European Radiology: Anterior chamber fortification predicts optic nerve invasion in retinoblastoma!

In children with retinoblastoma (RB), optic nerve (ON) infiltration is a major risk factor
for advanced disease.
Orbital MRI is an important imaging modality
to determine risk factors for advanced disease such as ON infiltration.

The function of the orbital lymphatic system is consistent with that of the brain, maintaining retinal balance
by mediating the removal of toxic metabolites around blood vessels from the retina to distal ON.
While it is well known that the sugar water pathway within the orbit can be observed with GBCA-enhanced heavy T2-weighted (hT2) MRI, standard T1-weighted generally does not show the small amount of GBCA
crossing the blood-eye barrier after intravenous injection.

Recently, a study published in the journal European Radiology evaluated imaging markers of ON infiltration in a large cohort of a national RB center, providing an imaging reference for accurate preoperative risk stratification of RB patients
.

The study included 539 orbital MRIs performed with orbital coils, each child under general anaesthesia
.
Differences in AC-to-lens signal intensity ratios (ΔSIRs) were determined between plain sweep and GBCA-enhanced T1-weighted images and correlated with
histopathologically present ON infiltrates.

In a multivariate analysis adjusted for tumor size, the ∆SIR of RB eyes was an independent and significant predictor of ON infiltration (P < 0.
05) and increased
with increasing degree of infiltration.

Figure Retinal blastoma with optic nerve invasion as an example
of orbital MRI.
Sagittal (A, F) and axial fat saturation (B, G) T1-weighted MRI after injection of gadolinium contrast agent (GBCA).

Axial T2-weighted (C, H), axial primitive (D, I), and GBCA enhanced (E, J) T1-weighted MRI images
.
(A-E) A 36-month-old boy with right-sided retinoblastoma (RB) with optic nerve (ON) infiltration
.
While the anterior chamber (AC) of the right eye shows GBCA enhancement (short arrow of B+E), the optic nerve does not show GBCA enhancement (long arrow of B+E).

Subsequent histological analysis shows ON infiltration before lamination
.
(F-J) A 40-month-old boy with right RB with ON infiltration
.
Both the right AC and the distal ON show significant GBCA enhancement (G, J, short and long arrows, respectively).

This study reveals a correlation between anterior chamber GBCA enhancement and optic nerve invasion in retinoblastoma, which may be due to intraorbital lymphatic dysfunction, and may serve as an important indication
of increased brain GBCA excretion in the diagnosis of neurological pathology.

Original source:

Katerina Deike-Hofmann,Paula von Lampe,Maija Eerikaeinen,et al.
Anterior chamber enhancement predicts optic nerve infiltration in retinoblastoma.
DOI:10.
1007/s00330-022-08778-4