Benefit of Static FET PET in Pretreated Pediatric Brain Tumor Patients with Equivocal Conventional MRI Results

Abstract

Background MRI has shortcomings in differentiation between tumor tissue and post-therapeutic changes in pretreated brain tumor patients.

Patients We assessed 22 static FET-PET/CT-scans of 17 pediatric patients (median age 12 years, range 2–16 years, ependymoma n=4, medulloblastoma n=4, low-grade glioma n=6, high-grade glioma n=3, germ cell tumor n=1, choroid plexus tumor n=1, median follow-up: 112 months) with multimodal treatment.

Method FET-PET/CT-scans were analyzed visually by 3 independent nuclear medicine physicians. Additionally quantitative FET-Uptake for each lesion was determined by calculating standardized uptake values (SUVmaxT/SUVmeanB, SUVmeanT/SUVmeanB). Histology or clinical follow-up served as reference.

Results Static FET-PET/CT reliably distinguished between tumor tissue and post-therapeutic changes in 16 out of 17 patients. It identified correctly vital tumor tissue in 13 patients and post-therapeutic changes in 3 patients. SUV-based analyses were less sensitive than visual analyses. Except from a choroid plexus carcinoma, all tumor entities showed increased FET-uptake.

Discussion Our study comprises a limited number of patients but results corroborate the ability of FET to detect different brain tumor entities in pediatric patients and discriminate between residual/recurrent tumor and post-therapeutic changes.

Conclusions We observed a clear benefit from additional static FET-PET/CT-scans when conventional MRI identified equivocal lesions in pretreated pediatric brain tumor patients. These results warrant prospective studies that should include dynamic scans.

Zusammenfassung

Hintergrund Die MRT ist in der Differenzierung zwischen Tumorgewebe und therapieassoziierten Veränderungen bei vorbehandelten Hirntumorpatienten limitiert.

Patienten Wir untersuchten retrospektiv 22 FET-PET/CT Untersuchungen von 17 multimodal behandelten pädiatrischen Patienten (medianes Alter 12 Jahre, Spannbreite 2–16 Jahre, Ependymom n=4, Medulloblastom n=4, niedriggradiges Gliom n=6, hochgradiges Gliom n=3, Keimzelltumor n=1, Choroid-Plexus Tumor n=1, mediane Beobachtungszeit: 112 Monate).

Methode 22 FET-PET/CT Scans/Läsionen wurden unabhängig visuell von 3 Nuklearmedizinern bewertet. Zusätzlich wurde für jede Läsion die quantitative FET-Aufnahme durch Berechnung von standardisierten Aufnahmewerten (SUV) bestimmt (SUVmaxT/SUVmeanB, SUVmeanT/SUVmeanB). Als Referenz dienten die Histologie oder die klinische Verlaufsbeurteilung.

Ergebnisse Die statische FET-PET/CT unterschied bei 16 von 17 Patienten zuverlässig zwischen Tumorgewebe und therapieassoziierten Veränderungen: 13 Patienten mit vitalem Tumorgewebe sowie 3 Patienten mit posttherapeutischen Veränderungen. Die SUV-basierte Analyse war weniger sensitiv als die visuelle Analyse. Alle untersuchten Tumorentitäten außer einem Choroid-Plexus Karzinom zeigten eine gesteigerte FET-Aufnahme.

Diskussion Die Ergebnisse unterstreichen die Möglichkeit der Erkennung unterchiedlicher Tumorentitäten bei Kindern. Hierbei erscheint eine Diskriminierung zwischen Residual-/Rezidivtumor und therapieassoziierten Veränderungen möglich.

Schlussfolgerung Das klinische Vorgehen wurde durch den Einsatz der statischen FET-PET/CT Untersuchungen bei uneindeutigen MRT-Untersuchungen vorbehandelter pädiatrischer Hirntumorpatienten vereinfacht. Dieser Nutzen sollte in prospektiven Studien durch Einsatz von dynamischen FET-PET/CT Untersuchungen gesichert werden.

Key words

FET - PET - Brain tumor - children - pretreated - pediatric

Schlüsselwörter

FET - PET - Hirntumor - Kinder - Jugendliche - multimodale Therapie

Publikationsverlauf

Artikel online veröffentlicht:
17. Februar 2021

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