[Magnetic resonance imaging (MRI) findings of temporal lobe radiation encephalopathy]

The imaging appearance of radiation encephalopathy (REP) was widely reported. However, there were few researches on imaging multiplicity of REP. The current study was designed to observe the morphological features of REP on magnetic resonance imaging(MRI) and to investigate its diagnostic value.

The MRI of 160 lesions with the diagnosis of temporal lobe REP on MRI was retrospectively analyzed in 104 patients with nasopharyngeal carcinoma (NPC). The MRI was performed after radiation therapy of NPC with an interval ranged from 8 months to 13 years. The imaging sequences included T1-weighted imaging and T2-weighted imaging additionally. T1-weighted imaging with injection of the contrast agent of Gd-DTPA was performed in 111 lesions and fluid attenuated inversion recovery (FLAIR) was obtained in 37 lesions, MR perfusion weighted imaging (PWI) was performed in 2 of them.

Unilateral temporal lobe was involved in 48 cases of REP, bilateral temporal lobe in 56 cases of REP respectively, with totally 160 lesions founded. The REP in the white matter displayed hyper-intensity signal on T2-weighted imaging which could be homogenous, whereas area with heterogeneous hypo-intensity signal could be seen in 59 of them otherwise with hyper-intensity signal, and 91 lesions of white matter were associated with gray matter lesions with an appearance of hypo-intensity signal on T1-weighted imaging and hyper-intensity signal on T2-weighted imaging. In 111 lesions with the Gd-DTPA enhanced T1-weigthed imaging, 91 showed the enhancement of brain parencyma. Hemorrhage and hemosiderosis were found in 5 lesions of REP.

REP in NPC has a multiplicity of the imaging features on MRI, in addition to the common involvement of white matter, including other relatively frequent findings, such as the involvement of gray matter, hemorrhage, hemosiderosis and blood-brain barrier destruction, those could be clearly revealed on MRI.