Findings from imaging examinations in 10 patients with pathologically confirmed RDD were retrospectively reviewed. Two radiologists evaluated the lesion location, shape, size, number, edge, cerebral edema, homogeneous or heterogeneous appearance, attenuation and signal intensity, degree of enhancement, and the relation between lesions and meninges.
RDD in CNS showed similar features in imaging: an extra-axial, well-circumscribed, dura-based mass, isodense or hyperdense on CT, isointensity on T1-weighted imaging and isointensity with hypointensity on T2-weighted imaging. The mass enhanced markedly and homogeneously after the administration of contrast agent and demonstrated dural tail sign in all cases. Significant perifocal edema was associated with the masses. Remarkably, seven patients (77.8%) showed strong hypointensity within isointensity on T2-weighted or FLAIR images and no calcification was observed in CT images or pathologic specimens.
Although RDD in the CNS is a rare process, it should be considered in the differential diagnoses for meningioma. We believe that a typical representation of hypointensity irrelevant to calcification on T2-weighted or FLAIR images can suggest the diagnosis of RDD.