Kim H J, Im J H, Yang S O, Moon D H, Ryu J S, Bong J K, Nam K P, Cheon J H, Lee M C, Lee H K
Department of Nuclear Medicine, Asan Medical Center, University of Ulsan, Seoul, Korea.
J Nucl Med. 1997 Nov;38(11):1703-11.
Iodine-123-N-(3-iodopropene-2-yl)-2beta-carbomethoxy-3beta-( 4-chlorophenyl) tropane (123I-IPT) is a new dopamine transporter ligand that selectively binds the dopamine reuptake sites. Transporter concentrations have been known to decrease in Parkinson's disease patients. The purpose of this study was to evaluate the usefulness of IPT as an imaging agent for measuring changes in transporter concentrations in Parkinson's disease.
IPT labeled with 6.78 +/- 0.67 mCi 123I was injected intravenously as a bolus into eight normal controls (mean age 41 +/- 12 yr) and 17 Parkinson's disease patients (mean age 55 +/- 9 yr). Dynamic SPECT scans of the brain were then performed for 5 min each over 120 min on a triple-headed gamma camera equipped with medium-energy collimators. Regions of interest were drawn on the middle set of the image at the level of the basal ganglia (BG) for each subject. Time-activity curves were generated for the left BG, right BG and occipital cortex (OCC). The empirical ratios between BG-OCC and OCC, which represent specific-to-nonspecific binding ratios, were computed at various time points. The statistical parameter k3/k4 was estimated by two methods: a variation of the graphic method that derives the ratio of ligand distribution volumes (R[V]) and the area ratio method (R[A]), in which the ratio is calculated from the areas under the specific and nonspecific binding activity curves.
The mean (BG-OCC)/OCC ratio for normal controls (3.07 +/- 0.73) was significantly higher than that for Parkinson's disease patients at 115 min (1.10 +/- 0.56) (p = 2.76 x 10[-5]). The mean R(V) and R(A) for normal controls were 2.06 +/- 0.27 and 1.50 +/- 0.15, respectively. The mean R(V) and R(A) for Parkinson's disease patients were 0.78 +/- 0.31 and 0.65 +/- 0.24, respectively. Both R(V) and R(A) for normal controls were significantly higher than those for Parkinson's disease patients (p values for R(V) and R(A) were 1.91 x 10(-8) and 3.46 x 10(-10), respectively). The R(V) has linear relationships with both R(A) and (BG-OCC)/OCC ratio at 115 min. The R(V) has a higher correlation (r = 0.99) with R(A) than it does with (BG-OCC)/OCC (r = 0.93).
The R(V), R(A) and (BG-OCC)/OCC for Parkinson's disease patients were clearly separated from those of normal controls, and they may be useful outcome measures for clinical diagnosis. The simplest (BG-OCC)/OCC ratio, requiring a single late time point, could be useful in clinical situations, whereas R(V) or R(A) is preferred when the dynamic data are available. The findings suggest that 123I-IPT is a useful tracer for diagnosing Parkinson's disease and studying dopamine reuptake sites.
碘 - 123 - N -（3 - 碘丙烯 - 2 - 基）- 2β - 甲氧羰基 - 3β -（4 - 氯苯基）托烷（123I - IPT）是一种新型多巴胺转运体配体，可选择性结合多巴胺再摄取位点。已知帕金森病患者的转运体浓度会降低。本研究的目的是评估IPT作为测量帕金森病患者转运体浓度变化的成像剂的效用。
将标记有6.78±0.67毫居里123I的IPT以团注方式静脉注射到8名正常对照者（平均年龄41±12岁）和17名帕金森病患者（平均年龄55±9岁）体内。然后在配备中能准直器的三头伽马相机上，于120分钟内每隔5分钟对大脑进行一次动态单光子发射计算机断层扫描（SPECT）。为每个受试者在基底神经节（BG）水平的图像中间层绘制感兴趣区域。生成左侧BG、右侧BG和枕叶皮质（OCC）的时间 - 活性曲线。在不同时间点计算代表特异性与非特异性结合比的BG - OCC与OCC之间的经验比值。通过两种方法估计统计参数k3/k4：一种是推导配体分布体积比（R[V]）的图形方法的变体，另一种是面积比方法（R[A]），即从特异性和非特异性结合活性曲线下的面积计算该比值。
正常对照者在115分钟时的平均（BG - OCC）/OCC比值（3.07±0.73）显著高于帕金森病患者（1.10±0.56）（p = 2.76×10[-5]）。正常对照者的平均R(V)和R(A)分别为2.06±0.27和1.50±0.15。帕金森病患者的平均R(V)和R(A)分别为0.78±0.31和0.65±0.24。正常对照者的R(V)和R(A)均显著高于帕金森病患者（R(V)和R(A)的p值分别为1.91×10(-8)和3.46×10(-10)）。在115分钟时，R(V)与R(A)以及（BG - OCC）/OCC比值均呈线性关系。R(V)与R(A)的相关性（r = 0.99）高于其与（BG - OCC）/OCC的相关性（r = 0.93）。
帕金森病患者的R(V)、R(A)和（BG - OCC）/OCC与正常对照者明显不同，它们可能是临床诊断的有用结果指标。最简单的（BG - OCC）/OCC比值只需一个晚期时间点，在临床情况下可能有用，而当有动态数据时，R(V)或R(A)更受青睐。研究结果表明，123I - IPT是诊断帕金森病和研究多巴胺再摄取位点的有用示踪剂。
