Low-flow vascular malformation: contribution of sequential postcontrast MRI acquisitions.

A 50-year-old man was referred for subacute intracranial hypertension. MRI revealed a well-circumscribed lesion in the posterior fossa that was hypointense on T1-weighted imaging and hyperintense on T2-weighted imaging (figure 1, A and E). Cerebral blood volume map and sequential postcontrast T1-weighted images showed progressive increase in the homogeneity of the contrast enhancement, indicating that the lesion had low but substantial flow (figure 1, B–D). Digital subtraction angiography showed a vascular lesion with a central to peripheral pattern of vascularity and absence of early venous return (figure 1, F–H). The lesion was resected. Pathologic examination revealed a capillary-venous malformation (figure 2). This case highlights that MRI can identify low flow in vascular malformations.