mrimaster

Small Bowel MRI (Enterography MRI Protocol and Planning)

Indications for small bowel mri scan

Contraindications

Patient preparation for Enterography MRI

Oral Contrast

The purpose of utilizing an oral contrast agent is to achieve specific signal intensities in the bowel lumen on different types of MRI images. On T2-weighted images, the aim is to produce a high signal intensity in the bowel lumen, while on T1-weighted images, a low signal intensity in the lumen is desired. The low signal intensity on T1-weighted images is particularly crucial for identifying mural enhancement on post-contrast T1-weighted images.

Water alone is insufficient for achieving adequate bowel distention during MR enterography. However, when water is mixed with a solution containing mannitol or sorbitol, better distention can be achieved. Furthermore, the addition of 5ml of Metoclopramide to the mixture significantly enhances the rate of water evacuation from the stomach.

In our department we use the proportion below,

  • 2x Oral mannitol 500ml solution 
  • 5ml of Metoclopramide  

We recommend that patients consume a minimum volume of 1 liters of oral contrast, although some patients may find it difficult to comply with this requirement. To ensure proper distal transit, we implement a minimum delay of 30 minutes from the initiation of contrast ingestion to the imaging procedure.

Positioning for for Enterography MRI

Prone imaging is highly recommended to improve gastric emptying and bowel loop separation
MRI small bowel positioning

Recommended Enterography MRI Protocols and Planning

Enterography MRI Localizer

To localize and plan the sequences, it is necessary to obtain an initial three-plane HASTE localizer. These fast single-shot localizers have an acquisition time of under 25 seconds, making them ideal for accurate localization of abdominal structures.

mri small bowel localizer image

T2 TRUEFISP coronal 4mm

Plan the coronal slices on the axial image. Position the block horizontally across the abdomen as shown, and ensure that the positioning block is also checked in the other two planes. Establish an appropriate angle vertically across the abdomen in the sagittal plane. Make sure the slices adequately cover the entire abdomen, extending from the anterior abdominal wall to the erector spinae muscle. The field of view (FOV) should be large enough to encompass the abdomen and pelvis, ranging from the stomach to the pubic symphysis. To prevent wraparound artifacts, utilize phase oversampling. Instruct the patient to hold their breath during image acquisition. (In our department, we instruct the patients to breathe in and out twice before giving the “breathe in and hold” instruction.)

Protocol Parameters TRUEFISP coronal

TR

4-5

TE

2-3

FLIP

60

NEX

1

SLICE

4 MM

MATRIX

320×320

FOV

400-450

PHASE

R>L

OVERSAMPLE

50%

IPAT

OFF

T2 TRUEFISP axial

Plan the axial slices on the coronal image, position the block horizontally across the abdomen as shown, and ensure that the positioning block is also checked in the other two planes. Establish an appropriate angle horizontally across the abdomen in the sagittal plane. The slices must be sufficient to cover the entire abdomen and pelvis from the stomach to the pubic symphysis. Phase oversampling can be used to avoid wrap-around artifacts. Instruct the patient to hold their breath during image acquisition.

The axial scan is performed as two separate blocks with a 20-30% slice overlap between them. The scan is performed this way to avoid any RF inhomogeneity-related artifacts by conducting the scans at the isocenter of the magnet. Use the composing function in the scanner to stitch the two blocks together.

MRI small bowel (enterography) axial planning

Protocol Parameters TRUEFISP axial

TR

4-5

TE

2-3

FLIP

60

NEX

1

SLICE

4 MM

MATRIX

320×256

FOV

350-400

PHASE

A>P

OVERSAMPLE

50%

IPAT

ON

Pause for buscopan injection

Before proceeding to the next step, intravenously inject 0.5 to 1 ml of Buscopan according to the manufacturer’s instructions and departmental policy. Wait for 30 seconds before starting the next scan, as Buscopan takes a few seconds to start its function.

Warning

* Buscopan injection should not be administered to patients with myasthenia gravis, megacolon, narrow-angle glaucoma, tachycardia, prostatic enlargement with urinary retention, mechanical stenoses in the region of the gastrointestinal tract, or paralytic ileus.*

T1 VIBE DIXON \ flash fat sat 3d 0.9-1 mm coronal pre-contrast

Plan the coronal slices on the axial image. Position the block horizontally across the abdomen as shown, and ensure that the positioning block is also checked in the other two planes. Establish an appropriate angle vertically across the abdomen in the sagittal plane. Make sure the slices adequately cover the entire abdomen, extending from the anterior abdominal wall to the erector spinae muscle. The field of view (FOV) should be large enough to encompass the abdomen and pelvis, ranging from the stomach to the pubic symphysis. To prevent wrap-around artifacts, phase oversampling, and in the case of 3D blocks, slice oversampling must be used. Instruct the patient to hold their breath during image acquisition. (In our department, we instruct the patients to breathe in and out twice before giving the “breathe in and hold” instruction.)

