Objective    To study the signs and features of congenital pineal cyst on CT and MRI.     Methods    CT and MRI findings in 26 cases of congenital pineal cyst were retrospectively analyzed.     Results    The lesions in all cases presented as a cystic mass with an intact

smooth cystic wall where enhancement could be seen. The MRI signal intensity and CT value of the cyst wall were similar to those of gray matter of the brain

while signal intensity of the cystic fluid displayed like water with long T

1

and long T

2

and its CT value was similar to that of CSF.    Conclusion    The diagnosis of congenital pineal cyst may be missed if we only refer to CT plain scan. MR images

especially those in sagittal views

are helpful in displaying the relationship of pineal cyst with the posterior part of the third ventricle

so MRI is superior to CT

and should be the first choice in diagnosis.