MRI Protocols

T1 vs. T2 images

• T1 images = 1 type of tissue is bright white = FAT
• T2 images = 2 types of tissue are bright white = FAT and WATER

T1 images

• Because fat is bright, subcutaneous fat and bone marrow will appear bright white
• Conversly, CSF is fat free and will show as black
• Bone cortex is black as it contains no free protons
• Pathology
  • Loss of bright white bone marrow in vertebral bodies indicates increased water content and suggests pathology such as trauma, infection or cancer

T2 images

• Anything that is bright on T2 but black on T1 is water
• CSF will appear white in addition to subcutaneous fat and bone marrow
• Bone cortex is black as it contains no free protons
• Pathology
  • Increased brightness within the vertebral body indicates increased water content and suggests pathology such as trauma, infection or cancer

STIR images

• STIR (Short Tau Inversion Recovery) suppresses signal from fatty tissues so ONLY water is bright
• Abnormal low signal on T1 (reduced fat content) and increased signal on STIR (increased water content) suggests pathology such as discitis

FLAIR images

• FLAIR (Fluid Attenuated Inversion Recovery) is used for brain imaging
• Signal from free fluid (such as CSF) is suppressed
• Comparing this to T2 allows a high signal area on T2 (?CSF) to be compared to a high signal on these images indicating infection, tumour or areas of demyelination

DWI images and ADC images

• DWI (Diffusion Weighted Imaging) and ADC (Apparent Diffusion Coefficient) images are viewed together
• High signal on DWI and low signal on ADC indicates restricted diffusion e.g. infarction, cancer or abscess

Gadolinium contrast

• Produces a very high signal
• Abnormal tissue such as inflamed, cancerous tissue is often more vascular and enhances post-contrast

Specific pathologies

Central cord syndrome

Last Updated on June 12, 2024 by Andrew Crofton