MRI protocol for intraocular pathology

General description

This is our standard MRI protocol to visualize the eye and internal structures. It contains isotropic 3D sequences, which can be used for an accurate assessment of the lesion’s dimensions and extent. These scans are complemented with 2D sequences with a higher in-plane resolution that allow for a more detailed radiological evaluation. The scans are generally planned such that all relevant structures, e.g. tumor and adjacent optic nerve, are visible in a single slice. In addition to these anatomical sequences, the protocol contains functional sequences, which provide biomarkers of the lesion’s vascularity (perfusion-weighted imaging) and cellularity (diffusion-weighted imaging). These scans are particularly valuable for the differential diagnosis, but can also be used as an early marker of treatment response.

References

• The technical rationale behind this protocol is described in MRI of Uveal Melanoma
• The images acquired with this protocol have been further described/validated in the following studies:
  • MR imaging characteristics of uveal melanoma with histopathological validation
  • Comparison of Magnetic Resonance Imaging–Based and Conventional Measurements for Proton Beam Therapy of Uveal Melanoma
  • MR-based follow-up after brachytherapy and proton beam therapy in uveal melanoma
  • Eye-specific quantitative dynamic contrast-enhanced MRI analysis for patients with intraocular masses
  • Geometrical accuracy of magnetic resonance imaging for ocular proton therapy planning
  • Quantitative Perfusion-Weighted Magnetic Resonance Imaging in Uveal Melanoma
  • Quantitative assessment of perfusion-weighted magnetic resonance imaging for the differential diagnosis of various intraocular lesions
  • Reproducibility of Perfusion-Weighted and Diffusion-Weighted Magnetic Resonance Imaging in Patients with Ocular Tumours
• This protocol also forms the basis for our eyelid protocol and for the protocol we use for ocular proton therapy planning.

Requirements

Hardware:

• 3 Tesla MRI
• Surface (receive) coil (we use a 47 mm Philips receive coil)
• A support for the head (we use the MaxSupport™ wide shaped (red) variant from Medeo)
• Preferably a mask/goggles for positioning of the coil (ours are made from radiotherapy thermoplastic material and Velcro)
• A power injector to administer a bolus of 0.1 mmol/kg gadoterate meglumine (Dotarem) 6 s after the start of the dynamic scan, followed by a 20 ml injection of isotonic saline with an injection rate of 2 ml/s
• The affected eye is closed with a piece of tape and subsequently covered with wet gauze to limit susceptibility artifacts at the air-cornea interface

Sequences:

• For the 3D sequences, we use a variable refocusing angle to allow for longer echo-trains without blurring, which substantially reduces the scan time. The Philips implementation is called BrainVIEW, but other vendors have similar options (e.g. SPACE on Siemens and CUBE on GE).
• To increase the temporal and spatial resolution of the dynamic contrast enhancement (DCE) scan, the outer part of k-space is acquired over multiple dynamics. On Philips this is called ViewSharing, on Siemens TWIST and on GE TRICKS.
• For the quantification of the perfusion data (and T1 of the tumor), we determine the B1 with the DREAM sequence.

Protocol description

Scans

Planning

3Dtra

Main geometry for the 3D sequences. As these scans have an isotropic resolution and can thus be reformatted in any orientation, they are scanned without angulation.
We plan them in the axial plane, with frequency encoding in the LR direction, to prevent fold-over artifacts.

Dyn

Same geometry as 3Dtra, but with slightly smaller FOV in the FH direction, to facilitate a higher temporal resolution for the dynamic scan.

Obl

The orientation of multi-slice scans is tailored to the location and geometry of the tumor. It is typically perpendicular to the sclera and chosen such that the lesion and associated pathology are visualized in one slice.
For patients with complex pathology, e.g. both retinal detachment and optic nerve invasion, we perform these scans twice with different orientations.

Sequence details

Download the Philips examcard (release 5.6.1.2), or view the complete list of scan parameters.

3D T2

An isotropic 3D T2-weighted sequence with fat suppression, allowing for a 3D visualization of the eye and surrounding anatomy.

Main sequence parameters:

Scan duration

02:57 min

Sequence type

3D TSE

TR/TE

2500 / 330 ms

ACQ voxelsize

0.78 x 0.80 x 0.80 mm

REC voxelsize

0.26 x 0.26 x 0.40 mm

WFS (pix) / BW (Hz)

0.74 / 588

TSE factor / shot length

117 / 616 ms

Fat saturation

SPIR

View the full sequence details.

3D T1

An isotropic 3D T1-weighted sequence, allowing for a 3D visualization of the eye and surrounding anatomy.

Main sequence parameters:

Scan duration

02:07 min

Sequence type

3D TSE

TR/TE

400 / 31 ms

ACQ voxelsize

0.80 x 0.80 x 0.80 mm

REC voxelsize

0.36 x 0.36 x 0.40 mm

WFS (pix) / BW (Hz)

1.78 / 244

TSE factor / shot length

20 / 188 ms

View the full sequence details.

MS T1

A T1-weighted sequence with an increased in-plane resolution, allowing for a better assessment of the origin of the lesion and its relation to the surrounding anatomy.

