The pineal gland: a comparative MR imaging study in children and adults with respect to normal anatomical variations and pineal cysts.

This study was undertaken to evaluate the variations in appearance of the normal pineal gland. The findings of 1000 consecutive MR imaging examinations obtained at 0.5 T were studied. The age of the patients ranged from 1 day to 83 years, and findings in children and adults were compared. In all age groups the pineal gland appeared mainly in three forms: (1) nodule-like, (2) crescent-like and (3) ring-like. Overall prevalences of these forms were 52%, 26% and 22%, respectively. Apparent differences in frequencies were evident in children and adults with respect to the crescent- and ring-like types. Cystiform pineal lesions 5 mm or larger in one diameter (anteroposterior, sagittal or transverse) were taken to be true pineal cysts, when compared with the gland's ring-like appearance (less than 5 mm). Pineal cysts had a prevalence of 0.6% in children and 2.6% in adults. No symptomatic pineal cyst with mass effect on the lamina tecti was detected in the series. Besides identifying the three anatomical types of the pineal gland as seen on MR imaging and addressing the potential significance of differences in their frequencies in children and adults, the author tries to explain the previous discrepancy between the MR imaging and autopsy series findings with respect to frequencies of the pineal cysts.