The Concept of CMR
Slides, videos and moreEvaluating CMR
Imaging Techniques
Computed Tomography (CT)
- 1Key Points (1 page)
- 2Determining Total Adiposity With Computed Tomography (1 page)
- 3Determining Tissue Area or Mass Using CT (1 page)
- 4Measuring Skeletal Muscle Mass Using CT (1 page)
- 5Measuring Intra-abdominal Fat Using MRI and CT (2 pages)
- 6Measuring Ectopic Fat Using CT (2 pages)
- 7References (1 page)
Determining Total Adiposity With Computed Tomography
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Figure 1: 
Figure 1: There are a number of imaging techniques for determining total and regional body composition. Computed tomography (CT) and magnetic resonance imaging (MRI) provide cross-sectional images that can be used to determine total adiposity and are one of the most accurate tools available for directly quantifying body composition at a tissue level. As such, CT and MRI (discussed further in Magnetic Resonance Imaging) are often considered the criterion measures for assessing intra-abdominal (visceral) fat and skeletal muscle in vivo. Other imaging techniques—such as dual energy x-ray absorptiometry (DEXA) and ultrasound—are also useful clinical imaging techniques for assessing total and intra-abdominal adiposity. The strengths and weaknesses of DEXA and ultrasonography are addressed in another section (see Others).
CT uses ionizing radiation and differences in tissue x-ray attenuation to produce cross-sectional images of the body (1, 2). X-ray attenuation depends mainly on matter density and is commonly expressed in Hounsfield units (HU). Lower density tissues such as fat have lower HU ratings than higher density tissues such as muscle or bone. Cross-sectional CT images are composed of many pixels, each with a HU value reflecting the molecular composition of the tissue. Although CT is easier to use than MRI, radiation exposure makes it unsuitable for multiple-image whole body tissue quantification and for use in children and premenopausal women (Figure 1).
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