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Phantom evaluation of scatter and attenuation correction in thallium-201/technetium-99m acquisition in myocardial
Y Ohyama1, S Tomiguchi, T Kira
1Department of Radiology, Kumamoto University School of Medicine, Japan.
Purpose:
This phantom study was carried out to evaluate the usefulness of scatter correction combined with transmission-based attenuation correction in separate and simultaneous 201Tl/99mTc myocardial SPECT.
Methods:
An anthropomorphic torso phantom was used in this study. We used the triple-energy-window (TEW) method for scatter correction and transmission computed tomography (TCT) images for attenuation correction. Images without corrections (UC) and images with corrections (SAC) for scatter and attenuation were reconstructed for the evaluation.
Results:
The differences in defect size between 99mTc and 201Tl UC images led to interpretation errors in separate (separate protocol) and simultaneous dual-isotope studies (simultaneous protocol). These errors were more prominent in the infero-posterior wall in the simultaneous protocol. Improvement for overestimation in object size and underestimation in defect contrast was visually obtained, and increased contrast was also shown by the myocardium-to-defect count (MD) ratios on SAC images in the separate and simultaneous protocols. However, 201Tl SAC images in the simultaneous protocol still had less defect contrast than the corresponding 201Tl SAC images in the separate protocol.
Conclusions:
From the results of our phantom experiment, separate rest 201Tl/stress 99mTc-sestamibi acquisitions may be recommended in clinical practice. Further clinical and phantom studies will be needed to validate the method using scatter correction combined with transmission-based attenuation correction.