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Fetal Abdomen MRI Protocol and Planning

Indications for fetal brain MRI scan

Contraindications

Patient preparation for fetal brain MRI scan

Positioning for fetal brain MRI scan

Recommended MRI Fetal Abdomen Scan Protocols and Planning

localiser

A three-plane HASTE (Half-Fourier Acquisition Single-shot Turbo Spin Echo) localizer is commonly used in magnetic resonance imaging (MRI) to localize and plan sequences. HASTE localizers 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 localizer sequence. These slices help in accurately identifying the position and orientation of the anatomy of interest, which is important for planning subsequent imaging sequences.

fetal abdomen MRI planning and protocol of localiser

T2 HASTE sagittal 6 mm Respiratory gated

Begin by planning the sagittal slices on the coronal localizer 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 sensors

Parameters

TR

2000-3000

TE

90-100

FLIP

130

NEX

1

SLICE

6 MM

MATRIX

320×320

FOV

400-480

PHASE

A>P

OVERSAMPLE

20%

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.

Advanced MRI scanners are equipped with built-in table sensors

T2 HASTE coronal 6 mm Respiratory gated

Plan the coronal slices on the sagittal localizer 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.

fetal abdomen MRI planning and protocol of coronal large fov scans

Parameters

TR

2000-3000

TE

90-100

FLIP

130

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.

fetal abdomen MRI planning and protocol of axial large fov scans

Parameters

TR

2000-3000

TE

90-100

FLIP

130

NEX

1

SLICE

6 MM

MATRIX

320×320

FOV

400-480

PHASE

A>P

OVERSAMPLE

10%

IPAT

ON

T2 HASTEcoronal localiser fetal abdomen

Plan the single-slice axial localiser on the coronal uterus scans. Angle the positioning block vertically across the fetal abdomen. Verify the positioning block in the other two planes to ensure proper alignment. In the axial scans, establish an appropriate horizontal angle across the fetal abdomen. The field of view (FOV) must be sufficiently large to cover the entire fetal abdomen, typically ranging from 200 mm to 250 mm. It is important to include an appropriate amount of oversampling to prevent wrap-around artifacts. These scans usually take approximately 1 to 2 seconds and can be performed either as a breath-hold or using the respiratory sensor.

Please note that the position of the fetus may vary among different patients and during different trimesters. Therefore, it is crucial to plan the localiser according to the position of the fetal abdomen. The reference points mentioned in the planning process remain the same.

fetal abdomen MRI planning and protocol of coronal localiser scan

Parameters

TR

1000-1300

TE

90-100

FLIP

130

NEX

1

SLICE

6 MM

MATRIX

320×320

FOV

400-480

PHASE

A>P

OVERSAMPLE

30%

IPAT

ON

T2 HASTE sagittal localiser fetal abdomen

Plan the single-slice sagittal localizer scan on the axial uterus scans. Angle the positioning block horizontally across the fetal abdomen. Verify the positioning block in the other two planes to ensure proper alignment. In the coronal localizer scan, establish an appropriate horizontal angle across the fetal abdomen. The field of view (FOV) must be sufficiently large to cover the entire fetal abdomen, typically ranging from 200 mm to 250 mm. It is important to include an appropriate amount of oversampling to prevent wrap-around artifacts. These scans usually take approximately 1 to 2 seconds and can be performed either as a breath-hold or using the respiratory sensor.

Please note that the position of the fetus may vary among different patients and during different trimesters. Therefore, it is crucial to plan the localizer according to the position of the fetal abdomen. The reference points mentioned in the planning process remain the same.

Parameters

TR

4-5

TE

2-3

FLIP

60

NEX

1

SLICE

5 MM

MATRIX

320×320

FOV

400-480

PHASE

A>P

OVERSAMPLE

10%

IPAT

ON

 

T2 HASTE axial 3mm fetal abdomen

Plan the axial scans on the coronal localizer. Angle the positioning block horizontally across the fetal abdomen. Verify the positioning block in the other two planes to ensure proper alignment. In the sagittal localizer, establish an appropriate horizontal angle across the fetal abdomen. The number of slices should be sufficient to cover the entire fetal abdomen and pelvis, ranging from the mid chest to the symphysis pubis. The field of view (FOV) must be large enough to cover the entire brain, typically ranging from 180 mm to 220 mm. It is important to include an appropriate amount of oversampling to prevent wrap-around artifacts. 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.

