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J Nucl Med. 2008; 49 (Supplement 1):230P
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Neurosciences: Neurology

Neurology Posters

CT-based attenuation correction provides more accurate tracer distribution in brain SPECT than Chang’s method

Etsuko Imabayashi1, Hiroshi Matsuda1, Ichiei Kuji1 and Akira Seto1

1 Nuclear Medicine, Saitama Medical University, International Medical Center, Hidaka, Saitama, Japan

992

Objectives: Chang’s method (CHANG) for attenuation correction (AC) does not take the structure and inhomogeneity outside the brain into account. CT-based attenuation correction (CTAC) has been expected to give accurate tracer distribution. In the present study, we compared brain SPECT images of a phantom and human brain between CHANG and CTAC.

Methods: A SPECT/CT system (Symbia T6, Seimens) was used. A Hoffman 3D brain phantom was set in a head holder made of a carbon fiber for human use at supine, oblique, and lateral positions. The phantom was wrapped of not by the clay which had similar Hounsfield unit to skull. In a human study, the 20 Tc-99m ECD SPECT images without significant perfusion defects were chosen. Each projection data were reconstructed with ordered subsets expectation maximization method with two kinds of ACs; CHANG and CTAC. In a human study, SPECT with these ACs were compared using statistical parametric mapping 2. Moreover,using a NEUROSTAT program, asymmetry of tracer distribution between left and right hemispheres was compared in 10 regions of cerebral cortex.

Results: The phantom study showed that CTAC provided constant tracer distribution irrespective of brain positions in the presence or absence of the clay. On the contrary, both brain positions and the presence of the clay influenced the tracer distribution in CHANG. In human study, CTAC showed more increased distribution in inferoposterior areas than CHANG maybe due to accurate AC by a head holder or a thickened skull at the posterior fossa. CTAC and CHANG showed inverse asymmetries between hemispheres in 20% regions.

Conclusions: CTAC can provide accurate tracer distribution in brain SPECT. Ignorance of attenuation by a head holder or a thickened skull in CHANG may lead to incorrect diagnosis.





This Article
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Right arrow Email this article to a friend
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Right arrow Articles by Imabayashi, E.
Right arrow Articles by Seto, A.
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Right arrow Articles by Imabayashi, E.
Right arrow Articles by Seto, A.