How to plan a lumbar spine MRI protocol

This step-by-step guide is for MRI students, radiographers and technologists who wish to improve their planning skills and master the lumbar spine MRI protocol.

What you will learn:

1. What key factors to consider in lumbar spine MRIs, and how to think when facing trade-offs.
2. How to set up the patient and scanner.
3. What pulse sequences to use, and how to plan them.
4. How to avoid the common lumbar spine artifacts.
5. What great lumbar spine images should look like.

The lumbar spine is the lower part of your spine. It’s the backbone of our movement and support, literally. It carries much of our body weight, enables flexibility for bending and twisting, and protects the nerves controlling the lower body.

This lower back area is a common source of pain and neurological conditions, which is why the lumbar spine study is one of the most highly requested protocols in MRI.

How to Balance the 3 Trade-offs in Lumbar Spine MRIs

In MRI, we always face a trade-off between 3 key metrics:

• Scan Time: How fast a pulse sequence can be completed.
• Resolution: How much detail the image can display.
• SNR: How clear the image is, meaning how much signal we have compared with noise.

Improving one of these metrics often reduces the performance of the others. To decide what trade-offs to make, we must consider the needs of each clinical situation.

For lumbar spine MRIs, we face these challenges:

• High scan volume: Lumbar spine MRI is a common exam, so even a few extra minutes per sequence can quickly affect the full patient list.
• Complex axial planning: Five angled slice groups are planned across the disc levels. This takes time, and overlapping groups can cause cross-talk artifacts.
• Balance detail and motion: Disc margins, the canal, and nerve roots need to stay sharp, but bowel motion and CSF pulsation can cause ghosting during longer scans.

Therefore, we typically:

1. Keep scan time short enough to move a high volume of lumbar studies through the list, and to give bowel and CSF motion less opportunity to blur the images.
2. Maintain adequate resolution so that disc margins, the thecal sac and the exiting nerve roots stay sharp, particularly on the small-field-of-view axial groups.
3. Preserve enough SNR to keep the fluid-to-cord and disc-to-nerve contrast readable, which 4 mm slices and one to two averages generally provide.

Lumbar Spine Health Conditions and the MRI Sequences That Reveal Them

The lumbar spine MRI study can help us diagnose a wide range of health conditions. The table below lists some of the most common conditions, and what pulse sequences that reveal them:

The step-by-step guide below will show you how to set up and perform a lumbar spine MRI protocol in practice.

We will perform the protocol in 3 parts:

1. Set up the Patient and MRI Scanner
2. Plan and Acquire the Protocol Sequences
3. Review the Images

Part 1: Set up the Patient and MRI Scanner

1. Position the Patient in the Scanner

Lay the patient feet-first and supine (on their back) with the lumbar region aligned at the scanner’s isocenter.

Using a feet-first position makes the scan feel less claustrophobic for the patient, which reduces the risk of motion artifacts.

Place a dedicated lumbar spine coil at the patient’s back. Positioned correctly, it covers the whole lumbar region and gives the signal needed for clear images.

✅ Correct Patient Positioning:

2. Check the Scanner’s Hardware Settings

Once the patient is in place, review your scanner’s hardware settings.

In this guide, we will use the following settings:

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, load 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 lumbar spine.

✅ Correct Setup of Localizer Images for Lumbar 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 that a standard lumbar spine MRI protocol includes, why we perform them, and how to set them up.

The 6 Sequences of a Standard Lumbar Spine MRI

1. Coronal T2 TSE
2. Sagittal T2 TSE
3. Sagittal STIR TSE
4. Sagittal T1 TSE
5. Axial T2 TSE, Multi-Block and Multi-Angle
6. Axial T1 TSE, Multi-Block and Multi-Angle

We mainly use TSE sequences because they let us create image contrasts in T2- and T1-weighting, as well as inversion recovery for fat suppression. These contrasts help us to assess the integrity of the lumbar spine and check for common pathologies. Using TSE sequences also keeps the scan time short.

There is no single correct way to run a lumbar spine protocol. The setup below is a good standard for most cases, but your organization may have its own guidelines, so always check those and follow them where they apply.

The values in the tables below are worked examples for the 1.5 T setup used in this guide. Exact numbers vary by scanner, coil and department, so treat them as a starting point rather than as fixed limits.

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

1. Coronal T2 TSE

✅ Correct Planning:

Planning Instructions:

• Use the spinal cord as a reference point.
• Ensure the slices cover all 5 intervertebral discs: L1-L2, L2-L3, L3-L4, L4-L5, and L5-S1.
• Align slices as follows:
  • Axial Localizer: Parallel to the transverse processes of the lumbar vertebrae.
  • Sagittal Localizer: Parallel to the spinal cord, so the coronal slices follow the lumbar curve.

Parameters for Coronal T2 TSE:

2. Sagittal T2 TSE

✅ Correct Planning:

Planning Instructions:

• Use the spinal cord as the main anatomical reference.
• Ensure slices extend from the last two thoracic vertebrae (T11 and T12) at the top of the spine, down to the sacrum (S1) at the bottom of the spine.
• Align slices as follows:
  • Axial Localizer: Symmetrical to the vertebral bodies.
  • Coronal Localizer: Parallel to the spinal cord.

