QSPECTによる脳血流測定 : PETとの比較(<特集>最新の画像診断法)  [in Japanese] Cerebral Blood Flow Measurements using Quantitative SPECT : Comparison with PET(<SPECIAL ISSUE>Neuroimaging Update)  [in Japanese]

^<123>I-IMPを用いたdual table autoradiogaphy(DTARG)定量的SPECT(QSPECT)を一側性の閉塞性脳血管障害患者15例に施行した.この方法により得られた安静時脳血流量とアセタゾラミド負荷時の血管反応性から血行力学的脳虚血の重症度分類をStage 0〜IIまでの3段階に分類した.このDTARG QSPCT分類を,同時期に施行した^<15>Oガス吸入によるPET測定から分類した重症度分類と比較した.15例中10例では,QSPECTとPET分類がStage II(QSPECTでは安静時脳血流の低下と10%以下の血管反応性,PETでは酸素摂取率の増加)で一致した.2例では,両者がStage I(QSPECTでは10〜30%の血管反応性または正常な安静時脳血流量10%以下の血管反応性,PETでは脳血液量の増加)で一致した.残りの3例では,PETでStage Iにもかかわらず,QSPECTではStage IIであった.QSPECTとPETでの安静時脳血流量には有意の正相関(r=0.786)が得られた.これらのことから,DTARG QSPECTはPETに比べ血行力学的脳虚血の重症度を過大評価する傾向にあるものの80%の精度をもつことが判明し,閉塞性脳血管障害の治療方針決定に有用であると考えられた.

The dual table autoradigography (DTARG) quantitative SPECT (QSPECT) method using ^<123>I-IMP was performed on 15 patients with unilateral major cerebral artery occlusive diseases. Severity of hemodynamic brain ischemia was classified into three stages (stages 0 to II) based upon the vasodilative function calculated from cerebral blood flow (CBF) values at rest and during acetazolamide challenge. This staging by DTARG QSPECT was compared with staging of hemodynamic brain ischemia also classified into stage 0 to stage II by ^<15>O gas inhalation steady state method using PET. Out of 15 patients, 10 patients diagnosed as stage II in QSPECT and PET (decreased baseline CBF with deceased vascular response below 10% increase by QSPECT and elevation of oxygen extraction fraction by PET). Two patients showed concordant stage I conditions for both methods (vascular response between 10 and 30% increase or normal baseline CBF with vascular response below 10% increase by QSPECT and elevation of cerebral blood volume by PET). The remaining 3 patients showed stage II conditions according QSPECT in spite of stage I diagnosis based on PET. Baseline CBF values by QSPECT showed significantly high correlation (r=0.786) to data aquired by PET. Although DTARG QSPECT has a tendency to overestimate the severity of hemodynamic brain ischemia, it provides high accuracy of 80% in this staging as compared with PET. These results suggest that DTARG QSPECT has a high clinical value in managing patients with cerebrovascular occlusive diseases.