How to Plan a Shoulder MRI Protocol (Clock Face Method)

Intro to Shoulder MRIs

How to Perform a Shoulder MRI with Clock Face Method

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 shoulder.

✅ Correct Setup of Localizer Images for Shoulder 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 shoulder MRI protocol includes, why we perform them, and how to set them up.

Planning Additional Localizers for the Clock Face Method

Before we acquire our high-resolution sequences, we need additional localizers to plan our sequences according to specific anatomical structures using the clock face method.

We’ll run two different localizer sequences:

1. Two-Plane Localizer (Sagittal and Coronal Views):
2. Axial PD Fat-Saturated Localizer

1. Two-Plane Localizer (Sagittal and Coronal Views):

✅ Correct Planning:

Planning Instructions:

• Use the glenoid fossa and rim as your anatomical references.
• Align the slices as follows:
  • Sagittal localizer: Run parallel to the glenoid rim to visualize the glenohumeral joint clearly.
  • Coronal localizer: Run perpendicular to the glenoid rim, also showing the glenohumeral joint.
• Both localizers share the same center and give us clear visualization of the glenoid fossa and rim.
• Use appropriate geometry parameters:
  • Slice number: Enough to cover the shoulder region (12-15 slices).
  • Slice thickness: 5-6 mm for good overview imaging.
  • Slice gap: 1 mm to prevent crosstalk while maintaining coverage.
• Set the fold-over direction (phase encoding) to anterior-posterior to reduce motion artifacts.

✅ Sagittal Localizer – Correct Image Example:

✅ Coronal Localizer – Correct Image Example:

2. Axial PD Fat-Saturated Localizer:

✅ Correct Planning:

Planning Instructions:

• Use the supraspinatus tendon as your anatomical reference.
• Align the slices as follows:
  • Sagittal localizer: Angle the slice package perpendicular to the glenoid bone tips.
  • Coronal localizer: Center slices over the glenohumeral joint.
• Use appropriate geometry parameters:
  • Slice number: Enough to cover the shoulder joint and supraspinatus tendon area (20-25 slices).
  • Slice thickness: 4 mm for detailed visualization.
  • Slice gap: 0.8 mm to maintain anatomical continuity.
• Set the fold-over direction (phase encoding) to anterior-posterior for straight shoulder view.
• Center the field of view over the shoulder for optimal positioning.

✅ Axial PD Fat-Sat Localizer – Correct Image Example:

The 6 Sequences of a Standard Shoulder MRI Protocol

Once we have all localizers, we will run the following 6 sequences:

1. Sagittal PD Fat-Saturated TSE
2. Coronal PD Fat-Saturated TSE
3. Axial PD Fat-Saturated TSE
4. Sagittal T1 TSE
5. Coronal T2 TSE
6. Axial T1 TSE

We mainly use Turbo Spin Echo sequences for this study. These sequences let us create multiple types of contrasts, including PD with fat suppression, T1, and T2 weighting. This helps us assess the integrity of the shoulder structures and check for common pathologies while maintaining high resolution for small structures.

The order of sequences is very important for the clock face method. Each sequence helps us plan the next one for optimal visualization of shoulder anatomy.

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

1. Sagittal PD Fat-Saturated TSE

✅ Correct Planning:

Planning Instructions:

• Plan the stack using the sagittal and coronal localizers and axial localizer views.
• Use the glenoid fossa and tips of the glenoid bone as your anatomical references.
• Align the slices as follows:
  • Coronal localizer: Parallel to the upper and lower tips of the glenohumeral joint, connecting these two points.
  • Axial localizer: Parallel to the glenoid rim to follow the clock face orientation.
  • Sagittal localizer: Center the slice package properly for coverage from deltoid muscle to scapular notch.
• Use appropriate geometry parameters:
  • Slice number: Enough to fully cover the shoulder region (29 slices).
  • Slice thickness: 3 mm for high resolution without sacrificing scan time or SNR.
  • Slice gap: 0.3 mm (10% of slice thickness) to enhance small structure visibility.
• Set the fold-over direction (phase encoding) to anterior-posterior to reduce motion artifacts.

Parameters for Sagittal PD Fat-Saturated TSE:

2. Coronal PD Fat-Saturated TSE

✅ Correct Planning:

Planning Instructions:

• Plan the stack using the sagittal PD FS sequence we just acquired.
• Use the glenoid fossa (12 o'clock to 6 o'clock positions) as your anatomical reference.
• Align the slices as follows:
  • Sagittal PD FS: Orient from the 12 o'clock down to the 6 o'clock positions on the glenoid, connecting these two points using the clock face approach.
  • Axial localizer: You can align perpendicular to the glenoid rim for clear articular surface views, or parallel to the supraspinatus tendon for exceptional rotator cuff visualization (recommended).
• Use appropriate geometry parameters:
  • Slice number: Enough to cover shoulder region from side to side.
  • Slice thickness: 3 mm for high resolution.
  • Slice gap: 0.3 mm to maintain small structure visibility.
• Coverage should extend from the front portion of the coracoid process to two slices behind the humeral head.
• Set the fold-over direction (phase encoding) to anterior-posterior for optimal image quality.

