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3.0T Orbits THRIVE - Manchester

ExamCard
Prof. Jackson, Alan Manchester, University of Manchester
de Kok, Wendy Philips Healthcare

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ExamCard Purpose

The ExamCard exists of high-resolution acquisitions only, as the structures to be examined in the orbital region are very small.

T2-weighted TSE sequences are acquired in both transverse and coronal plane.

A 3D-THRIVE based sequence is also included for pre and post-contrast scanning.

 

THRIVE is used instead of a standard fat-suppressed sequence because it has isotropic resolution and gives excellent MPRs. Moreover, SPAIR results in more uniform fat suppression.

ExamCard Layout

Image examples

coronal T2W-TSE transverse T2W_TSE isotropic T1W_3D_TFE
coronal T2W-TSE
transverse T2W_TSE
isotropic T1W_3D_TFE

 

Both coronal and transverse T2-weighted TSE sequences contain 40 slices of 3 mm, and have a pixel size of 0.53 x 0.65 mm.

 

Voxel size of T1W_3D_TFE is 0.91 x 0.91 x 0.95 mm. Profile order is chosen such that optimal T1-weighting is achieved. This scan is acquired pre-contrast injection and is meant to acquire high-resolution T1-weighted anatomical images of the orbital region.

 

post-contrast THRIVE sagittal MPR of THRIVE
post-contrast THRIVE
sagittal MPR of THRIVE

 

SPAIR fat suppression is applied in the post-contrast scan, to increase sensitivity for detection of contrast enhancement: contrast to noise ratio between enhancing regions and suppressed fat will be optimal.

SPAIR is chosen as the fat suppression technique as it is insensitive for B1-variations.

 

As the original dataset is isotropic, MPR reconstructions can be generated.

SPAIR frequency offset

The optimal SPAIR frequency offset can vary over patients. To quickly find the optimal offset, the ExampleCard "orbit fat suppression offset" can be added into this ExamCard. It consists of (amongst others) a group of four fast coronal scans with varying frequency offsets.

 

Clinical example

A 45-year old female patient underwent MR-imaging of the orbits on a 1.5T-system in October 2003. She was almost blind in the right eye. The images showed a lesion of the right anterior clinoid process, possibly a meningioma. Surgery or other treatment was not performed at that time.

 

In February 2005, an MR-examination was requested as part of a follow-up. The exam was performed on a 3.0T-system, because it can offer better resolution and SNR than the 1.5T-system.

Examination parameters / contrast injection protocol

The patient was positioned head first and supine. The 8-channel SENSE Head coil was used to execute the ExamCard as described above.

Gadolinium-based contrast of Magnevist (Schering) at 0.2ml/kg was administered with hand injection, prior to the THRIVE-SPAIR sequence.

Images / diagnosis

transverse T2W_TSE Post-contrast THRIVE Sagittal MPR
transverse T2W_TSE
Post-contrast THRIVE
Sagittal MPR

 

Image examples of the clinical case are shown. The arrows indicate the possible lesion, and the invasion into the optic canal.

 

The radiologist reports:

"Allowing for differences in scan parameters at 1.5T and 3.0T, I believe that the appearances on both scans are static. There is, once again, a durally based mass lesion involving the right anterior clinoid process and planum with extension anteriorly to involve the optic canal and optic nerve at the orbital apex. The features remain entirely consistent with a meningioma."



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ExamCard
Achieva 3.0T
Release 1
Brain, Neuro
 

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