1. DW-MRI and MRS to Differentiate Radiation Necrosis and Recurrent Disease in Gliomas P101 Exams 4135 (Brain-O), DSS data import attempt Thomas Chong

2. Brain-O Phantom Test “Patient” 101, Exam 4135  Scan of MRS HD Sphere, a.k.a. “Brain-O”  Same scan protocol and data post-processing conducted as has been done for patients enrolled in study  Saturation bands applied to periphery of sphere Purpose  Consistently and systematically low MRS S/N necessitates re-evaluation of data collection procedures  Homogeneous metabolite solution provides near ideal control test for scanner and methods

3. MRS Sphere Phantom Contents Chemical composition matched to close to brain metabolite concentrations

4. MRS Data Post-Processing Identical to Methods Used for Protocol Data Metabolite ppm boundaries manually selected. Because solution within sphere is known to be homogeneous, results provide information on best-case data error magnitudes (i.e. Noise) attributable to:  ppm boundary selection errors resulting from background noise and/or discretization errors  Also, sphere-air boundary error effects are of interest

5. Homogeneity => Clean Data & Good S/N Following figures show overlays of all MRS data  Distinct, sharp peaks with low background noise  No phase inversion in observed data Change of total peak signal tracked going from center to outside of sphere  Absolute signal magnitude diminishes from center to periphery

6. Homogeneity => Clean Data & Good S/N Max

11. Recorded choline amount (in MRS units) via area under choline peak varies with location, assumed to be from systematic signal gain changes. Less variability in Cho/NAA supports this.

13. All three metabolite amount figures shows similar correlation between absolute magnitude and proximity to periphery.

14. Ratio values are robust to systematic changes in absolute signal strength

15. Cho/NAA Error Analysis of Interior Homogeneous Region Avg = 0.79; note, ratio of known soln conc is 3.0/12.5mM = 0.24 ? Conclusion: 2-sigma error for Cho/NAA for given methods is no better than ~0.08 Note, this is for best case situation.

16. Peak Maximum Shift Data Difference between each metabolite peak maximum and literature values computed by post-processing tool  Collateral “free” info  Check for systematic trends, non-linear errors # Literature metabolite peaks ppms from De Graaf article refNAA = 2.02 refCre = 3.03 refCho = 3.22

20. INTERPRET DSS, jMRUI Raw MRS data P-files saved, downloaded MR3 SAGE version (more recent than AW2 version) used to load and save to *.sdf, *.shf files INTERPRET DSS could not successfully load shf/sdf data files. Request for jMRUI license access repeated. (originally sent 1/25/08)‏

21. MRS Protocol Update Recommendation Based on consistent lack of sufficiently high Cho/NAA S/N to allow meaningful interpretation of data, suggestion is to  Increase voxel size to as large as practical  Other ways to improve S/N?