1. Metabolic mapping of human gliomas Assessment with simultaneous MR/PET imaging for preoperative „hot-spot“ imaging of suspected anaplastic gliomas S. Bisdas 1, T. Nägele 1, R. Ritz 2, A. Boss 3, A. Kolb 3, B. Pichler 3, U. Ernemann 1 1 Department for Diagnostic and Interventional Neuroradiology 2 Department of Neurosurgery 3 Laboratory for Preclinical Imaging and Imaging Technology, Werner Siemens Foundation Eberhard-Karls-University Tübingen/DE

2. Background Histopathological grade remains one of the most important prognostic factors. The grading of gliomas has some limitations when is reached by biopsy. Tumor grade heterogeneity, sampling error, inter and intra-observer variability. MR-perfusion, MRS, PET are useful imaging surrogates.

3. MRPET MR- PET Technical developments 1. MR-compatible PET scanner 2. Re-adjustment of MR-field-geometry 3. New attenuation correction methods

4. Purpose To evaluate the simultaneous MR-PET imaging using a newly launched integrated MR-PET system for metabolic mapping in patients with suspected anaplastic gliomas.

5. MR-PET

6. MR-PETMR-PETPET/CT original5mm Gauss WB-Acqusition 256 2 matrix

7. Patients 18 consecutive patients with newly diagnosed gliomas, indistinctive of being grade II or III Each patient received MET-PET, CSI-MRS (TE: 30/135), T1-w MR perfusion Imaging-guided biopsies in tumor sites being suspect in ≥2 modalities: 1. MET uptake ratio > 2 2. K trans > 0.03 3. Cho/NAA ratio > 1.6

8. Data acquisition PET and MR data acquisition were simultaneously started. PET data were acquired for 25 min, rebinned and reconstructed using a 3D OSEM algorithm (matrix 256x256x153, voxel 1.25 mm 3 ) The attenuation maps were computed from 3D MRI datasets applying an algorithm combining pattern recognition and atlas registration.

9. MRI exam protocol  T2-weighted TSE (TR/TE = 4000 /105; matrix 288x320)  FLAIR; TR/TE/TI=10000/106/2500; matrix 168x320)  T1-weighted FLASH (TR/TE/a = 23/7.4/25 0 ; matrix 176x256)  DWI SS-EPI (TR/TE=3000/791 ; FOV= 230x230; matrix 128x128)  3D TOF MRA (TR/TE/a = 22 ms/3.7 ms/18 0 ; FOV= 150x200; matrix 202x384).  1 H-MRS, SE CSI (PRESS) ;TR/TE1/TE2 = 1700/135/30; voxel 1.0x1.0x1.5; excitations = 3; 6:46min)  Dynamic T1-weighted VIBE, double flip angle technique

10. Simultaneous MR-PET imaging

11. Results 26 anaplastic lesions in MRS 24 positive lesions in MET-PET 14 positive sites in MR- perfusion 12 WHO-grade III and 6 WHO-grade II gliomas

12. Comparison to histopathology Sensitivity (%)Specificity (%) MET-PET75100 MR-perfusion70100 MRS8584

13.  Sensitivity  Sensitivity Specificity  Sensitivity Sensitivity Specificity

14. Case 1

15. Case 2

16. Case 3 Grade II Grade III

17. Take-home points Integrated MR-PET imaging feasible Artifact-free diagnostic and molecular imaging Comprehensive glioma grading Improves the efficacy of the targeted biopsies