CT and MRI appearance of osteolytic intraosseous meningioma of the orbit

Objective To study CT and MRI findings of osteolytie intmosseons meningioma of the orbit and evaluate their clinical significance. Methods Eight cases of osteolytic meningioma arising from the orbital bone were confirmed by histopathology. CT and MRI findings of these meningiomas were analyzed retrospectively. Results Among the 8 cases of benign intransseous meningioma of the orbit, 5 were meningotheliomatous, 2 fibrotic and 1 transitional in histopathology. Their locations included 4 in the lateral and superior walls, 3 in the lateral wall, and only one in the lesser wing of sphenoid bone neighboring the orbital apex. The maximum diameter of the lesions ranged from 18 to 47 mm (mean,29 ram). All lesions showed a relatively well-defined margin with 6 cases having an oval shape, and 2 cases having an irregular contour. On CT, 6 lesions demonstrated bony destruction with coarse margin and 2 lesions showed bony cystic dilatation with a well-defined margin. On non-contrast CT, 7 lesions showed isodensity to gray matter and 1 lesion revealed a slight hypodensity. Three lesions showed moderate enhancement on postcontrast CT.On MR T, WI, 6 lesions of osteolytic intaosseous meningioma of the orbit demonstrated isointensity compared to gray mater and 2 lesions slight hypointyensity. On T2WI, 6 lesions showed isointensity and 2 lesions slight hyperintensity. On contrast-enhanced MRI, 6 lesions showed moderate enhancement and 2 lesions exhibited marked enhancement. Heterogeneous signal intensity with inhomogeneous enhancement was seen in 3 lesions on MR images. The time-intensity curve (TIC) of dynamic contrast enhancement of 3 tumors on MRI appeared as rapid enhancing and slow wash-out pattern in 2 cases, rapid enhancing and rapid wash-out pattern in the third one. In comparison to CT, MRI appeared to show the secondary and complicated changes of the lesions more clearly. Conclusions Isointensity with moderate contrast enhancement appears to be the typical manifestation of intraosseous osteolytic meningioma of the orbit on MR. CT is useful for judging the original site of these lesions. MRI is superior to CT in depicting the extent of these lesions. Combined imaging findings of CT and MRI can provide more comprehensive information for diagnosis and therapy of these tumors. Key words: Meningioma;  Orbital neoplasms;  Tomography;  X-ray computed;  Magnetic resonance imaging