Clinical study| Volume 62, P133-137, April 2019

Magnetic resonance characterization of the ‘dot sign’ in colloid cysts of the third ventricle

Published:November 26, 2018DOI:


      • While considered essentially pathognomonic of Rathke’s cleft cysts, the presence of an intracystic nodule on MRI – the so-called ‘dot’ sign – has not been comprehensively described for colloid cysts of the third ventricle.
      • Here, we retrospectively characterized the prevalence and MRI characteristics of the ‘dot sign’ in colloid cysts at a single-institution.
      • The ‘dot sign’ was observed in 38% of radiologically verified colloid cysts – the ‘dot’ displayed low intensity with respect to cyst fluid on T2-weighted sequences in all cases.
      • An intracystic low T2 ‘dot’ is a common MRI feature of colloid cysts of the third ventricle, and to our knowledge not previously systematically described.



      To determine the incidence of the ‘dot sign’ in patients with colloid cysts of the third ventricle and to characterise its MRI appearances.

      Materials and Methods

      Single institution retrospective analysis between January 2007 and October 2016 of all patients with either an imaging or imaging and histology-confirmed diagnosis of colloid cysts of the 3rd ventricle was undertaken. For all cases, MRI signal intensities of the cyst fluid component were graded by two independent radiologists relative to brain parenchyma. Presence of a dot, and if present, its size and relative position within the cyst were recorded. Signal intensities of the dot were then similarly assessed.


      37 cases of colloid cyst were identified. Of these 37.8% (n = 14) demonstrated the dot sign. The majority (11 of 14) were observed inferiorly within the cyst; two cases were anteroinferior, and one other was posterior. All identified intracystic nodules displayed low signal intensity with respect to cyst fluid on T2 weighted sequences, and only two nodules were hypointense to fluid on T1-weighted imaging, with the remainder either iso- or hyperintense.


      An intracystic low T2 ‘dot’ is a common MRI feature of colloid cysts of the third ventricle, and to our knowledge not previously systematically described. Presence of such a dot should not only not dissuade from a diagnosis of colloid cyst being made, but should in fact be used to strengthen the imaging diagnosis.


      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Journal of Clinical Neuroscience
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • El Khoury C.
        • Brugières P.
        • Decq P.
        • Cosson-Stanescu R.
        • Combes C.
        • Ricolfi F.
        • et al.
        Colloid cysts of the third ventricle: are MR imaging patterns predictive of difficulty with percutaneous treatment?.
        AJNR. 2000 Mar 1; 21: 489-492
        • Bender B.
        • Honegger J.B.
        • Beschorner R.
        • Ernemann U.
        • Horger M.
        MR imaging findings in colloid cysts of the sellar region: comparison with colloid cysts of the third ventricle and Rathke's cleft cysts.
        Acad Radiol. 2013 Nov 30; 20: 1457-1465
        • Maeder P.P.
        • Holtås S.L.
        • Basibüyük L.N.
        • Salford L.G.
        • Tapper U.A.
        • Brun A.
        Colloid cysts of the third ventricle: correlation of MR and CT findings with histology and chemical analysis.
        AJR Am J Roentgenol. 1990 Jul; 155: 135-141
        • Young W.B.
        • Silberstein S.D.
        Paroxysmal headache caused by colloid cyst of the third ventricle: case report and review of the literature. headache.
        J Head Face Pain. 1997; 37: 15-20
        • Chan R.C.
        • Thompson G.B.
        Third ventricular colloid cysts presenting with acute neurological deterioration.
        Surg Neurol. 1983 Apr 1; 19: 358-362
        • Shuangshoti S.
        • Phonprasert C.
        • Suwanwela N.
        • Netsky M.G.
        Combined neuroepithelial (colloid) cyst and xanthogranuloma (xanthoma) in the third ventricle.
        Neurology. 1975; 25: 547
        • Armao D.
        • Castillo M.
        • Chen H.
        • Kwock L.
        Colloid cyst of the third ventricle: imaging-pathologic correlation.
        AJNR. 2000 Sep 1; 21: 1470-1477
        • Scotti G.
        • Scialfa G.
        • Colombo N.
        • Landoni L.
        MR in the diagnosis of colloid cysts of the third ventricle.
        AJNR. 1987 Mar; 1: 370-372
        • Algin O.
        • Ozmen E.
        • Arslan H.
        Radiologic manifestations of colloid cysts: a pictorial essay.
        Can Assoc Radiol J. 2013 Feb 28; 64: 56-60
        • Lach B.
        • Scheithauer B.W.
        • Gregor A.
        • Wick M.R.
        Colloid cyst of the third ventricle: a comparative immunohistochemical study of neuraxis cysts and choroid plexus epithelium.
        J Neurosurg. 1993 Jan; 78: 101-111
        • Hayashi Y.
        • Tachibana O.
        • Muramatsu N.
        • et al.
        Rathke cleft cyst: MR and biomedical analysis of cyst content.
        J Comput Assist Tomogr. 1999; 23: 34-38
        • Byun W.M.
        • Kim O.L.
        • Sug Kim D.
        MR imaging findings of Rathke's cleft cysts: significance of intracystic nodules.
        AJNR. 2000 Mar; 1, 21(3): 485-488
        • Binning M.J.
        • Gottfried O.N.
        • Osborn A.G.
        • Couldwell W.T.
        Rathke cleft cyst intracystic nodule: a characteristic magnetic resonance imaging finding.
        J Neurosurg. 2005 Nov; 103: 837-840
        • Wang S.S.
        • Xiao D.Y.
        • Yu Y.H.
        • Jing J.J.
        • Zhao L.
        • Wang R.M.
        Diagnostic significance of intracystic nodules on MRI in Rathke’s cleft cyst.
        Int J Endocrinol. 2012 Sep; 12: 2012
        • Osborn A.G.
        • Preece M.T.
        Intracranial cysts: radiologic-pathologic correlation and imaging approach.
        Radiology. 2006; 239: 650-664
        • Park M.
        • Lee S.K.
        • Choi J.
        • Kim S.H.
        • Kim S.H.
        • Shin N.Y.
        • et al.
        Differentiation between cystic pituitary adenomas and Rathke cleft cysts: a diagnostic model using MRI.
        AJNR. 2015 Oct 1; 36: 1866-1873
        • Lavrador J.P.
        • Brogna C.
        • Vergani F.
        • Hasegawa H.
        • Aizpurua M.
        • Bhangoo R.
        Third-ventricle enterogenous cyst presentation mimicking a colloid cyst: uncommon presentation of a rare disease and literature review.
        Acta Neurochir. 2017 Mar 1; 159: 465-468