N-isopropyl-p—［123I］iodoamphetamine single photon emission computed tomographyの脳腫瘍における臨床的有用性—各種画像との比較検討

REGIONAL CEREBRAL BLOOD FLOW IMAGES OF SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY BY N-ISOPROPYL-P-[I-123] IODOAMPHETAMINE IN PATIENTS WITH BRAIN TUMOR

　抄録　脳腫瘍における局所脳血流量を知る目的で，髄膜腫8例，glioblastoma multiforme 3例，oligo-astrocytoma 2例，他7例，計20例の脳腫瘍に対し延べ27回，N-isopropyl-P-［123I］iodoamphetamine（IMP）による　single photon emission computed tomography （SPECT）を行い，脳血管造影，X線CT，^81mKrおよび^99mTcによるSPECT所見と比較検討した。5例においては術前後に検査を行い腫瘍周辺部の血流変化を検討した。SPECT撮像はIMPの静注後20分，2時間，6時間後より開始した。腫瘍部分は2例がhot areaとして12例がcold areaとして示された。hot areaとして示された2例も2時間以後の撮像ではcold areaとして認められることにより腫瘍部分でのIMPのwashoutの亢進が示唆された。他検査との比較では，Tc-SPECTにて示された血液脳関門の破壊や，脳血管造影にて示されたvascularityの多寡とは必ずしも一致しなかった。一方，腫瘍周辺部の血流低下はよく示され，経時的な術後の改善が捉えられた。三次元的局所脳血流イメージを非侵襲的に容易に得ることが出来るという点で脳腫瘍に対してIMPによるSPECT像は有用と思われる。

Regional cerebral blood flow (r-CBF) was stu-died by single photon emission computed tomogra-phy (SPECT) using N-isopropyl-p-[I-123] iodoam-phetamine (IMP) in order to evaluate CBF in patients with brain tumor.

Total 27 studies were carried out in 20 patient, including 8 patients with meningioma, 3 with glioblastoma multiforme, 2 with oligoastrocytoma, and 7 with other intracranial tumors. All CBF images by IMP-SPECT were obtained by using a rotating gamma camera with dual heads. In the serial scans, each scan was started at 20 mi-nutes, 2 hours and 6 hours after intravenous in-jection of I-123 IMP (3 mCi). The all IMP-SPECT images were compared with cerebral angiogram, X-ray CT (plain and/or enhancement), and imagesof Kr-81 m SPECT and Tc-99 m SPECT. In 5 patients (4 patients with meningioma and 1 with glioblastoma multiforme) this comparative study was performed before and after surgery to evalu-ate the r-CBF changes surrounding tumor.

The abnormal lesion on Xray-CT was identified as hot area on CBF image by IMP-SPECT in two cases with meningioma, and in 14 cases the lesion showed cold area. Totally 80% of cases showed abnormal findings on CBF images by IMP-SPECT. The cases which showed no abnormal findings on IMP-SPECT images included 1 case with meningioma which located in frontal base, 2 with small intracranial brain tumor which was smaller than 2 cm in diameter, and 1 whith pi-tuitary adenoma. On the IMP-SPECT images scan-ned 2 hours after injection, hot area, which was identified in two cases with meningioma on the images 20 minutes after injection, was changed into cold area. This change indicated that IMP was washed out faster at the area of brain tumor. Although in 13 cases, perifocal cold area was identified and this suggested decrease of r-CBF, this cold area was smaller than that of Kr-81 m SPECT. The images of IMP-SPECT did not cor-relate with that of lesion, which suspected to be disrupted of blood-brain barrier by Xray-CT and Tc-99 m SPECT, nor with vascularity which was shown in angiogram or Kr-81 m SPECT. Serial scan of IMP-SPECT revealed that r-CBF surround-ing brain tumor was decreased before operation, it was gradually increased after operation. Peri-focal cold area was found for 1 week after opera-tion but reduced or absent 1 month after.

IMP-SPECT with using a rotating gamma ca-mera was considered to be non invasive three dimensional r-CBF study. IMP-SPECT was con-sidered to be feasible in evaluating the CBF in the perifocal area of brain tumor but not in CBF of brain tumor itself. In addition serial IMP-SPECT studies were also believed to be useful in evaluating the changes of r-CBF after operation.