DW-MRI and MRS to Differentiate Radiation Necrosis and Recurrent Disease in Gliomas P13 Exam 4019, Validity Revisited Thomas Chong

P13 Exam 4019 Valid Voxel Maps S43 S53 S63 - many borderline valid cases where NAA peak corrupted by broad, large underlying peak, possibly lactate. - These were counted as not valid

Low Percentage of “Valid” MRS Spectra No metabolite amount info obtainable from most data  best, cleanest P1, P2, P5 Motivated investigation into possible spatial correlations  No clear correlations obvious. Need more data Slide 6 of 25 from 12/17/07 status

Low Percentage of “Valid” MRS Spectra Artifacts present in MRS protocol data are consistent with those seen by other researchers  large baseline distortions  exceptionally broadened metabolite peaks  large phase errors Other observed data corrupting factor  SNR of cho, cre, or naa peaks reduced by large unknown resonance peak  broad non-metabolite peak, or non-constant floor MRS signal interpretation for tumors recognized as a complicated task – see INTERPRET project (International Network for Pattern Recognition of Tumours Using Magnetic Resonance), a consortium of 10 EU countries [1] Slide 7 of 25 from 12/17/07 status

INTERPRET MRS project – so? what of it? Still, how to distinguish artifacts from presence of unwanted/unknown substances? Common recognition that MRS data interpretation is not easy:  see above name of the big EU project  rigorous process for deciding validity of MRS voxel data in their database entailed up to 3 expert spectrologists. Slide 11 of 25 from 12/17/07 status

INTERPRET MRS project – so? what of it? Useful SNR and WBW measures defined  phantom reference gives info on data variability (it's noisy, based on successive bimonthly meas.)‏  automated program to check spectrum for WBW 10 Tumor recognition tool does not utilize track of time trend changes in data Slide 12 of 25 from 12/17/07 status

Cho/ NAA, P13 Exam 4019 S43 S53 S63

Vox 174: Low S/N in S53 from Lactate Peak May Affect Accuracy of Ratio Value S43 INVERTED PEAK AREA CALCULATIONS Voxel Number174 Choline (65-77img)/ ( ppm)= Creatine (77-87img)/ ( ppm)= NAA ( img)/ ( ppm)= Cho/NAA:1.32 Choline shift from ref 3.22 =0.01 Creatine shift from ref 3.03 =0.02 NAA shift from ref 2.02 =0.02 S53 Voxel Number174 Choline (68-74img)/ ( ppm)= Creatine (75-83img)/ ( ppm)= NAA ( img)/ ( ppm)= Cho/NAA:0.29 Choline shift from ref 3.22 =0.02 Creatine shift from ref 3.03 =0.06 NAA shift from ref 2.02 =0.08

Large Cho/NAA Difference Between Adjacent S53 Voxels 174 & 188 Shows Variability from User- Boundary Selection Error Voxel Number174 Choline (68-74img)/ ( ppm)= Creatine (75-83img)/ ( ppm)= NAA ( img)/ ( ppm)= Cho/NAA:0.29 Choline shift from ref 3.22 =0.02 Creatine shift from ref 3.03 =0.06 NAA shift from ref 2.02 =0.08 Voxel Number188 Choline (59-71img)/ ( ppm)= Creatine (76-85img)/ ( ppm)= NAA ( img)/ ( ppm)= Cho/NAA:1.00 Choline shift from ref 3.22 =0.06 Creatine shift from ref 3.03 =0.05 NAA shift from ref 2.02 =0.05

Voxel Number174 Choline (68-74img)/ ( ppm)= Creatine (75-83img)/ ( ppm)= NAA ( img)/ ( ppm)= Cho/NAA:0.29 Choline shift from ref 3.22 =0.02 Creatine shift from ref 3.03 =0.06 NAA shift from ref 2.02 =0.08 Voxel Number174 Choline (64-74img)/ ( ppm)= Creatine (75-83img)/ ( ppm)= NAA ( img)/ ( ppm)= Cho/NAA:0.53 Choline shift from ref 3.22 =0.07 Creatine shift from ref 3.03 =0.06 NAA shift from ref 2.02 =0.08 Effect of User Boundary Selection Error on Cho/NAA Increased Sensitivity of Cho/NAA to “Noise” when Cho S/N is Low

2/29/08 Status Proceed with pursuit of qualitative measure of quality?  Requires: collection of background intensity (for S/N calculation) > 4ppm, computation of water bandwidth  Requires: Access to pfiles (waiting on Scott)‏