Radiation hepatitis manifests clinically as jaundice and hepatomegaly several weeks after radiation therapy. The presumed underlying mechanisms are Kupffer cell and vascular endothelial damage. Imaging identifies the boundary between normal and irradiated liver to be sharply defined and corresponding to the radiation port, a finding not seen with overlapping ports. Once regeneration starts, the sharp boundary becomes less well defined. Radiation hepatitis is iso- to hypodense relative to normal liver on CT. Vessels in the involved region appear normal. Postcontrast, CT appearance is inconsistent and ranges from hypo- to hyperdense.
The involved liver parenchyma is mostly hypoechoic on US. Radiation hepatitis is hypointense on T1- and hyperintense on T2-weighted MR images. Anecdotal reports describe iron colloidenhanced MRI showing decreased uptake in acute radiation-induced hepatic injury. Eventually abnormalities either resolve or the involved liver segments atrophy.
This is radiology images of Radiation hepatitis after prior radiation therapy for breast carcinoma. CT outlines a focal, sharply defined anterolateral defect (arrow).