Imaging Features of Atypical Oligodendroglial Tumor

Objective: To explore the Imaging features of atypical oligodendroglial tumors(OG) in order to improve the diagnostic abilities. Method: The CT, MRI findings of 12 patients pathologically confirmed OG was retrospectively studied. Results: 13 lesions were found in 12 cases(7 lesions were situated in deeply and 5 were superficial), ranged in age from 23 to 60 years. 10 patients are older than 40 years(83.3%). 9 cases showed solid masses with a ill-defined border, manifested as slight low signal on T1 WI and high singal on T2 WI. Among them, the leision was uniformity signal in 1 case, and heterogeneous signal in 8 cases accompany hemorrhage or necrosis. After contrast scanning, th leision had a patched mild to moderate in 7 cases, a ring-shaped enhancement in 1 case, which solid part showed high singal on DWI, and no enhancement in 1 case, respectively. 3 cases manifested as cystic leision, with thick walls and unclear boundaries. The cyst fluid showed long T1 and long T2 signal intensity. The cyst wall showed isointense signal on T1 WI and slight hyperintense on T2 WI, one of which showed high signal on DWI. All of the leision had no enhancement after contrast administration. Calcification was seen on CT in 3 cases. Serious peritumoral edema was seen in 2 cases. 2 lesions crossed the mildline and 1 lesion infiltrated the adjacent basal ganglion and thalamus. Conclusion: Atypical MRI manifestation of OG included occuring in middle-aged and old people, multiple lesion, deep site, serious peritumoral edema, crossing the mildline, infiltrated into deep tissue, circular enhancement, restricted diffusion on DWI, cystic mass. It still has relative features on imaging, and comprehensive analysis can elevate the accuracy of diagnosis.