Improvement of Spatial Resolution and Reliability of rCBF Imaging in the Patients of Senile Dementia or Another Neuropsychologic Disease.

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An improvement of spatial resolution of tomographic regional cerebral blood flow (rCBF) image and the assessment of reliability of rCBF value were carried out.For an improved imaging of rCBF by Xe-133 inhalation method with a ring type single photon emission CT, a new collimator system and a data acquisition program were developed. The new collimator was designed to obtain 100cpm per pixel for 1,850MBq of Xe-133 gas inhalation. In the new program, the stepping rotaion-angle of the detector ring was changed into 1.4 degree for every 180 degree of collimator rotation. Sensitivity was 13.5Kcps/37KBq/m1 and the spatial resolution in FWHM was 13.6mm at the center and 10.3 mmat the 6cm apart from the center of 20cm cylindrical phantom. This new collimator system enabled to provide for more reliable measurement especially at the deep structure of the brain.To compose the system software assembly and patient detabase, a hard disk (320MB) system was introduced. And previous patient data was re-filled up.For an assessment of reliability of rCBF value with our improved SPECT system, The rCBF data measured in 56 healthy subjects who ranged in age from 1.3 to 80 years was analyzed. The mean CBF in children less than five years of age was about twice that found in adults. The mean CBF decreased rapidly with age until 22 years of age in females and 24 years of age in males. Thereafter, there was a slow decrease and a negative correlation with age was found. In adults, the mean CBF in females was slightly higher than that of males.Thus improved method for quantitative rCBF was very powerful tool for diagnosis or follow-up study especially in the patients with dementia or another neuropsychologic disease.