ABSTRACT
Diagnostic neuroimaging is central to modern neurology practice. Magnetic resonance imaging (MRI) is the investigation of choice in most circumstances and in routine clinical use produces images that resemble gross pathology. MRI also offers physiological information beyond anatomical imaging. In neuroradiology, plain x-rays are used for assessing integrity of ventricular shunt tubing, screening after spinal trauma and occasionally to locate a foreign body. MRI is the pre-eminent neuroimaging modality offering the highest sensitivity and diagnostic specificity in most clinical circumstances. Gradient echo or susceptibility weighted imaging depend on local field in homogeneities from paramagnetic substances, such as iron or gadolinium contrast media, and the signal loss they cause. Diffusion weighted imaging is extremely useful in acute stroke imaging but has wider applications such as prion disease, encephalitis, some metabolic disorders, grading tumour malignancy and differentiating between necrotic tumours and pyogenic abscesses. MR and computed tomography angiography have greatly reduced the need for invasive digital subtraction catheter angiography.
