A descriptive neuroimaging study of retinoblastoma in children: magnetic resonance imaging features.

Purpose: Retinoblastoma (RB) is the most common intraocular malignancy of childhood. Magnetic resonance imaging (MRI) is essential for initial diagnosis, tumour extension, staging, and treatment planning of RB. Awareness of neuro-imaging findings and determining local extent are essential for early diagnosis and therapy guidance. The purpose of this study is to evaluate and to provide a detailed list of neuroimaging features of RB to improve the diagnostic work-up of children with RB.

Material and methods: Retrospective review was performed among children with confirmed RB diagnosis. MRI features were identified to evaluate: 1) growth pattern; 2) intraocular extension; 3) extraocular extension; 4) central nervous system disease; 5) conventional MRI characteristics of the RB lesions; and 6) DWI and ADC characteristics. These features were compared between unilateral and bilateral RB lesions.

Results: Twenty-four children (male/female: 18/6) were included in this study. The mean age at the time of diagnosis was 14.7 (11.4) months. In total, 34 RB lesions (bilateral = 18) were evaluated for the study. The most common features on MRI were: 1) endophytic RB lesion (50%); 2) subretinal haemorrhage (38%); 3) scleral involvement (3%); 4) leptomeningeal disease (12%); 5) contrast enhancement (97%); and 6) restricted diffusion (88%). The mean ADC value was 0.64 (0.15) × 10^-3 mm²/s. Choroidal invasion (p = 0.05) and scleral involvement (p = 0.04) were significantly higher for bilateral RB lesions.

Conclusions: Contrast enhancement and restricted diffusion are the most common neuroimaging features of RB. Choroidal invasion and scleral involvement are more frequently seen in bilateral disease.