Parameters for Coronal PD Fat-Saturated TSE:

3. Axial PD Fat-Saturated TSE

✅ Correct Planning:

Planning Instructions:

• Plan the stack using the coronal PD FS sequence we just acquired.
• Use the glenoid rim and clock face reference as your anatomical references.
• Align the slices as follows:
  • Coronal sequence: Set perpendicular slice position on top of the coronal plane.
  • Sagittal sequence: Refer to the glenoid fossa as the face of the clock. Orient the angulation to the 9 to 3 o'clock position (drawing a line from left to right across the glenoid).
• Use appropriate geometry parameters:
  • Slice number: Enough to cover from acromioclavicular joint to two slices below articular capsule.
  • Slice thickness: 3 mm for high resolution.
  • Slice gap: 0.3 mm to maintain anatomical continuity.
• Position the field of view on the axial plane for a straight view (slices may appear skewed on other planes due to oblique shoulder angles).
• Set the fold-over direction (phase encoding) to anterior-posterior for optimal imaging.

Parameters for Axial PD Fat-Saturated TSE:

4. Sagittal T1 TSE

✅ Correct Planning:

Planning Instructions:

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

Parameters for Sagittal T1 TSE:

5. Coronal T2 TSE

✅ Correct Planning:

Planning Instructions:

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

Parameters for Coronal T2 TSE:

6. Axial T1 TSE

✅ Correct Planning:

Planning Instructions:

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

Parameters for Axial T1 TSE:

How to Avoid Artifacts When Planning the Sequences

The table below lists the 5 common shoulder 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 shoulder MRI:

1. Rotator cuff tendons (supraspinatus, infraspinatus, subscapularis, teres minor)
2. Glenoid labrum and articular surfaces
3. Glenohumeral joint and joint capsule
4. Acromioclavicular joint
5. Bone marrow of the humeral head and glenoid
6. Subacromial-subdeltoid bursa
7. Biceps tendon and superior labral complex

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

PD Fat-Saturated – Best for Soft Tissue, Labral, and Rotator Cuff Pathology

Proton Density Fat-Saturated (PD FS) imaging provides excellent soft tissue contrast while suppressing fat, making it ideal for evaluating shoulder joint structures.

In shoulder MRI, PD FS sequences are the gold standard for detecting rotator cuff tears, labral injuries, and joint effusions. They enhance soft tissues and fluids without fat signal interference, making tears appear as bright signal that interrupts the normally dark tendon or labrum. This contrast is optimal for detecting subtle tendinosis and capsular pathologies.

The three planes captured in PD FS provide comprehensive coverage. Each plane helps plan the next using the clock face method, ensuring optimal visualization of all shoulder structures.

✅ Sagittal PD FS of the Shoulder – Correct Image Example:

Things to Look for in Sagittal PD FS:

• Glenoid fossa clearly outlined with good contrast
• Coracoid process visible and well-defined
• Supraspinatus tendon integrity along its full length
• Joint effusion or fluid collections appearing bright

✅ Coronal PD FS of the Shoulder – Correct Image Example:

Things to Look for in Coronal PD FS:

• Supraspinatus tendon displayed throughout its length in single slices
• Clear visualization of rotator cuff insertions
• Labral morphology and signal intensity
• Acromioclavicular joint and subacromial space

✅ Axial PD FS of the Shoulder – Correct Image Example:

Things to Look for in Axial PD FS:

• Labrum appearing as a small dark structure around the glenoid
• Rotator cuff tendons (infraspinatus, subscapularis, superior glenohumeral ligament)
• Complete coverage from the acromioclavicular joint downward
• Biceps tendon and bicipital groove pathology

T1 TSE – Highlight Fat-Containing Tissues and Anatomical Structure

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 shoulder MRI, T1 sequences are valuable for evaluating bone marrow pathology, fatty infiltration of muscles, and overall anatomical structure. T1 contrast helps identify bone marrow changes, muscle atrophy, and provides baseline anatomy for comparison with other sequences

✅ Sagittal T1 of the Shoulder – Correct Image Example:

Things to Look for in Sagittal T1:

• Bone marrow signal intensity and any pathological changes
• Muscle anatomy and fatty infiltration patterns
• Structural integrity compared to PD FS sequences
• Overall glenohumeral joint alignment

✅ Axial T1 of the Shoulder – Correct Image Example:

Things to Look for in Axial T1:

• Fatty infiltration of rotator cuff muscles
• Bone marrow changes in the humeral head or glenoid
• Muscle volume and atrophy assessment
• Comparison with PD FS for structure evaluation

T2 TSE – Highlight Fluid-Related Tissues and Inflammation

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

In shoulder MRI, T2 sequences help confirm pathology seen on other sequences and distinguish real inflammation from magic angle artifacts. They are particularly useful for evaluating edema, inflammation, joint effusions, and confirming whether increased signal on other sequences represents true pathology.

✅ Coronal T2 of the Shoulder – Correct Image Example:

Things to Look for in Coronal T2:

• Joint effusion and synovial thickening
• Bone marrow edema appearing bright
• Confirmation of tendon pathology versus magic angle artifact
• Fluid collections in the subacromial-subdeltoid bursa

Final Checks:

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

1. Rotator Cuff Coverage: All four rotator cuff tendons must be clearly visible with sharp definition, especially the supraspinatus throughout its length in coronal PD FS.
2. Labral Visualization: The glenoid labrum must appear as a dark triangular structure around the glenoid in axial and coronal views with high resolution.
3. Clock Face Alignment: Slices must be properly angled according to glenoid anatomy, with coronal views following 12-6 o'clock and axial views following 9-3 o'clock orientation.
4. Fat Suppression Quality: PD FS sequences must show uniform fat suppression so that soft tissue abnormalities and fluid appear clearly without fat signal interference.
5. Image Quality and Coverage: All sequences must have strong SNR, excellent spatial resolution for small structures, and complete coverage from acromioclavicular joint to inferior glenohumeral joint.

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