Fig. 2
Three different high-grade glioma post-treatment patients with routine follow-up MRI studies demonstrating no contrast enhancement initially (1a, 2a, 3a; all contrast-enhanced T1-weighted images). Upon further MRI follow-up, a new contrast-enhancing lesion was discovered in the right temporal lobe (1b; arrow), right frontal lobe (2b; arrow) and left temporal lobe (3b; arrow). rCBV (relative cerebral blood volume) values derived from Dynamic susceptibility weighted perfusion MRI performed at the time of lesion discovery revealed below-threshold rCBV values for all three patients (1c, 2c, 3c; arrows), suggesting the diagnosis of treatment-related changes. 18F-FET PET performed at the time of MRI = T1 demonstrated high tracer uptake (TBR; tumor to background ratio) and correctly overturned the diagnosis to tumor progression in all cases (1d, 2d, 3d; arrows).
