[Studies on the pathophysiological principles of brain scintigraphy using Tc99m pertechnate]

Objective symmetry detector method for gammaencephalography. IV. Investigation of brain tumours

Sixty-six cases with possible brain tumour were objectively classified as having normal or abnormal 99TcmO4 distribution in the skull recorded by the symmetry detector method for gammaencephalography. The diagnostic accuracy in 37 confirmed tumour cases was about 95 percent. Astrocytomas I-II were seperated from astrocytomas III-IV by the degree of abnormality, and meningiomas were seperated from astrocytomas by diverging time-dependent changes in the pathologic isotope accumulation. The high diagnostic accuracy was obtained in spite of low spatial resolution and simplicity of the method. The careful choice of evaluation parameters and the restriction of their normal variance were necessary and effective in optimizing the method.

Objective symmetry detector method for gammaencephalography. III. Diagnosis of abnormal 99TcmO4 distribution in the skull

The objective classification of results of the previously described symmetry detector method for gamma encephalography is reported. The different evaluation parameters were chosen after comparing their detectability in different subregions of the head or as a result of findings in certain patients. The detectability was estimated from the results of phantom measurements related to the normal ranges of evaluation parameters. The borders of the classification criterion are discussed in relation to the number of evaluation parameters used.

Objective symmetry detector method for gammaencephalography. II. Normal range

A standardized clinical examination procedure of a previously described symmetry detector method for gammaencephalography is presented and the results obtained from a reference group of subjects without known neurologic disorders are reported. The 99TcmO4 distribution in the skull was investigated by 208 evaluation parameters obtained from measurements of 24 subregions of the skull from 48 symmetrical positions. Mean values and associated inter-individual and intra-individual standard deviations are given. Different sources of variation are discussed in relation to the results obtained. The method enables the 99TcmO4 distribution in the skull to be objectively classified as normal or abnormal.