**7. MRI's uses in the staging and prognosis of retinoblastoma**

Although MRI can aid in the diagnosis of retinoblastoma by the aforementioned characteristics, it is more widely used for the staging of retinoblastoma. Like all other malignancies, tumor staging in retinoblastoma is essential for the prognosis predictions.

The use of MRI has changed the accuracy of assessing metastatic risk factors as the initial retinoblastoma staging of patients before the use of MRI varied after MR imaging were obtained.

The extension of retinoblastoma is usually by direct extension into adjacent structures. Intraocular extension of the tumor can easily be visualized during examination in patients with good posterior pole visualization. MR imaging has been widely used to evaluate the extra-ocular and intracranial extension and can also aid in the evaluation of intraocular tumor extension [11].

Intraocular extension can be detected by choroidal irregularities. Choroidal invasion identification is important in the prognosis of the disease. It changes the prognosis of retinoblastoma by increasing the mortality rate up to 24–65% depending on the severity of invasion [12].

In the assessment of extra-ocular retinoblastoma extension, the most important structure to evaluate is the optic nerve. Involvement of the optic nerve in retinoblastoma alters the prognosis and the management of the disease. The overall mortality rate of retinoblastoma without optic nerve invasion is 10%. If the invasion of the optic nerve reaches through the lamina cribrosa, the mortality may rise up to 15%. Moreover, if the extension is posterior to the lamina cribrosa the mortality rises up to 44%. This makes the optic nerve assessment by MR imaging crucial in any retinoblastoma case with proper identification of the level of optic nerve invasion. On MRI, the affected optic nerve appears thickened and irregular with high enhancement of the nerve itself and the area surrounding it [11].

A study showed that the specificity of MRI in detecting optic nerve invasion past the lamina cribrosa to reach up to 80% and a sensitivity of 74%. This makes MR imaging the most superior non-invasive method in the detection of retinoblastoma optic nerve invasion [13] (**Figures 13** and **14**).

Ophthalmic surgeons require extra measurements of the invasion to take extra precautions during the enucleation of the affected eye. It is important for the MR image to demonstrate if the retrolaminar optic nerve invasion extends more than 5 mm posteriorly. This is particularly crucial to identify prior to surgical intervention as the tumor may be cut through during the enucleation. If such complication happens, the distal part of the tumor that remains is connected to the brain and may progress to brain metastasis. In such cases, the surgeon might consider doing an orbitotomy to be able to reach further posterior and dissect at least 10 mm from

#### **Figure 13.**

*MRI T2 weighted image of brain and orbit showing right globe retrolental hypo-intense tumor core, retro bulbar extension and extensive long segment right optic nerve invasion resulting in right globe proptosis.*

**51**

of over 90%.

*Uses of Radiological Imaging in Retinoblastoma DOI: http://dx.doi.org/10.5772/intechopen.86828*

optic nerve regardless of MR findings.

**8. Conclusion**

**Figure 14.**

*retinoblastoma.*

alters the management plan.

cistern. It represents 1.5–5% of all RB patients [15].

the suggested tumor margin. Despite the advancement of MRI, it has limitations in detecting microscopic optic nerve invasion. Studies have shown a discrepancy between histological results in optic nerve assessment (gold standard) and MRI results [14]. This dictates the need for thorough histopathological assessment of the

*MRI T1 weighted image with contrast of the same patient delineating the retrobulbar extension, enhanced and enlarged right optic nerve, leptomeningeal enhancement due to direct extension and CSF seeding of* 

An important disease entity in retinoblastoma is the trilateral retinoblastoma disease. It refers to rare disease that is characterized by bilateral ocular RB and a primitive midline neuroectodermal tumor in the pineal region or the suprasellar

Retinoblastoma is the most common primary ocular malignancy in children. Diagnostic imaging has changed the accuracy of diagnosing and staging retinoblastoma. There are many imaging modalities that are currently in use for retinoblastoma tumor like ultrasonography, computerized tomography and magnetic resonance imaging. MR images of the brain and spinal cord need to be obtained routinely in retinoblastoma patients in institutes where MRI is accessible. They aid in the diagnosis and prognosis of the disease. As the retinoblastoma tumor seeding may spread via cerebrospinal fluid and reach the intracranial resulting in brain metastasis, MRI can clearly delineate these metastatic lesions, which eventually

MRI can show retrolaminar optic nerve and choroidoscleral infiltration and spread

A purely ocular tumor confined within the globe reaches a survival rate of 90% AT 5-years whereas a tumor that has extended outside the globe has a mortality rate

of tumor into the brain and spine more accurately than other diagnostic imaging.

