The trends and significance of SSTR PET/CT added to MRI in follow-up imaging of low-grade meningioma treated with fractionated proton therapy

Carola Lütgendorf-Caucig, Maciej Pelak, Birgit Flechl, Petra Georg, Piero Fossati, Markus Stock, Tatjana Traub-Weidinger, Christine Marosi, Christine Haberler, Gloria Zechmeister-Machhart, Lauritz Hermsmeyer, Eugen Hug, Anton Staudenherz

Research output: Journal article (peer-reviewed)Journal article

Abstract

PURPOSE: Overexpression of the somatostatin receptor (SSTR) has led to adoption of SSTR PET/CT for diagnosis and radiotherapy planning in meningioma, but data on SSTR expression during follow-up remain scarce. We investigated PET/CT quantifiers of SSTR tracers in WHO grade I meningioma following fractionated proton beam therapy (PBT) compared to standard response assessment with MRI.

METHODS: Twenty-two patients diagnosed with low-grade meningioma treated by PBT were included. Follow-up included clinical visits, MRI, and [68Ga]Ga-DOTATOC PET/CT scans. Radiologic tumor response, MRI and PET volume (VMRI and VPET), maximum and mean standardied uptake value (SUVmax/SUVmean), total lesion activity (TLA), and heterogeneity index (HI) were evaluated.

RESULTS: Median follow-up was 35.3 months (range: 6.4-47.9). Nineteen patients (86.4%, p = 0.0009) showed a decrease of SUVmax between baseline and first follow-up PET/CT (median: -24%, range: -53% to +89%) and in 81.8% of all cases, the SUVmax, SUVmean, and TLA at last follow-up were eventually lower than at baseline (p = 0.0043). Ambiguous trends without significance between the timepoints analyzed were observed for VPET. HI increased between baseline and last follow-up in 75% of cases (p = 0.024). All patients remained radiologically and clinically stable. Median VMRI decreased by -9.3% (range 0-32.5%, p < 0.0001) between baseline and last follow-up.

CONCLUSION: PET/CT in follow-up of irradiated meningioma showed an early trend towards decreased binding of SSTR-specific tracers following radiation and MRI demonstrated consistently stable or decreasing tumor volume. Translational research is needed to clarify the underlying biology of the subsequent increase in SSTR PET quantifiers.

Original languageEnglish
JournalStrahlentherapie und Onkologie
Early online date19 Oct 2022
DOIs
Publication statusE-pub ahead of print - 19 Oct 2022

Keywords

  • Follow-up
  • Magnetic resonance imaging
  • Radiation therapy
  • Somatostatin receptor
  • Standardized uptake value

ASJC Scopus subject areas

  • Radiology, Nuclear Medicine and Imaging
  • Oncology

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