**4. Magnetic resonance imaging in retinoblastoma**

Magnetic resonance imaging is a type of imaging that use strong magnetic fields and magnetic field gradients to generate anatomical images without the use of ionization radiation.

Magnetic resonance imaging is considered the examination of choice to assess the retinoblastoma tumor extension extraocularly as it has high soft tissue contrast. Although retinoblastoma is usually diagnosed clinically by fundoscopy examination; in cases of unclear ocular medium, MRI can even be used in diagnosing retinoblastoma.

**45**

**Figure 6.**

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

asymmetrical thickening [5].

pattern.

*matrix = 256 × 179; number of excitations = 1].*

clearly detectable on MR images (**Figure 7**).

The European Retinoblastoma Imaging Collaboration (ERIC) released a recommended guideline protocol for MR imaging in retinoblastoma. This MR retinoblastoma protocol uses a 1.5 T in T1 weighted images scout view and turbo spin-echo T2 and PD images if the brain as well as 2 mm thick T2 images of the eye in sagittal cuts. Later axial T1 images and T2 with fat suppression of the orbit with contrast medium of 0.1 mmol/kg gadopentetate dimeglumine are obtained. The advanced use of high resolution three-dimensional T2 weighted imaging allows for then

In this guideline a post laminar optic nerve invasion is characterized by abnor-

*Axial T2-weighted fat sat images: TR = 3600 ms; TE = 95 ms; echo train length = 15; slice thickness = 2.5 mm; FOV = 150 × 150 mm; matrix = 320 × 240; number of excitations = 2].* When approaching MRI images of an intraocular lesion, one of the first parameters to be assessed is the axial length and eye volume as well as the laterality of the disease. Thorough examination of the brain images is also a major step for the detection of any syndromic associations or intracranial metastasis. These parameters are very beneficial in the differentiation of similar intraocular lesions. In cases of persistent fetal vasculature (PFV), they can present with leukocoria or strabismus as well. However, the globe size is markedly smaller in PFV cases (**Figure 6**). On MRI the retinoblastoma tumor borders usually exhibit an irregular lobulated

The eye parameters are relatively smaller in eyes with retinoblastoma with the

Retinoblastoma can also be associated with retinal detachment which can be

*Axial T2 WI image of brain and orbit showing bilateral microphthalmia, hyaloid canal, a characteristic finding of PFV. Images of brain cortex are characteristic of type II cobblestone lissencephaly, hydrocephaly with* 

*dysplastic white matter, over all finding are of Walker-Warburg syndrome.*

Retinoblastoma on T1 weighted MR imaging appears as relatively hyper-intense compared to the adjacent normal vitreous. It also contains areas of low signal intensity within the hyper-intense tumor that reflects the areas of calcification (**Figure 8**).

size of the tumor volume inversely proportional to the size of the globe [6].

0.4 mm sections with high SNR that is sensitive to detect calcification.

mal contrast enhancement of the optic nerve that is > = 2 mm length or any

*Sagittal and axial T1-weighted images: repetition time (TR) = 475 ms; echo time (TE) = 10 ms; slice thickness = 2 mm; field of view (FOV) = 150 × 150 mm;*  *Uses of Radiological Imaging in Retinoblastoma DOI: http://dx.doi.org/10.5772/intechopen.86828*

*Retinoblastoma - Past, Present and Future*

**44**

**Figure 5.**

**Figure 4.**

*nerve due to local invasion.*

ionization radiation.

*calcification suggestive of metastasis.*

**4. Magnetic resonance imaging in retinoblastoma**

Magnetic resonance imaging is a type of imaging that use strong magnetic fields

and magnetic field gradients to generate anatomical images without the use of

*A non-contrast brain CT for follow up of retinoblastoma patient, showed solid suprasellar mass with faint* 

*CT (bone window image) showing right globe enlargement, hyperdense vitreous due to hemorrhage, retrolental intraocular solid mass with central large dystrophic calcification and an enlarged proximal calcified optic* 

Magnetic resonance imaging is considered the examination of choice to assess the retinoblastoma tumor extension extraocularly as it has high soft tissue contrast. Although retinoblastoma is usually diagnosed clinically by fundoscopy examination; in cases of unclear ocular medium, MRI can even be used in diagnosing retinoblastoma.

The European Retinoblastoma Imaging Collaboration (ERIC) released a recommended guideline protocol for MR imaging in retinoblastoma. This MR retinoblastoma protocol uses a 1.5 T in T1 weighted images scout view and turbo spin-echo T2 and PD images if the brain as well as 2 mm thick T2 images of the eye in sagittal cuts. Later axial T1 images and T2 with fat suppression of the orbit with contrast medium of 0.1 mmol/kg gadopentetate dimeglumine are obtained. The advanced use of high resolution three-dimensional T2 weighted imaging allows for then 0.4 mm sections with high SNR that is sensitive to detect calcification.

In this guideline a post laminar optic nerve invasion is characterized by abnormal contrast enhancement of the optic nerve that is > = 2 mm length or any asymmetrical thickening [5].

*Sagittal and axial T1-weighted images: repetition time (TR) = 475 ms; echo time (TE) = 10 ms; slice thickness = 2 mm; field of view (FOV) = 150 × 150 mm; matrix = 256 × 179; number of excitations = 1].*

*Axial T2-weighted fat sat images: TR = 3600 ms; TE = 95 ms; echo train length = 15; slice thickness = 2.5 mm; FOV = 150 × 150 mm; matrix = 320 × 240; number of excitations = 2].*

When approaching MRI images of an intraocular lesion, one of the first parameters to be assessed is the axial length and eye volume as well as the laterality of the disease. Thorough examination of the brain images is also a major step for the detection of any syndromic associations or intracranial metastasis. These parameters are very beneficial in the differentiation of similar intraocular lesions. In cases of persistent fetal vasculature (PFV), they can present with leukocoria or strabismus as well. However, the globe size is markedly smaller in PFV cases (**Figure 6**).

