Fetal Spine MRI Protocol and Planning
Indications for fetal spine MRI scan
- Meningomyelocele
- Sacrococcygeal teratomas
- Processes obstructing the airway (such as neck mass or congenital high airway obstruction)
- Complications of monochorionic twins requiring surgery
- Chest masses
Contraindications
- Any electrically, magnetically or mechanically activated implant (e.g. cardiac pacemaker, insulin pump biostimulator, neurostimulator, cochlear implant, and hearing aids)
- Intracranial aneurysm clips (unless made of titanium)
- Pregnancy (risk vs benefit ratio to be assessed)
- Ferromagnetic surgical clips or staples
- Metallic foreign body in the eye
- Metal shrapnel or bullet
Patient preparation for fetal spine MRI scan
- A satisfactory written consent form must be taken from the patient before entering the scanner room
- Ask the patient to remove all metal object including keys, coins, wallet, any cards with magnetic strips, jewellery, hearing aid and hairpins
- Ask the patient to undress and change into a hospital gown
- An intravenous line must be placed with extension tubing extending out of the magnetic bore
- Claustrophobic patients may be accompanied into the scanner room e.g. by staff member or relative with proper safety screening
- Offer earplug or headphones possibly with music for extra comfort
- Explain the procedure to the patient and answer questions
- Note down the hight and weight of the patient
- Pregnancy scanning consent must be taken before the procedure
Positioning for fetal spine MRI scan
- Position the patient in supine position with head pointing towards the magnet (head first supine)
- Position the patient over the spine coil and place the body coils over abdomen and pelvis (nipple down to elbow three inches below symphysis pubis)
- Securely tighten the body coil using straps to prevent respiratory artefacts
- Give a pillow under the head and cushions under the legs for extra comfort
- Centre the laser beam localiser over mid abdomen
- Register the patient in the scanner as head first supine
Recommended MRI Fetal Spine Scan Protocols and Planning
Fetal Spine Scan localiser
A three-plane HASTE (Half-Fourier Acquisition Single-shot Turbo Spin Echo) localiser is commonly used in magnetic resonance imaging (MRI) to localise and plan sequences. HASTE localisers are fast and can be acquired in under 25 seconds, making them useful for localizing abdominal and pelvic structures.
To obtain the best results, it is generally recommended to acquire at least 3-4 slices in all planes (axial, sagittal, and coronal) during the localiser sequence. These slices help in accurately identifying the position and orientation of the anatomy of interest, which is important for planning subsequent imaging sequences.
T2 HASTE sagittal 6 mm Respiratory gated
Begin by planning the sagittal slices on the coronal localiser and position the block parallel to the gravid uterus. Verify the positioning block in the other two planes to confirm proper alignment. It is essential to provide an appropriate angle in the axial plane, which should be perpendicular to the gravid uterus. The number of slices should be sufficient to cover the entire abdomen and pelvis, from right to left. The field of view (FOV) must be wide enough to encompass the whole abdomen and pelvis, typically ranging from 400 mm to 480 mm. However, it is important to note that these scans usually take approximately 35 to 40 seconds, which can be challenging for a pregnant woman to hold her breath. To address this issue, we perform the scan under respiratory gating. There are two options for respiratory gating: the liver dome method or the table respiratory sensors. In our department, we utilise the table respiratory sensor.
Parameters
TR 4-5 | TE 2-3 | FLIP 60 | NEX 1 | SLICE 6 MM | MATRIX 320×320 | FOV 400-480 | PHASE R>L | OVERSAMPLE 30% | IPAT ON |
Table sensors
Advanced MRI scanners are equipped with built-in table sensors that detect the respiratory waveform and trigger data acquisition during the expiration phase of the respiratory cycle. Proper patient positioning over the sensor is critical for accurate respiratory gating. This method eliminates the need for external respiratory gating equipment, such as sensors and belts.
T2 HASTE coronal 6 mm Respiratory gated
Plan the coronal slices on the sagittal localiser and position the block parallel to the gravid uterus. Verify the positioning block in the other two planes for proper alignment. An appropriate angle should be set in the axial plane, running parallel across the gravid uterus. The number of slices should be sufficient to cover the entire abdomen and pelvis, from the anterior abdominal wall to the spinous process of the vertebrae. The field of view (FOV) must be large enough to encompass the entire abdomen and pelvis, typically ranging from 400 mm to 480 mm. However, it is important to note that these scans usually take approximately 30 to 35 seconds, which can be challenging for a pregnant woman to hold her breath. To address this issue, we perform the scan under respiratory gating. There are two options for respiratory gating: the liver dome method or the table respiratory sensors. In our department, we utilise the table respiratory sensor.
