Radiomics in paediatric neuro-oncology : MRI textural features as diagnostic and prognostic biomarkers

Motivation: Brain and central nervous system tumours form the second most common group of cancers in children in the UK, accounting for 27% of all childhood cancers. Despite current advances in magnetic resonance imaging (MRI), non-invasive characterisation of paediatric brain tumours remains challenging. Radiomics, the high-throughput extraction and analysis of quantitative image features (e.g. texture), offers potential solutions for tumour characterisation and decision support. Aim and Methods: In search for diagnostic and prognostic oncological markers, the aim of this thesis was to study the application of MRI texture analysis (TA) for the characterisation of paediatric brain tumours. To this end, single and multi-centre experiments were carried out, within a supervised classification framework, on clinical MR imaging datasets of common brain tumour types. Results: TA of conventional MRI was successfully used for diagnostic classification of common paediatric brain tumours. A key contribution of this thesis was to provide evidence that diagnostic classification could be optimised by extending the analysis to include three-dimensional features obtained from multiple MR imaging slices. In addition to this, TA was shown to have a good cross-centre transferability, which is essential for long-term clinical adoption of the technique. Finally, fifteen textural features extracted from T2-weighted MRI were identified to be of significant prognostic value for paediatric medulloblastoma. Conclusion: It was shown that MRI TA provides valuable quantifiable information that can supplement qualitative assessments conducted by radiologists, for the characterisation of paediatric brain tumours. TA can potentially have a large clinical impact, since MR imaging is routinely used in the brain cancer clinical work-flow worldwide, providing an opportunity to improve personalised healthcare and decision-support at low cost

Maturational networks of human fetal brain activity reveal emerging connectivity patterns prior to ex-utero exposure

Abstract A key feature of the fetal period is the rapid emergence of organised patterns of spontaneous brain activity. However, characterising this process in utero using functional MRI is inherently challenging and requires analytical methods which can capture the constituent developmental transformations. Here, we introduce a novel analytical framework, termed “maturational networks” (matnets), that achieves this by modelling functional networks as an emerging property of the developing brain. Compared to standard network analysis methods that assume consistent patterns of connectivity across development, our method incorporates age-related changes in connectivity directly into network estimation. We test its performance in a large neonatal sample, finding that the matnets approach characterises adult-like features of functional network architecture with a greater specificity than a standard group-ICA approach; for example, our approach is able to identify a nearly complete default mode network. In the in-utero brain, matnets enables us to reveal the richness of emerging functional connections and the hierarchy of their maturational relationships with remarkable anatomical specificity. We show that the associative areas play a central role within prenatal functional architecture, therefore indicating that functional connections of high-level associative areas start emerging prior to exposure to the extra-utero environment