Highlights
- •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.
Abstract
Purpose
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.
Results
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.
Conclusions
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.
Keywords
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Article info
Publication history
Published online: November 26, 2018
Accepted:
November 10,
2018
Received:
September 25,
2018
Identification
Copyright
© 2018 Elsevier Ltd. All rights reserved.
