Cerebral Microbleeds: Cerebral microbleeds in relation to hypertensive arteriopathy

The cerebral microbleed (CMB) mimics form two types: those that contain blood products and those that do not (resembling CMBs because of shared signal intensity and morphology on gradient-recalled echo (GRE) MRI). This chapter describes both types, and outlines how these can be differentiated from true CMBs. It suggests a topographical approach to the recognition of CMB mimics on brain imaging. The GRE sequences used in the detection of CMBs are sensitive not only to blood breakdown products (deoxyhemoglobin, methemoglobin, hemosiderin and ferritin) but also to other paramagnetic substances such as calcium, manganese and iron, all of which may appear as foci of low signal. In lobar regions of the brain, common CMB mimics include vascular flow voids and hypointensities arising from partial volume artefact. The development of susceptibility-weighted imaging (SWI) has improved the detection of structures containing extravascular blood products, as well as those containing venous deoxygenated blood.