N-isopropyl—（123I） p-iodoamphetamine （123I-IMP）による内頸動脈閉塞症の脳血流動態の検討

CEREBRAL PERFUSION IMAGING WITH N-ISOPROPYL-(123I) P-IODOAMPHETAMINE (123I-IMP):ITS PLANAR IMAGING AND SEMIQUANTITATIVE ANALYSIS IN CASES WITH INTERNAL CAROTID OCCLUSION

　抄録　内頸動脈閉塞症17例で健常人5例を対照とし，¹²³I-IMP脳血流シンチグラフィーを行い，臨床症状と対比し，本症の脳循環動態を把握する上で本法の有用性を検討した。¹²³I-IMP 3mCi静注後ガンマカメラで6方向からのシンチグラムを記録した。血流低下の評価にはシンチグラム所見のほか各半球カウントの差異を半定最的指標（PIA）として算出し，これらを用いた。¹²³I-IMP脳血流シンチグラムでは本症で神経学的に無症状の3例（N群）では全例正常，TIAsを呈する4例（T群）中2例にて低血流領域を認め，他2例は正常であった。Completed strokeを呈する10例（CS群）では全例に中大脳動脈領域を中心として明瞭な低血流領域を認めた。大脳半球のPIAはコントロール群（C群）に比べ，N群では有意差を認めず，T群，CS群では有意に増大していた。また小脳半球PIAはC群に比べ，N群，T群では有意差なく，CS群では有意に減少していた。大脳半球PIAと小脳半球PIAの間には有意の負の相関が認められ，テント上病変における反対側小脳血流低下が示唆された。¹²³I-IMP脳血流シンチグラフィーは広く一般に施行可能であり内頸動脈閉塞症の脳循環動態を把握する上で1つの有用な検査法であると考えられる。

Occlusion of internal carotid artery (ICA) is one of the most common cause of stroke, and the single common arterial lesion considered for extra-intracranial bypass. The symptoms of ICA occlu-sion are not uniform; some shows transient ische-mic attacks (TIAs), others comp+leted stroke at the onset. So, measurement of cerebral blood flow might be needed to evaluate the prognosis, or to select surgical candidate in ICA occlusion. Several methods, such as Xe-133 intracarotid method, Xe-133 inhalation method etc, have been applied for the assessment of cerebral blood fiow in cases with ICA occlusion. No previous report was found by the newly developed ¹²³I-IMP in this connection.

The purpose of the present study is first to demonstrate the feasibility of¹²³I-IMP planar brain scintigraphy and its semiquantitative analysis in 17 cases with ICA occlusion. After intravenous injec-tion of 3 mCi of ¹²³I-IMP, brain scintigrams were obtained from anterior, Towne, vertex, posterior, right lateral and left lateral views, and were recorded on magnetic tape and Poraloid films. Semiquantitative analysis was performed as a percent index of asymmetry (PIA) from the dif-ference of each hemispheric count in the scinti-grams by use of on-lined minicomputer system. Clinical manifestations of these 17 cases were, completed stroke in 10, TIAs in 4, and no neuro-logical symptom in 3.

¹²³I-IMP brain scitigrams demonstrated low flow lesion in 10 out of 10 completed stroke, in 2 out of 4 TIAs and normal perfusion in all cases with no neurological symptoms. PIA of cerebral hemisphere was significantly increased in the group of TIAs and that of completed stroke than in control (p <0.01). PIA of cerebellar hemisphere was significantly decreases in the group of completed stroke than in control (p <O.01). Significant cor-relation was found between PIA of cerebral hemisphere and PIA of cerebllar hemisphere (p <O.01). From these preliminary results, crossed cerebellar diaschisis might be demonstrated by semiquantitative analysis of ¹²³I-IMP brain scinti-graphy.

In conclusion, it is suggested that ¹²³I-IMP planar scintigraphy and its semiquantitative analysis might be a useful method for the assessment of cerebral blood flow perfusion in cases with ICA occlusion.