Advances in neuroradiology, like most medical imaging specialties, are driven by technical improvements and clinical refinements of investigation paradigms. Technically, the emphasis has always been to improve image quality whilst reducing the use of ionizing radiation. This has led to a greater reliance on computer post-processing of the images and use of modalities that do not involve ionizing radiation, such as MRI and Doppler ultrasound. In the last few years sub-specialization of neuroradiologists has occurred with specialists in paediatric neuroradiology, head and neck imaging, and interventional neuroradiologists emerging from a reducing number of generalists. This chapter describes in detail the main imaging modalities used in clinical practice. The intention is to show how each technology is deployed for investigations and treatments. The emphasis is on helping the reader to understand which is the most appropriate type of imaging in different circumstances,when contrast enhancement of scans is needed (and when it is not) and how different modalities frequently complement each other. The more infrequently used techniques are set in context within neuroradiology and specialist functional imaging and research imaging are briefly described. © 2008 Elsevier Ltd. All rights reserved.