Fig. 4

Two patients with recurrence within rChoNAA > 2 but outside of T1 post-contrast delineated GTV. A Axial pre-treatment T1PC from patient with rGBM treated with re-RT. Yellow outlines the CTV and magenta contour outlines the pre-treatment rChoNAA > 2 volume. B Pre-treatment T2/FLAIR. C rChoNAA > 2 overlaid pre-treatment T1PC. D Post-treatment T1PC. An area of recurrence is seen medially that was identified by the initial rChoNAA > 2 maps. E Sagittal pre-treatment T1PC from a separate patient with rGBM treated with re-RT. Yellow outlines the CTV and magenta contour outlines the pre-treatment rChoNAA > 2 volume. F Pre-treatment T2/FLAIR. G rChoNAA > 2 overlaid pre-treatment T1PC. H Post-treatment T1PC. Area of recurrence posteriorly was largely included in the rChoNAA > 2 volume but not T1PC volume. Note that areas of recurrence are not avidly enhancing due to concurrent bevacizumab administration