mrimaster

MRA and MRV of Subclavian Artery and Vein

Indications for MRA (magnetic resonance angiography) and MRV (venography) of subclavians

Contraindications

Patient preparation for MRA and MRV of Subclavian Artery and Vein

Positioning for arm down MRA and MRV of subclavians

MRA (magnetic resonance angiography) and MRV (venography) of subclavian and neck artery positioning photo

Recommended MRA and MRV of Subclavian Protocols and Planning

localiser arm down MRA and MRV of subclavians

A three-plane TrueFISP localizer must be taken initially to localize and plan the sequences. These are fast single-shot localizers with under 25s acquisition time, which are excellent for localizing vascular structures. Take at least 5-8 slices in all planes to get the best results.

T1 flash 3D coronal .9mm -1.1mm pre-contrast

Plan the coronal slices on the sagittal plane; angle the positioning block parallel to the carotid arteries and veins (alternatively, make it parallel to the cervical spine). Check the positioning block in the other two planes. Provide an appropriate angle in the axial plane (parallel to the right and left shoulder joint). The slices must be sufficient to cover the subclavians from the anterior chest wall to the spinous process of the vertebrae. The Field of View (FOV) must be large enough to cover both shoulder joints. Phase oversampling and slice oversample must be used to avoid wrap-around artifacts. Instruct the patient to hold their breath during image acquisition (in our institution, we instruct patients to breathe in and out twice before the “breath in and hold” instruction). It is highly advisable to use Parallel Acquisition Technique to reduce the scan time (the scan time should be less than 16 seconds to get the best results).

magnetic resonance angiography(MRA) whole body protocols and planning of chest and neck post contrast scans

Parameters

TR

2-3

TE

1-2

FLIP

20

NEX

1

SLICE

1 MM

MATRIX

384×384

FOV

400-450

PHASE

R>L

OVERSAMPLE

50%

IPAT

OFF

Parallel acquisition technique (IPAT)

Parallel imaging is an advanced MRI technique that accelerates image acquisition by simultaneously utilizing multiple receiver coils to acquire data. In conventional MRI, the image is acquired sequentially from each coil, which can be time-consuming. In parallel imaging, the data from multiple coils is collected simultaneously, significantly reducing the scan time.

This method relies on spatial information obtained from the different receiver coils and utilizes algorithms to reconstruct the final image. By combining information from multiple coils, parallel imaging enhances the signal-to-noise ratio and improves the quality of the final image.

Parallel imaging offers several advantages, such as reducing motion artifacts, enabling high-resolution imaging, and minimizing the need for patient breath-holding. Moreover, it allows for faster scanning, reducing the overall examination time, which is particularly beneficial for patients who may find longer scans uncomfortable or challenging.

Contrast administration and timing of scans

Guess timing technique:- This is one of the simplest methods. It works by estimating the time of contrast travel from the site of injection to the vascular structure of the abdomen. This technique is highly dependent upon the site of contrast injection, age of the patient, cardiac output, and vascular anatomy. Generally, the contrast takes about 15-20 seconds to travel from the antecubital vein to the arch of the aorta. Therefore, the post-contrast T1 acquisition should start within 15 seconds of contrast administration.

Care bolus technique:– “Care bolus” is the most commonly used bolus detection technique. This technique uses a coronal fast gradient refocused sequence. Real-time images are obtained every second through the vascular structure of interest (normally placed over the heart). The operator can then observe the contrast bolus arriving in the heart and subsequently switch to the centric 3D sequence.

Planning care bolus
Plan the coronal care bolus slice on the sagittal plane; angle the slice parallel to the ascending aorta. Check the positioning block in the other two planes. Provide an appropriate angle in the axial plane (parallel to the right and left shoulder joint). Use a saturation band on both sides of the care bolus slice to avoid artifacts from breathing and heartbeats.

Care bolus scans must start one second prior to the contrast administration. The operator can then watch the scans live and wait for the contrast bolus to arrive in the heart. When the contrast reaches the heart, the care bolus must be stopped immediately, and the patient instructed to hold their breath before starting the centric 3D dynamic sequence.