fetal abdomen MRI planning and protocol of axial scan

Parameters

TR

1500-2500

TE

90-100

FLIP

130

NEX

1

SLICE

3 MM

MATRIX

256×256

FOV

200-250

PHASE

A>P

OVERSAMPLE

30%

IPAT

ON

T1 tse/ T1 VIBE axial 3mm breath hold fetal brain

Plan the axial scans on the coronal localizer. Angle the positioning block horizontally across the fetal abdomen. Verify the positioning block in the other two planes to ensure proper alignment. In the sagittal localizer, establish an appropriate horizontal angle across the fetal abdomen. The number of slices should be sufficient to cover the entire fetal abdomen and pelvis, ranging from the mid-chest to the symphysis pubis. The field of view (FOV) must be large enough to cover the entire brain, typically ranging from 180 mm to 220 mm. It is important to include an appropriate amount of oversampling to prevent wrap-around artifacts. However, it is crucial to understand that these scans typically last for 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.

fetal abdomen MRI planning and protocol of axial scan

Parameters

TR

4-5

TE

2-3

FLIP

60

NEX

1

SLICE

3 MM

MATRIX

2560×256

FOV

200-250

PHASE

A>P

OVERSAMPLE

30%

IPAT

ON

EPI DWI axial 3mm free berthing fetal abdomen

Plan the axial scans on the coronal localizer. Angle the positioning block horizontally across the fetal abdomen. Verify the positioning block in the other two planes to ensure proper alignment. In the sagittal localizer, establish an appropriate horizontal angle across the fetal abdomen. The number of slices should be sufficient to cover the entire fetal abdomen and pelvis, ranging from the mid-chest to the symphysis pubis. The field of view (FOV) must be large enough to cover the entire brain, typically ranging from 180 mm to 220 mm. It is important to include an appropriate amount of oversampling to prevent wrap-around artifacts. EPI DWI free-breathing scans typically have a duration of around 90 to 120 seconds and are conducted while the patient breathes normally.

fetal abdomen MRI planning and protocol of axial scan

Parameters

TR

4000-6000

TE

70-80

FLIP

60

NEX

1

SLICE

3 MM

MATRIX

192×192

FOV

250-300

PHASE

A>P

OVERSAMPLE

10%

bvalue

b0        b500   b1000

T2 HASTE coronal 3mm fetal abomen

Plan the coronal scans using the axial localizer. Angle the positioning block vertically across the fetal abdomen. Verify the positioning block in the other two planes to ensure proper alignment. In the sagittal localizer, establish an appropriate vertical angle across the fetal abdomen. The number of slices should be sufficient to cover the entire fetal abdomen and pelvis, ranging from the fetal anterior abdominal wall to the erector spinae muscle. The field of view (FOV) must be large enough to cover the entire brain, typically ranging from 180 mm to 220 mm. It is important to include an appropriate amount of oversampling to prevent wrap-around artifacts. 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.

fetal abdomen MRI planning and protocol of coronal scan

Parameters

TR

1500-2500

TE

90-100

FLIP

130

NEX

1

SLICE

3 MM

MATRIX

256×256

FOV

200-250

PHASE

A>P

OVERSAMPLE

30%

IPAT

ON

T2 HASTE sagittal 3mm fetal abdomen

Plan the sagittal scan on the axial scans. Angle the positioning block horizontally across the fetal abdomen. Verify the positioning block in the other two planes to ensure proper alignment. In the coronal scan, establish an appropriate horizontal angle across the fetal abdomen. The number of slices should be sufficient to cover the entire fetal abdomen and pelvis from one side to the other. The field of view (FOV) must be large enough to cover the entire brain, typically ranging from 180 mm to 220 mm. It is important to include an appropriate amount of oversampling to prevent wrap-around artifacts. 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.

Parameters

TR

1500-2500

TE

90-100

FLIP

130

NEX

1

SLICE

3 MM

MATRIX

256×256

FOV

200-250

PHASE

A>P

OVERSAMPLE

30%

IPAT

ON

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