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DW-MRI and MRS to Differentiate Radiation Necrosis and Recurrent Disease in Gliomas

P13 Exam 4019, Validity Revisited Thomas Chong. DW-MRI and MRS to Differentiate Radiation Necrosis and Recurrent Disease in Gliomas. P13 Exam 4019 Valid Voxel Maps. S53. S43. S63. - many borderline valid cases where NAA peak corrupted by broad, large underlying peak, possibly lactate.

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DW-MRI and MRS to Differentiate Radiation Necrosis and Recurrent Disease in Gliomas

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

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

  3. Low Percentage of “Valid” MRS Spectra Slide 6 of 25 from 12/17/07 status • 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

  4. Low Percentage of “Valid” MRS Spectra Slide 7 of 25 from 12/17/07 status • 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]

  5. INTERPRET MRS project – so? what of it? Slide 11 of 25 from 12/17/07 status • 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.

  6. INTERPRET MRS project – so? what of it? Slide 12 of 25 from 12/17/07 status • 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 < 8Hz, SNR > 10 • Tumor recognition tool does not utilize track of time trend changes in data

  7. Cho/ NAA, P13 Exam 4019 S53 S43 S63

  8. Vox 174: Low S/N in S53 from Lactate Peak May Affect Accuracy of Ratio Value S53 S43 INVERTED PEAK AREA CALCULATIONS Voxel Number 174 Choline (65-77img)/ (3.31-3.12ppm)= 6383 65 77 Creatine (77-87img)/ (3.12-2.97ppm)= 5694 77 87 NAA (144-153img)/ (2.10-1.96ppm)= 4849 144 153 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 Voxel Number 174 Choline (68-74img)/ (3.26-3.17ppm)= 1755 68 74 Creatine (75-83img)/ (3.15-3.03ppm)= 2970 75 83 NAA (140-150img)/ (2.16-2.01ppm)= 6150 140 150 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

  9. Large Cho/NAA Difference Between Adjacent S53 Voxels 174 & 188 Shows Variability from User-Boundary Selection Error Voxel Number 188 Choline (59-71img)/ (3.40-3.21ppm)= 3840 59 71 Creatine (76-85img)/ (3.14-3.00ppm)= 3000 76 85 NAA (141-151img)/ (2.14-1.99ppm)= 3855 141 151 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 Number 174 Choline (68-74img)/ (3.26-3.17ppm)= 1755 68 74 Creatine (75-83img)/ (3.15-3.03ppm)= 2970 75 83 NAA (140-150img)/ (2.16-2.01ppm)= 6150 140 150 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

  10. Effect of User Boundary Selection Error on Cho/NAA Increased Sensitivity of Cho/NAA to “Noise” when Cho S/N is Low Voxel Number 174 Choline (68-74img)/ (3.26-3.17ppm)= 1755 68 74 Creatine (75-83img)/ (3.15-3.03ppm)= 2970 75 83 NAA (140-150img)/ (2.16-2.01ppm)= 6150 140 150 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 Number 174 Choline (64-74img)/ (3.32-3.17ppm)= 3270 64 74 Creatine (75-83img)/ (3.15-3.03ppm)= 2970 75 83 NAA (141-153img)/ (2.14-1.96ppm)= 6210 141 153 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

  11. 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)‏

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