Pituitary fossa: chemical shift effect in MR imaging

Area of Science:

• Medical Imaging
• Biophysics
• Neuroimaging

Background:

• Magnetic resonance (MR) imaging is crucial for visualizing anatomical structures like the pituitary fossa.
• Understanding artifacts in MR imaging is essential for accurate diagnosis.
• The water-fat interface in anatomical regions can produce characteristic signal patterns.

Purpose of the Study:

• To investigate the influence of chemical shift on MR imaging of the pituitary fossa.
• To determine the origin of the low-intensity signal observed at the water-fat interface within the pituitary fossa.
• To differentiate true anatomical signals from imaging artifacts.

Main Methods:

• Healthy volunteers underwent conventional MR imaging of the pituitary fossa.
• Additional MR imaging was performed with reversed frequency-encoding gradients.
• Further imaging involved interchanging phase- and frequency-encoding gradients.

Main Results:

• A thin, black stripe was consistently observed at the water-fat interface in conventional MR images of the pituitary fossa.
• Altering the frequency-encoding gradient or interchanging phase- and frequency-encoding gradients modified this stripe.
• The observed low-intensity signal within the pituitary fossa was directly linked to changes in gradient configurations.

Conclusions:

• The low-intensity signal observed at the water-fat interface within the pituitary fossa is a chemical shift misregistration artifact.
• This finding clarifies the nature of signal variations in pituitary fossa MR imaging.
• Understanding chemical shift effects improves the interpretation of MR images in neuroimaging.