Transient reduction in venous susceptibility during posterior reversible encephalopathy syndrome.

We report a case of posterior reversible encephalopathy syndrome (PRES) in which followed-up MRI demonstrated a transient reduction in venous signal on initial SWAN images. The progressive normalization of venous signal on D10 and D40 imaging paralleled the progressive decrease of hyperperfusion on CBF images. Decreased venous susceptibility has never been reported in PRES; it relates most likely to a transient BOLD effect induced by brain hyperperfusion.