Parameters
TR 4-5 | TE 2-3 | FLIP 60 | NEX 1 | SLICE 6MM | MATRIX 320×320 | FOV 400-480 | PHASE R>L | OVERSAMPLE 30% | IPAT ON |
T2 HASTE axial 6 mm Respiratory gated
Plan the axial slices on the sagittal scans and angle the position block perpendicular through the gravid uterus. Verify the positioning block in the other two planes for proper alignment. An appropriate angle should be set in the coronal plane, running perpendicular across the gravid uterus. The number of slices should be sufficient to cover the entire abdomen and pelvis, from the diaphragm to the pubic symphysis. The field of view (FOV) must be large enough to encompass the entire abdomen and pelvis, typically ranging from 400 mm to 480 mm. However, it is important to note that these scans usually take approximately 40 to 45 seconds, which can be challenging for a pregnant woman to hold her breath. To address this issue, we perform the scan under respiratory gating. There are two options for respiratory gating: the liver dome method or the table respiratory sensors. In our department, we utilise the table respiratory sensor.
Parameters
TR 4-5 | TE 2-3 | FLIP 60 | NEX 1 | SLICE 6 MM | MATRIX 320×320 | FOV 400-480 | PHASE R>L | OVERSAMPLE 30% | IPAT ON |
T2 HASTE coronal localiser fetal spine
Plan the coronal spine localiser on the large FOV coronal uterus scans. Align the position block parallel to the fetal spine. Confirm the positioning block in the other two planes for proper alignment.In the axial scans, ensure that the angle is appropriately parallel to the line along the transverse process of the vertebral body of the fetal spine. The field of view (FOV) should adequately cover the entire spine, typically ranging from 280mm to 320mm. It is important to include a sufficient amount of oversampling to prevent any wrap-around artifacts. These scans usually take approximately 2 to 4 seconds and can be performed either with a breath-hold or using the respiratory sensor.
Please note that the position of the fetal spine may vary among different patients and during different trimesters. Therefore, it is crucial to plan the localizer based on the position of the fetal spine. The reference points mentioned in the planning process remain unchanged.
Parameters
TR 4-5 | TE 2-3 | FLIP 60 | NEX 1 | SLICE 6 MM | MATRIX 320×320 | FOV 400-480 | PHASE R>L | OVERSAMPLE 30% | IPAT ON |
T2 HASTE axial localiser fetal spine
Plan the axial spine localiser on the large FOV coronal uterus scans. Align the position block perpendicular to the fetal spine. Confirm the positioning block in the other two planes for proper alignment. In the coronal scans, establish an appropriate angle perpendicular to the fetal spine. The field of view (FOV) should adequately cover the entire spine, typically ranging from 280mm to 320mm. It is important to include a sufficient amount of oversampling to prevent any wrap-around artifacts. These scans usually take approximately 2 to 4 seconds and can be performed either with a breath-hold or using the respiratory sensor.
Please note that the position of the fetal spine may vary among different patients and during different trimesters. Therefore, it is crucial to plan the localizer based on the position of the fetal spine. The reference points mentioned in the planning process remain unchanged.
Parameters
TR 4-5 | TE 2-3 | FLIP 60 | NEX 1 | SLICE 6 MM | MATRIX 320×320 | FOV 400-480 | PHASE R>L | OVERSAMPLE 30% | IPAT ON |
T2 HASTE sagittal localiser fetal spine
Plan the sagittal spine localiser on the large FOV sagittal uterus scans. Align the position block parallel to the fetal spine. Confirm the positioning block in the other two planes for proper alignment. In the axial scans, establish an appropriate angle parallel to the line along the center of the vertebral body and the spinous process of the fetal spine. The field of view (FOV) should adequately cover the entire spine, typically ranging from 280mm to 320mm. It is important to include a sufficient amount of oversampling to prevent any wrap-around artifacts. These scans usually take approximately 2 to 4 seconds and can be performed either with a breath-hold or using the respiratory sensor.
Please note that the position of the fetal spine may vary among different patients and during different trimesters. Therefore, it is crucial to plan the localizer based on the position of the fetal spine. The reference points mentioned in the planning process remain unchanged.
Parameters
TR 4-5 | TE 2-3 | FLIP 60 | NEX 1 | SLICE 6 MM | MATRIX 320×320 | FOV 400-480 | PHASE R>L | OVERSAMPLE 30% | IPAT ON |
T2 HASTE sagittal 3mm fetal spine
Plan the sagittal scans using the coronal spine localiser. Align the position block parallel to the fetal spine and confirm its positioning in the other two planes. In the axial scans, establish an appropriate angle parallel to the line along the center of the vertebral body and the spinous process of the fetal spine. The field of view (FOV) should sufficiently cover the entire spine, typically ranging from 280mm to 320mm. Ensure an adequate amount of oversampling to prevent wrap-around artifacts. The slices should cover the spine from the lateral border of the right transverse process to the lateral border of the left transverse process.
