Program Information
Iterative Reconstruction of SPECT Brain with Priors Based On MRI T1 and T2 Image
Q Gu*, J Bowsher , T Truong , N Chen , Duke Kunshan University|Duke University, Kunshan, Jiangsu
Presentations
SU-J-CAMPUS-IT-4 (Sunday, July 30, 2017) 4:00 PM - 5:00 PM Room: Imaging ePoster Theater
Purpose: This study investigates the use of MRI T1 and T2 images in the reconstruction of SPECT brain images at the midbrain level.
Methods: Source images at the midbrain level were downloaded from BrainWeb. SPECT projection data were simulated for Tc99m-ECD brain perfusion studies. These simulations modeled noise and spatial resolution. SPECT images were then reconstructed by maximum a posteriori (MAP) methods, with the prior probability distribution generated from either gradient-echo T1 or fast-spin-echo T2 MRI images, and using an Iterative Coordinate Descent (ICD) algorithm. SPECT images were also reconstructed by Ordered Subsets Expectation Maximization (OSEM). Reconstructed images were compared to the true, phantom radiotracer distribution by visual inspection, root mean square error (RMSE), and contrast to noise ratio (CNR).
Results: Relative to the T2-based prior, utilizing the T1-based prior for SPECT image reconstruction improved RMSE and CNR by 27% and 29% respectively. Relative to the best iterations for OSEM, the T1-based prior improved RMSE by 40% and CNR by a factor of 3. Visually, the SPECT image reconstructed with the T1-based prior was closest to the true phantom distribution, notably capturing certain structures that were not well reconstructed using the T2 image. Both MAP images were superior to OSEM visually and by RMSE and CNR.
Conclusion: The quality of SPECT images reconstructed utilizing MRI images depends substantially on the MRI sequence utilized. For this study, gradient-echo T1 MRI provided more accurate SPECT image reconstruction than fast-spin-echo T2 MRI. Both MRI sequences resulted in better RMSE and CNR than OSEM without use of MRI.
Funding Support, Disclosures, and Conflict of Interest: This project was supported by the NMRC (National Medical Research Council) Research Training Fellowship from Singapore MOH (Ministry of Health). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Medical Research Council,Singapore.
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