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Atrium of lateral ventricle

The atrium of the lateral ventricle, also known as the trigone, is a widened area located at the intersection of the body, occipital horn, and temporal horn of each lateral ventricle in the brain. It serves as an important anatomical landmark within the ventricular system, bordered by crucial structures such as the splenium of the corpus callosum, thalamus, and tapetum. The atrium plays a key role in cerebrospinal fluid (CSF) circulation and is a region of clinical significance, especially in neuroimaging and neurosurgical procedures.

Synonyms

  • Trigone of the lateral ventricle

  • Ventricular trigone

  • Atrium (ventricular atrium)

Function

  • Acts as a confluence for the body, occipital horn, and temporal horn of the lateral ventricle

  • Facilitates the circulation and distribution of cerebrospinal fluid (CSF) within the lateral ventricles

  • Serves as an important anatomical landmark for radiological and surgical orientation

  • Proximity to the choroid plexus, which is involved in CSF production

MRI Appearance

  • T2-Weighted Images:

    • Appears as CSF signal intensity (bright/hyperintense)

    • The atrium is clearly visualized as a bright, fluid-filled area at the ventricular intersection

    • The choroid plexus within the atrium may appear slightly hypointense or isointense compared to CSF, sometimes with calcifications in older patients

  • T1-Weighted Images:

    • The atrium appears hypointense (dark), consistent with the typical CSF signal

    • The choroid plexus may appear slightly hyperintense relative to CSF, especially if there is calcification or increased protein content

  • FLAIR (Fluid-Attenuated Inversion Recovery):

    • CSF in the atrium is suppressed (dark) on FLAIR images

    • The margins of the atrium are sharply defined

    • Any abnormal signal (hyperintensity) within the atrium suggests pathology, such as hemorrhage or infection

CT Appearance

  • The atrium of the lateral ventricle appears as a hypodense (dark) region consistent with CSF density

  • Choroid plexus within the atrium is often hyperdense due to physiological calcifications, especially in elderly patients

  • Enlarged atrium may be seen in conditions such as hydrocephalus or atrophy

MRI images

Atrium - Lateral ventricle mri 3t coronal image