慢性分裂症のポジトロンCT所見

Positron CT Findings of Chronic Schizophrenics

　抄録　5例の男子正常例（平均年齢36歳）と15例の慢性分裂症例（うち女子2例，平均年齢42歳，平均罹患年数17年）のポジトロンCT画像を比較・検討した。分裂症例はすべて抗精神病薬を服用していた。標識化合物には，検査直前1回吸入させた11C-CO₂と，10〜15分前経口投与した11C-グルコース（ともに10〜20 mCi）を用いた。

　正常例では両標識化合物でともに前頭部に高活性を認め，多少の左右差はあっても，標識化合物によっての画像の相違はなかった。

　Positron CT images of 15 chronic schizophrenics (2 females and 13 males) were examined in contrast to 5 male controls. Average age of controls was 36 years and that of schizophrenics was 42 years. Schizophrenic cases were ill over 6 years, averaging 17 years. All were under antipsychotic drug therapy.

　Tracer compounds were 11 C-CO₂ and 11 C-glucose photosynthesised, the former being inhalated once just before and the latter being administered orally 10-15 minutes before examinations.

　On positron CT images of all normal controls, hyper-radioactivities in frontal regions were observed. Some asymmetries of activities were observed but not remarkable. There wes no difference between the images with 11 C-CO₂ and those with 11 C-glucose.

　In schizophrenic cases, (1) 7 out of 15 cases showed hypo-activities in the frontal regions both with 11 C-CO₂ and 11 C-glucose. (2) With 11 C-glucose, relative activities in the brain were lower than those in the soft tissues around the scalp, suggesting the lowered selective uptake of 11 C-glucose by the brain. (3) With 11 C-CO₂, 4 cases showedhigher activities in the right temporal regions and their subcortex than the left.

　By consideration of relationships between these positron CT findings and clinical data such as present age, age of onset of illness, duration of illness, psychiatric symptoms, present drug amount, summed drug amount from administration, EEG and X-ray CT findings, significant correlation was recognized only between low frontal radioactivities and apathy-abulia as main symptom.

　Limitation on the explanation of the findings with the image alone was discussed.