Objective: To describe the diagnostic validity of a gadolinium-enhanced routine brain MRI scan with 5 mm section thickness for the detection of optic nerve involvement in patients with retinoblastoma.
Methods: Medical records of primarily enucleated retinoblastoma patients who underwent routine preoperative brain MRI scan with section thickness of 5 mm were retrospectively reviewed. Preoperative magnetic resonance images were independently reviewed in a masked fashion by two radiologists and compared with histological findings.
Results: 41 eyes of 41 patients were included and the mean age at enucleation was 23.1 months. Among 41 eyes, 14 eyes were diagnosed to have post-laminar optic nerve invasion on histopathology. The accuracy, sensitivity and specificity of MRI for the diagnosis of post-laminar invasion were 73.2%, 35.7% and 92.6%, respectively, by the first radiologist and 78.0%, 42.9% and 96.3%, respectively, by the second radiologist. Moderate agreement was found between two radiologists (κ =0.48, p<0.01).
Conclusions: Compared with the results of previous studies using orbital MRI with less than 3 mm section thickness, routine brain MRI with section thickness of 5 mm showed comparable specificity but inferior sensitivity in detecting optic nerve involvement of retinoblastoma.