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Pineal gland

The pineal gland, also known as the epiphysis cerebri, is a small, cone-shaped neuroendocrine organ located in the midline of the brain, between the superior colliculi, just posterior to the third ventricle. It is part of the epithalamus and measures about 5–8 mm in adults. The pineal gland is composed of pinealocytes, supporting glial cells, and often contains physiological calcifications that increase with age.

Its primary function is neuroendocrine regulation, including secretion of melatonin, which controls circadian rhythm and seasonal biological cycles. The gland also plays a role in puberty regulation, sleep-wake cycles, and neuroimmunomodulation.

Synonyms

  • Epiphysis cerebri

  • Pineal body

  • Conarium

Function

  • Secretes melatonin, regulating circadian rhythm and sleep-wake cycles

  • Influences pubertal development and reproductive cycles

  • Contributes to neuroendocrine regulation of seasonal rhythms

  • Plays a role in immune modulation and antioxidant defense

MRI Appearance

T1-weighted images:

  • Pineal gland typically appears isointense to gray matter

  • May contain punctate low-signal foci from calcifications

  • Pineal cysts appear hypointense with thin walls

T1 Post-Contrast (Gadolinium-enhanced):

  • Normal pineal gland enhances homogeneously due to rich vascular supply (lack of blood–brain barrier)

  • Pineal cysts demonstrate peripheral rim enhancement

  • Neoplasms (pineocytoma, pineoblastoma) may show intense or heterogeneous enhancement

T2-weighted images:

  • Gland is usually isointense to slightly hyperintense relative to gray matter

  • Pineal cysts appear bright (hyperintense) with thin hypointense capsule

  • Heterogeneous hyperintensity may indicate pathology or cystic change

STIR (Short Tau Inversion Recovery):

  • Pineal gland itself appears isointense to low signal

  • Cysts and inflammatory changes appear hyperintense, aiding in differentiation

  • Useful for detecting edema or cystic degeneration

CT Appearance:

  • Pineal gland often contains physiological calcifications, appearing hyperdense, especially in adults

  • Soft tissue portion appears as a small, isodense midline structure posterior to the third ventricle

  • Pineal cysts appear as well-defined hypodense lesions, sometimes with rim calcification

  • CT is useful for detecting calcification patterns, hemorrhage, and mass effect

MRI images

Pineal gland AXIAL IMAGE

MRI images

Pineal gland mri sag image -img-00000-00000