Objective To investigate the pathogenesis pathology,CT diagnosis and differential diagnosis of hydranencephaly.Methods CT manifestations and clinical data of 9 cases with hydranencephaly were analysed retrospectively.Results CT findins of 9 cases were almost defects of bilateral cerebral hemisphere and ventricle.Only a little remainder of occipital,frontal and/or temporal lobes were appearence.The structure of subtentorium was normal.Conclusion CT scan directly shows all appearances of hydranencephaly and is great valuable for diagnosing this disease.

Objective To study the value of CT perfusion imaging(CTPI)on brain hemodynamic of the aged with cerebral infarction. Methods The 48 patients who were doubted with cerebral infarction underwent 16-slice CT plain scanning and CTPI within 24 hours of onset. The cerebral blood flow(CBF), mean transit time(MTT)and time to peak(TTP)of contrast-medium in region of interest(FOV)were used as brain hemodynamic parameters in comparation with contralateral regions. All cases were followed up with MRI after 3-10 days. Results Ischemia lesion was found on CT plain scanning in 40.9% of patients, while 93.2% of patients showed abnormal perfusion on CTPI. The sensibility of CTPI in identifying ischemia area was 93.2%, and the specificity was 100%. CBF in research area was significantly reduced, MTT and TTP were remarkably increased in contrast to counterparts(P＜0.01). Conclusions CT perfusion imaging can sensitively reveal the hemodynamic condition of cerebral ischemia, which could provide the important information for early diagnosis and treatment of the elderly with brain infarction.