MRI can reliably differentiate optic nerve inflammation from tumor invasion in retinoblastoma with orbital cellulitis

Retinoblastoma and beyond: pediatric orbital mass lesions

Various space occupying lesions can arise in the orbit, ranging from developmental anomalies to malignancies, and many of the diseases occurring in children are different from the pathologies in the adult population. As the clinical presentation is frequently nonspecific, radiologic evaluation is essential for lesion detection and characterization as well as patient management. While orbital masses may in some cases involve multiple compartments, a simple compartmental approach is the key for the diagnosis on imaging studies, and MRI is the modality of choice. This pictorial review presents the most common and characteristic non-emergent pediatric orbital lesions, stressing their MRI and CT appearances, including specific differentiating features. The lesions are subdivided into 4 compartments: intraocular, intraconal, extraconal, and orbital walls. Retinoblastoma, Coats disease and persistent fetal vasculature; optic pathway glioma and lymphovascular malformations; rhabdomyosarcoma, infantile hemangioma, neurofibroma and lymphoma; neuroblastoma, leukemia/myeloid sarcoma, Langerhans cell histiocytosis and dermoid are reviewed in their respective compartments.

Optic nerve thickening on high-spatial-resolution MRI predicts early-stage postlaminar optic nerve invasion in retinoblastoma

OBJECTIVES

To assess the diagnostic accuracy of nerve thickening on MRI to predict early-stage postlaminar optic nerve invasion (PLONI) in retinoblastoma. Furthermore, this study aimed to incorporate measurements into a multiparametric model for radiological determination of PLONI.

METHODS

In this retrospective multicenter case-control study, high-spatial-resolution 3D T2-weighted MR images were used to measure the distal optic nerve. Histopathology was the reference standard for PLONI. Two neuroradiologists independently measured the optic nerve width, height, and surface at 0, 3, and 5 mm from the most distal part of the optic nerve. Subsequently, PLONI was scored on contrast-enhanced T1-weighted and 3D T2-weighted images, blinded for clinical data. Optic nerve measurements with the highest diagnostic accuracy for PLONI were incorporated into a prediction model for radiological determination of PLONI.

RESULTS

One hundred twenty-four retinoblastoma patients (median age, 22 months [range, 0-113], 58 female) were included, resulting in 25 retinoblastoma eyes with histopathologically proven PLONI and 206 without PLONI. ROC analysis of axial optic nerve width measured at 0 mm yielded the best area under the curve of 0.88 (95% confidence interval: 0.79, 0.96; p < 0.001). The optimal width cutoff was ≥ 2.215 mm, with a sensitivity of 84% (95% CI: 64, 95%) and specificity of 83% (95% CI: 75, 89%) for detecting PLONI. Combining width measurements with the suspicion of PLONI on MRI sequences resulted in a prediction model with an improved sensitivity and specificity of respectively up to 88% and 92%.

CONCLUSION

Postlaminar optic nerve thickening can predict early-stage postlaminar optic nerve invasion in retinoblastoma.

CLINICAL RELEVANCE STATEMENT

This study provides an additional tool for clinicians to help determine postlaminar optic nerve invasion, which is a risk factor for developing metastatic disease in retinoblastoma patients.

KEY POINTS

• The diagnostic accuracy of contrast-enhanced MRI for detecting postlaminar optic nerve invasion is limited in retinoblastoma patients. • Optic nerve thickening can predict postlaminar optic nerve invasion. • A prediction model combining MRI features has a high sensitivity and specificity for detecting postlaminar optic nerve invasion.

