Task-based evaluation of a 4D MAP-RBI-EM image reconstruction method for gated myocardial perfusion SPECT using a...

Area of Science:

• Medical Imaging
• Nuclear Cardiology
• Image Reconstruction

Background:

• 4D gated myocardial perfusion (MP) SPECT is crucial for diagnosing cardiac abnormalities.
• Accurate reconstruction of 4D cardiac images is essential for reliable diagnosis, especially for subtle motion defects.
• Existing reconstruction methods may struggle to balance noise and resolution for optimal motion detection.

Purpose of the Study:

• To evaluate a novel 4D iterative maximum a posteriori rescaled-block expectation-maximization (MAP-RBI-EM) image reconstruction method for 4D gated MP SPECT.
• To compare the performance of the new method against traditional 3D filtered back projection (FBP) and 3D ordered subset expectation maximization (OS-EM) with attenuation, collimator-detector response, and scatter (ADS) corrections.
• To assess human observer performance in detecting regional myocardial wall motion abnormalities using different reconstruction techniques.

Main Methods:

• A realistic 4D NURBS-based Cardiac-Torso (NCAT) phantom simulating cardiac motion was used.
• Projection data were generated with and without noise, including ADS effects.
• Reconstructions were performed using 3D FBP, 3D OS-EM with ADS corrections, and the 4D MAP-RBI-EM method with ADS corrections.
• Image quality was assessed using normalized mean squared error (NMSE) and averaged normalized standard deviation (NSDav) to optimize reconstruction parameters.
• A task-based human observer study using receiver operating characteristic (ROC) analysis and area under the curve (AUC) was conducted to evaluate detection performance.

Main Results:

• The 4D MAP-RBI-EM method demonstrated the best trade-off between bias (NMSE) and noise (NSDav) among the tested methods.
• Human observers achieved significantly higher detection performance for regional myocardial wall motion abnormalities using images reconstructed with the 4D MAP-RBI-EM method.
• The AUC values from ROC analysis confirmed the superior diagnostic performance of the optimized 4D MAP-RBI-EM reconstruction.

Conclusions:

• The NMSE-NSDav trade-off is a reliable indicator of observer performance in detecting regional motion abnormalities.
• The optimized 4D MAP-RBI-EM method with ADS corrections significantly improves the detection of regional myocardial wall motion abnormalities in 4D gated MP SPECT compared to 3D FBP and 3D OS-EM.
• This advanced reconstruction technique holds significant promise for enhancing diagnostic accuracy in cardiac imaging.