How to plan a pituitary gland MRI protocol

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

What you will learn:

1. Key factors in pituitary MRIs, including trade-offs.
2. Patient and scanner setup tips.
3. Best pulse sequences and planning techniques.
4. Ways to avoid common artifacts.
5. What great pituitary images should look like.

The pituitary gland is a small but powerful gland at the base of your brain. It regulates hormones that control growth, metabolism, and reproduction. Despite its size, it plays a key role in maintaining the body’s balance.

Given its importance, the pituitary is often evaluated with MRI to detect tumors, hormonal imbalances, and structural abnormalities, making it a core area of study in brain imaging.

How to Balance the 3 Trade-offs in Pituitary MRIs

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

1. Scan Time: How fast a pulse sequence can be completed.
2. Resolution: How much detail the image can display.
3. SNR: How clear the image is, how much signal relative to noise.

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

For pituitary MRIs, we face these challenges:

• The gland is roughly 10 mm across, and the lesions we hunt for are often 3 mm or smaller. Without high resolution, a microadenoma can fall below the voxel size and simply not appear.
• High resolution means small voxels, and small voxels cost signal. We need enough SNR left to still see the gland clearly against surrounding fat and vessels.
• A pituitary study is requested less often than routine brain, spine, or knee scans, which gives us more room to spend on scan time if resolution and SNR need it.

Therefore, we typically:

1. Prioritize resolution, since a lesion smaller than the voxel is invisible regardless of everything else.
2. Maintain enough SNR to keep that resolution diagnostic, buying it back with extra averages where needed.
3. Optimize scan time last, since this study can usually afford a longer slot than routine scans.

High-resolution images are needed to see this tiny structure clearly and detect subtle abnormalities. However, we must still ensure a good SNR and adequate scan time too.

Pituitary Health Conditions and the MRI Sequences That Reveal Them

The pituitary gland MRI study can help us diagnose a wide range of health conditions. The table below lists some of the most common conditions and which pulse sequences reveal them:

This step-by-step guide below will show you how to set up and perform a pituitary 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 and the Coils

Lay the patient head-first and supine (on their back).

Make sure the laser is centered on the glabella (the spot between the eyebrows) to align the pituitary gland perfectly with the scanner’s isocenter.

Use a high-quality coil optimized for the sella turcica and surrounding structures. This setup gives us strong signal coverage for imaging the optic chiasm, infundibulum, and cavernous sinuses.

✅ 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 pituitary gland.

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

The 6 Sequences of a Standard Pituitary MRI

1. Axial T2 FLAIR
2. Sagittal T1 TSE
3. Coronal T1 TSE
4. Coronal T2 TSE  (Optional)
5. Post-contrast Sagittal T1 TSE
6. Post-contrast Coronal T1 TSE

Turbo Spin Echo is the workhorse of this protocol for two reasons. Its refocusing pulses make it far more resistant to susceptibility distortion than gradient echo, which matters because the sella sits directly above the air-filled sphenoid sinus. It is also efficient enough to acquire thin, high-resolution slices in a workable scan time.

The axial T2 FLAIR at the start is a whole-brain survey. It checks for findings outside the sella before attention narrows to the gland.

Post-contrast T1 shows which tissue takes up gadolinium. That is what separates a normal gland from an adenoma, defines lesion margins and reveals cavernous sinus invasion.

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

1. Axial T2 FLAIR

✅ Correct Planning:

Planning Instructions:

• Use a full field-of-view (FOV) to cover the entire brain.
• Align slices as follows:
  • Sagittal Localizer: Middle slice should be parallel to the AC-PC line (Anterior Commissure - Posterior Commissure).
  • Coronal Localizer: Rotate the FOV slightly to ensure it’s perpendicular to the mid-sagittal line.
• Expand slices to cover the brain from the vertex to the foramen magnum.
• Minimize slice gap and slice thickness for finer slices while maintaining reasonable scan time.

Parameters for Axial T2 FLAIR:

Because we are imaging the entire brain in this scan, rather than the pituitary specifically, we don’t need as high resolution, and can instead prioritize scan time slightly more.

2. Sagittal T1 TSE

✅ Correct Planning:

Planning Instructions:

• Use a small field-of-view (FOV) to focus on the pituitary gland and surrounding structures.
• Copy the image position from the sagittal localizer as a starting point.
• Align slices as follows:
  • Axial Localizer: Scroll to the slice where the gland is clearly visible, centre the slice package over it, and angle it parallel to the mid-sagittal line.
  • Coronal Localizer: Centre the package on the gland and angle it parallel to the mid-sagittal line here as well.
• Expand coverage laterally to include the optic nerves and the vessels on either side.
• Reduce slice thickness and keep the slice gap below 20% of slice thickness, and no more than 30%.

Parameters for Sagittal T1 TSE:

3. Coronal T1 TSE

✅ Correct Planning:

Planning Instructions:

• Use a small field-of-view (FOV) to focus on the pituitary gland and surrounding structures.
• Copy the orientation and geometry from the sagittal T1 if your scanner allows it, then adjust the angle.
• Align slices as follows:
  • Sagittal Localizer: Angle the package perpendicular to the floor of the sella turcica. This usually needs a small counter-clockwise adjustment.
  • Axial Localizer: Check that the field of view is perpendicular to the mid-sagittal line.
  • Coronal Localizer: Place the centre of the package directly on the pituitary gland.
• Extend coverage from the optic nerves anteriorly to the dorsum sellae posteriorly.
• Minimize slice gap and slice thickness for precise imaging of small structures.

Parameters for Coronal T1 TSE:

4. Coronal T2 TSE (Optional)

If the outcome of the scan is already clear from the previous sequences, you can skip running this sequence.

