Learning objectives
To provide a review of the MRI physics of diffusion weighted imaging (DWI).
To illustrate current utilities of diffusion weighted imaging (DWI).
To highlight the expanded scope of practice in abdominal and pelvic imaging.
Background
DWI harnesses the erratic motion of water molecules to generate image contrast.
Well-established uses of DWI include differentiating benign from malignant lesions,
detecting and characterising disease activity in the context of inflammatory bowel disease.
Apart from these common utilities,
we explore the scope for DWI in the context of the most common abdominal and pelvic pathologies a trainee radiologist may encounter.
Findings and procedure details
Brownian Motion and Diffusion
Brownian motion,
also known as diffusion,
describes the random motion of water molecules due to thermal energy.
Diffusion weighted imaging harnesses the diffusion characteristics of water molecules in order to generate signal contrast.1
Table 1: Key definitions in diffusion2
Isotropic diffusion
Equal probability of movement in all directions
Anisotropic diffusion
Variable probability of movement in all directions
The motion of water molecules may be 'free' or 'restricted',
depending on: distribution between intra and extracellular compartments,
barriers such as cell membranes and...
Conclusion
DWI has a multitude of common utilities therefore the need to increase understanding amongst trainee radiologists is essential to ensure we utilise this imaging sequence to its fullest capacity.
References
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Diffusion weighted imaging: Technique and applications.World J Radiol.
2016;8(9):785-798.
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The basis of anisotropic water diffusion int he nervous system- a technical review.NMR Biomed 2002:15:325-455.
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Diffusion-Weighted MR Imaging of the Brain.
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Diffusion MRI : Theory,
Methods,
and Applications,
Theory,
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Oxford University Press,
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5.Dietrich O,
Biffar A,
Baur-Melnyk A,
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Technical aspects of diffusion imaging of the body.Eur J...