Differentiation between high and low grade tumours in paediatric patients by using apparent diffusion coefficients

ObjectiveThis study was performed to confirm the hypothesis that pre-operative apparent diffusion coefficient (ADC) can be used to distinguish between “low grade” and “high grade” tumours in paediatric patients.Material and methodsADC values were retrospectively evaluated in thirty-six paediatric brain tumours. Twenty-one children with low grade brain tumours (12 WHO I astrocytomas, 1 giant cell tumour, 1 pilomyxoid astrocytoma, 4 WHO II astrocytomas, 2 craniopharyngiomas and 1 ganglioglioma) and 15 children with high grade brain tumours (6 medulloblastomas, 3 WHO III ependymomas, 1 PNET, 1 malignant rhabdoid tumour, 1 malignant germ cell tumour, 1 WHO III astrocytoma, 1 WHO IV astrocytoma, 1 rhabdomyosarcoma metastasis) were included in this study. Minimum and mean ADC values were compared between low grade and high grade tumours and cut-off values were evaluated.ResultsThe cut-off values to differentiate low and high grade paediatric brain tumours were 0.7 × 10−3 mm2/s and 1.0 × 10−3 mm2/s for minimum ADC and average ADC values respectively. All but one high grade infratentorial ependymoma showed significantly lower ADC values than low grade brain tumours in children.ConclusionCombining the information obtained from conventional MR imaging with the ADC values may increase the accuracy of pre-operative differentiation between low grade and high grade paediatric tumours. Cut-off values can help to discern low from high grade tumours. However, it has to be considered that there is a substantial overlap between tumour types previously described in the literature.