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FIG 1. MR images of patients with GBM.
A, Axial postcontrast T1-weighted images. There is an enhancing tumor with central, irregular hypoenhancement consistent with necrosis.
B, Axial T2-weighted images of the same patient shown in panel A. High T2-weighted signal intensity surrounds the tumor, with signal intensity approaching that of CSF as seen in the lateral ventricles. The T2-weighted signal intensity change respects the cortical ribbon. The appearance is indicative of vasogenic edema (grade 2, extending more than 1 cm from the tumor, per definitions in Table 1).
C, Axial postcontrast T1-weighted images of another GBM patient. As in the first case there is an enhancing tumor with irregular central hypoenhancement indicating necrosis.
D, Axial T2-weighted images of the same patient shown in panel C. Adjacent to the enhancing portion of the tumor, there is increased T2-weighted signal intensity, which is significantly lower than that of CSF, which extends into the cortex and does not respect the cortical ribbon. The gray-white distinction is obscured. The region corresponds to areas of mildly low T1-weighted signal intensity. This appearance reflects the presence of nonenhancing tumor (nCET). There is also a sliver of higher T2-weighted signal intensity change at the medial margin of the tumor, which indicates a small amount of edema.
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