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1.5T MRA of the spinal cord arteries - Maastricht UMC

ExamCard
Dr. Backes, Walter Maastricht University Medical Center

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The ExamCard was created on Intera 1.5T release 11, but is compatible with higher Intera 1.5T releases and Achieva 1.5T.

ExamCard purpose

Due to their small calibers, clinical imaging of spinal cord arteries and veins was until recently only possible using catheter angiography. Recent advances in MR technology have enabled the use of MR angiography for the depiction of these vessels.

 

Requirements

  1. A large craniocaudal FOV is required (~50 cm), because the AKA may originate from any segmental artery of the thoracolumbar spine and its location varies strongly between individual patients,
  2. A high spatial resolution is required for visualization, as spinal cord arteries and veins have submillimeter to millimeter calibers.
  3. The spatial courses of intradural arteries and veins are quite similar. This could lead to misinterpretations. Reliable differentiation can only be based on temporal differences in the arrival and transit time of a contrast bolus, which requires temporal resolutions in the order of the arteriovenous (AV) transit time of blood in the spinal cord (~10 seconds).

This ExamCard proposes to use a dual phase 3D contrast-enhanced MRA for the depiction of the spinal arteries and veins. This approach has been shown successful for the localization of the AKA at 1.5T field strength. 

ExamCard overview

 

For all scans: check that the appropriate coil elements are selected.

 

The reference scan does not require a breathhold.

 

For an optimal timing of the CE scan, the contrast arrival time needs to be determined both proximal and distal.

 

Total examination time (including patient preparation and administration): ~ 45 minutes.

ExamCard workflow and planning

T2W TSE SAG This image is used to count the disk level.bTFE TRA Depict Th5-L5.MIP 3D GADO Planning: 
On Sagittal survey: Make sure the dorsal FOV lies just against the fat. 
On bFFE TRA: FOV must encompass entire myelum as well as the dorsal part of the aorta.
T2W TSE SAG
bTFE TRA
MIP 3D GADO
This image is used to count the disk level.
Depict Th5-L5.
Planning: On Sagittal survey: Make sure the dorsal FOV lies just against the fat. On bFFE TRA: FOV must encompass entire myelum as well as the dorsal part of the aorta.

Patient preparation

Position the Synergy Spine coil on the table.

 

Prepare the contrast injector:

- 45 ml of a 0.5M contrast agent and

- >50 ml of saline for flush and KVO

or

- 22 ml of a 1.0M contrast agent and

- >50 ml of saline for flush and KVO

 

Prepare the patient with an IV-line.

Instruct the patient to lie still.

Contrast agent / injection protocol

If a conventional 0.5M Gd contrast agent is used, the following injection protocol is advised: 

For the timing bolus:

  - 2 ml contrast agent @ 3 ml/sec is injected, followed by a flush of

  - 25 ml saline @ 3 ml/sec

For the actual contrast-enhanced scan:

  - 43 ml contrast agent @ 3 ml/sec are injected, followed by a flush of

  - 25 ml saline @ 3 ml/sec

 

If a 1.0M contrast agent is used, the injection speed of the saline is adjusted to 1.5 ml/sec:

For the timing bolus:

  - 2 ml contrast agent @ 3 ml/sec is injected, followed by a flush of

  - 25 ml saline @ 1.5 ml/sec

For the actual contrast-enhanced scan:

  - 20 ml contrast agent @ 3 ml/sec are injected, followed by a flush of

  - 25 ml saline @ 1.5 ml/sec

Post-processing / analysis

Subtraction:

When the patient has been lying still very nicely, use the 3D MASK 4NSA from the 3D GADO 4DYN scan. This will result in the best SNR, as the mask contains less noise (due to the 4NSA).

When the patient has been moving, use the 3D MASK 1NSA scan to subtract.

 

Visualization:

(Thin) MIP can be used to visualize the anatomy. Be aware that most images shown in literature and presentations have been created using curved MPR.

 

Results example Open segmental arteries: 
Left: T6 - T11, and L3-L4<br>
Right: T5 - T10, and L3<br>
Collateralisation: strong from lumbal area and upper thoracic regions.<br> 
Adamkiewicz artery originates  T8 left.<br><br>
Results example
Open segmental arteries: Left: T6 - T11, and L3-L4
Right: T5 - T10, and L3
Collateralisation: strong from lumbal area and upper thoracic regions.
Adamkiewicz artery originates T8 left.

References

  1. Backes WH, Nijenhuis RJ, Mess WH, Wilmink FA, Schurink GW, Jacobs MJ.
    Magnetic resonance angiography of collateral blood supply to spinal cord in thoracic and thoracoabdominal aortic aneurysm patients. J Vasc Surg. 2008 Aug;48(2):261-71.
  2. Backes WH, Nijenhuis RJ.
    Advances in spinal cord MR angiography. AJNR Am J Neuroradiol. 2008 Apr;29(4):619-31.
  3. Mull M, Nijenhuis RJ, Backes WH, Krings T, Wilmink JT, Thron A.
    Value and limitations of contrast-enhanced MR angiography in spinal arteriovenous malformations and dural arteriovenous fistulas. AJNR Am J Neuroradiol. 2007 Aug;28(7):1249-58.
  4. Jaspers K, Nijenhuis RJ, Backes WH.
    Differentiation of spinal cord arteries and veins by time-resolved MR angiography. J Magn Reson Imaging. 2007 Jul;26(1):31-40.
  5. Krings T, Lasjaunias PL, Hans FJ, Mull M, Nijenhuis RJ, Alvarez H, Backes WH, Reinges MH, Rodesch G, Gilsbach JM, Thron AK.
    Imaging in spinal vascular disease. Neuroimaging Clin N Am. 2007 Feb;17(1):57-72. Review.
  6. Nijenhuis RJ, Jacobs MJ, Jaspers K, Reinders M, van Engelshoven JM, Leiner T, Backes WH.
    Comparison of magnetic resonance with computed tomography angiography for preoperative localization of the Adamkiewicz artery in thoracoabdominal aortic aneurysm patients. J Vasc Surg. 2007 Apr;45(4):677-85.
  7. Nijenhuis RJ, Jacobs MJ, van Engelshoven JM, Backes WH.
    MR angiography of the Adamkiewicz artery and anterior radiculomedullary vein: postmortem validation. AJNR Am J Neuroradiol. 2006 Aug;27(7):1573-5.
  8. Nijenhuis RJ, Mull M, Wilmink JT, Thron AK, Backes WH.
    MR angiography of the great anterior radiculomedullary artery (Adamkiewicz artery) validated by digital subtraction angiography. AJNR Am J Neuroradiol. 2006 Aug;27(7):1565-72.
  9. Nijenhuis RJ, Leiner T, Cornips EM, Wilmink JT, Jacobs MJ, van Engelshoven JM, Backes WH.
    Spinal cord feeding arteries at MR angiography for thoracoscopic spinal surgery: feasibility study and implications for surgical approach. Radiology. 2004 Nov;233(2):541-7.


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ExamCard
Achieva 1.5T, Intera 1.5T
Release 1, Release 11, Release 12, Release 2
Abdominal MRA, angio, Extracranial MRA, Thoracic MRA, Vascular
 

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