MRI and CT diagnosis of pilomyxoid astrocytoma

Objective To investigate the MRI and CT manifestations of pilomyxoid astrocytoma (PMA). Methods The MRI and CT findings of 39 patients with PMA confirmed by surgical pathology at the Department of Neuroradiology, Beijing Tiantan Hospital, Capital Medical University from September 2010 to August 2014 were analyzed retrospectively. Nineteen of them were males and 20 were females. The age ranged from 10 months to 47 years. Results There were 25 patients with PMA in the hypothalamic/chiasmatic region. Their median age of onset was 5.83. The mean maximum diameter of the foci was 47.44 mm. There was no obvious peritumoral edema; however, they had varying degrees of hydrocephalus. The banding hypointensities were observed on T2WI in 14 patients. The solid components of PMA showed intralesional multiple-ring enhancement in 22 patients. Diffusion weighted magnetic resonance imaging (DWI) of 3 patients showed that the diffusion was not restricted, and 9 of them showed subarachnoid dissemination. CT examination revealed that 6 patients had calcification and 1 had bleeding. There were 14 patients in the non-hypothalamic/chiasmatic region; their median age of onset was 17. The mean maximum diameter of the foci was 39.43 mm; 6 patients had mild peritumoral edema and 3 had mild hydrocephalus. The banding hypointensities were observed in the hyperintensities on T2WI in 6 patients. The foci of 11 patients showed obviously enhanced. The enhancement pattern was "stellate" enhancement of mural nodule in cystic foci. DWI examination revealed that the diffusion was not restricted in 1 case. No subarachnoid dissemination was observed. Magnetic resonance spectroscopy (MRS) examination was performed in 3 cases; the solid components of the foci met the MRS spectral lines of general glioma. CT examination revealed that 2 patients had calcification and 2 had bleeding. Conclusions PMA may occur in all parts of the brain. It shows a cystic and solid mass. The solid components can be enhanced obviously. The age of onset in the hypothalamic/chiasmatic region is younger and subarachnoid dissemination is common. The age of onset in the non-hypothalamic/chiasmatic region is older. The " stellate" enhancement of mural nodule after enhancement has more characteristics. Key words: Astrocytoma; Brain neoplasms; Tomography, X-ray computed; Magnetic resonance imaging