Pineal gland ADC values in children aged 0 to 4 years: normative data and usefulness in the differential diagnosis with trilateral retinoblastoma.

Purpose: Normative ADC values of the pineal gland in young children are currently lacking, however, these are potentially useful in the differential diagnosis of pineal involvement in trilateral retinoblastoma, which is challenging when the size of the tumor is less than 10-15 mm. The main objective of this study was to establish ADC reference values of the normal pineal gland in a large cohort of children between 0 and 4 years.

Methods: This retrospective study was conducted in a tertiary pediatric hospital. We collected 64 patients with normal MRI examination (between 2017 and 2024) and clinical indication unrelated to the pineal gland, and divided them into 5 age groups (0 to 4 years). Gland size and mean ADC values were calculated, using the ellipsoid formula and ROI/histogram analysis, respectively. The established values were tested in three cases of trilateral retinoblastoma (10 to 20 months).

Results: Mean ADC values were always above 1000 × 10^- 6 mm²/s, while in patients with trilateral retinoblastoma they were around 800 × 10^- 6 mm²/s. Pineal ADC values were identical in both genders. The volume of the pineal gland showed a tendency to increase with age.

Conclusions: We present ADC reference data for the pineal gland in children under 4 years of age. The distribution of mean ADC values of trilateral retinoblastoma was significantly different from the normative values, hence, the use DWI/ADC may help to identify small trilateral retinoblastoma in children with ocular pathology.