Hounsfield units (HU)
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Indications
- Hounsfield units are used with CT scanning to assess
- radiographic density of non-enhanced lesions
- contrast enhancement of lesions
- evaluation of a fatty liver
Procedure
- obtained from a linear transformation of the measured CT attenuation coefficients
- radiodensity of distilled water at standard temperature & pressure = 0 HU
- radiodensity of air at standard temperature & pressure = -1000 HU
- a change of 1 HU represents a change of 0.1% of the attenuation coefficient of water
Interpretation
- lesions > 20 HU on non-contrast CT images are considered hyperdense
- an increase > 15 HU between precontrast & postcontrast CT imaging is considered enhancement.
Notes
- created by & named after Sir Godfrey Hounsfield
- common HU values[3]
- lung -500 HU
- kidney 30 HU
- liver 40-60 HU
- muscle 10-40 HU
- adipose tissue (fat) -100 to -50 HU
- blood 30-45 HU
- CSF 15 HU
- brain
- grey matter 37-45 HU
- white matter 20-30 HU
- bone
- cancellous bone 700 HU
- cortical bone 3000 HU
More general terms
References
- ↑ Thomas S, Grimm L, Brady MP Renal Cell Carcinoma: Recognition and Follow-up. Medscape. April 18, 2016 http://reference.medscape.com/features/slideshow/renal-cell-carcinoma
- ↑ 2.0 2.1 Weerakkody Y, Greenway K et al Hounsfield unit https://radiopaedia.org/articles/hounsfield-unit
- ↑ 3.0 3.1 Wikipedia: Hounsfield scale https://en.wikipedia.org/wiki/Hounsfield_scale