ABSTRACT
Objective To summarize the important HR-MRI manifestations of orbital disease in extraconal compartment.Methods Forty-four patients with extraconal orbital disease identified pathologically were analysed retrospectively. MRI of the orbit at 1.5 Tesla was performed with surface coil, thin slice, suitable bandwidth, small field of view (FOV) and large matrix. The analyzed criteria of imaging appearance were: location, shape,size, margins, extent, adjacent structures, and signal intensity.Results Lymphoma, hemangioma, rhabdomyosarcoma, metastasis, pseudotumor, and phlegmon accounted for 70% of all extraconal orbital diseases. Three cases of haemangioma had round shape and clear margin; most lymphoma had irregular shape, unclear margin and big volume; while most rhabdomyosarcoma and metastasis had round shape and unclear margin. The effect of space-occupying of lymphoma was not obvious. One case of lymphangioma had high signal intensity on both T 1- and T 2-weighted images without enhancement. Melanomametastasis appeared hyperintense on T 1- weighted and hypointense on T 2-weighted images. The contrast-enhancement of haemangioma was much more prominent than others. There were characteristic of rhabdomyosarcoma, metastasis, pseudotumor, and phlegmon about their age,clinical history and examination. Conclusion Location criteria, morphological changes, MRI signal intensity, clinical history and the effect of space-occupying are very useful in the differential diagnosis of the orbital disease.