Drzezga A, Arnold S, Minoshima S, Noachtar S, Szecsi J, Winkler P, Römer W, Tatsch K, Weber W, Bartenstein P
Department of Nuclear Medicine, Technische Universität, München, Germany.
J Nucl Med. 1999 May;40(5):737-46.
The aim of this study was to evaluate an observer-independent analysis of 18F-fluorodeoxyglucose (FDG) PET studies in patients with temporal or extratemporal epilepsy.
Twenty-seven patients with temporal epilepsy and 22 patients with extratemporal epilepsy were included in the study. All patients with temporal epilepsy and 7 patients with extratemporal epilepsy underwent surgical treatment. In patients who showed significant postoperative improvement (temporal, n = 23; extratemporal, n = 6), the epileptogenic focus was assumed to be located in the area of surgical resection. In extratemporal epilepsy patients who did not undergo surgery, the focus localization was determined using a combination of semiology, ictal and interictal electroencephalography, [99mTc]ethyl cysteinate dimer SPECT, MRI and [11C]flumazenil PET. Visual analysis was performed by two experienced and two less experienced blinded observers using sagittal, axial and coronal images. In the automated analysis after anatomic standardization and generation of three-dimensional stereotactic surface projections (SSPs), a pixelwise comparison of 18F-FDG uptake with an age-matched reference database (n = 20) was performed, resulting in z score images. Pixels with the maximum deviation were detected, summarized and attached to one of 20 predefined surface regions of interest. For comparison with 18F-FDG PET and MR images, three-dimensional overlay images were generated.
In patients with temporal epilepsy, the sensitivity was comparable for visual and observer-independent analysis (three-dimensional SSP 86%, experienced observers 86%-90%, less experienced observers 77%-86%). In patients with extratemporal epilepsy, three-dimensional SSP showed a significantly higher sensitivity in detecting the epileptogenic focus (67%) than did visual analysis (experienced 33%-38%, each less experienced 19%). In temporal lobe epilepsy, there was moderate to good agreement between the localization found with three-dimensional SSP and the different observers. In patients with extratemporal epilepsy, there was a high interobserver variability and only a weak agreement between the localization found with three-dimensional SSP and the different observers. Although three-dimensional SSP detected multiple lesions more often than visual analysis, the determination of the highest deviation from the reference database allowed the identification of the epileptogenic focus with a higher accuracy than subjective criteria, especially in extratemporal epilepsy.
Three-dimensional SSP increases sensitivity and reduces observer variability of the analysis of 18F-FDG PET images in patients with extratemporal epilepsy and is, therefore, a useful tool in the evaluation of this patient group. The benefit of this analytical approach in patients with temporal epilepsy is less apparent.
本研究的目的是评估对颞叶或颞叶外癫痫患者进行的18F-氟脱氧葡萄糖（FDG）PET研究的独立于观察者的分析。
本研究纳入了27例颞叶癫痫患者和22例颞叶外癫痫患者。所有颞叶癫痫患者和7例颞叶外癫痫患者接受了手术治疗。在术后有显著改善的患者中（颞叶癫痫，n = 23；颞叶外癫痫，n = 6），假定致痫灶位于手术切除区域。对于未接受手术的颞叶外癫痫患者，采用症状学、发作期和发作间期脑电图、[99mTc]半胱氨酸乙酯二聚体SPECT、MRI和[11C]氟马西尼PET相结合的方法确定病灶定位。由两名经验丰富和两名经验较少的盲法观察者使用矢状位、轴位和冠状位图像进行视觉分析。在进行解剖标准化并生成三维立体定向表面投影（SSP）后的自动分析中，将18F-FDG摄取与年龄匹配的参考数据库（n = 20）进行逐像素比较，生成z评分图像。检测出偏差最大的像素，汇总并附着到20个预定义的表面感兴趣区域之一。为了与18F-FDG PET和MR图像进行比较，生成了三维叠加图像。
在颞叶癫痫患者中，视觉分析和独立于观察者的分析（三维SSP为86%，经验丰富的观察者为86%-90%，经验较少的观察者为77%-86%）的敏感性相当。在颞叶外癫痫患者中，三维SSP在检测致痫灶方面的敏感性（67%）显著高于视觉分析（经验丰富的观察者为33%-38%，经验较少的观察者均为19%）。在颞叶癫痫中，三维SSP发现的定位与不同观察者之间存在中度至良好的一致性。在颞叶外癫痫患者中，观察者间变异性较高，三维SSP发现的定位与不同观察者之间只有较弱的一致性。尽管三维SSP比视觉分析更常检测到多个病灶，但与参考数据库的最大偏差的确定比主观标准能更准确地识别致痫灶，尤其是在颞叶外癫痫中。
三维SSP提高了颞叶外癫痫患者18F-FDG PET图像分析的敏感性，降低了观察者变异性，因此是评估该患者群体的有用工具。这种分析方法在颞叶癫痫患者中的益处不太明显。
