Pineal cysts: MR imaging.

MR brain scans of 672 consecutive patients were examined prospectively to determine the incidence of high-signal pineal glands on T2-weighted images. The scans were obtained on either a 0.15-T or 0.5-T unit. This finding was present in 29 patients, none of whom had hydrocephalus or symptoms of a pineal mass. A CT scan was available in 17 of these cases and none of these demonstrated a solid pineal mass. Because of the frequency of this observation (4.3%) and the absence of associated findings, it was concluded that benign pineal cysts are the most likely explanation for this high signal. It is important for the radiologist to consider benign cysts in the differential diagnosis of a bright pineal gland on T2-weighted MR images.