DOI: 10.1007/s00259-018-3940-4Pages: 1031-1040

Hybrid MR-PET of brain tumours using amino acid PET and chemical exchange saturation transfer MRI

1. Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine

2. University College London, Department of Medical Physics & Biomedical Engineering

3. UCL Institute of Neurology, Department of Brain Repair and Rehabilitation

4. German Cancer Research Centre (DKFZ), Medical Physics in Radiology

5. German Center for Neurodegenerative Diseases (DZNE)

6. University of Cologne, Department of Neurology

7. Universities of Cologne and Bonn, Center of Integrated Oncology (CIO)

8. Juelich-Aachen Research Alliance (JARA), Section JARA-Brain

9. RWTH University of Aachen, Department of Nuclear Medicine

10. RWTH Aachen University, Department of Neurology, Faculty of Medicine

Correspondence to:
N. Jon Shah
Tel: +49 2461 61 6836
Email: n.j.shah@fz-juelich.de

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Abstract

Purpose

PET using radiolabelled amino acids has become a promising tool in the diagnostics of gliomas and brain metastasis. Current research is focused on the evaluation of amide proton transfer (APT) chemical exchange saturation transfer (CEST) MR imaging for brain tumour imaging. In this hybrid MR-PET study, brain tumours were compared using 3D data derived from APT-CEST MRI and amino acid PET using O-(2-18F-fluoroethyl)-L-tyrosine (18F-FET).

Methods

Eight patients with gliomas were investigated simultaneously with 18F-FET PET and APT-CEST MRI using a 3-T MR-BrainPET scanner. CEST imaging was based on a steady-state approach using a B1 average power of 1μT. B0 field inhomogeneities were corrected a Prametric images of magnetisation transfer ratio asymmetry (MTRasym) and differences to the extrapolated semi-solid magnetisation transfer reference method, APT# and nuclear Overhauser effect (NOE#), were calculated. Statistical analysis of the tumour-to-brain ratio of the CEST data was performed against PET data using the non-parametric Wilcoxon test.

Results

A tumour-to-brain ratio derived from APT# and 18F-FET presented no significant differences, and no correlation was found between APT# and 18F-FET PET data. The distance between local hot spot APT# and 18F-FET were different (average 20 ± 13 mm, range 4–45 mm).

Conclusion

For the first time, CEST images were compared with 18F-FET in a simultaneous MR-PET measurement. Imaging findings derived from18F-FET PET and APT CEST MRI seem to provide different biological information. The validation of these imaging findings by histological confirmation is necessary, ideally using stereotactic biopsy.

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  • Accepted: Jan 4, 2018
  • Online: Feb 24, 2018

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