title: Is visual assessment of thyroid attenuation on unenhanced CT of the chest useful for detecting hypothyroidism?
abstract: OBJECTIVE
  To determine if visual assessment of the attenuation of morphologically normal appearing thyroid glands on unenhanced computed tomography (CT) of the chest is useful for identifying patients with decreased thyroid function.
  
  
  METHODS
  This was a retrospective study of 765 patients who underwent both unenhanced CT of the chest and thyroid function tests performed within 1 year of the CT examination. Attenuation of the thyroid gland was visually assessed in each patient relative to the attenuation of the surrounding muscles to categorise the gland as "low attenuation" (attenuation similar to surrounding muscles) or "high attenuation" (attenuation greater than surrounding muscles). Thyroid attenuation was quantitatively measured in each case to determine the validity of the visual assessment. Results of thyroid function tests were used to classify thyroid function as hypothyroid, euthyroid, or hyperthyroid. Data were analysed to determine the relationship between visual assessment of thyroid attenuation and status of thyroid function.
  
  
  RESULTS
  Thyroid glands of low attenuation were present in 4.2% (32/765) of the patients. Nearly half (47%) of the patients with low-attenuation thyroids had hypofunctioning thyroid glands. Compared to patients with high-attenuation thyroids, patients with low-attenuation thyroids were significantly more likely to have decreased thyroid function (clinical and subclinical hypothyroidism) and significantly less likely to be euthyroid (p<0.0001). Quantitative measurement of thyroid attenuation confirmed the validity of the visual assessment.
  
  
  CONCLUSIONS
  Low attenuation of an otherwise normal-appearing thyroid gland on unenhanced CT of the chest is strongly associated with decreased thyroid function.
authors: Department of Radiology, University Hospital, Rutgers New Jersey Medical School, Newark, NJ, USA. Electronic address: maldjipd@njms.rutgers.edu.
authors: P D
authors: PD
authors: Maldjian
authors: Department of Radiology, University Hospital, Rutgers New Jersey Medical School, Newark, NJ, USA.
authors: T
authors: T
authors: Chen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013961:Thyroid Gland / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014796:Visual Perception