Thesis (Ph.D.) - Cairo University - Faculty of Medicine - Department of Radio-diagnosis

Purpose: Retinoblastoma is the most common intraocular childhood malignancy. The initial imaging assessment affects the treatment plan. Our aim is to assess diagnostic accuracy of preoperatively performed magnetic resonance (MR) imaging for detection of tumor extent in patients with histopathologically proved retinoblastoma. Materials and methods: Fifty-eight eyes (in 30 girls and 27 boys) with retinoblastoma were reviewed on unenhanced T1WI, T2WI and gadolinium-enhanced T1-weighted MR images with and without fat suppression. Imaging and pathologic findings such as involvement of choroid, ciliary body, optic nerve, sclera, orbital fat, and pineal gland were compared. Results:The accuracy of MRI in detection of choroidal invasion is about 86.2%; with sensitivity, 95.3% and specificity, 60%. Regarding prelaminar optic nerve invasion, MRI has 60% sensitivity and 82.9% specificity, 75.8% accuracy. Postlaminar optic nerve invasion was correctly detected in 23 eyes; with MRI accuracy, 86.2%; sensitivity, 85.2%; specificity, 87%. Of nine eyes with histologically proven scleral invasion, MRI has accuracy, 93%; sensitivity, 55.6%; specificity, 100%. Extra-ocular fat invasion was suspected on MRI in 5/58 eyes with accuracy, 98.3%; sensitivity, 100%; specificity, 98%. Anterior chamber enhancement is correlated well main MRI and histolopathology findings. Tumor size was statistically associated with postlaminar optic nerve invasion (P=.002) and choroidal invasion (u=.007). Conclusion: MR imaging shows promising role for tumor staging and detection of metastatic risk factors. Tumor diameter, measured with MR imaging, is associated with postlaminar optic nerve and choroidal involvement

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