Iwabuchi Yu, Nakahara Tadaki, Kameyama Masashi, Yamada Yoshitake, Hashimoto Masahiro, Ogata Yuji, Matsusaka Yohji, Katagiri Mari, Itoh Kazunari, Osada Takashi, Ito Daisuke, Tabuchi Hajime, Jinzaki Masahiro
Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjyuku-ku, Tokyo, 160-8582, Japan.
Department of Diagnostic Radiology, Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, Tokyo, Japan.
Ann Nucl Med. 2018 Jun;32(5):363-371. doi: 10.1007/s12149-018-1256-x. Epub 2018 Apr 13.
Quantification of the tracer distribution would add objectivity to the visual assessments of dopamine transporter (DAT) single photon emission computed tomography (SPECT) data. Our study aimed to evaluate the diagnostic utility of fractal dimension (FD) as a quantitative indicator of tracer distribution and compared with the conventional quantitative value: specific binding ratio (SBR). We also evaluated the utility of the combined index SBR/FD (SBR divided by FD).
We conducted both clinical and phantom studies. In the clinical study, 150 patients including 110 patients with Parkinsonian syndrome (PS) and 40 without PS were enrolled. In the phantom study, we used a striatal phantom with the striatum chamber divided into two spaces, representing the caudate nucleus and putamen. The SBR, FD, and SBR/FD were calculated and compared between datasets for evaluating the diagnostic utility. Mann-Whitney test and receiver-operating characteristics (ROC) analysis were used for analysis.
ROC analysis revealed that the FD value had high diagnostic performance [the areas under the curve (AUC) = 0.943] and the combined use of SBR and FD (SBR/FD) delivered better results than the SBR alone (AUC, 0.964 vs 0.899; p < 0.001). The sensitivity, specificity, and accuracy, respectively, were 79.1, 85.0, and 80.7% with SBR, 84.5, 97.5, and 88.0% with FD, and 92.7, 87.5, and 91.3% with SBR/FD.
Our results confirmed that the FD value is a useful diagnostic index, which reflects the tracer distribution in DAT SPECT images. The combined use of SBR and FD was more useful than either used alone.
对示踪剂分布进行定量分析将为多巴胺转运体（DAT）单光子发射计算机断层扫描（SPECT）数据的视觉评估增添客观性。我们的研究旨在评估分形维数（FD）作为示踪剂分布定量指标的诊断效用，并与传统定量值：特异性结合率（SBR）进行比较。我们还评估了联合指标SBR/FD（SBR除以FD）的效用。
我们进行了临床研究和体模研究。在临床研究中，纳入了150例患者，其中包括110例帕金森综合征（PS）患者和40例非PS患者。在体模研究中，我们使用了一个纹状体体模，其纹状体腔被分为两个空间，分别代表尾状核和壳核。计算并比较数据集之间的SBR、FD和SBR/FD，以评估诊断效用。采用曼-惠特尼检验和受试者工作特征（ROC）分析进行分析。
ROC分析显示，FD值具有较高的诊断性能[曲线下面积（AUC）=0.943]，SBR和FD联合使用（SBR/FD）的结果优于单独使用SBR（AUC，0.964对0.899；p<0.001）。SBR的敏感性、特异性和准确性分别为79.1%、85.0%和80.7%，FD分别为84.5%、97.5%和88.0%，SBR/FD分别为92.7%、87.5%和91.3%。
我们的结果证实，FD值是一个有用的诊断指标，可反映DAT SPECT图像中的示踪剂分布。SBR和FD联合使用比单独使用任何一种都更有用。
