The circumventricular organs of the brain: conspicuity on clinical 3T MRI and a review of functional anatomy
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The circumventricular organs (CVOs) occupy seven midline locations around the ventricles. They contain specialized ependymal cells called tanycytes and have an incomplete blood–brain barrier (BBB). We hypothesized that appearances of the lesser known CVOs on contrast-enhanced MRI might lead to confusion in image interpretation whereby they might be mistaken for pathology-related abnormal contrast enhancement. We therefore assessed the normal appearances and prevalence of contrast enhancement of the CVOs on routine clinical brain MRI and reviewed the functional anatomy of the CVOs.
We retrospectively reviewed sagittal and coronal pre- and post-contrast T1-weighted brain 3T MR images in 100 adult patients with normal findings. We assessed the presence of the median eminence (ME), neurohypophysis (NH), pineal gland (PG), subforniceal organ (SFO), organum vasculosum of the lamina terminalis (OVLT), subcommissural organ (SCO), and the area postrema (AP).
The frequency of contrast enhancement of the seven CVOs was as follows: ME in 100 %, NH in 96 %, PG in 84 %, SFO in 1 %, OVLT in 34 %, SCO in 0 %, and AP in 2 %.
The main CVOs (ME, NH, and PG) are well known and appreciated on brain imaging. However, there is a little awareness of the minor CVOs among neuroimagers. This is the first study of contrast enhancement prevalence of the SF, OV, SC, and AP on brain MRI. All the latter are small, faint, rarely visualized, and therefore not likely to cause misinterpretation with significant sources of pathology that cause breakdown of the BBB, such as tumor or inflammation.
KeywordsCircumventricular organs Blood brain barrier MRI
- 1.Altman DG (1991) Mathematics for kappa. In: Altman DG (ed) Practical statistics for medical research, 1st edn. Chapman & Hall, London, pp 406–407Google Scholar
- 12.Johanson CE (2008) Choroid plexus-cerebrospinal fluid circulatory dynamics: impact on brain growth, metabolism, and repair. In: Conn PM (ed) Neuroscience in medicine, 3rd edn. Humana Press, Totowa, pp 181–184Google Scholar
- 19.McKinley MJ, McAllen RM, Davern P, Giles ME, Penschow J, Sunn N, Uschakov A, Oldfield BJ (2003) The sensory circumventricular organs of the mammalian brain. Adv Anat Embryol Cell Biol 172:III–XII, 1–122Google Scholar