Dose reduction in half-time myocardial perfusion SPECT-CT with multifocal collimation

Area of Science:

• Nuclear Medicine
• Cardiovascular Imaging
• Radiopharmacy

Background:

• Technological advancements in myocardial perfusion imaging suggest potential for reduced radiotracer doses.
• Evaluating the equivalence of quantitative stress myocardial perfusion defect measures is crucial for optimizing imaging protocols.

Purpose of the Study:

• To compare quantitative measures of stress myocardial perfusion defects using Tc-99m sestamibi with standard low-energy high-resolution (LEHR) collimators versus a lower dose SPECT-CT system (IQ·SPECT) utilizing cardiac multifocal collimators.
• To assess the diagnostic accuracy and reliability of reduced-activity SPECT-CT imaging.

Main Methods:

• Ninety-three patients underwent one-day rest-stress gated SPECT-CT.
• Stress SPECT-CT images were acquired using both LEHR collimators (13 minutes) and IQ·SPECT (7 minutes) with Tc-99m sestamibi (925-1100 MBq).
• Low-dose IQ·SPECT was simulated by subsampling full-dose data; abnormalities were quantified using total perfusion deficit (TPD) scores.

Main Results:

• Excellent correlation (R ≥ 0.93) was observed between LEHR and IQ·SPECT TPD scores across all simulated doses.
• Bland-Altman analysis indicated minimal bias between the two methods.
• Statistically significant differences in TPD scores were noted at quarter and eighth doses, but overall diagnostic equivalence was maintained.

Conclusions:

• Quantitative stress SPECT-CT imaging with IQ·SPECT is feasible using half the standard injected activity and in half the acquisition time.
• IQ·SPECT offers a promising alternative for myocardial perfusion imaging, potentially reducing patient radiation dose and improving workflow efficiency.