Parameters for Sagittal T2 TSE:

3. Sagittal STIR TSE

✅ Correct Planning:

Planning Instructions:

• Copy the slice geometry and planning directly from the sagittal T2 sequence.
• Maintain identical slice angulation, coverage, and positioning to get precise comparison between T2 and STIR images.

Parameters for Sagittal STIR TSE:

4. Sagittal T1 TSE

✅ Correct Planning:

Planning Instructions:

• Copy the slice geometry and planning directly from the sagittal T2 sequence.
• Maintain identical slice angulation, coverage, and positioning to get precise comparison between T2 and T1 images.

Parameters for Sagittal T1 TSE:

5. Axial T2 TSE, Multi-Block and Multi-Angle

✅ Correct Planning:

Planning Instructions:

• Use multi-angle and multi-stack techniques to ensure precise alignment and full coverage of each intervertebral level.
• Align slices parallel to each of the 5 lumbar intervertebral spaces: L1-L2, L2-L3, L3-L4, L4-L5, and L5-S1.
• Use the coronal view to center slices left-to-right across the vertebrae.
• Use the sagittal view to center anterior-to-posterior and ensure slices are parallel to the intervertebral discs.
• For each intervertebral space:
  • Adjust the plane orientation and slice angulation so the group sits parallel to the disc space and as perpendicular to the spinal canal as that allows.
  • Center each axial group over the intervertebral disc and spinal canal.
• Artifact Prevention:
  • Verify slice angulations across stacks to avoid cross-talk artifacts, particularly at the lumbar spine’s posterior aspect.
  • Minimize slice overlap while maintaining full coverage of the edges and central regions of each intervertebral space.

Parameters for Axial T2 TSE:

6. Axial T1 TSE, Multi-Block and Multi-Angle

✅ Correct Planning:

Planning instructions:

• Copy the slice planning and geometry from the axial T2 sequence to maintain identical alignment.

Parameters for Axial T1 TSE:

How to Avoid Artifacts When Planning the Sequences

The table below lists the 5 common lumbar 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 lumbar spine MRI:

1. Spinal cord and cauda equina
2. The 5 lumbar intervertebral discs, and the body and posterior elements of each lumbar vertebra
3. Nerve roots
4. Ligaments
5. Surrounding structures, including paraspinal muscles and epidural space

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

T2 TSE – Highlights Fluid-Related Tissues and Conditions

T2-weighted imaging makes fluids appear bright. This contrast is ideal to detect abnormalities associated with high water content.

In the lumbar spine, T2 images especially 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 excels at visualizing nerve root impingement, synovial cysts, and perineural edema, as well as soft-tissue injuries like torn ligaments and tendons.

✅ Axial T2 of Lumbar Spine – Correct Image:

Axial T2 focuses on cross-sectional details of the spinal canal and neural foramina. By using multi-block and multi-angle acquisitions to align with each intervertebral disc, we can capture nerve root compression, foraminal narrowing, and lateralized disc herniations.

✅ Sagittal T2 of Lumbar Spine – Correct Image:

Sagittal T2 reveals a longitudinal view of the spine, allowing for assessment of overall alignment, hydration of discs, and the degree of spinal stenosis or nerve root compression.

✅ Coronal T2 of Lumbar Spine – Correct Image:

Coronal T2 gives a wide perspective of the spine's alignment, identifying coronal plane pathologies such as scoliosis, lateral disc herniations, or ligamentous abnormalities.

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 lumbar spine, this contrast is 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 because of its ability to differentiate fat from other tissues.

✅ Axial T1 of Lumbar Spine – Correct Image:

Axial T1 focuses on detailed anatomy at the level of the spinal canal and foramina. By using multi-block and multi-angle acquisitions to align with each intervertebral disc, we can visualize foraminal narrowing and chronic degenerative conditions.

✅ Sagittal T1 of Lumbar Spine – Correct Image:

Sagittal T1 provides a midline view, showing vertebral bodies, intervertebral discs, and chronic bony changes. It complements sagittal T2 by offering a clearer view of bone marrow and structural abnormalities.

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

STIR (Short TI Inversion Recovery) suppresses fat signal strongly, which makes water-rich tissues stand out more clearly than on a standard 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 lumbar spine, this contrast is particularly useful for identifying bone marrow edema and infections like discitis or myelitis. STIR also helps detect inflammatory change where bright adjacent fat would obscure the increased water content on a standard T2 sequence.

✅ Sagittal STIR of Lumbar Spine – Correct Image:

The STIR sequence’s main purpose is to detect edema and inflammation, which is best seen in the sagittal plane. This lets us view the entire spine so we don’t miss any fluid-related changes across vertebrae or discs.

Final Checks:

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

1. Spinal Cord and Nerve Roots: The conus medullaris must be clearly visible on the sagittal images, and the cauda equina and exiting nerve roots on the axial images.
2. Disc and Endplate Clarity: All five lumbar discs, L1-L2 down to L5-S1, must appear sharp with visible margins, so that any Modic or herniation change can be assessed.
3. Coverage and Alignment: Sagittal slices must cover from T11–T12 to S1, the coronal slices must include all five lumbar levels, and axial slices must align parallel to each disc space.
4. Fat Suppression on STIR: STIR images must show strong, even fat suppression, with bone marrow edema or inflammation standing out clearly.
5. Image Quality and Artifacts: Images must have strong SNR and crisp detail, with no motion, flow, chemical shift, wrap-around or cross-talk artifact over the region of interest.