Enhanced MR imaging of hypertrophic pachymeningitis.

Objective: This report illustrates the contrast enhancement characteristics on MR imaging of three patients with hypertrophic pachymeningitis and provides an explanation for the observed imaging findings.

Conclusions: A differential pattern of enhancement, consisting of intense enhancement of the peripheral margin of the abnormal pachymeninges, was present in all cases. In two patients, much of the remaining abnormal pachymeninges did not enhance at all. On the basis of the microscopic pathology of hypertrophic pachymeningitis, the physiology of normal meningeal enhancement on MR imaging, and the described MR appearance of other pachymeningeal lesions, this differential pattern of enhancement should strongly suggest the diagnosis of hypertrophic pachymeningitis.