Magnetic resonance imaging (MRI) was performed in 40 patients with nasopharyngeal carcinoma (NPC) before and after i.v. administration of Cadolinium-DTPA(Gd-DTPA), for evaluating the role of Gd-DTPA-enhanced imaging in the differentiation of recurrent nasopharyngeal carcinoma (PNPC) from post-radiation fibrosis (RF). MRI diagnosis and findings were confirmedby pathology (n=16) and long-term serial MR/CT and clinical follow-up (n=24), including 3 untreated primary NPC cases,20RNPC cases and 17 RF cases. The results indicated that post-contrast T1 weighted imaging exhibited excellent contrast between thelesion and the surrounding tissue, therefore, it was superior to the Pre-conbet T1WI in showing the relationship between lesionsand adjacent tissues, especially for those lesions located submucosally, and the ones with intl’aCndal invasion. All the NPC andRNPC demonstrated mild to moderate enhancement, with the pattern of homogenous masses or patches. Only 5 cases of the RFgroup demonstrated mild enhancement, which was found in 4 of the 5 cases within one year after radiotherapy. Of the 5 cases,4revealed linear-shaped enhancement. The mean value of enhancement percentage showed marked difference between the twogroups (P<0.05), however, some overlapping existed in their mean ± SD. Gd-DTPA enhanced MR imaging could offer importantinformation for differentiating from RF, on the basis of the intensity and pattern characteristics of the enhancement. It couldalso be helpful in separating thickened mucosa or sinus secretion from tumor, and was superior to unenhanced MR imaging in theearly diagnosis of intracranial involvement of NPC. Magnetic resonance imaging (MRI) was performed in 40 patients with nasopharyngeal carcinoma (NPC) before and after iv administration of Cadolinium-DTPA(Gd-DTPA), for evaluating the role of Gd-DTPA-enhanced imaging in the differentiation of recurrent nasopharyngeal carcinoma (PNPC) from post-radiation fibrosis (RF). MRI diagnosis and learned were confirmed by pathology (n=16) and long-term serial MR/CT and clinical follow-up (n=24), including 3 untreated primary NPC cases, 20RNPC cases and 17 RF cases. The results indicated that post-contrast T1 weighted imaging exhibited excellent contrast between thelesion and the surrounding tissue, therefore, it was superior to the Pre-conbet T1WI in showing the relationship between lesions and adjacent tissues, especially for those Lesions located submucosally, and the ones with intl’aCndal invasion. All the NPC and RNPC showed mild to moderate enhancement, with the pattern of homogenous masses or patches. Only 5 cases of the RFgroup demonstra Ted mild enhancement, which was found in 4 of the 5 cases within one year after radiotherapy. Of the five cases, 4revealed linear-shaped enhancement. The mean value of the drawing percentage difference marked the difference between the twogroups (P<0.05), However, Some overlapping existed in their mean ± SD. Gd-DTPA enhanced MR imaging could offer importantinformation for differentiating from RF, on the basis of the intensity and pattern characteristics of the enhancement. It couldalso be helpful in separating thickened mucosa or sinus secretion from tumor, And was inferior to unenhanced MR imaging in theearly diagnosis of intracranial involvement of NPC.