Figure 4. Parametric maps of (a) cerebral blood flow (CBF), measured in ml 100 g^–1 min^–1, (b) cerebral blood volume (CBV), measured in ml and (c) mean transit time (MTT), measured in s, in a patient who collapsed in the hospital while visiting a relative. A plain CT at 1 h was normal. The maps show typical reduction of CBF and prolongation of MTT in the territory supplied by the basilar artery, with preserved CBV.