Structural brain imaging as a diagnostic tool in dementia, why and how?

The demands for more people to be investigated due to cognitive failure and suspected dementia are increasing as increasing numbers of us get older and the incidence of dementia increases. An important part of a dementia study includes the structural imaging of the brain. Two imaging techniques, Computed Tomography (CT) and Magnetic Resonance Imaging (MRI), are used in this context. They differ in many ways and one question is which of the methods should be used in the first instance. Considering the large number of investigations to be expected in the future it is vital that they be cost-effective. Structural imaging aims partly to find secondary causes of cognitive failure and partly to provide support in the differential diagnostic reasoning. The methods differ; CT is significantly cheaper but exposes the patient to radiation, MRI is expensive but does not use X-rays. MRI provides better imaging of cerebrovascular lesions than CT as well as better imaging of structures near the skull base. The difference in diagnostic accuracy is small and it is doubtful whether that difference justifies the large difference in cost.