High prevalence of pineal cysts in healthy adults demonstrated by high-resolution, noncontrast brain MR imaging

Abstract

Background and purpose: Although the prevalence of pineal cysts in autopsy series has been reported as being between 25% and 40%, MR studies have documented their frequency to range between 1.5% and 10.8%. The purpose of this high-resolution brain MR imaging study at 1.9T was to determine the prevalence of pineal cysts in healthy adults.

Materials and methods: Brain MR images of 100 healthy young volunteers were randomly selected from our International Consortium for Brain Mapping project data base. Cysts were detected as circular areas of isointensity relative to CSF on both 3D gradient-echo T1-weighted and 2D fast spin-echo T2-weighted images. The inner diameters of all visualized pineal cysts were measured, and a criterion of 2.0 mm of the largest inner cross-sectional diameter was used to categorize cysts as being either small cystic changes (<2.0-mm diameter) or pineal cysts (>2.0-mm diameter).

Results: Twenty-three percent (23/100) of the volunteers had pineal cysts with a mean largest inner cross-sectional diameter of 4.3 mm (range, 2-14 mm); 13% (13/100) demonstrated cystic changes involving the pineal gland with the largest inner cross-sectional diameter of less than 2.0 mm. There was a slight female predominance. Two subjects with long-term follow-up scans showed no symptoms or changes in the size of their pineal cysts.

Conclusion: On high-resolution MR imaging, the prevalence of pineal cysts was 23% in our healthy group of adults, which is consistent with previous autopsy studies. Long-term follow-up studies of 2 cases demonstrated the stability of the cysts.

Figure 1.

Large pineal cyst in a healthy 38-year-old man. A, Sagittal noncontrast T1WI (gradient-echo; TR/TE/flip angle = 24 ms/6 ms/25°). B, Axial T2WI (fast spin-echo; TR/TE/echo-train length = 4200 ms/128 ms/14). C, Sagittal noncontrast follow-up T1WI, 8 years and 7 months after initial scans. D, Sagittal noncontrast follow-up T2WI, 8 years and 7 months after initial scans. The arrows indicate the pineal cyst. The pineal cyst touches the superior colliculi of the quadrigeminal plate without causing any deformity. However, no evidence of an obstructive hydrocephalus or of a narrowing of the aqueduct of the midbrain is seen.

Figure 2.

Small cystic change in the pineal gland of a healthy 25-year-old man. A, Sagittal noncontrast T1WI (gradient echo; TR/TE/flip angle = 24 ms/6 ms/25°). B, Axial T2WI (fast spin-echo; TR/TE/echo-train length = 4200 ms/128 ms/14). The arrows point to the cystic change in the pineal gland.