Hutterer Markus, Ebner Yvonne, Riemenschneider Markus J, Willuweit Antje, McCoy Mark, Egger Barbara, Schröder Michael, Wendl Christina, Hellwig Dirk, Grosse Jirka, Menhart Karin, Proescholdt Martin, Fritsch Brita, Urbach Horst, Stockhammer Guenther, Roelcke Ulrich, Galldiks Norbert, Meyer Philipp T, Langen Karl-Josef, Hau Peter, Trinka Eugen
Department of Neurology, University of Regensburg Medical School, Regensburg, Germany
Wilhelm Sander-Neurooncology Unit, University of Regensburg Medical School, Regensburg, Germany.
J Nucl Med. 2017 Jan;58(1):129-137. doi: 10.2967/jnumed.116.176610. Epub 2016 Jul 28.
O-(2-F-fluoroethyl)-l-tyrosine (F-FET) PET is a well-established method increasingly used for diagnosis, treatment planning, and monitoring in gliomas. Epileptic activity, frequently occurring in glioma patients, can influence MRI findings. Whether seizures also affect F-FET PET imaging is currently unknown. The aim of this retrospective analysis was to investigate the brain amino acid metabolism during epileptic seizures by F-FET PET and to elucidate the pathophysiologic background.
Ten patients with 11 episodes of serial seizures or status epilepticus, who underwent MRI and F-FET PET, were studied. The main diagnosis was glioma World Health Organization grade II-IV (n = 8); 2 patients suffered from nonneoplastic diseases. Immunohistochemical assessment of LAT1/LAT2/CD98 amino acid transporters was performed in seizure-affected cortex (n = 2) and compared with glioma tissues (n = 3).
All patients exhibited increased seizure-associated strict gyral F-FET uptake, which was reversible in follow-up studies or negative shortly before and without any histologic or clinical signs of tumor recurrence. F-FET uptake corresponded to structural MRI changes, compatible with cortical vasogenic and cytotoxic edema, partial contrast enhancement, and hyperperfusion. Patients with prolonged postictal symptoms lasting up to 8 wk displayed intensive and widespread (≥ 1 lobe) cortical F-FET uptake. LAT1/LAT2/CD98 was strongly expressed in neurons and endothelium of seizure-affected brains and less in reactive astrocytosis.
Seizure activity, in particular status epilepticus, increases cerebral amino acid transport with a strict gyral F-FET uptake pattern. Such periictal pseudoprogression represents a potential pitfall of F-FET PET and may mimic brain tumor. Our data also indicate a seizure-induced upregulation of neuronal, endothelial, and less astroglial LAT1/LAT2/CD98 amino acid transporter expression.
O-(2-氟乙基)-L-酪氨酸（F-FET）正电子发射断层扫描（PET）是一种成熟的方法，越来越多地用于胶质瘤的诊断、治疗规划和监测。癫痫活动在胶质瘤患者中经常出现，可影响磁共振成像（MRI）结果。目前尚不清楚癫痫发作是否也会影响F-FET PET成像。本回顾性分析的目的是通过F-FET PET研究癫痫发作期间的脑氨基酸代谢，并阐明其病理生理背景。
对10例经历了11次连续癫痫发作或癫痫持续状态且接受了MRI和F-FET PET检查的患者进行了研究。主要诊断为世界卫生组织II-IV级胶质瘤（n = 8）；2例患者患有非肿瘤性疾病。对癫痫发作影响的皮层（n = 2）进行LAT1/LAT2/CD98氨基酸转运体的免疫组织化学评估，并与胶质瘤组织（n = 3）进行比较。
所有患者均表现出癫痫发作相关的脑回F-FET摄取增加，在随访研究中这种摄取是可逆的，或者在肿瘤复发的任何组织学或临床体征出现前不久为阴性。F-FET摄取与结构性MRI变化相对应，符合皮层血管源性和细胞毒性水肿、部分对比增强和血流灌注增加。癫痫发作后症状持续长达8周的患者表现出强烈且广泛（≥1个脑叶）的皮层F-FET摄取。LAT1/LAT2/CD98在癫痫发作影响的大脑的神经元和内皮细胞中强烈表达，在反应性星形细胞增生中表达较少。
癫痫发作活动，特别是癫痫持续状态，会增加脑氨基酸转运，呈现严格的脑回F-FET摄取模式。这种发作期假性进展是F-FET PET的一个潜在陷阱，可能会误诊为脑肿瘤。我们的数据还表明癫痫发作可诱导神经元、内皮细胞以及较少的星形胶质细胞LAT1/LAT2/CD98氨基酸转运体表达上调。
