Target Volume Determination 2015

Glioblastoma = Grade IV glioma

Glioblastoma

Glioblastoma

T1 + Gd

FLAIR + Gd

T2

T1 + Gd

FLAIR

T1

Major problems

True extent of tumour

Some little helpers... • Dynamic contrast-enhanced T1w imaging – Malignant and vital foci • Dynamic contrast-enhanced susceptibiltity imaging – Malignant foci in non-enhancing gliomas • Spectroscopy – Malignant and vital foci – DD tumor vs. Oedema • PET with 18-FDG, 18-FET, or 11-C- Methionine – Metabolically active tumour

• True extent of tumour – Oedema or Tumor? – Tumour in seemingly normal brain tissue? • Heterogeneity of tumours – Grade III components without BBB disturbance – BBB disturbance or neovascular changes? • Treatment-induced changes – T2 hyperintensities – BBB disturbance

• Gliomas: – Grade II: Everything that is T2 hyperintense is tumour! – Grade III and IV: » GTV: Contrast-enhancing area » T2-hyperintensities: Grade II components plus edema -> CTV » Tumour to be expected even in seemingly normal brain • Metastases: – Tumor confined to contrast-enhancing area – T2 hyperintensities are oedema! • Lymphoma: – Is a generalised CNS disease