Background

Gliomas are the most common primary brain tumour. They are graded using the WHO classification system, with Grade II‐IV astrocytomas, oligodendrogliomas and oligoastrocytomas. Low‐grade gliomas (LGGs) are WHO Grade II infiltrative brain tumours that typically appear solid and non‐enhancing on magnetic resonance imaging (MRI) scans. People with LGG often have little or no neurologic deficit, so may opt for a watch‐and‐wait‐approach over surgical resection, radiotherapy or both, as surgery can result in early neurologic disability. Occasionally, high‐grade gliomas (HGGs, WHO Grade III and IV) may have the same MRI appearance as LGGs. Taking a watch‐and‐wait approach could be detrimental for the patient if the tumour progresses quickly. Advanced imaging techniques are increasingly used in clinical practice to predict the grade of the tumour and to aid clinical decision of when to intervene surgically. One such advanced imaging technique is magnetic resonance (MR) perfusion, which detects abnormal haemodynamic changes related to increased angiogenesis and vascular permeability, or" leakiness" that occur with aggressive tumour histology. These are reflected by changes in cerebral blood volume (CBV) expressed as rCBV (ratio of tumoural CBV to normal appearing white matter CBV) and permeability, measured by K trans.

Objectives

To determine the diagnostic test accuracy of MR perfusion for identifying patients with primary solid and non‐enhancing LGGs (WHO Grade II) at first presentation in children and adults. In performing the quantitative analysis for this review, patients with LGGs were considered disease positive while patients with HGGs were considered disease negative.