Myocardial perfusion imaging with a solid-state camera: simulation of a very low dose imaging protocol

Area of Science:

• Nuclear cardiology
• Medical imaging technology

Background:

• Dedicated cardiac cameras offer potential for reduced injected doses in SPECT myocardial perfusion imaging (MPI).
• Determining the minimal required counts for accurate MPI is crucial for dose reduction strategies.

Purpose of the Study:

• To assess the feasibility of very low dose MPI by identifying the minimal myocardial count level needed for accurate results.
• To explore the limits of dose reduction in SPECT MPI using list-mode data acquisition and simulation.

Main Methods:

• Seventy-nine patients underwent standard-dose (99m)Tc-sestamibi MPI using a dedicated cardiac camera.
• List-mode data were reframed to simulate 6 lower-dose datasets by reconstructing various fractions of original counts.
• Automated software quantified total perfusion deficit (TPD) and ejection fraction; minimal left ventricular counts were determined.

Main Results:

• Excellent correlations (r ≥ 0.95) were observed between original and simulated low-count scans for perfusion and function analysis.
• A minimum of 1.0 million left ventricular counts was determined sufficient, with low SD for TPD (1.7%) and ejection fraction (4.2%).
• This count level corresponds to an effective injected dose of 92.5 MBq for 14-min or 125.8 MBq for 10-min acquisition.

Conclusions:

• 1.0 million counts are adequate for accurate quantitative perfusion and function parameters in MPI, comparable to 8.0 million counts.
• Dedicated cardiac cameras can achieve accurate MPI in under 10 minutes with an effective radiation dose below 1 mSv.
• These findings support significantly reduced injected doses for SPECT MPI without compromising diagnostic accuracy.