Imaging findings of intraventricular pilocytic astrocytoma.

Objective: The aim of this study is to present the clinical and imaging findings of 16 patients with intraventricular pilocytic astrocytomas (PAs).
Methods: 16 patients with histopathological diagnosis of intraventricular PA between February 2016 and January 2022 were evaluated retrospectively. Imaging and clinical findings of the patients, as well as apparent diffusion coefficient (ADC) measurements were analyzed.
Results: Of 16 patients, 8 (%50) were male and 8 (%50) were female. The mean age of the patients was 20.8 years (2-44 years range). The most common symptoms in the patients were headache and ataxia. The mean long-axis size of lesions was found to be 48.19 ± 21.59 (range, 15-92 mm). 9 out of 16 lesions (56.2%) were located in the fourth ventricle. The majority of the lesions were iso-hypointense in T ₁ W and hyperintense in T ₂ W images. The mean ADC value of PAs was 1.57 × 10 ^-3 ± 0.2 mm ² /s, while the mean thalamic ADC and white matter ADC values were found to be 0.78 × 10 ^-3 ± 0.04 and 0.76 × 10 ^-3 ± 0.06 mm ² /s, respectively. There was a statistically significant difference between the ADC values obtained from the solid components of the lesions and the thalami/white matter ( p < 0.001).
Conclusion: PAs often originate from midline structures, however, they can also be located intraventricularly. Although intraventricular PAs are frequently seen in pediatric population, it should be kept in mind that they can also be seen in adults, albeit rarely.
Advances in Knowledge: PA should be considered in the differential diagnosis of intraventricular neoplasms in case of high ADC values.