How to Plan a Thoracic Spine MRI Protocol

Intro to Thoracic Spine MRIs

This hardware setup is widely used in clinical practice. It balances acquisition time, image quality, and patient comfort.

3. Capture the Initial Localizer Images

Before we can perform any MRI protocol, we must always capture initial localizer images of the patient. These images act as a guide for planning the detailed scans we will perform next.

We should always capture localizers in three planes:

1. Axial
2. Sagittal
3. Coronal

Once acquired, upload the initial localizer images into the three viewports.

Then, scroll through each of the image stacks to locate a central slice that clearly shows the anatomy of the thoracic spine.

✅ Correct Setup of Localizer Images for Thoracic Spine MRI:

Part 2: Plan and Acquire the Protocol Sequences

When all preparations are ready, we can start planning and acquiring the protocol sequences.

Let's go through the pulse sequences a standard thoracic spine MRI protocol includes, why we perform them, and how to set them up.

The 5 Sequences of a Standard Thoracic Spine MRI Protocol

1. Coronal T2 TSE
2. Sagittal T2 TSE
3. Sagittal STIR TSE
4. Sagittal T1 TSE
5. Axial T2 and T1 TSE (Single or Double Stack)

We mainly use Turbo/Fast Spin Echo sequences for this study. These sequences provide fast acquisition with excellent soft tissue contrast. They work well for creating multiple contrasts, including T2, T1, and inversion recovery for fat suppression. This helps us assess the thoracic spine and detect common pathologies while keeping scan time short.

In the sections below, we go through how to plan and set up each sequence.

1. Planning Coronal T2 TSE

✅ Correct Planning:

Planning Instructions:

• Use the spinal cord and transverse processes as your anatomical references.
• Align the slices as follows:
  • Axial Localizer: Parallel to the transverse processes of the thoracic vertebrae.
  • Sagittal Localizer: Follow the natural arch of the spinal cord through the thoracic region.
• Use appropriate geometry parameters:
  • Slice number: Enough to fully cover all 12 thoracic vertebrae, typically 18–22 slices.
  • Slice thickness: 4 mm, thick enough for good SNR while maintaining adequate resolution.
  • Slice gap: 0.4 mm, 10% of slice thickness to prevent crosstalk while ensuring continuity.
• Set the fold-over direction (phase encoding) to foot-head (FH) to align with cerebrospinal fluid flow and reduce the risk of flow artifacts.
• Ensure the field of view covers the transverse processes bilaterally without cutting them off.
• Include at least one cervical vertebra above T1 and one lumbar vertebra below T12 for complete coverage.

Parameters for Coronal T2 TSE:

2. Planning Sagittal T2 TSE

✅ Correct Planning:

Planning Instructions:

• Use the spinal cord as your anatomical reference.
• Align the slices as follows:
  • Axial Localizer: Center the slices over the vertebral bodies.
  • Coronal Localizer: Parallel to the spinal cord, following the natural curvature of the thoracic spine.
• Use appropriate geometry parameters:
  • Slice number: Enough to cover the thoracic spine from right to left, including surrounding muscles and tendons, typically 14–18 slices.
  • Slice thickness: 4 mm, thick enough for good SNR while maintaining adequate resolution.
  • Slice gap: 0.4 mm, 10% of slice thickness to prevent crosstalk while ensuring continuity.
• Set the fold-over direction (phase encoding) to foot-head (FH) to align with cerebrospinal fluid flow and reduce the risk of flow artifacts.
• Ensure coverage extends from at least one cervical vertebra to one lumbar vertebra.
• Position slices to cover paraspinal muscles and any visible coil boundaries.

Parameters for Sagittal T2 TSE:

3. Planning Sagittal STIR TSE

✅ Correct Planning:

Planning Instructions:

• Copy the slice geometry and planning from the previous sagittal T2 TSE sequence.
• Keep the same slice angulation, coverage, and positioning to ensure images of different contrasts can be clearly compared.

