MRI interpretation
Systematic approach

Key points

  • Start by checking the patient and image details
  • Look at all the available image planes
  • Compare the fat-sensitive with the water-sensitive images looking for abnormal signal
  • Correlate the MRI appearances with available previous imaging
  • Relate your findings to the clinical question

Check the image details

When interpreting an imaging investigation, always check the image and patient details.

Look at all image planes available and compare the fat-sensitive images with the water-sensitive images.

Any abnormality found should be considered with reference to the clinical question in mind.

Image and patient information

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Image and patient information

  • Check that the images are of the correct patient
  • Check the time and date to ensure you are looking at the most up to date images
  • Check you are looking at the correct body part – and the correct side if dealing with the limbs

MRI planes

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MRI planes and sequences

  • Check all images planes (axial, coronal, sagittal, or oblique)

MRI sequences

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MRI sequences

  • Look at the fat-sensitive T1 images which often provide good anatomical detail of the area being studied
  • Compare with the water-sensitive images – such as the T2-weighted or STIR images

Abnormal MRI signal

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Abnormal MRI signal

  • Check for abnormalities of MRI signal
  • Determine the nature of the signal change – abnormal fat or fluid?
  • Note the anatomical location, size and shape of the abnormality
  • The combination of standard T1 images (fat sensitive) and STIR images (water sensitive) can be compared to determine the amount of fat and water within a body part
  • In this pair of images, the high signal mass seen on the T1 image is dark on the STIR image – confirming it contains fat and no water
  • These are typical signal characteristics of a lipoma

Other imaging

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Other imaging

  • Correlate the images with previous imaging – either previous MRIs or other imaging modalities
  • For some body parts correlation with plain X-ray images should be considered part of the routine assessment of the MRI images
  • This plain X-ray gives a good overview of the anatomy and shows good detail of the cortical bone
  • The MRI provides no detail of the cortical bone, but shows the bone medulla and soft tissue structures – such as the cruciate ligaments – not visible on the X-ray image
  • ACL = Anterior Cruciate Ligament
  • PCL = Posterior Cruciate Ligament

The clinical question

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The clinical question

  • Relate your findings to the clinical features and the specific clinical question
  • Both of these images show an area of abnormal high signal within the grey and white matter of the brain
  • Patient 1: gradually worsening headaches and seizures – diagnosis = brain tumour
  • Patient 2: sudden onset left hemiplegia – diagnosis = acute cerebral infarct
  • Although the MRI appearances provide information regarding the position and size of the areas of abnormality, it is the different clinical histories which provide the strongest clues to the diagnosis in both cases