Radiation therapy of the brain, neck, and spine can be associated with
radiation-induced changes that are increasingly evident radiologicall
y, These changes affect the central nervous system (focal necrosis, di
ffuse white matter injury, atrophy, mineralizing microangiopathy, tela
ngiectasia, optic neuropathy, large vessel vasculopathy), bone (fatty
replacement of marrow, osteoradionecrosis, sinus inflammation), and su
perficial and deep soft tissues and include neoplasia, Focal necrosis,
which most commonly occurs at the treatment site, is seen at computed
tomography (CT) and magnetic resonance (MR) imaging as a ring-enhanci
ng mass with edema and mass effect, findings similar to those of tumor
recurrence, Diffuse white matter injury appears as hypoattenuating (a
t CT) or hyperintense (at MR imaging) small foci near the frontal or o
ccipital horns or as a confluent band extending from the ventricles to
the corticomedullary junction, Fatty replacement of marrow is the mos
t common osseous complication seen on MR images, Osteoradionecrosis, w
hich occurs most often in the mandible, appears as a focal lytic area
at CT and with abnormal marrow signal and cortical destruction at MR i
maging, The most common changes in the superficial soft tissues of the
head and neck, edema and fibrosis, are seen radiologically as skin th
ickening and increased soft-tissue attenuation with stranding of subcu
taneous fat, Meningioma, the most common radiation-induced CNS tumor,
can be distinguished from spontaneous meningiomas on the basis of clin
ical characteristics leg, presence of focal alopecia and scalp atrophy
).