Arch and Carotids

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Protocol Name = MRB14 MRA Arch-Carotids 1.09
Entry = Head First
Position = Supine
Coil = 8NVARRAY_A
Series number = 8
Series Notes Pulse Sequence Mode Imaging Options Plane FOV Thickness Spacing Frequency Phase TR TE Flip Angle
3 pl loc Spin Echo 2D Seq, Fast, SS 3-PLANE 36.0 10.0 5.0 256 128 Minimum 120.0
Calibration Gradient Echo 2D Fast, Calib AXIAL 48.0 7.0 0.0
AXL 2D TOF MRA NECK Vasc TOF SPGR 2D FC, Seq, EDR, Fast AXIAL 22.0 1.5 0.0 256 160 Minimum Minimum 60
COR 3D MRA pre Vasc TOF SPGR 3D EDR, Fast, ZIP2, Asset CORONAL 30.0 2.8 512 256 Minimum 30
COR 3D MRA +C FT Vasc TOF SPGR 3D EDR, Fast, ZIP2, Fluoro, Asset CORONAL 30.0 2.8 512 256 Minimum 30
---OPTIONAL--- Gradient Echo 2D Seq, Fast 3-PLANE 36.0 10.0 5.0 256 128
AXL 2D TOF GRE Vasc TOF 2D FC, Seq, EDR AXIAL 22.0 1.5 0.0 256 160 Minimum Minimum 60
AXL 3D TOF BIFURCATION Vasc TOF SPGR 3D FC, ZIP512 AXIAL 24.0 1.6 256 192 33.0 Minimum 30


Overview
This carotid MRA protocol is based on the earlier protocols devised by Dr. Richard Watts and the team of Physicists and Radiologists at Cornell. It is based on a cleverly designed 3D Gd MRA pulse sequence which starts initially without any phase encoding in the slice direction. This enables acquisition of a Projection of the 3D volume at a temporal rate of two times per second. In this mode, the operator watches for the arrival of the Gadolinium bolus. When the operator sees the bolus arriving in the carotid arteries, the phase encoding is activated to begin the 3D Gd MRA scan beginning with acquisition of the center of K-space.

Sometimes it is difficult to see the contrast arriving in the carotid arteries. To make the contrast easier to detect, the 2D Projection image can be shifted down into the chest. This way the operator can watch Gadolinium entering via the subclavian vein, passing through the right heart, then through the lungs, back to the left heart and finally with Gadolinium reaches the aortic arch, the 3C scan is activated. This ensures perfect bolus timing for every case.

In order to position the 3D volume optimally, we first acquire a 20 time-of-flight scan of the carotid arteries. This is done in two acquisitions. One high resolution 2D TOF from the circle of Willis down to the base of the neck. This provides an additional sequence for evaluating the carotid bulb where disease is most prevelant. A second 2D time-of-flight scan is performed to identify the location of the aortic arch for positioning the 3D volume correctly.


Indications
• Stroke
• Suspected stroke
• Transient ischemic attack (TIA)
• Confirm carotid ultrasound finding
• Pre-op for carotid endarterectomy


Scheduling
• MRA of the neck with Gadolinium
• MRA of Head (optional)
• MRA of Chest (optional)

First Ask:
1. Have you had carotid MRA before?
2. Have you had carotid ultrasound or doppler ultrasound?
3. Have you had carotid artery surgery?
4. Have you had a carotid endarterectomy?


Patient Preparation
• Start intravenous line (20 or 22 gauge iv) in the right arm to avoid filling the left brachiocephalic vein with highly concentrated gadolinium.
• Valium (diazepam: 5-10mg po) or Xanax (1-2 mg po) if patient is claustrophobic. Instruct the patient not to take the Valium until arriving at the MRI center in case we are running behind schedule. Also the patient will need to be accompanied by a friend or relative to take them home and absoutely they cannot drive for 10 hours.

Coil: A neurovascular coil which extends down low enough on the chest to include the aortic arch is essential for simultaneously imaging the carotid origins and the bifurcations with a single injection of contrast. If a neurovascular, head/neck coil is not available then it maybe acceptable to use a torso array coil with elements placed anterior and posterior to the upper chest and neck. For our MRI devices, use neurovascular coil, "NVARRAY".

Patient Positioning: Supine, head first,

Landmark: If imaging neck only, Landmark just below the angle of mandible. If imaging brain and neck landmark above the angle of the mandible and use larger FOV.


Billing Code
MRA Head or Neck: 770541 MRI Neck:770540 N Computer Reconstructions: 76375


ICD9 Codes
433.1 Carotid Atherosclerosis
433.1 Basilare artery atherosclerosis
Cerebral artery atherosclerosis
442.81 Carotid aneurysm in neck
437.3 Intracranial internal carotid aneurysm
442.82 Subclavian artery aneurysm
437.3 Cerebral artery aneurysm
430 Ruptured
747.81 Congenital
446.7 Takayusu’s Disease
446.1 Giant Cell arteritis
446.1 Kawasaki Disease
447.6 Arteritis, unspecified
446.7 Aortic arch
437.4 Cerebral


Normal Dictation
The Patients carotid arteries and neck were imaged on Sagittal T1,Axial 2D TOF and coronal 3D dynamic Gd:MRA. MRA data was post-processed on a computer work station to obtain reformations and sub-volume MIP’s optimized for each carotid artery and the aortic arch.
Clinical Statement:

Technique:

Findings:
The great vessel origins are all widely patent. Both right and left carotid arteries have normal caliber and contour with no significant stenosis, atherosclerotic disease or dissection. The vertebrae is larger suggesting (right/left) dominance.

Impression:
Normal Carotid MRA


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May 19, 2010  Tags: , , ,   Posted in: head-neck-arch, MRA, vascular