Role of Arterial Spin Labelling Magnetic Resonance Perfusion in The Grading of Pediatric Brain Tumors

Pediatric brain tumors are one of the most common malignancies in children and represent a leading cause of cancer-related morbidity and mortality worldwide. Accurate preoperative tumor grading plays a pivotal role in determining treatment strategies, surgical planning, prognosis and long-term follow-up. Histopathological grading remains the reference standard; however, non-invasive imaging capable of predicting tumor grade preoperatively are increasingly sought to optimize patient management.

Conventional magnetic resonance imaging (MRI) provides excellent anatomical resolution and lesion localization; nevertheless, substantial overlap persists in morphological imaging features between low-grade and high-grade pediatric brain tumors. In children, contrast enhancement does not correlate with tumor grade, unlike the way it does in adults. Diffusion parameters overlap between benign and aggressive lesions as well, limiting the accuracy of conventional MRI in reliable tumor grading when used alone.

Advanced MRI techniques, particularly perfusion imaging, have emerged as valuable adjuncts for tumor characterization by evaluating tumor vascularity and microcirculation. Arterial spin labelling (ASL) is a non-contrast perfusion MRI technique that quantifies cerebral blood flow (CBF) using magnetically labeled arterial blood water as an endogenous tracer. This technique is especially advantageous in the pediatric population, as it eliminates exposure to gadolinium-based contrast agents and avoids ionizing radiation, aligning with current safety recommendations in children.

High-grade pediatric brain tumors typically demonstrate increased angiogenesis, microvascular proliferation and elevated perfusion compared with low-grade tumors. Recent studies have shown that ASL-derived perfusion parameters correlate with tumor grade and histopathological aggressiveness in pediatric brain tumors.

Despite growing evidence supporting its diagnostic value, arterial spin labelling (ASL) remains underutilized in routine clinical practice for pediatric brain tumor grading. Further prospective studies are required to validate its diagnostic performance and establish its role as a reliable non-invasive imaging biomarker.