Parameters for Sagittal STIR TSE:

4. Planning Sagittal T1 TSE

✅ Correct Planning:

Planning Instructions:

• Copy the slice geometry and planning from the previous sagittal T2 TSE sequence.
• Keep the same slice angulation, coverage, and positioning to ensure images of different contrasts can be clearly compared.
• Use saturation bands placed anterior to the thoracic spine to suppress motion artifacts from the heart, lungs, and aorta. Position the saturation band close to the imaging region but outside the field of view to avoid suppressing signal from the spine itself.

Parameters for Sagittal T1 TSE:

5. Planning Axial T2 and T1 TSE

✅ Correct Planning:

Planning Instructions:

• Use the spinal cord and intervertebral discs as your anatomical references.
• Align the slices as follows:
  • Coronal Localizer: Perpendicular to the spinal cord.
  • Sagittal Localizer: Parallel to the intervertebral disc spaces in the middle of the thoracic region.
• Unlike the lumbar spine, the thoracic spine typically uses a single stack technique covering the entire thoracic region. However, for larger patients, a double stack may be necessary.
• Use appropriate geometry parameters:
  • Slice number: Enough to cover all 12 thoracic vertebrae. For a single stack, use 35–50 slices. For a double stack, use 20–25 slices per stack.
  • Slice thickness: 4 mm, thick enough for good SNR while maintaining adequate resolution.
  • Slice gap: 0.4 mm, 10% of slice thickness to prevent crosstalk while ensuring continuity.
• Set the fold-over direction (phase encoding) to anterior-posterior (AP) to avoid motion artifacts from the heart and respiratory movement.
• For double stack acquisitions:
  • Position the first stack to cover the upper thoracic region.
  • Position the second stack to cover the lower thoracic region.
  • Minimize overlap between stacks to reduce crosstalk artifacts, or position them with a small gap in an area of less clinical interest.
• The angulation compared to the discs is much less than in the lumbar spine. You can use almost pure axial slices.

Parameters for Axial T2 TSE:

‍Parameters for Axial T1 TSE:

How to Avoid Artifacts When Planning the Sequences

The table below lists the 5 common thoracic spine artifacts, and what techniques you can use to avoid them:

Part 3: Review the Images

Finally, we will review the images to ensure all the anatomical information we need is clear.

These key structures must be clearly visible in a thoracic spine MRI:

1. Spinal cord
2. All 12 thoracic intervertebral discs
3. Vertebral bodies and posterior processes
4. Transverse processes
5. Ligaments
6. Surrounding structures, including paraspinal muscles, heart, lungs, and aorta

Below, we will go through all the different image contrasts and explain their specific role in imaging the thoracic spine.

T2 TSE – Highlights Fluid-Related Tissues and Conditions

T2-weighted imaging makes fluids appear bright. This contrast is ideal for tissues and abnormalities with high water content.

In the thoracic spine, T2 sequences help us view the spinal cord, cerebrospinal fluid (CSF), intervertebral discs, and fluid-related pathologies. Hydrated discs, cysts, or areas of inflammation appear bright, helping us detect conditions like disc degeneration, herniation, and spinal stenosis. T2 also helps us visualize ligaments and assess soft-tissue integrity.

We acquire T2 in coronal, sagittal, and axial views to get complete anatomical coverage. Coronal views show the overall alignment and transverse processes. Sagittal views reveal longitudinal details of the spine and discs. Axial views provide cross-sectional details of the spinal canal and neural structures.

✅ Coronal T2 TSE of Thoracic Spine – Correct Image Example:

Things to Look for in Coronal T2:

• All 12 thoracic vertebrae should be visible and centered.
• The spinal cord should appear bright and continuous.
• Transverse processes should be clearly visible bilaterally.
• Intervertebral discs should be clearly visible and properly hydrated.

✅ Sagittal T2 TSE of Thoracic Spine – Correct Image Example:

Things to Look for in Sagittal T2:

• The spinal cord should appear bright and continuous along the entire thoracic length.
• All intervertebral discs should be visible with clear disc margins.
• Check for disc herniations, spinal stenosis, or cord compression.
• No blurring or motion artifacts from cardiac or respiratory motion.

