ESTRO 2024 - Abstract Book

S2029

Clinical - Paediatric

ESTRO 2024

Material/Methods:

Sixty participants were included prospectively in the IMPALA study [3,4,5,6] and were divided to three groups: 22 irradiated patients with medulloblastoma or ependymoma, 17 non-irradiated pilocytic astrocytoma and 21 healthy controls matched to irradiated group for age, sex and handedness. PFT survivors were at least 5 years post-treatment. All participants underwent both conventional and more ecological (EPIREAL) episodic memory tests [7], as well as semantic, working and procedural memory tests [2]. A multimodal MRI including a DTI sequence was also performed for each subject. In each group, mean diffusivity (MD) and fractional anisotropy (FA) were extracted from right and left-brain structures (thalamus, caudate nucleus, putamen, hippocampus (anterior posterior), whole cerebellum (anterior-posterior) and cerebellum’s white matter (WM)). Mean and maximum doses of irradiation for each structure were extracted from initial treatment plan. Comparisons between groups in term of MD, FA values and neurocognitive scores were assessed using the Kruskal-Wallis test. Correlations were evaluated using Spearman's rank correlation coefficient (r). In irradiated group, the median total dose(range) was 54 (50.0; 59.4) Gy. Right and left hippocampus received respectively a median mean and maximum doses of 45.34 (18.73;55.79) Gy and 51.40 (36.16;58.00) Gy. The median mean dose to cerebellum was 50.97 [44.92;56.68] Gy. The MD values in right and left hippocampus were significantly higher in irradiated PFT compared to non irradiated and control groups (p<0.001, p=0.021, p=0.017, p=0.014, respectively). The right and left cerebellum and left thalamus’ MD values were significantly higher in PFT groups compared to the control (p<0.001, P<0.001, p=0.011 and p<0.001, P<0.001, p=0.021 respectively). FA values in right and left caudate nucleus, right and left putamen and right thalamus were significantly higher in irradiated PFT compared to non-irradiated (p=0.011, p=0.016, p=0.023, p<0.001, p=0.034 respectively) and control (p<0.001, p=0.006, p<0.001, p<0.001, p=0.011 respectively). FA values in anterior right and posterior left hippocampus were significantly higher in irradiated group compared to control (p=0.013 and p=0.024 respectively). FA values in posterior left hippocampus and right putamen were also higher in non-irradiated group compared to control (p=0.049 and p=0.030 respectively). Considering the impact of RT on the microstructure of brain structures involved in memory, significant correlations were found between RT total dose received and MD values in left cerebellum WM (r=- 0.52, p=0.034) and FA values in the posterior left cerebellum (r=0.58, p=0.016). Results:

FA and MD values in cerebellum (WM) were significantly correlated with the maximum dose received by this structure (r=0.55, p=0.021, r=-0.63, p=0.007 respectively).

The maximum dose to the left caudate nucleus was significantly correlated to MD values in this structure (r=0.48, p=0.049).

Considering neuropsychological outcomes, in both irradiated and non-irradiated groups, patients had lower scores in all memory systems with significant differences in irradiated patients in working, episodic and semantic memory compared to control (0.001< p <0.04). Non-irradiated patients had significantly lower scores in working and semantic memory compared to control (0.001< p <0.04).

Compared to non-irradiated patients, irradiated patients had significantly lower results in working memory and episodic memory especially in verbal anterograde memory (p=0.010) and EPIREAL recall (p<0.05), while their