However, it is important to consider that these scans generally take approximately 20 to 25 seconds, which can pose challenges for pregnant individuals in holding their breath. To address this concern, we conduct the scan using respiratory gating. In our department, we utilize the table respiratory sensor as the preferred method for respiratory gating.
Parameters
TR 4-5 | TE 2-3 | FLIP 60 | NEX 1 | SLICE 6 MM | MATRIX 320×320 | FOV 400-480 | PHASE R>L | OVERSAMPLE 30% | IPAT ON |
T1 tse/VIBE sagittal 3mm fetal spine
Plan the sagittal scans using the coronal spine localiser. Align the position block parallel to the fetal spine and confirm its positioning in the other two planes. In the axial scans, establish an appropriate angle parallel to the line along the center of the vertebral body and the spinous process of the fetal spine. The field of view (FOV) should sufficiently cover the entire spine, typically ranging from 280mm to 320mm. Ensure an adequate amount of oversampling to prevent wrap-around artifacts. The slices should cover the spine from the lateral border of the right transverse process to the lateral border of the left transverse process.
These scans usually last approximately 15 to 20 seconds and cannot be performed under respiratory gating. Therefore, kindly request the patient to hold their breath during this short duration. Based on our experience, most patients are willing to comply with the breath-holding instructions for a scan of this duration.
Parameters
TR 4-5 | TE 2-3 | FLIP 60 | NEX 1 | SLICE 6 MM | MATRIX 320×320 | FOV 400-480 | PHASE R>L | OVERSAMPLE 30% | IPAT ON |
T2 HASTE axial 3mm fetal spine
Plan the axial scans using the sagittal spine localiser. Align the position block perpendicular to the fetal spine and verify its positioning in the other two planes. In the coronal localizer, establish an appropriate angle that is perpendicular to the fetal spine. The field of view (FOV) should adequately encompass the entire spine, typically ranging from 280mm to 320mm. Ensure a sufficient amount of oversampling to prevent wrap-around artifacts. The slices should cover the entire spine, starting from the C1 vertebra down to the coccyx.
However, it is important to consider that these scans generally take approximately 20 to 25 seconds, which can pose challenges for pregnant individuals in holding their breath. To address this concern, we conduct the scan using respiratory gating. In our department, we utilize the table respiratory sensor as the preferred method for respiratory gating.
Parameters
TR 4-5 | TE 2-3 | FLIP 60 | NEX 1 | SLICE 6 MM | MATRIX 320×320 | FOV 400-480 | PHASE R>L | OVERSAMPLE 30% | IPAT ON |
T1 tse/VIBE axial 3mm fetal spine
Plan the axial scans using the sagittal spine localiser. Align the position block perpendicular to the fetal spine and verify its positioning in the other two planes. In the coronal localizer, establish an appropriate angle that is perpendicular to the fetal spine. The field of view (FOV) should adequately encompass the entire spine, typically ranging from 280mm to 320mm. Ensure a sufficient amount of oversampling to prevent wrap-around artifacts. The slices should cover the entire spine, starting from the C1 vertebra down to the coccyx.
These scans usually last approximately 15 to 20 seconds and cannot be performed under respiratory gating. Therefore, kindly request the patient to hold their breath during this short duration. Based on our experience, most patients are willing to comply with the breath-holding instructions for a scan of this duration.
Parameters
TR 4-5 | TE 2-3 | FLIP 60 | NEX 1 | SLICE 6 MM | MATRIX 320×320 | FOV 400-480 | PHASE R>L | OVERSAMPLE 30% | IPAT ON |
T2 HASTE coronal 3mm fetal spine
Plan the coronal scans using the sagittal spine localiser. Align the position block parallel to the fetal spine and confirm its positioning in the other two planes. In the axial scans, ensure that the angle is appropriately parallel to the line along the transverse process of the vertebral body of the fetal spine. The field of view (FOV) should adequately encompass the entire spine, typically ranging from 280mm to 320mm. Make sure to include a sufficient amount of oversampling to prevent wrap-around artifacts. The slices should cover the entire spine coronally, extending from the vertebral body to the spinous process.
However, it is important to consider that these scans generally take approximately 20 to 25 seconds, which can pose challenges for pregnant individuals in holding their breath. To address this concern, we conduct the scan using respiratory gating. In our department, we utilize the table respiratory sensor as the preferred method for respiratory gating.
Parameters
TR 4-5 | TE 2-3 | FLIP 60 | NEX 1 | SLICE 6 MM | MATRIX 320×320 | FOV 400-480 | PHASE R>L | OVERSAMPLE 30% | IPAT ON |