4D reconstruction for low-dose cardiac gated SPECT

Area of Science:

• Nuclear Medicine
• Medical Imaging Physics
• Cardiovascular Imaging

Background:

• Myocardial perfusion imaging (MPI) using gated single photon emission computed tomography (GSPECT) involves high radiation doses (>9 mSv).
• Reducing radiation exposure is crucial to minimize population-based cancer risks associated with frequent GSPECT use.

Purpose of the Study:

• To quantitatively assess the utility of advanced 4D reconstruction for GSPECT at significantly reduced imaging doses.
• To determine if 4D reconstruction can maintain diagnostic accuracy while lowering radiation exposure.

Main Methods:

• Monte Carlo simulations using the 4D NURBS-based cardiac-torso (NCAT) phantom for GSPECT at half and quarter dose levels.
• Comparison of 4D and 3D reconstruction methods against standard clinical spatiotemporal reconstruction (ST121) at full dose.
• Evaluation using metrics: myocardial accuracy, LV wall bias-variance, uniformity, TAC accuracy, and perfusion defect detectability.

Main Results:

• 4D reconstruction at quarter dose (∼2.25 mSv) showed superior myocardial accuracy and regional bias-variance compared to standard dose ST121.
• Similar performance in LV wall TAC accuracy and perfusion defect detectability was observed.
• 4D images exhibited reduced noise artifacts, better LV wall definition, and greater consistency across dose levels.

Conclusions:

• 4D reconstruction achieves better or comparable performance at quarter dose (75% reduction) versus conventional GSPECT at standard dose.
• Preliminary patient data suggest 4D reconstruction at quarter dose outperforms higher-dose 3D methods.
• This significant dose reduction in GSPECT warrants further research into optimal reconstruction strategies and broader clinical validation.