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Optimizing cervical spine imaging: coils and parameters

Application Tip
Rijckaert, Yvonne Philips Healthcare Philips Global

 

Imaging the cervical spine is more difficult than imaging the thoracic and lumbar spine. The following provides tips for optimizing cervical spine images and provides information on the items:

 

  • Choose the right coil
  • Optimize resolution with flexible matrix
  • Optimize contrast

CHOOSE THE RIGHT COIL

An array of RF coils is available for cervical spine imaging. When selecting a coil for your patient, note the remarks with the figures below.

 

        Synergy Spine coil                                         Synergy Head/Neck coil

Cervical Spine imaging Left: Synergy Spine coil                                                        Right: Synergy Head/Neck coil
Cervical Spine imaging
Left: Synergy Spine coil Right: Synergy Head/Neck coil

  

Synergy Spine coil                                              

  • Position the patient's neck to conform with the curve of the Synergy Spine coil, and to cover the spine down to thoracic 4 using 1 coil element only. Do not add element 2 to avoid artifacts originating from the lungs and heart.                         
  • Combine the Synergy Spine coil with strong homogeneity correction.
  • CLEAR (Constant Level Appearance, available in Release 8) may be used.                       

 

Synergy Head/Neck coil

  • The 15 degree tilted head coil puts the patient's neck in a relaxed position and covers the spine down to thoracic 4. 
  • Because the Synergy Head/Neck coil (available for 1.0 T and 1.5 T) combines the standard head coil with two surface coils - positioned anterior and posterior - the Synergy Head/Neck coil provides optimal SNR.
  • Use CLEAR (Constant Level Appearance, available in Release 8) for best results.

 

 

 

Q-Neck coil                                  C1 coil                                       C3 coil

C-Spine imaging with Q-Neck coil, C1 and
C-Spine imaging with Q-Neck coil, C1 and

 

Quadrature Neck coil

  • Note that coverage of the Quadrature Neck coil depends on the patient's neck size. Coverage on a patient with a long, slender neck will be greater than on a patient with a short, thick neck. In the image above, the patient's neck is stretched which can be uncomfortable.
  • Because it is a volume coil, this coil provides good SNR.

 

Circular surface coils: C1 or C3

  • Consider using a C1 or C3 coil for patients with a short, slender neck to boost SNR.
    The C1 circular surface coil (opening 17 cm) covers the spine down to thoracic 2 (left).
    The C3 circular surface coil (opening 11 cm) covers the spine down to cervical 7 (right).
  • Combine these surface coils with a weak homogeneity correction.
  • Combinations of different coils are possible. For example, combine the Synergy Spine coil for sagittal imaging with a circular surface coil (e.g. C3) for axial imaging.

OPTIMIZE RESOLUTION WITH FLEXIBLE MATRIX

Imaging the cervical spine is more difficult than imaging the thoracic and lumbar spine, because it requires combining a small FOV with thin slices and a high matrix - leading to small voxels and lower SNR, but also leads to longer scan times. Flexible matrix - available from Rel. 7.1.2. onward - enables fine tuning of the protocol's resolution, SNR and scan time.

 

Use the flexible matrix size ...

... to avoid having to choose between either 256 for faster imaging or 512 for high resolution imaging - you can choose intermediate values in steps of 16.

 

Set fold-over direction to FH for sagittal imaging ...

... to obtain the best resolution in the AP direction and the fewest flow artifacts.

A FOV of 250 mm, flexible matrix of 272 (recon 512) and a scan percentage of 75% produces a pixel size of 0.92 mm in AP and 1.23 mm in FH direction (0.49 x 0.49 recon).

 

Set fold-over direction to LR for axial imaging ...

... to achieve optimal resolution in the AP direction and the fewest flow artifacts.

A FOV of 150 mm, flexible matrix of 176 and a scan percentage of 70% produces a pixel size of 0.85 mm in AP and 1.22 mm in LR direction (0.59 x 0.59 recon).

 

Note that axial sequences have a smaller FOV and a smaller matrix size in order to achieve the same pixel size. Also scan time will be shorter.  

OPTIMIZE CONTRAST

MTC effects can lower contrast between cord and CSF in T1-weighted imaging. Therefore, to improve image quality:

 

Remove REST slabs ...

... if possible - to reduce MTC effects.

 

Choose a low SAR mode ...

... to reduce MTC.

By reducing the maximum allowed SAR, the amplitude of the B1 transmit field is decreased.

 

Choose a very short TE and a short TR (+-400ms) ...

... to obtain the darkest CSF signal.

 

 

Another challenge is higher CSF pulsation in the cervical spine region versus the thoracic and lumbar spine regions:

 

Choose the highest possible TSE factor in sagittal T2-weighted TSE sequences ...

... to attain the smallest echo spacing and fewest flow void artifacts.

 

Switch off flow compensation ...

... for higher TSE factors and smaller echo spacings to further reduce flow voids.

Choose a long TR of +-4000 ms and a long TE of +-120 ms to obtain high signal from CSF.



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Application Tip
Achieva 1.5T, Intera 1.5T
Release 1, Release 10, Release 11, Release 9
Explorer / Nova Dual, Master / Nova, Nova, Nova Dual, Omni / Stellar, Power / Pulsar, Pulsar
Cervical spine, Neuro
 

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