✅ Correct Planning:

Planning Instructions:

• Copy the slice geometry and planning from the previous coronal T1 sequence.
• Maintain identical slice angulation, coverage, and positioning to ensure precise comparison between T2 and T1 images.

Parameters for Coronal T2 TSE:

5. Post-Contrast Sagittal T1 TSE

These are the standard post-contrast acquisitions. Where a microadenoma is suspected, a dynamic series is added on top: serial coronal T1 sets from the moment of injection, one every 10–30 seconds for 3–5 minutes.

The adenoma stands out most in the first 30–60 seconds, while the normal gland has enhanced and the adenoma has not.

✅ Correct Planning:

Planning Instructions:

• Copy the slice geometry and planning from the pre-contrast sagittal T1 sequence.
• Maintain identical slice angulation, coverage, and positioning to ensure precise comparison between pre- and post-contrast images.

Parameters for Post-Contrast Sagittal T1 TSE:

6. Post-Contrast Coronal T1 TSE

✅ Correct Planning:

Planning Instructions:

• Copy the slice geometry and planning from the pre-contrast coronal T1 sequence.
• Maintain identical slice angulation, coverage, and positioning to ensure precise comparison between pre- and post-contrast images.

Parameters for Post-Contrast Coronal T1 TSE:

How to Avoid Artifacts When Planning the Sequences

The table below lists the 6 common pituitary gland artifacts, and what techniques you can use to avoid them:

How to Prepare and Administer the Contrast Injection

Before you perform post-contrast sequences, prepare and administer the contrast injection carefully to ensure imaging quality and patient safety.

Follow these steps:

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 pituitary MRI:

1. Pituitary gland
2. Infundibulum (pituitary stalk)
3. Sella turcica, including the floor and the dorsum sellae
4. Optic chiasm
5. Cavernous sinuses and internal carotid arteries
6. Hypothalamus
7. Sphenoid sinus
8. Clivus

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

T2 FLAIR – Focused Fluid Imaging without CSF Interference

T2 FLAIR keeps the T2-weighting that makes water-rich tissue bright, but adds an inversion pulse that nulls free-flowing cerebrospinal fluid (CSF). Oedema, protein-rich cyst contents and inflammatory change stay bright, while the CSF that would obscure them turns dark.

In the pituitary region, T2 FLAIR is especially useful for identifying edema, cysts, or inflammatory changes in the gland or adjacent structures. It also helps visualize mass effects on the optic chiasm and asymmetry in the cavernous sinuses.

✅ Axial T2 FLAIR of Pituitary – Correct Image:

An Axial T2 FLAIR provides cross-sectional details of the gland, internal carotid arteries, and cavernous sinuses. This view is best for assessing asymmetry and detecting fluid-related pathology localized in the transverse plane.

T1 TSE – Highlight 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 pituitary region, T1 TSE is the sequence that delineates the gland, stalk and vasculature. It helps identify gland asymmetry, stalk thickening, and parasellar abnormalities.

✅ Sagittal T1 TSE of Pituitary – Correct Image:

Sagittal T1 TSE provides a midline view of the pituitary gland, stalk, and sphenoid sinus. This view is ideal for assessing the gland’s vertical relationships with the optic chiasm and hypothalamus.

✅ Coronal T1 TSE of Pituitary – Correct Image:

Coronal T1 TSE captures the lateral extent of the pituitary gland and its relationship to the cavernous sinuses. This view is best for identifying gland asymmetry or parasellar invasion.

T2 TSE – Highlights Fluid-Related Tissues and Conditions

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

In the pituitary region, T2 TSE excels at detecting cystic changes, fluid accumulation, or inflammation. It also highlights structural relationships between the gland, sphenoid sinus, and clivus.

✅ Coronal T2 TSE of Pituitary – Correct Image:

Coronal T2 TSE offers a frontal view of the pituitary gland, optic chiasm, and cavernous sinuses. This view is ideal for evaluating gland symmetry, fluid-related pathologies, and stalk abnormalities.

Post-Contrast T1 – Clearest View of Structural and Vascular Abnormalities

Post-contrast T1 imaging is the gold standard for detecting enhancing lesions and abnormal blood flow. It highlights areas with contrast uptake, such as tumors, inflammation, or vascular changes, with particular detail.

In the pituitary region, post-contrast T1 highlights enhancement patterns in the gland and stalk, helping differentiate normal tissue from tumors or cysts. It also assesses vascular structures and potential cavernous sinus invasion.

✅ Post-Contrast Sagittal T1 TSE of Pituitary – Correct Image:

Sagittal post-contrast T1 TSE enhances the visualization of the gland, stalk, and hypothalamus. This view is ideal for detecting subtle lesions or enhancement abnormalities along the vertical axis.

✅ Post-Contrast Coronal T1 TSE of Pituitary – Correct Image:

Coronal post-contrast T1 TSE provides detailed imaging of the gland’s lateral structures, including the cavernous sinuses and internal carotid arteries. This view is best for detecting asymmetric enhancement and parasellar masses.

Final Checks:

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

1. Gland and Stalk Visibility: The pituitary gland and stalk must be fully visible and symmetric in sagittal and coronal T1 views.
2. Contrast Enhancement: Post-contrast T1 images must show clear, symmetric enhancement; look for subtle delayed uptake.
3. Stalk and Optic Chiasm Coverage: Slices must include the entire stalk and extend up to the optic chiasm.
4. CSF Suppression: In axial T2 FLAIR, CSF around the gland should be dark to reveal edema or fluid-related changes.
5. Image Quality and Artifacts: All images must have strong SNR, sharp borders, and no motion, aliasing, or ghosting artifacts.

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