Dysembryoplastic neuroepithelial tumors:: CT, MR findings and imaging follow-up:: A study of 53 cases

Purpose: To evaluate CT and MRI features and long term imaging follow-up of a large series of dysembryoplastic neuroepithelial tumors (DNTS). Patients and methods: We retrospectively analyzed CT (100%) and MR imaging (83%) findings of 53 patients with complex (n=14), simple (n=6) or non specific histological forms (n=33) of DNTS. All patients underwent epilepsy surgery for the treatment of drug resistant partial seizures. Preoperative radiological follow-up from two to 10 years (81%) and a post-operative follow-up from one to 13 years (92%) were available. Results: DNTs are intracortical tumors with no mass effect and no peritumoral edema. An associated deformity of the overlying skull was observed in 44% of the 34 patients with a cortical lesion of the convexity. We found a contrast enhancement of the lesion in 21% of cases, a calcic hyperdensity in 36% of cases and a cystic part in 7.5% of cases. DNTs were hypodense (82 %)on CT examinations and had a decreased signal on the T1 Weighted Images (95%) and a hypersignal in T2 Weighted Images (100%) on MR imaging. Eighty-one percent of patients had a mean preoperative radiological follow-up of four years and the tumor was stable in size in all cases; 92 % of patients had a mean post-operative radiological follow-up of 4.5 years and no recurrence was seen. Conclusion: Three radiological features of DNTs are helpful for the diagnosis: cortical location, absence of mass effect and no surrounding edema. Clinical radiological and histopathological findings have to be considered together in order to assess the diagnosis and to differentiate DNTs, which are stable lesions from gliomas.