McNally Kelly A, Paige A LeBron, Varghese George, Zhang Heping, Novotny Edward J, Spencer Susan S, Zubal I George, Blumenfeld Hal
Department of Neurology, Yale University School of Medicine, New Haven, Connecticut 06520-8018, USA.
Epilepsia. 2005 Sep;46(9):1450-64. doi: 10.1111/j.1528-1167.2005.06705.x.
The goal of neuroimaging in epilepsy is to localize the region of seizure onset. Single-photon emission computed tomography with tracer injection during seizures (ictal SPECT) is a promising tool for localizing seizures. However, much uncertainty exists about how to interpret late injections, or injections done after seizure end (postictal SPECT). A widely available and objective method is needed to interpret ambiguous ictal and postictal scans, with changes in multiple brain regions.
Ictal or postictal SPECT scans were performed by using [99mTc]-labeled hexamethyl-propylene-amine-oxime (HMPAO), and images were analyzed by comparison with interictal scans for each patient. Forty-seven cases of localized epilepsy were studied. We used methods that can be implemented anywhere, based on freely downloadable software and normal SPECT databases (http://spect.yale.edu). Statistical parametric mapping (SPM) was used to localize a single region of seizure onset based on ictal (or postictal) versus interictal difference images for each patient. We refer to this method as ictal-interictal SPECT analyzed by SPM (ISAS).
With this approach, ictal SPECT identified a single unambiguous region of seizure onset in 71% of mesial temporal and 83% of neocortical epilepsy cases, even with late injections, and the localization was correct in all (100%) cases. Postictal SPECT, conversely, with injections performed soon after seizures, was very poor at localizing a single region based on either perfusion increases or decreases, often because changes were similar in multiple brain regions. However, measuring which hemisphere overall had more decreased perfusion with postictal SPECT, lateralized seizure onset to the correct side in approximately 80% of cases.
ISAS provides a validated and readily available method for epilepsy SPECT analysis and interpretation. The results also emphasize the need to obtain SPECT injections during seizures to achieve unambiguous localization.
癫痫神经影像学的目标是确定癫痫发作起始区域。发作期单光子发射计算机断层扫描（ictal SPECT），即在癫痫发作期间注射示踪剂，是一种很有前景的癫痫发作定位工具。然而，对于如何解读延迟注射，即癫痫发作结束后进行的注射（发作后期SPECT），仍存在很多不确定性。需要一种广泛可用且客观的方法来解读模糊的发作期和发作后期扫描结果，这些扫描结果涉及多个脑区的变化。
使用[99mTc]标记的六甲基丙烯胺肟（HMPAO）进行发作期或发作后期SPECT扫描，并将图像与每位患者的发作间期扫描结果进行比较分析。对47例局限性癫痫患者进行了研究。我们采用了基于可免费下载的软件和正常SPECT数据库（http://spect.yale.edu）、可在任何地方实施的方法。使用统计参数映射（SPM）根据每位患者的发作期（或发作后期）与发作间期差异图像来确定癫痫发作起始的单一区域。我们将这种方法称为通过SPM分析的发作期-发作间期SPECT（ISAS）。
采用这种方法，发作期SPECT在71%的内侧颞叶癫痫和83%的新皮质癫痫病例中确定了单一明确的癫痫发作起始区域，即使是延迟注射，且所有病例（100%）的定位均正确。相反，发作后期SPECT在癫痫发作后不久进行注射，基于灌注增加或减少来定位单一区域的效果很差，这通常是因为多个脑区的变化相似。然而，通过测量发作后期SPECT中哪个半球总体灌注减少更多，在大约80%的病例中可将癫痫发作起始定位于正确的一侧。
ISAS为癫痫SPECT分析和解读提供了一种经过验证且易于获得的方法。结果还强调了在癫痫发作期间进行SPECT注射以实现明确定位的必要性。
