MRI Sequences in Clinical Medicine

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MRI Sequences in Clinical Medicine

• Magnetic Resonance Imaging (MRI) is a versatile imaging modality that provides detailed anatomical and functional information about various body tissues.
• There are four primary MRI sequences, each sequence has its unique characteristics and clinical applications.

T1-Weighted Sequence:

• T1-weighted sequence is the most commonly used MRI sequence. 
• It provides excellent anatomical detail and is used for anatomical reference. 
• In T1-weighted images, gray matter appears gray, and white matter appears white, reflecting the same color as real life. 
• T1-weighted sequence is also used for contrast administration, as contrast material is taken up by masses, making them light up and easier to see.

T2-Weighted Sequence:

• T2-weighted sequence is the water-sensitive sequence. 
• It is used to detect pathologic water in the brain, such as edema. 
• Edema is a common finding in various neurological conditions, such as stroke, tumors, and inflammation. T2-weighted sequence is also used to detect other pathologies, such as demyelination, hemorrhage, and infection.

Diffusion-Weighted Imaging (DWI):

• DWI is a sequence that detects the diffusion of water molecules in tissues. 
• DWI is used to detect stroke, as diffusion is restricted in acute infarcts, making them bright on DWI. 
• However, any process that restricts diffusion, such as highly cellular tumors, clotted blood, and pus under pressure, can also be bright on DWI. 
• DWI is also used to detect other pathologies, such as abscesses, epidural hematomas, and tumors.

Gradient-Recalled Echo (GRE) Sequence:

• GRE sequence is sensitive to metals, particularly iron. 
• GRE is used to detect iron deposition in the brain, such as in neurodegenerative disorders, and to detect hemorrhage. 
• GRE sequence is also used to detect other pathologies, such as calcifications, bone lesions, and vascular malformations.

In summary, There are four primary MRI sequences:

• T1W is for anatomy and contrast.
• T2W is for water and edema.
• DWI is for stroke and acute infarct.

• GRE is for metal, iron, and blood.