| Abstract | 「はじめに」脳腫瘍のスクリーニングにおけるRI検査の適応はMooreの131I Sodium diiodofluorescein DIFの先駆的業績以来, 他臓器のスキャンに比し遙かに広範囲である. 現在その放射性医薬品として汎用されているものは99mTcO4であり, かつこれに限られているといっても過言ではない. その原因はuniversal scanning agentとしての99mTcと, 脳に特異的とされる血液脳関門blood brain barrier (以下b. b. b. と略す) との優れた組合せが他核種の開発をそれ程必要としないこともあった. 本研究は腫瘍親和性核種としての67Ga-citrateと99mTcO4の両核種を用いたcombined techniqueを脳腫瘍に用い, その意義について考慮を試みた. 「対象および方法」三井記念病院放射線科における脳スキャンのうち99mTcO4および67Ga-citrateの両核種を相ついで用いた症例は22例あり, これに東京大学医学部放射線科で施行した3例 (症例No. 4, 6, 9) を加えると25例になる. |
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| Abstract | [Summary]68Ga compounds have been evaluated as diagnostic agents for the detection of intracranial lesions but have now not routinly been used for brain scintigraphy, because of its positron emitter property. There have been used to demonstrate 67Ga-citrate localization within a variety of neoplasma as well as in inflammatory lesions. However, its use in the detection of brain tumor have not been widely evaluated. 99mTcO4 has most widely been used as brain scan agent. In some instances, however, Tc fails to demonstrate lesions which can be diagnosed with other radiopharmaceuticls. In order to compare the merits of Ga with Tc, we have used both agents in 25 patients for brain scanning. Method and Materials : patients were randomly selected to participate in the study. Our series was composed of 25 patients, 22 histologically proven cases and other 3 cases not yet proven. 2cases of brain abscess, one of them was associated with ventriculitis, 8 cases of metastaticcarcinoma, 4 cases of meningioma, one case of meningosarcoma, 2 cases of acoustic neurinoma, one case of pituitary chromophobe adenoma, of astrocytoma, of oligodendroglioma, of glioma, and of meningitis respectively. 3 cases, which have not yet been histologically verified, were observed for up to one year following the initial study without any aggravation of central nervous pathology. The results were summarized in Table 1. Tc followed by Ga was injected in each case. Patient received an intravenous dose of 5-10m Ci of Tc and a routine 4 view study was performed on a rectilinear scanner beginning 30 minutes after injection. The patient received an intravenous dose of 1.5-3.0mCi of Ga and the scanning was performed in 30 min., 24 hrs and in some cases in 48 hrs after injection. Results and Discussion : Abnormality detected on the Ga and Tc scan was classified into the following 4 categories, : absent, faintly or slightly visible, moderate up-take and marked uptake. Each patient was classified into the following 4 groups. Group I : The Ga view outlines the brain lesions more accurately, and hyperconcentrated in comparision with Tc. Group II : The Tc view outlines more accurately and hyperconcentrated in comparision with Ga.Group III : Ga scan demonstrats an accumulation which is distributed exactly like that of Tc. Group IV : negative both in Ga and Tc scan 12 cases with abscess, meningioma, metastatic lesions and benign intracranial increased pressure were classified into Group I, 6 cases with metastatic lesions and acoustic neurinoma into GroupII, 3 cases with abscess and metastatic lesions into Group II, and 4 cases with meningioma, acoustic neurinoma, pituitary adenoma and meningitis into Group IV. Progmatically Tc remains the agent for routine screening work. When the scan was difficult to be interpreted with Tc, the attributes of Ga appear to justify the additional effort especially in the case of meningioma, metastatic lesions, and abscess. Malignant lymphoma and postoperative assessment of the brain tumor are, as reported before, first choice of Ga scan. |
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