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[Magnetic resonance perfusion weighted imaging manifestation of late radiation-induced encephalopathy at temporal lobe].

BACKGROUND & OBJECTIVE
The imaging appearances of radiation-induced encephalopathy (REP) of nasopharyngeal carcinoma (NPC) patients were widely reported. As a new technique, magnetic resonance perfusion weighted imaging (MR PWI) is gradually applied to clinical study of REP. This study was designed to observe the characteristics of REP of NPC patients on MR PWI, and investigate its diagnostic value.


METHODS
The MRI and MR PWI records of 26 volunteers and 19 NPC patients with 37 lesions of MRI-diagnosed temporal lobe REP were retrospectively analyzed. The MRI was performed 30 months to 9 years after radiation therapy for NPC. The imaging sequences included T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), MR PWI, and Gd-DTPA-contrasted T1WI.


RESULTS
Unilateral temporal lobe was involved in 1 case of REP, and bilateral temporal lobes in 18 cases of REP. MR PWI revealed that in edema areas of REP, relative cerebral blood volume (rCBV) and relative cerebral blood flood (rCBF) were decreased, mean transit time (MTT), time to peak (TTP), and time of arrival (TO) were delayed simultaneously; in demolished blood-brain barrier areas of REP, rCBV and rCBF were normal, but MTT, TTP, and TO were delayed; no blood perfusion was observed in myelinopathy areas of REP.


CONCLUSION
MR PWI can clearly reveal brain blood perfusion changes in various lesions of REP, and indicate that obvious malfunction of brain blood perfusion is occurred in REP.