On MRI the retinoblastoma tumor borders usually exhibit an irregular lobulated pattern.

The eye parameters are relatively smaller in eyes with retinoblastoma with the size of the tumor volume inversely proportional to the size of the globe [6].

Retinoblastoma can also be associated with retinal detachment which can be clearly detectable on MR images (**Figure 7**).

Retinoblastoma on T1 weighted MR imaging appears as relatively hyper-intense compared to the adjacent normal vitreous. It also contains areas of low signal intensity within the hyper-intense tumor that reflects the areas of calcification (**Figure 8**).

#### **Figure 6.**

*Axial T2 WI image of brain and orbit showing bilateral microphthalmia, hyaloid canal, a characteristic finding of PFV. Images of brain cortex are characteristic of type II cobblestone lissencephaly, hydrocephaly with dysplastic white matter, over all finding are of Walker-Warburg syndrome.*

#### **Figure 7.**

*MRI orbit T1 weighted fat saturated with contrast imaging showing bilateral faintly enhanced retrolental retinal based mass with right retinal detachment.*

#### **Figure 8.**

*MRI T1 weighted image with contrast, faintly enhanced retrolental mass at left globe corresponding to retinoblastoma tumor core.*

#### **Figure 9.**

*MRI T2 weighted fat saturated image of the orbits showing low signal of retrolental mass corresponding to retinoblastoma tumor at left globe with mild reduction of size of globe.*

A study compared the efficacy of MRI in calcification detection by comparing in vivo T2 weight MRI with ex vivo high-resolution CT. It has found the T2WI correlated well with CT findings. Therefore, combining examination with

**47**

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

ultrasonography and MRI with gradient-echo sequence is thought to be the stan-

On T2 weighted imaging, the retinoblastoma tumor is usually darker than the vitreous resulting in a relative hypo-intense lesion within the vitreous with further patches of hypointensity within corresponding to calcification area

*Axial T2 weighed MRI of the brain and orbit showing a hypointense tumor of the right globe, filling 80% if the* 

Diffusion-weighted imaging (DWI) is a type of MR imaging that depends on the motion of water molecule within the tissue. Highly cellular tissue exhibits lower diffusion coefficients making this modality useful for tumor characterization. DWI is wisely wised for orbital disease as well as brain malignancy. On diffusion weighted imaging (*P* value 1000) the retinoblastoma tumor shows diffuse

A pulse sequence form of DWI that generates various imaging is referred to as ADC images (apparent diffusion coefficient) which measures the magnitude of diffusion resulting a numerical value. The mean ADC value of retinoblastoma was

The low ADC values of retinoblastoma tumors are attributed to the tightly

mm2

In addition, the ADC value was lower in tumors with optic nerve invasion which may correlate with the tumor's likelihood to be poorly differentiated and

mm2

/s, medium tumors

/s, and large tumors (>15 mm) was of

packed nature of high nuclear cytoplasmic ratio of the tumor (**Figure 11**). The use of ADC value images has shown to be well correlated with the degree of tumor differentiation in a study conducted in Saudi Arabia. The ADC value was analyzed in different sized tumors and was shown to be significantly different with various sized tumors. It demonstrates an inverse correlation of the ADC value with the tumor size. The ADC value

dard diagnostic approach for any patient with retinoblastoma [4].

*globe with areas of hypo-intensity representing calcification or retinoblastoma tumor core.*

**5. Diffusion weighted imaging in retinoblastoma**

(**Figures 9** and **10**).

**Figure 10.**

restriction.

0.49 ± 0.12 × 10<sup>−</sup><sup>3</sup>

0.38 ± 0.11 × 10<sup>−</sup><sup>3</sup>

 mm2 /s.

of small tumors (<10 mm) was 0.55 ± 0.09 × 10<sup>−</sup><sup>3</sup>

/s value.

(>10–15 mm) was 0.48 ± 0.09 × 10<sup>−</sup><sup>3</sup>

mm2

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

#### **Figure 10.**

*Retinoblastoma - Past, Present and Future*

*retinal based mass with right retinal detachment.*

**46**

**Figure 9.**

**Figure 7.**

**Figure 8.**

*retinoblastoma tumor core.*

*MRI T2 weighted fat saturated image of the orbits showing low signal of retrolental mass corresponding to* 

*MRI orbit T1 weighted fat saturated with contrast imaging showing bilateral faintly enhanced retrolental* 

*MRI T1 weighted image with contrast, faintly enhanced retrolental mass at left globe corresponding to* 

A study compared the efficacy of MRI in calcification detection by comparing in vivo T2 weight MRI with ex vivo high-resolution CT. It has found the T2WI correlated well with CT findings. Therefore, combining examination with

*retinoblastoma tumor at left globe with mild reduction of size of globe.*

*Axial T2 weighed MRI of the brain and orbit showing a hypointense tumor of the right globe, filling 80% if the globe with areas of hypo-intensity representing calcification or retinoblastoma tumor core.*

ultrasonography and MRI with gradient-echo sequence is thought to be the standard diagnostic approach for any patient with retinoblastoma [4].

On T2 weighted imaging, the retinoblastoma tumor is usually darker than the vitreous resulting in a relative hypo-intense lesion within the vitreous with further patches of hypointensity within corresponding to calcification area (**Figures 9** and **10**).