MR Imaging of Adverse Effects and Ocular Growth Decline after Selective Intra-Arterial Chemotherapy for Retinoblastoma

This retrospective multicenter study examines therapy-induced orbital and ocular MRI findings in retinoblastoma patients following selective intra-arterial chemotherapy (SIAC) and quantifies the impact of SIAC on ocular and optic nerve growth. Patients were selected based on medical chart review, with inclusion criteria requiring the availability of posttreatment MR imaging encompassing T2-weighted and T1-weighted images (pre- and post-intravenous gadolinium administration). Qualitative features and quantitative measurements were independently scored by experienced radiologists, with deep learning segmentation aiding total eye volume assessment. Eyes were categorized into three groups: eyes receiving SIAC (Rb-SIAC), eyes treated with other eye-saving methods (Rb-control), and healthy eyes. The most prevalent adverse effects post-SIAC were inflammatory and vascular features, with therapy-induced contrast enhancement observed in the intraorbital optic nerve segment in 6% of patients. Quantitative analysis revealed significant growth arrest in Rb-SIAC eyes, particularly when treatment commenced ≤ 12 months of age. Optic nerve atrophy was a significant complication in Rb-SIAC eyes. In conclusion, this study highlights the vascular and inflammatory adverse effects observed post-SIAC in retinoblastoma patients and demonstrates a negative impact on eye and optic nerve growth, particularly in children treated ≤ 12 months of age, providing crucial insights for clinical management and future research.

Diagnostic Imaging for Retinoblastoma Cancer Staging: Guide for Providing Essential Insights for Ophthalmologists and Oncologists

Retinoblastoma is the most common cause of all intraocular pediatric malignancies. It is caused by the loss of RB1 tumor suppressor gene function, although some tumors occur due to MYCN oncogene amplification with normal RB1 genes. Nearly half of all retinoblastomas occur due to a hereditary germline RB1 pathogenic variant, most of which manifest with bilateral tumors. This germline RB1 mutation also predisposes to intracranial midline embryonal tumors. Accurate staging of retinoblastoma is crucial in providing optimal vision-, eye-, and life-saving treatment. The AJCC Cancer Staging Manual has undergone significant changes, resulting in a universally accepted system with a multidisciplinary approach for managing retinoblastoma. The authors discuss the role of MRI and other diagnostic imaging techniques in the pretreatment assessment and staging of retinoblastoma. A thorough overview of the prevailing imaging standards and evidence-based perspectives on the benefits and drawbacks of these techniques is provided. Published under a CC BY 4.0 license. Test Your Knowledge questions for this article are available in the supplemental material.

Can Enhancement Pattern in Normal-Sized Optic Nerves on Magnetic Resonance Imaging Better Predict Tumor Invasion in Retinoblastoma Eyes?

Introduction

Optic nerve (ON) enhancement alone without ON thickening on contrast-enhanced magnetic resonance imaging (CE-MRI) can be associated with post-laminar optic nerve invasion (PLONI) in eyes with group E retinoblastoma. A few case reports and retrospective studies in the literature show a poor correlation between ON enhancement on MRI and ON invasion on histopathological examination (HPE). There is no universal consensus on the management of such cases. It is desirable that the presence and extent of a true ON invasion be reliably picked up before planning upfront enucleation in order to avoid stage II disease.

Methods

In a prospective study conducted at a tertiary eye care center in North India, all retinoblastoma patients presenting with ON enhancement on imaging were evaluated. Demographic and imaging details, histopathological findings, and treatment details were recorded. The length and pattern of enhancement noted on MRI were correlated with histopathology. Follow-up was done till the end of the study period.

Results

Six group E retinoblastoma eyes were evaluated. 3 eyes (50%) showed solid enhancement, 2 eyes (33.33%) had tram track pattern and 1 eye (16.66%) showed punctate enhancement pattern on CE-MRI. On histopathology, 5 (83.33%) cases showed PLONI and all 6 (100%) had ON head infiltration. The cut end of the ON was free in all cases. On correlating MRI and HPE, all eyes with solid enhancement pattern showed PLONI, of which 2/3 (66.6%) had diffuse ON infiltration. Only 50% of eyes with tram track patterns showed PLONI. The case which showed a punctate enhancement pattern showed focal infiltration by tumor cells with vacuolated cytoplasm on HPE. At the last follow-up, all patients were alive and free of disease.

Conclusion

ON enhancement patterns may make it more predictive for PLONI on HPE. Solid enhancement pattern appears to correlate better with the extent of ON invasion on HPE, and longer lengths of solid ON enhancement may be considered for neoadjuvant chemotherapy rather than upfront enucleation.