Dr Daniel J Bell and Dr Henry Knipe et al.

Obesity is defined as a body mass index (BMI) greater than 30 kg/m2. It is described as being a "modern epidemic" due to increased rates of metabolic syndrome and other complications in these patients, along with a high and increasing prevalence. 

Obesity rates vary around the world but over 60% of the American population is classified as overweight, obese or morbidly obese. 

Body mass index (BMI), which is calculated as the weight of an individual (in kilograms) divided by their height (in meters), is the basis for the most widespread classification system, but its generality is questionable, and race/ethnicity and gender should be accounted for 6. The World Health Organization and National Institute of Health have proposed the following classification 7:

  • overweight: 25-29.9 kg/m2
  • obese: 30-39.9 kg/m2
  • extremely/severely/morbidly obese: ≥40 kg/m2 or ≥35 kg/m2 with comorbidity

However, in a radiology patient the weight and thoracoabdominal circumference may be more useful to know in terms of being able to scan due to physical restrictions, e.g. table weight limits and bore diameter 3

There are numerous challenges when imaging morbidly obese patients, from practical considerations such as transportation, weight limits for imaging equipment and technical points of gaining diagnostic imaging studies. Ultrasound is the most affected modality 4

Moreover in obese patients, additional numbers of x-ray photons are required to achieve images of the same quality, resulting in a small, but increased ionizing radiation dose

Image quality can be reduced due to beam hardening and limited field of view, but there is the trade-off of increased contrast due to greater intra-abdominal fat 3

A variety of non-surgical treatments have been attempted in these patients with disappointing results. Surgical approaches to treating obesity, collectively known as bariatric procedures, have been far more promising and are now routinely used to treat patients with morbid obesity 1,2.

Obesity increases the risk of many conditions including being an independent risk factor for cancer. It has a significant effect on life expectancy 10,11:

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Article information

rID: 32542
Section: Gamuts
Synonyms or Alternate Spellings:
  • Large body habitus
  • Morbid obesity
  • Extreme obesity

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Cases and figures

  • Case 1
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  • Case 2: Prader-Willi syndrome
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  • Case 3
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  • Case 4: with breast cancer
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  • Case 5: spinal epidural lipomatosis
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  • Case 6: incomplete imaging despite large FOV
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  • Case 7: morbid obesity
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