MRI combined with 18F -FDG PET and 11C -MET PET in differentiating tumefactive demyelinating lesion and glioma

Objective To explore the value of MRI combined with 18 F-fluoro-2-deoxy-D-glucose ( 18 F-FDG) PET and 11 C-methionine ( 11 C-MET) PET on differentiating tumefactive demyelinating lesion (TDL) and glioma. Methods Fourteen cases of TDL and 17 cases of glioma were confirmed by pathology directly or internal medicine treatment. MRI was used to observe the lesion boundary, T 1 WI, T 2 WI and diffusion - weighted imaging (DWI) signal intensity, enhancement (including ring enhancement and open - ring enhancement, etc.), mass effect, peripheral edema, and the presence of central venectasia, corpus callosum engagement, central necrosis and gray matter engagement. 18 F-FDG PET and 11 C-MET PET were used to calculate relative uptake values.  Results Among all TDL cases, MRI showed that mass effect of 8 cases (8/14) were grade 0, 4 cases (4/14) gradeⅠ, one case (1/14) was gradeⅡ and one case (1/14) gradeⅢ; the peripheral edema of 12 cases (12/14) were gradeⅠand 2 cases (2/14) gradeⅡ. Among all glioma cases, the mass effect of 2 cases (2/17) were grade 0, 6 cases (6/17) gradeⅠ, 7 cases (7/17) gradeⅡand 2 cases (2/17) grade Ⅲ; the peripheral edema of 7 cases (7/17) were grade Ⅰ and 10 cases (10/17) grade Ⅱ. The differences between TDL and glioma were statistically significant (Fisher's exact probability: P = 0.032, 0.024). 18 F-FDG PET and 11 C-MET PET were not statistically significant in differentiating TDL and glioma (Fisher's exact probability: P = 0.182, 0.081).  Conclusions Mass effect and peripheral edema showed in MRI can be used for the differential diagnosis of TDL and glioma. The value of PET-CT in differentiating TDL and glioma is unsure. DOI: 10.3969/j.issn.1672-6731.2017.10.009