Updated Recommendations for Retinoblastoma Imaging: 2025 ERIC and ERG Guidelines

Overview

Retinoblastoma imaging guidelines have been updated by the European Retinoblastoma Imaging Collaboration and the European Retinoblastoma Group to incorporate advances in MRI technology and refined diagnostic criteria. High-resolution MRI protocols are emphasized for accurate staging and differentiation from mimicking conditions, with ultrasound as a complementary tool and CT no longer recommended.

Background

Retinoblastoma is the most common intraocular malignancy in children, typically diagnosed by fundoscopy and ultrasonography under general anesthesia. Imaging plays a critical role in confirming diagnosis when fundoscopy is limited and in assessing tumor extension, particularly via MRI. The eighth edition of the AJCC TNM classification provides comprehensive staging, guiding treatment decisions. Advances in imaging technology and research have prompted updated guidelines to standardize MRI protocols and reporting.

Data Highlights

Ultrasound with high-frequency probes (up to 22 MHz) detects microcalcifications, nearly pathognomonic for retinoblastoma. MRI should be performed on 3-T systems with multi-channel head coils or 1.5-T systems with surface coils. Recommended MRI parameters include an in-plane pixel size ≤ 0.3 × 0.3 mm and slice thickness ≤ 2 mm. Axial isotropic 3D heavily T2-weighted sequences with slice thickness ≤ 0.5 mm are preferred for orbit imaging. CT is no longer recommended due to low sensitivity and radiation risks.

Key Findings

• Ultrasound remains essential for detecting intratumoral calcifications, especially when fundoscopy is limited.
• CT is discouraged due to low diagnostic accuracy and radiation exposure risks in children.
• High-resolution contrast-enhanced MRI is the gold standard for pretreatment staging, assessing intra- and extraocular spread, and intracranial involvement.
• Optimal MRI hardware includes 3-T systems with multi-channel head coils or 1.5-T systems with surface coils covering both eyes.
• General anesthesia is recommended to minimize eye movement and ensure high-quality imaging; the "feed-and-swaddle" technique is a less preferred alternative for infants under 6 months.
• MRI protocols should include axial isotropic 3D heavily T2-weighted sequences and pre- and post-contrast 2D axial T1-weighted spin echo images aligned precisely with the optic nerve axis.

Clinical Implications

Clinicians should prioritize high-resolution MRI over CT for retinoblastoma evaluation to reduce radiation exposure and improve diagnostic accuracy. Ultrasound remains a valuable adjunct for detecting calcifications. Proper patient preparation, including general anesthesia, is critical for obtaining optimal imaging quality. Standardized MRI protocols enhance detection of tumor extent and guide appropriate management.

Conclusion

The updated 2025 ERIC and ERG guidelines emphasize the central role of high-resolution MRI in retinoblastoma diagnosis and staging, recommending against CT use and advocating for standardized imaging protocols to improve patient outcomes.

References

1. AJCC 8th Edition (2024) -- TNM Classification for Retinoblastoma
2. ERIC 2012 -- Initial Retinoblastoma Imaging Guidelines
3. ERIC Adaptations -- Imaging Guideline Updates
4. Multiple Studies 2012-2024 -- Advances in Retinoblastoma Imaging
5. Ultrasound and MRI Imaging Studies -- Detection of Microcalcifications