A 53-year-old woman with invasive thymoma with extensive intraluminal tumor thrombus. HU densities measured on the mass lesion are, 41 on non-contrast-enhanced CT (NCCT) image, 76 on contrast-enhanced CT images in the arterial phase, and 86 on contrast-enhanced CT images in the 70 seconds delayed phase. HU densities are compatible with significant enhancement of the mass. Note all ROIs are placed on non-necrotic solid parts of the mass.(Arrow: SVC) (Protocol: 64 detector scanner, 180 mAs, 120 kV, slice thickness: 5 mm, Contrast material: 60 ml Iohexol.) (Early phase images acquired 25 seconds after contrast administration and late phase images acquired 70 seconds after contrast administration.)