MRI small bowel (enterography) coronal flash planning and protocols

Protocol Parameters T1 FLASH Coronal

TR

3-4

TE

1-2

FLIP

12

NEX

1

SLICE

1 MM

MATRIX

384X320

FOV

400-450

PHASE

R>L

OVERSAMPLE

50%

IPAT

OFF

T2 HASTE 4 mm coronal

Plan the coronal slices on the axial image. Position the block horizontally across the abdomen as shown, and ensure that the positioning block is also checked in the other two planes. Establish an appropriate angle vertically across the abdomen in the sagittal plane. Make sure the slices adequately cover the entire abdomen, extending from the anterior abdominal wall to the erector spinae muscle. The field of view (FOV) should be large enough to encompass the abdomen and pelvis, ranging from the stomach to the pubic symphysis. To prevent wraparound artifacts, utilize phase oversampling. Instruct the patient to hold their breath during image acquisition. (In our department, we instruct the patients to breathe in and out twice before giving the “breathe in and hold” instruction.)

Protocol Parameters HASTE Coronal

TR

2000-2500

TE

90-100

FLIP

150

NEX

1

SLICE

4 MM

MATRIX

320X320

FOV

400-450

PHASE

R>L

OVERSAMPLE

50%

IPAT

ON

T2 HASTE 4 mm axial

Plan the axial slices on the coronal image, position the block horizontally across the abdomen as shown, and ensure that the positioning block is also checked in the other two planes. Establish an appropriate angle horizontally across the abdomen in the sagittal plane. The slices must be sufficient to cover the entire abdomen and pelvis from the stomach to the pubic symphysis. Phase oversampling can be used to avoid wrap-around artifacts. Instruct the patient to hold their breath during image acquisition.

The axial scan is performed as two separate blocks with a 20-30% slice overlap between them. The scan is performed this way to avoid any RF inhomogeneity-related artifacts by conducting the scans at the isocenter of the magnet. Use the composing function in the scanner to stitch the two blocks together.

Pause for buscopan + gadolinium injection

MRI small bowel (enterography) axial planning

Protocol Parameters HASTE Axial

TR

2000-2500

TE

90-100

FLIP

150

NEX

1

SLICE

4 MM

MATRIX

320X320

FOV

400-450

PHASE

A>P

OVERSAMPLE

0%

IPAT

ON

Before proceeding to the next step, intravenously inject 0.5 to 1 ml of Buscopan (according to the manufacturer’s instructions and departmental policy) and 0.2ml\kg of gadolinium (according to the manufacturer’s instructions and departmental policy). Wait for 30 seconds before starting the next scan (Buscopan takes a few seconds to start its function).

T1 VIBE DIXON \ T1 flash fat sat 3d 0.9-1 mm coronal post contrast

Plan the coronal slices on the axial image. Position the block horizontally across the abdomen as shown, and ensure that the positioning block is also checked in the other two planes. Establish an appropriate angle vertically across the abdomen in the sagittal plane. Make sure the slices adequately cover the entire abdomen, extending from the anterior abdominal wall to the erector spinae muscle. The field of view (FOV) should be large enough to encompass the abdomen and pelvis, ranging from the stomach to the pubic symphysis. To prevent wrap-around artifacts, phase oversampling, and in the case of 3D blocks, slice oversampling must be used. Instruct the patient to hold their breath during image acquisition. (In our department, we instruct the patients to breathe in and out twice before giving the “breathe in and hold” instruction.)

MRI small bowel (enterography) coronal flash planning and protocols

Protocol Parameters T1 FLASH Coronal

TR

3-4

TE

1-2

FLIP

12

NEX

1

SLICE

1 MM

MATRIX

384X320

FOV

400-450

PHASE

R>L

OVERSAMPLE

50%

IPAT

OFF

T1 VIBE DIXON \ T1 flash fat sat 3d 1-1.5 mm axial post contrast

Plan the axial slices on the coronal image, position the block horizontally across the abdomen as shown, and ensure that the positioning block is also checked in the other two planes. Establish an appropriate angle horizontally across the abdomen in the sagittal plane. The slices must be sufficient to cover the entire abdomen and pelvis from the stomach to the pubic symphysis. To prevent wrap-around artifacts, phase oversampling, and in the case of 3D blocks, slice oversampling must be used. Instruct the patient to hold their breath during image acquisition. (In our department, we instruct the patients to breathe in and out twice before giving the “breathe in and hold” instruction.)

The axial scan is performed as two separate blocks with a 10-25% slice overlap between them. The scan is performed this way to avoid any RF inhomogeneity-related artifacts by conducting the scans at the isocenter of the magnet. Use the composing function in the scanner to stitch the two blocks together.