✅ Axial T2 TSE of Thoracic Spine – Correct Image Example:

Things to Look for in Axial T2:

• The spinal cord should be centered and clearly visible in the spinal canal.
• Transverse processes should be visible bilaterally.
• Check for neural foraminal narrowing or disc herniations.
• No motion artifacts from cardiac or respiratory motion, especially in the anterior spine.

T1 TSE – Highlights Fat-Containing Tissues and Structural Abnormalities

T1-weighted imaging makes fat appear bright and fluid dark. This contrast is ideal for fat-rich tissues and structural abnormalities. T1 shows anatomical structures clearly, since it helps us see where different solid tissues like muscle and fat meet.

In the thoracic spine, T1 sequences are ideal for assessing bone marrow, epidural fat, and the integrity of vertebral bodies. Chronic degenerative changes, such as Modic endplate changes, fractures, or tumors, are more apparent with T1 imaging. T1 also provides excellent views of the spinal cord morphology and vertebral body structures.

We acquire T1 in sagittal and axial views. Sagittal views show the overall anatomy, vertebral bodies, and chronic bony changes. Axial views provide detailed cross-sectional anatomy at the level of the spinal canal.

✅ Sagittal T1 TSE of Thoracic Spine – Correct Image Example:

Things to Look for in Sagittal T1:

• Vertebral bodies should show normal bone marrow signal with bright fat.
• The spinal cord should appear as a smooth, continuous structure with medium signal intensity.
• Check for fractures, Modic changes, or tumor involvement in vertebral bodies.
• Saturation bands should effectively suppress motion artifacts from the heart and lungs.

✅ Axial T1 TSE of Thoracic Spine – Correct Image Example:

Things to Look for in Axial T1:

• The spinal cord should be centered and clearly visible.
• Transverse processes should be clearly visible bilaterally.
• Check for foraminal narrowing or structural abnormalities.
• Vertebral bodies should show normal marrow signal.

STIR TSE – Clearest View of Fluid-Related Tissues and Conditions

STIR (Short Tau/TI Inversion Recovery) suppresses fat signals completely, which makes water-rich tissues stand out even clearer than with normal T2 TSE. This makes STIR ideal for detecting subtle fluid-related conditions like edema, inflammation, and infections, where increased water content would otherwise be obscured by fat.

In the thoracic spine, STIR is particularly useful for identifying bone marrow edema, infections like discitis or abscesses, inflammatory processes, and multiple sclerosis plaques. STIR provides high lesion visibility when water content might not be easily visible on standard T2 sequences.

We acquire STIR in the sagittal view to visualize the entire spine and detect any fluid-related changes across vertebrae or discs.

✅ Sagittal STIR TSE of Thoracic Spine – Correct Image Example:

Things to Look for in Sagittal STIR:

• Fat signal should be completely suppressed, visible as uniform dark signal in the subcutaneous layer and vertebral bodies.
• Bone marrow edema, if present, should appear bright and clearly stand out.
• Check for inflammatory processes, infections, or multiple sclerosis plaques.
• The spinal cord and discs should be clearly visible with good contrast.

Final Checks:

Before finishing a thoracic spine MRI, always check these 5 points to ensure diagnostic quality:

1. Spinal Cord and Discs: The spinal cord must appear continuous and clearly visible on all sagittal and axial images. All 12 thoracic intervertebral discs must be clearly visible with sharp margins.
2. Coverage and Alignment: Slices must fully cover from at least one cervical vertebra to one lumbar vertebra. Coronal slices must include transverse processes bilaterally. Axial slices should be perpendicular to the spinal cord.
3. Motion Artifact Suppression: Sagittal T1 images must show effective saturation band placement with minimal motion artifacts from the heart, lungs, or aorta.
4. Fat Suppression on STIR: STIR images must show complete fat suppression, with bone marrow edema or inflammation standing out clearly if present.
5. Image Quality and Artifacts: Images must have strong SNR, crisp detail, and no motion, wrap-around, flow, or susceptibility artifacts. The anterior portion of the spine near the heart should be free from motion blur.

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