FDG-PET-Bildgebung der limbischen Enzephalitis

Bei der limbischen Enzephalitis liefert die zerebrale FDG-PET essenzielle Informationen zur Unterstützung von Diagnose, Prognose und Therapiekontrolle. Mit zunehmender Bedeutung der limbischen Enzephalitis als „not to miss“-Diagnose wird der Stellenwert der zerebralen FDG-PET bei dieser Fragestellung weiter steigen. Zudem kommt der FDG-PET-Ganzkörperaufnahme bei Verdacht auf eine paraneoplastische Genese und unauffälligem Tumorscreening in den Routineuntersuchungen eine Schlüsselrolle zu.

Abstract

FDG-PET of the brain provides essential information to support diagnosis, prognosis and therapy monitoring in limbic encephalitis. With increasing attention to limbic encephalitis as „not to miss“ diagnosis, the importance of brain FDG-PET will continue to increase for this indication. Furthermore, whole-body FDG-PET/CT plays a key role in cases of suspected paraneoplastic genesis and unremarkable conventional imaging.

Kernaussagen

• Der Nachweis eines mesiotemporalen Hypermetabolismus mittels FDG-PET erlaubt bei passender Klinik die Diagnose einer definiten limbischen Enzephalitis auch bei unauffälliger MRT.

• Die FDG-PET zeigt bei limbischer Enzephalitis einen mesiotemporalen Hypermetabolismus in der akuten/subakuten Phase („inflammatory active State“) und einen mesiotemporalen Hypometabolismus in der postinflammatorischen chronischen Phase („State of Damage“).

• Ein mesiotemporaler Hypermetabolismus kann bei paraneoplastischer und bei nicht-paraneoplastischer Genese der limbischen Enzephalitis auftreten.

• Bei Patienten mit Anti-LGI1-Enzephalitis im Stadium der faziobrachialen dystonen Anfälle zeigt die FDG-PET einen stark ausgeprägten Hypermetabolismus in den Basalganglien.

• Ein Hypometabolismus mit starker Betonung posteriorer Hirnregionen und Beteiligung des visuellen Kortex spricht für eine Anti-NMDAR Enzephalitis, insbesondere bei jungen Frauen.

• Durch den Nachweis der Normalisierung des zerebralen Glukosestoffwechsels mittels FDG-PET-Verlauf kann ein Therapieerfolg objektiviert werden. Ein unzureichendes Therapieansprechen kann durch Nachweis eines „State of Damage“ dokumentiert werden.

• Mit PET/MRT-Hybridsystemen können komplementäre Informationen von MRT und FDG-PET bei der limbischen Enzephalitis in einem Untersuchungsgang gewonnen werden, sodass eine Verzögerung der Therapie durch eine separate PET nach einem Normalbefund in der MRT vermieden wird.

• Die dedizierte FDG-PET des Gehirns und die FDG-PET/CT des Körperstamms zur Tumorsuche können problemlos in einer Sitzung kombiniert werden, wobei die Schwelle für die Indikation zur jeweils ergänzenden Untersuchung bei Enzephalitisverdacht sehr niedrig angesetzt werden sollte.

• Die zerebrale FDG-PET im Rahmen einer Ganzkörper-PET zur Tumorsuche bei limbischer Enzephalitis sollte als dedizierte Hirnaufnahme nach dem zentrumspezifischen Protokoll erfolgen.

Schlüsselwörter

limbische Enzephalitis - Autoimmunerkrankung - Positronenemissionstomografie - Fluorodesoxyglukose - FDG

Keywords

limbic encephalitis - autoimmune - positron-emission tomography - fluorodeoxyglucose F18 - imaging

Publikationsverlauf

Artikel online veröffentlicht:
02. Dezember 2022

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