MRI small bowel (enterography) axial planning and protocol of DIXON scan

Protocol Parameters T1 FLASH Axial

TR

3-4

TE

1-2

FLIP

12

NEX

1

SLICE

2 MM

MATRIX

320X320

FOV

350-420

PHASE

A>P

OVERSAMPLE

30%

IPAT

ON

Post Enterography scan complications

Mannitol may lead to certain discomforts in the gastrointestinal tract following the procedure. These discomforts can include diarrhea, excess intestinal gas, and abdominal cramps. These symptoms may persist for a period of 1-2 days after the administration of mannitol.

Buscopan, while generally well-tolerated, can have some temporary side effects. One of the common side effects is blurred vision, which may last for approximately 15 to 30 minutes after the procedure. Additionally, Buscopan has the potential to increase heart rate and may cause dry mouth as well.

Optional Scans

T2 cine coronal 8mm

Multiphasic cine imaging is a crucial element in the assessment of MR enterography, as it offers valuable insights into bowel motility and function. Cine MR enterography is especially beneficial when it comes to examining narrowings and adhesions in the small intestine. Through the evaluation of bowel motility, this imaging method has proven to be advantageous in identifying abnormal lesions associated with conditions such as Crohn’s disease. Its effectiveness has led to its integration into disease activity scoring systems designed for this specific objective.

Cine images are obtained as single slices and can be acquired in any plane. Most commonly, they are acquired in the coronal plane due to the need for fewer slices to cover the entire abdomen. The scanning procedure begins from the anterior abdominal wall and continues by repeating the scan using the stack + function on the scanner until it reaches the sacrum level.

 Plan the coronal slice on the axial image. Position the imaging block horizontally across the abdomen as indicated, and ensure that the positioning block is also confirmed in the other two planes. Establish an appropriate vertical angle across the abdomen in the sagittal plane. The field of view (FOV) should be large enough to include the abdomen and pelvis, extending from the stomach to the pubic symphysis. This scan typically takes about 30 seconds to complete and can be performed while the patient breathes freely.

How to perform and interpret cine MR enterography. MRI protocol and planning image 1

Protocol Parameters True FISP coronal cine

DWI EPI 3 SCAN TRACE AXIAL 3MM FREE BREATHING

Plan the axial slices on the coronal image, position the block horizontally across the abdomen as shown, and ensure that the positioning block is also checked in the other two planes. Establish an appropriate angle horizontally across the abdomen in the sagittal plane. The slices must be sufficient to cover the entire abdomen and pelvis from the stomach to the pubic symphysis. Phase oversampling can be used to avoid wrap-around artifacts. Instruct the patient to hold their breath during image acquisition.

The axial scan is performed as two separate blocks with a 20-30% slice overlap between them. The scan is performed this way to avoid any RF inhomogeneity-related artifacts by conducting the scans at the isocenter of the magnet. Use the composing function in the scanner to stitch the two blocks together.

MRI small bowel (enterography) axial planning

Protocol Parameters Axial EPI DWI

TR

4-5

TE

2-3

FLIP

60

NEX

1

SLICE

4 MM

MATRIX

320×320

FOV

400-450

PHASE

R>L

OVERSAMPLE

50%

IPAT

OFF

TR

6000-7000

TE

90

IPAT

ON

NEX

 3     5     8

SLICE

3 MM

MATRIX

192X192

FOV

200-250

PHASE

R>L

GAP

10%

B VALUE

0
500
1000

T2 HASTE cornal 5 mm respiratory gated using table respiratory sensor

Respiratory gating in modern scanners can now be accomplished using built-in table respiratory sensors. This feature proves particularly beneficial when patients have irregular breathing patterns or are at risk of falling asleep during the scan. The advantage of table sensors is that they do not necessitate any specific planning. The only requirement is to ensure that the patient’s chest is accurately positioned over the table sensors to enable accurate monitoring of breathing. Additionally, it is important to select the appropriate gating option, such as the table sensor gating, in the protocol settings.

Plan the coronal slices on the axial image. Position the block horizontally across the abdomen as shown, and ensure that the positioning block is also checked in the other two planes. Establish an appropriate angle vertically across the abdomen in the sagittal plane. Make sure the slices adequately cover the entire abdomen, extending from the anterior abdominal wall to the erector spinae muscle. The field of view (FOV) should be large enough to encompass the abdomen and pelvis, ranging from the stomach to the pubic symphysis. Use phase oversampling to prevent wrap-around artifacts. Please advise the patient to maintain a gentle and steady breathing pattern throughout the entire scan.

For the table respiratory sensor sequences to function correctly, it is crucial to place the patient in a supine position.

Parameters

TR

2000-3000

TE

130

FLIP

150

NEX

1

SLICE

4MM

MATRIX

320X320

FOV

300-400

PHASE

R>L

OVERSAMPLE

50%

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