Meric P, Luft A, Seylaz J, Mamo H
Stroke. 1983 Jan-Feb;14(1):82-7. doi: 10.1161/01.str.14.1.82.
We tested the reproducibility of consecutive measurements of regional cerebral blood flow (rCBF) made in 13 areas of each hemisphere in patients with cerebrovascular diseases by the atraumatic 133Xe intravenous injection method. The data were analysed by a two-compartment model similar to that used in the Obrist inhalation method. Four parameters derived from the model were tested: Fg (flow of the fast-clearing compartment), FF and W (respectively fractional flow and relative tissue weight of the same compartment), ISI (initial slope index as defined by Risberg et al.). No significant variation was found in these four parameters between two consecutive rest measurements for all the areas studied and whatever the time interval between the measurements. The variances of the differences of Fg and ISI between the two measurements were found to be similar to those found in normal healthy subjects. The variances of FF and, consequently, W were greater than the values determined in healthy volunteers. An attempt to improve the quality of the results, by correcting them for the effects of PaCO2 changes between the measurements, resulted on the contrary in a general increase of the variances of the differences, showing the inadequacy of the correction coefficients used for healthy subjects at least for a proportion of the patients with cerebrovascular diseases. Sensitivity, tested by activation (hand work), shows a positive answer for FG but no significant change in ISI in any area. These findings demonstrate that in cases of cerebrovascular diseases the raw data (uncorrected for the changes in PaCO2) are the most reliable data but the meaning of the values found for FF and W must be regarded with caution since they may be affected by the "slippage" phenomenon. It is suggested that the ISI should only be used when there is evidence of a failure of the compartmental model, but only as a rough estimation of the flow level because of its lack of sensitivity.
我们采用无创性133Xe静脉注射法，对脑血管疾病患者每个半球13个区域的局部脑血流量（rCBF）进行连续测量，以检验其可重复性。采用类似于奥布里斯特吸入法中使用的双室模型对数据进行分析。对该模型得出的四个参数进行了检验：Fg（快速清除室的血流量）、FF和W（分别为同一室的分流分数和相对组织重量）、ISI（里斯伯格等人定义的初始斜率指数）。在所研究的所有区域，无论测量之间的时间间隔如何，两次连续静息测量之间这四个参数均未发现显著变化。发现两次测量之间Fg和ISI差值的方差与正常健康受试者的方差相似。FF以及相应的W的方差大于健康志愿者测定的值。试图通过校正测量之间PaCO2变化的影响来提高结果质量，结果却相反，差值的方差普遍增加，这表明至少对于一部分脑血管疾病患者，用于健康受试者的校正系数并不适用。通过激活（手部活动）进行的敏感性测试显示，FG有阳性反应，但任何区域的ISI均无显著变化。这些发现表明，在脑血管疾病病例中，原始数据（未校正PaCO2变化）是最可靠的数据，但对于FF和W所得到的值的意义必须谨慎看待，因为它们可能受到“滑动”现象的影响。建议仅在有证据表明室模型失效时才使用ISI，但由于其缺乏敏感性，只能作为血流水平的粗略估计。