T1 flash dynamic 3D coronal .9mm - 1.1mm post-contrast 2 measurements

Plan the coronal slices on the sagittal plane; angle the positioning block parallel to the carotid arteries and veins (alternatively, make it parallel to the cervical spine). Check the positioning block in the other two planes. Provide an appropriate angle in the axial plane (parallel to the right and left shoulder joint). The slices must be sufficient to cover the subclavians from the anterior chest wall to the spinous process of the vertebrae. The Field of View (FOV) must be large enough to cover both shoulder joints. Phase oversampling and slice oversample must be used to avoid wrap-around artifacts. Instruct the patient to hold their breath during image acquisition (in our institution, we instruct patients to breathe in and out twice before the “breath in and hold” instruction). It is highly advisable to use Parallel Acquisition Technique to reduce the scan time (the scan time should be less than 16 seconds to get the best results).

Parameters

TR

2-3

TE

1-2

FLIP

20

NEX

1

SLICE

1 MM

MATRIX

384×384

FOV

400-450

PHASE

R>L

OVERSAMPLE

50%

IPAT

OFF

The pre and post-contrast T1 scans should have identical parameters, except for the number of acquisitions in the post-contrast scans. If the parameters are not the same, it will be impossible to perform the subtraction of pre and post-contrast images. 

Positioning for arm up MRA and MRV of subclavians

Suggested sequence parameters and planning

localiser arm up MRA and MRV of subclavians

A three-plane TrueFISP localizer must be taken initially to localize and plan the sequences.

T1 flash 3D coronal .9mm -1.1mm pre-contrast

Plan the coronal slices on the sagittal plane; angle the positioning block parallel to the carotid arteries and veins (alternatively, make it parallel to the cervical spine). Check the positioning block in the other two planes. Provide an appropriate angle in the axial plane (parallel to the right and left shoulder joint). The slices must be sufficient to cover the subclavians from the anterior chest wall to the spinous process of the vertebrae. The Field of View (FOV) must be large enough to cover both shoulder joints. Phase oversampling and slice oversample must be used to avoid wrap-around artifacts. Instruct the patient to hold their breath during image acquisition

Parameters

TR

2-3

TE

1-2

FLIP

20

NEX

1

SLICE

1 MM

MATRIX

384×320

FOV

400-450

PHASE

R>L

OVERSAMPLE

50%

IPAT

OFF

 

Planning care bolus
Plan the coronal care bolus slice on the sagittal plane; angle the slice parallel to the ascending aorta. Check the positioning block in the other two planes. Provide an appropriate angle in the axial plane (parallel to the right and left shoulder joint). Use a saturation band on both sides of the care bolus slice to avoid artifacts from breathing and heartbeats.

The care bolus scans should commence one second before the administration of the contrast. During the scan, the operator can monitor it in real-time to detect when the contrast bolus reaches the heart. As soon as the contrast arrives in the heart, the care bolus must be promptly halted, and the patient should be advised to hold their breath before initiating the centric 3D dynamic sequence. It might be challenging to visualize the contrast during this stage, as it is the second dose of gadolinium, and the first dose could still be present in the heart.

T1 flash dynamic 3D coronal .9mm - 1.1mm post-contrast 2 measurements

Plan the coronal slices on the sagittal plane; angle the positioning block parallel to the carotid arteries and veins (alternatively, make it parallel to the cervical spine). Check the positioning block in the other two planes. Provide an appropriate angle in the axial plane (parallel to the right and left shoulder joint). The slices must be sufficient to cover the subclavians from the anterior chest wall to the spinous process of the vertebrae. The Field of View (FOV) must be large enough to cover both shoulder joints. Phase oversampling and slice oversample must be used to avoid wrap-around artifacts. Instruct the patient to hold their breath during image acquisition

Parameters

TR

2-3

TE

1-2

FLIP

20

NEX

1

SLICE

1 MM

MATRIX

384×320

FOV

400-450

PHASE

R>L

OVERSAMPLE

50%

IPAT

OFF