DOI: 10.1007/s00259-018-4090-4Pages: 2404-2412

Serial FLT PET imaging to discriminate between true progression and pseudoprogression in patients with newly diagnosed glioblastoma: a long-term follow-up study

1. University of Groningen, University Medical Centre Groningen, Department of Medical Oncology

2. VU University Medical Centre, Cancer Centre Amsterdam, Department of Medical Oncology

3. University of Groningen, University Medical Centre Groningen, Department of Neurology

4. University of Groningen, University Medical Centre Groningen, Department of Radiology

5. University of Groningen, University Medical Centre Groningen, Department of Pathology

6. University of Groningen, University Medical Centre Groningen, Department of Radiotherapy

7. University of Groningen, University Medical Centre Groningen, Department of Neurosurgery

8. University of Groningen, University Medical Centre Groningen, Department of Nuclear Medicine

9. University of Groningen, University Medical Centre Groningen, Department of Molecular Imaging

Correspondence to:
Annemiek M. E. Walenkamp
Tel: +31-50-3612821
Email: a.walenkamp@umcg.nl

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Abstract

Purpose

Response evaluation in patients with glioblastoma after chemoradiotherapy is challenging due to progressive, contrast-enhancing lesions on MRI that do not reflect true tumour progression. In this study, we prospectively evaluated the ability of the PET tracer 18F-fluorothymidine (FLT), a tracer reflecting proliferative activity, to discriminate between true progression and pseudoprogression in newly diagnosed glioblastoma patients treated with chemoradiotherapy.

Methods

FLT PET and MRI scans were performed before and 4 weeks after chemoradiotherapy. MRI scans were also performed after three cycles of adjuvant temozolomide. Pseudoprogression was defined as progressive disease on MRI after chemoradiotherapy with stabilisation or reduction of contrast-enhanced lesions after three cycles of temozolomide, and was compared with the disease course during long-term follow-up. Changes in maximum standardized uptake value (SUVmax) and tumour-to-normal uptake ratios were calculated for FLT and are presented as the mean SUVmax for multiple lesions.

Results

Between 2009 and 2012, 30 patients were included. Of 24 evaluable patients, 7 showed pseudoprogression and 7 had true progression as defined by MRI response. FLT PET parameters did not significantly differ between patients with true progression and pseudoprogression defined by MRI. The correlation between change in SUVmax and survival (p = 0.059) almost reached the standard level of statistical significance. Lower baseline FLT PET uptake was significantly correlated with improved survival (p = 0.022).

Conclusion

Baseline FLT uptake appears to be predictive of overall survival. Furthermore, changes in SUVmax over time showed a tendency to be associated with improved survival. However, further studies are necessary to investigate the ability of FLT PET imaging to discriminate between true progression and pseudoprogression in patients with glioblastoma.

This article is freely available, click here to access the full text/PDF

  • Accepted: Jul 9, 2018
  • Online: Jul 21, 2018

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