计数时间窗位置对SPECT测定肾小球滤过率的影响

Influence of counting time window position on SPECT determination of glomerular filtration rate

目的观察计数时间窗位置对SPECT测定肾小球滤过率(GFR)的影响。方法以231名北京地区健康居民为研究对象,分别采用双血浆法和99mTc-DTPA肾动态显像法测定GFR(GFRdt和GFRGates)。在以血流灌注相峰值点时间(峰时)为新时间原点的时间-计数率曲线上依次移动时间窗,于25个时间点上提取计数,并分别计算各点上的GFRGates。分析不同药物累积相峰时GFRGates与GFRdt的相关性。结果①左右肾脏血流灌注相峰时均值分别为(19.69±5.20)s和(20.29±5.19)s,基本呈正态分布。②肾滤过累积相峰时均值为(166.19±50.22)s,呈偏态分布,频数峰为132s。③时间窗位于累积相峰值区时GFRGates达到最大,在峰值两侧,GFRGates均减小。④时间窗位于累积相峰值左侧上升区时,GFRGates与GFRdt的相关系数随时间窗后移而增加;当后移到时间窗内含有部分峰值区段时,相关系数增速变缓;随着时间窗与峰值区段的重叠增加,相关系数达拐点,随后开始减小。结论在以肾血流灌注相峰时为原点的时间-计数率曲线上,提取86～145s时间窗计数,可获得受时间影响较小的GFR。

Objective To explore the influence of counting time window position on SPECT determination of glomerular filtration rate （GFR）. Methods A total of 231 health residents of Beijing area were enrolled. Dual plasma sample method and 99mTc-DTPA dynamic renal imaging were used to determining GFR （GFRdt and GFRGates）. The time window was moved in turn at time-count rate curve which taking blood perfusion phase peak as the new time origin, and 25 counts were extracted from 25 time points, then GFRcates was calculated, respectively. Among various cumulative phase peak time, the correlation between GFRG and GFRat was analyzed. Results ①At left and right renal blood perfusion phase peak time, the mean value was （19.69±5.20）s and （20.29±5.19）s, respectively, all were nearly normal distribution. ②At renal filtration accumulation phase peak time, the mean value was （166. 19±50.22）s, showing skewed distribution, and the frequency peak was 132 s. ③GFRGates was the maximum when the time window positioned on the cumulative phase peak area. On both sides of the peak value, GFRGates decreased. ④When time window in the accumulation phase peak raise on the left area, the correlation coefficient between GFRGates and GFRa increased with time window after the shift. When time window moved to some position that containing some peak section, the correlation coefficient was slowing. With the increase of time window and peak overlapping segments, the correlation coefficient reached inflection point, then began to decrease. Conclusion When 86-145 s time window counts are extracted from the time-count rate curve that taking blood perfusion phase peak as the time origin, GFR can be obtained with smaller influence of time.