MRI of hypothalamic hamartomas in children.

Eight cases of hypothalamic hamartomas (HH) diagnosed in children by clinical, biological and CT studies have been explored by MRI and compared with a control group of twenty children without hypothalamohypophyseal signs. MRI revealed the hamartoma in all cases. Its location and position relative to the floor of the third ventricle was precisely determined. The signal intensity of the lesion was identical to that of normal grey matter on T1-weighted images (300/600.28), but an hyperintense signal was observed over T2-weighted images (1800.60/120) in seven of the eight cases. These data suggest that HH are somewhat different in structure from normal brain tissue. MRI variations in signal intensity should be taken into account in the diagnostic work-up of these lesions.