Published online Jul 28, 2018. doi: 10.4329/wjr.v10.i7.65
Peer-review started: March 13, 2018
First decision: April 23, 2018
Revised: April 29, 2018
Accepted: May 23, 2018
Article in press: May 23, 2018
Published online: July 28, 2018
Pineal cysts (PC) are cysts which are frequently detected incidentally in brain magnetic resonance imaging (MRI). No clear consensus has been reached yet over the classification and follow-up procedures in routine clinical practice. PCs were classified based on MRI findings in the present study. Unilocular, smooth edged, ovoid PCs with homogenous interior structure and less than 2 mm wall thickness were considered typical PC, while multilocular PCs with walls thicker than 2 mm, septation or contour lobulation were considered atypical. In addition, size and natural changes in follow-up examinations were also investigated.
Lack of a consensus over radiological classification and follow-up of PC, and their radiological findings that resemble other lesions of pineal area create difficulties. Presentation of radiological studies dealing with PCs in different population including follow-up images taken at different series could help to resolve this uncertainty.
In the present study, PCs detected using brain MRI examinations in our population were classified based on radiological imaging features. In addition, whether PCs had significant size or nature changes were also evaluated.
A total of 9546 patients who had brain MRI examination in March 2010-January 2018 period were studied retrospectively for the presence of PCs. Sizes in three dimensions, volumes, contours, signal intensities, internal septation or loculation features and contrasting patterns of PCs were evaluated. Size and natural changes of PCs were investigated in patients during follow-up examinations with durations varying from 2 to 96 mo. Associations between PC frequency and gender, between PC volumes and gender and age, and amount of changes between initial and final sizes of PCs were statistically analyzed.
Fifty-six patients (44 female and 12 male) were found to have had PC. Age range of patients with PC was 5-61 (mean: 31.26 ± 12.73). Frequency of PC was 0.58%. PC incidence rates were significantly different in men and women. In terms of classification, 62.50% of the PCs were typical and 37.50% were atypical. Average PC sizes were 11.18 ± 3.03 mm in AP, 10.41 ± 2.72 mm in ML and 8.63 ± 2.47 mm in CC directions. Natural change was not observed in any PC with follow-ups. Average dimension changes in PCs with follow-ups were (-0.08 ± 0.53) mm, (-0.22 ± 0.87) mm, and (0.16 ± 0.56) mm in AP, ML and CC dimension, respectively. No significant difference was found between initial and final sizes of PCs which were monitored by follow-up examinations.
It was revealed in the present study that classification of PCs concluded to be unilocular (i.e., typical) based on routine MRI sequences could change to atypical when high resolution sequences indicated internal septations. No significant size or natural change was observed in follow-up examinations of PCs. Therefore, it could be suggested that asymptomatic PCs which do not show any size or natural changes during one- or two-year follow-ups should be removed from routine follow-up.
The present study showed that PCs are cysts frequently observed as incidental lesions in brain MRI series, that they have an average diameter of 10 mm and that they have signal features similar to CSF in T1 and T2 weighed series while giving higher signal intensities than CSF in FLAIR sequence. In addition, it was revealed that typical or atypical classification of PCs could change based on resolution of sequence used in identification of PCs. Elimination of frequent follow-ups of asymptomatic PCs could lower cost and labor burden on health care system.