**50**

*Uses of Radiological Imaging in Retinoblastoma DOI: http://dx.doi.org/10.5772/intechopen.86828*

#### **Figure 14.**

*Retinoblastoma - Past, Present and Future*

ing on the severity of invasion [12].

optic nerve invasion [13] (**Figures 13** and **14**).

been widely used to evaluate the extra-ocular and intracranial extension and can

Intraocular extension can be detected by choroidal irregularities. Choroidal invasion identification is important in the prognosis of the disease. It changes the prognosis of retinoblastoma by increasing the mortality rate up to 24–65% depend-

In the assessment of extra-ocular retinoblastoma extension, the most important

A study showed that the specificity of MRI in detecting optic nerve invasion past

Ophthalmic surgeons require extra measurements of the invasion to take extra precautions during the enucleation of the affected eye. It is important for the MR image to demonstrate if the retrolaminar optic nerve invasion extends more than 5 mm posteriorly. This is particularly crucial to identify prior to surgical intervention as the tumor may be cut through during the enucleation. If such complication happens, the distal part of the tumor that remains is connected to the brain and may progress to brain metastasis. In such cases, the surgeon might consider doing an orbitotomy to be able to reach further posterior and dissect at least 10 mm from

the lamina cribrosa to reach up to 80% and a sensitivity of 74%. This makes MR imaging the most superior non-invasive method in the detection of retinoblastoma

*MRI T2 weighted image of brain and orbit showing right globe retrolental hypo-intense tumor core, retro bulbar extension and extensive long segment right optic nerve invasion resulting in right globe proptosis.*

structure to evaluate is the optic nerve. Involvement of the optic nerve in retinoblastoma alters the prognosis and the management of the disease. The overall mortality rate of retinoblastoma without optic nerve invasion is 10%. If the invasion of the optic nerve reaches through the lamina cribrosa, the mortality may rise up to 15%. Moreover, if the extension is posterior to the lamina cribrosa the mortality rises up to 44%. This makes the optic nerve assessment by MR imaging crucial in any retinoblastoma case with proper identification of the level of optic nerve invasion. On MRI, the affected optic nerve appears thickened and irregular with

high enhancement of the nerve itself and the area surrounding it [11].

also aid in the evaluation of intraocular tumor extension [11].

**50**

**Figure 13.**

*MRI T1 weighted image with contrast of the same patient delineating the retrobulbar extension, enhanced and enlarged right optic nerve, leptomeningeal enhancement due to direct extension and CSF seeding of retinoblastoma.*

the suggested tumor margin. Despite the advancement of MRI, it has limitations in detecting microscopic optic nerve invasion. Studies have shown a discrepancy between histological results in optic nerve assessment (gold standard) and MRI results [14]. This dictates the need for thorough histopathological assessment of the optic nerve regardless of MR findings.

An important disease entity in retinoblastoma is the trilateral retinoblastoma disease. It refers to rare disease that is characterized by bilateral ocular RB and a primitive midline neuroectodermal tumor in the pineal region or the suprasellar cistern. It represents 1.5–5% of all RB patients [15].

### **8. Conclusion**

Retinoblastoma is the most common primary ocular malignancy in children. Diagnostic imaging has changed the accuracy of diagnosing and staging retinoblastoma. There are many imaging modalities that are currently in use for retinoblastoma tumor like ultrasonography, computerized tomography and magnetic resonance imaging. MR images of the brain and spinal cord need to be obtained routinely in retinoblastoma patients in institutes where MRI is accessible. They aid in the diagnosis and prognosis of the disease. As the retinoblastoma tumor seeding may spread via cerebrospinal fluid and reach the intracranial resulting in brain metastasis, MRI can clearly delineate these metastatic lesions, which eventually alters the management plan.

MRI can show retrolaminar optic nerve and choroidoscleral infiltration and spread of tumor into the brain and spine more accurately than other diagnostic imaging.

A purely ocular tumor confined within the globe reaches a survival rate of 90% AT 5-years whereas a tumor that has extended outside the globe has a mortality rate of over 90%.

This drastic difference makes staging and the use of ancillary testing vital for the prognosis and survival rate estimation which further guides the treatment decision.

It is now currently recommended for any newly diagnosed patient with retinoblastoma to undergo an MRI [13].

MRI can also offer hope for future advancement of early diagnosis. It has recently shown to aid in very early fetal diagnosis of retinoblastoma in a fetus with high-risk of RB and may be implemented as a part of future screening protocol in high risk population [16].
