activity, reduced acquisition time, and preserved image quality for the new CZT camera

Abstract

Background: For a 1-day myocardial perfusion SPECT (MPS) the recommendations for administered activity stated in the EANM guidelines results in an effective dose of up to 16 mSv per patient. Recently, a gamma camera system, based on cadmium zinc telluride (CZT) technology, was introduced. This technique has the potential to reduce the effective dose and scan time compared to the conventional NaI gamma camera. The aim of this study was to investigate if the effective dose can be reduced with a preserved image quality using CZT technology in MPS.

Methods: In total, 150 patients were included in the study. All underwent a 1-day (99m)Tc-tetrofosmin stress-rest protocol and were divided into three subgroups (n = 50 in each group) with 4, 3, and 2.5 MBq/kg body weight of administered activity in the stress examination, respectively. The acquisition time was increased in proportion to the decrease in administered activity. All examinations were analyzed for image quality by visual grading on a 4-point scale (1 = poor, 2 = adequate, 3 = good, 4 = excellent), by two expert readers.

Results: The total effective dose (stress + rest) decreased from 9.3 to 5.8 mSv comparing 4 to 2.5 MBq/kg body weight. For the patients undergoing stress examination only (35%) the effective dose, administrating 2.5 MBq/kg, was 1.4 mSv. The image acquisition times for 2.5 MBq/kg body weight were 475 and 300 seconds (stress and rest) compared to 900 seconds for each when using conventional MPS. The average image quality was 3.7 ± 0.5, 3.8 ± 0.5, and 3.8 ± 0.4 for the stress images and 3.5 ± 0.6, 3.6 ± 0.6, and 3.5 ± 0.6 for the rest images and showed no statistically significant difference (P = .62) among the 4, 3, and 2.5 MBq/kg groups.

Conclusions: The new CZT technology can be used to considerably decrease the effective dose and acquisition time for MPS with preserved high image quality.