Ziebell Morten, Pinborg Lars H, Thomsen Gerda, de Nijs Robin, Svarer Claus, Wagner Aase, Knudsen Gitte M
Neurobiology Research Unit and Cimbi, University of Copenhagen, Rigshospitalet, Copenhagen, Denmark.
J Nucl Med Technol. 2010 Jun;38(2):61-8. doi: 10.2967/jnmt.109.072801. Epub 2010 May 18.
A particularly sensitive step in the quantification of SPECT images of the dopamine transporter (DAT) is a correct delineation of the region of interest (ROI). In this study, we primarily compared the reproducibility of the following different approaches for ROI delineation in SPECT images of the DAT: the use of manual delineation (MD) on high-count striatal slides directly on the SPECT image, ROI delineation based on individual MR images (MRD), and oversized striatal ROIs-that is, the striatal volume of interest (SVI), as described previously. We also assessed the ability of the different approaches to identify striatal pathology in patients with parkinsonism.
Eight patients with highly variable reductions in cerebral DAT availability were SPECT-scanned twice with (123)I-labeled N-(3-iodoprop-(2E)-enyl)-2beta-carboxymethoxy-3beta-(4'-methylphenyl) nortropane bolus infusion setup and once with an MRI scanner. For SPECT/MRI coregistration, we used external fiducial markers visible on both MRI and SPECT. With the MD and MRD methods, the outcome parameters for DAT availability were the binding potentials and the ratio at equilibrium of specifically bound radioligand to nondisplaceable radioligand in tissue (BP(ND)). For the SVI method, the outcome parameter was the specific binding ratio (SBR).
No statistically significant difference in striatal BP(ND) intraobserver reproducibility was seen among any of the 3 methods. The intraobserver reproducibility average +/- SD for MD was 7.0% +/- 4.1%; for MRD, 5.7% +/- 5.4%; and for SVI, 6.7% +/- 6.0%. Mean intrasubject variability, as determined from the test-retest scans, did not differ with the 3 delineation methods used. The average (+/-SD) intrasubject variability of striatal BP(ND) was 11.9% +/- 10.0% with MD and 14.6% +/- 15.3% with MRD. With the SVI method, the intrasubject variability of striatal specific binding ratio was 10.0% +/- 10.2%. BP(ND) values obtained with the MD and MRD methods were similar (paired t test, P > 0.4).
In patients with reduced striatal DAT binding, the reproducibility of the outcome from ROI MD is comparable to both that obtained by delineation of ROI on individual MR images, followed by coregistration to the SPECT image, and that obtained with the SVI-based approach.
多巴胺转运体（DAT）单光子发射计算机断层扫描（SPECT）图像定量分析中一个特别敏感的步骤是正确划定感兴趣区域（ROI）。在本研究中，我们主要比较了以下不同的ROI划定方法在DAT的SPECT图像中的可重复性：直接在SPECT图像上的高计数纹状体切片上使用手动划定（MD）、基于个体磁共振成像（MRI）图像的ROI划定（MRD）以及如前所述的超大纹状体ROI，即感兴趣的纹状体体积（SVI）。我们还评估了不同方法识别帕金森综合征患者纹状体病变的能力。
8例脑DAT可用性有高度可变降低的患者，用（123）I标记的N-（3-碘丙-（2E）-烯基）-2β-羧甲氧基-3β-（4'-甲基苯基）去甲托烷团注给药设置进行两次SPECT扫描，并进行一次MRI扫描。对于SPECT/MRI配准，我们使用在MRI和SPECT上都可见的外部基准标记。使用MD和MRD方法时，DAT可用性的结果参数是结合电位以及组织中特异性结合放射性配体与不可置换放射性配体在平衡时的比率（BP（ND））。对于SVI方法，结果参数是特异性结合率（SBR）。
三种方法中任何一种在观察者内纹状体BP（ND）可重复性方面均未观察到统计学显著差异。MD的观察者内可重复性平均值±标准差为7.0%±4.1%；MRD为5.7%±5.4%；SVI为6.7%±6.0%。根据重测扫描确定的受试者内平均变异性，在所使用的三种划定方法中没有差异。MD时纹状体BP（ND）的受试者内平均变异性（±标准差）为11.9%±10.0%，MRD时为14.6%±15.3%。使用SVI方法时，纹状体特异性结合率的受试者内变异性为10.0%±10.2%。MD和MRD方法获得的BP（ND）值相似（配对t检验，P>0.4）。
在纹状体DAT结合降低的患者中，ROI MD结果的可重复性与通过在个体MR图像上划定ROI然后与SPECT图像配准获得的结果以及基于SVI的方法获得的结果相当。
