Intrahemispheric symmetry of brain perfusion. Part 1. Calculation procedure




single-photon emission computed tomography, SPECT, brain, rotation symmetry, intrahemispheric symmetry, perfusion, 99mTc-HMPAO


As has been noted in the analysis of the symmetry of radiopharmaceutical (RPh) distribution between the cerebral hemispheres according to the data of a single-photon emission computed tomography (SPECT), there are quasi-symmetric regions of perfusion in the hemispheres. This study is focused on the investigation of this observation that eventually will lead to the development of new quantitative criteria of the brain functional state in terms of effective perfusion, and possibly will provide new knowledge on the structural and functional patterns of the brain. The authors develop a methodology for estimating intrahemispheric symmetry (IHS) of brain perfusion based on SPECT data. 32 SPECT images of patients with different levels of brain perfusion were analyzed. Scintigraphic investigations of the brain were conducted with 99mTc-HMPAO on the gamma camera E.Cam (Siemens) with LEHR collimator. The SPECT investigation was conducted 15–20 minutes after the RPh injection. The tomography study included the collection of 128 projections for 128×128 matrix; the injected RPh activity amounted to 740 mBq. The developed computerized standardization procedure of spatial orientation of brain SPECT image was implemented using the Scintybrain software in the Matlab 2018 environment. The main criterion for finding quasi-symmetric lines of brain perfusion profile is the cross-correlation coefficient r and the standard deviation between them. The number of selected pairs of profile lines depends on the predetermined threshold rmin. The analysis of experimental data shows that it is recommended to adopt the rmin value equal to 0.94 for quantifying the brain IHS. This paper presents a hypothesis of intrahemispheric quasi-symmetry of brain perfusion. The developed method of IHS analysis provides a new diagnostic information about the spatial RPh distribution and represents a fundamentally new tool for assessing the interrelationships of circulatory disorders of brain tissues in its various segments.


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Typical location of center of mass of brain SPECT image





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