Main sequence parameters:

Scan duration

01:16 min

Sequence type

Multi-slice TSE

TR/TE

718 / 8.0 ms

ACQ voxelsize

0.50 x 0.50 x 2.00 mm

REC voxelsize

0.21 x 0.21 x 2.00 mm

WFS (pix) / BW (Hz)

1.60 / 272

TSE factor / shot length

6 / 48 ms

View the full sequence details.

MS T2

A T2-weighted sequence with an increased in-plane resolution, allowing for a better assessment of the origin of the lesion and its relation to the surrounding anatomy.

Main sequence parameters:

Scan duration

01:30 min

Sequence type

Multi-slice TSE

TR/TE

1331 / 90 ms

ACQ voxelsize

0.40 x 0.42 x 2.00 mm

REC voxelsize

0.21 x 0.21 x 2.00 mm

WFS (pix) / BW (Hz)

2.25 / 193

TSE factor / shot length

17 / 180 ms

View the full sequence details.

DWI

A diffusion-weighted sequence with two b-values (0 and 800 s/mm²) and ADC map. This sequence is particularly useful for differentiating between benign and malignant lesions.

Main sequence parameters:

Scan duration

01:41 min

Sequence type

Multi-slice TSE

TR/TE

1689 / 51 ms

ACQ voxelsize

1.25 x 1.42 x 2.40 mm

REC voxelsize

0.63 x 0.63 x 2.40 mm

WFS (pix) / BW (Hz)

0.688 / 631.3

TSE factor / shot length

Single shot / 492 ms

Fat saturation

SPIR

View the full sequence details.

3D T1 SPIR

An isotropic 3D T1-weighted sequence with fat suppression. This sequence is particularly useful when there is suspicion of extrascleral tumor extensions. In these patients it provides a reference to determine if the extraocular component is enhancing.

Main sequence parameters:

Scan duration

02:07 min

Sequence type

3D TSE

TR/TE

400 / 31 ms

ACQ voxelsize

0.80 x 0.80 x 0.80 mm

REC voxelsize

0.36 x 0.36 x 0.40 mm

WFS (pix) / BW (Hz)

1.78 / 244

TSE factor / shot length

20 / 188 ms

Fat saturation

SPIR

View the full sequence details.

T1 mapping

Flip angle series

Flip angle mapping sequence for T1 mapping. We use four flip angles (2, 5, 9 and 15 degrees) to accommodate the wide range of T1 values of intraocular masses.

Main sequence parameters:

Scan duration

00:07 min

Sequence type

3D GE

TR/TE

7.0 / 3.1 ms

Flip ange

2, 5, 9, 15 degrees

ACQ voxelsize

1.25 x 1.51 x 1.52 mm

REC voxelsize

1.00 x 1.00 x 1.00 mm

WFS (pix) / BW (Hz)

0.41 / 1059

Fat saturation

PROSET 11

View the full sequence details.

B1-mapping

B1 mapping using the DREAM sequence. This sequence is used to determine the actual flip angle for the T1 mapping and PWI analyses.

Main sequence parameters:

Scan duration

00:14 min

Sequence type

MS GE

TR/TE

7.1 / 2.3 / 3.6 ms

ACQ voxelsize

2.00 x 2.00 x 2.00 mm

REC voxelsize

1.00 x 1.00 x 2.00 mm

TFE dur. shot / acq (ms)

466.5 / 428.2

TFE shot interval (ms)

6997

WFS (pix) / BW (Hz)

0.40 / 1085

View the full sequence details.

PWI

Dynamic contrast-enhanced sequence for perfusion analysis of intraocular masses. TWIST is used to increase the temporal resolution.

Main sequence parameters:

Scan duration

03:59 min

Sequence type

3D GE

TR/TE

4.5 / 2.3 ms

Flip angle

13 degrees

ACQ voxelsize

1.25 x 1.51 x 1.52 mm

REC voxelsize

1.00 x 1.00 x 1.00 mm

WFS (pix) / BW (Hz)

0.39 / 1116

Fat saturation

PROSET 11

Dyn. scan time

00:01.9 s

Central/Periph. size

25% / 20%

View the full sequence details.

3D T1 SPIR Gd

3D T1-weighted sequence with fat suppression after gadolinium contrast administration. This sequence is used to determine the enhancement pattern of the intraocular masses. The sequence parameters are the same as the 3D T1 SPIR sequence.

Main sequence parameters:

Scan duration

02:07 min

Sequence type

3D TSE

TR/TE

400 / 31 ms

ACQ voxelsize

0.80 x 0.80 x 0.80 mm

REC voxelsize

0.36 x 0.36 x 0.40 mm

WFS (pix) / BW (Hz)

1.78 / 244

TSE factor / shot length

20 / 188 ms

Fat saturation

SPIR

View the full sequence details.

MS T1 SPIR Gd

T1-weighted sequence with fat suppression after contrast, the increased in-plane resolution allows for a better assessment of the lesion's relation to the surrounding anatomy.

Main sequence parameters:

Scan duration

01:22 min

Sequence type

Multi-slice TSE

TR/TE

510 / 8.0 ms

ACQ voxelsize

0.50 x 0.50 x 2.00 mm

REC voxelsize

0.21 x 0.21 x 2.00 mm

WFS (pix) / BW (Hz)

1.60 / 271

TSE factor / shot length

6 / 48 ms

Fat saturation

SPIR

View the full sequence details.