title: Intravenous contrast injection significantly affects bone mineral density measured on CT.
abstract: OBJECTIVE
  The objective is to evaluate the effect of intravenous contrast media on bone mineral density (BMD) assessment by comparing unenhanced and contrast-enhanced computed tomography (CT) examinations performed for other indications.
  
  
  METHODS
  One hundred and fifty-two patients (99 without and 53 with malignant neoplasm) who underwent both unenhanced and two contrast-enhanced (arterial and portal venous phase) abdominal CT examinations in a single session between June 2011 and July 2013 were included. BMD was evaluated on the three examinations as CT-attenuation values in Hounsfield Units (HU) in the first lumbar vertebra (L1).
  
  
  RESULTS
  CT-attenuation values were significantly higher in both contrast-enhanced phases, compared to the unenhanced phase (p < 0.01). In patients without malignancies, mean ± standard deviation (SD) HU-values increased from 128.8 ± 48.6 HU for the unenhanced phase to 142.3 ± 47.2 HU for the arterial phase and 147.0 ± 47.4 HU for the portal phase (p < 0.01). In patients with malignancies, HU-values increased from 112.1 ± 38.1 HU to 126.2 ± 38.4 HU and 130.1 ± 37.3 HU (p < 0.02), respectively. With different thresholds to define osteoporosis, measurements in the arterial and portal phase resulted in 7-25% false negatives.
  
  
  CONCLUSIONS
  Our study showed that intravenous contrast injection substantially affects BMD-assessment on CT and taking this into account may improve routine assessment of low BMD in nonquantitative CT.
  
  
  CONCLUSIONS
  • Routine CT may gain a role in bone attenuation measurements for osteoporosis • Contrast media injection has substantial influence on CT-derived bone density • Contrast-enhanced CT leads to underestimation of osteoporosis compared to unenhanced CT • Adjusting for contrast injection phase may improve CT screening protocols for osteoporosis.
authors.affiliation: Department of Radiology and Internal Medicine-Geriatrics, University Medical Center Utrecht, Postbus 85500, Postbox: E.03.511, 3508, GA, Utrecht, Netherlands, e.pompe@umcutrecht.nl.
authors.forename: Esther
authors.initials: E
authors.lastname: Pompe
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Willemink
authors.forename: Gawein R
authors.initials: GR
authors.lastname: Dijkhuis
authors.forename: Harald J J
authors.initials: HJ
authors.lastname: Verhaar
authors.forename: Firdaus A A
authors.initials: FA
authors.lastname: Mohamed Hoesein
authors.forename: Pim A
authors.initials: PA
authors.lastname: de Jong
mesh_terms: D000328:Adult; D000368:Aged; D015519:Bone Density / Q000502:physiology*; D002292:Carcinoma, Renal Cell / Q000150:complications; D003287:Contrast Media / Q000008:administration & dosage; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D007680:Kidney Neoplasms / Q000150:complications; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014571:Urologic Neoplasms / Q000150:complications
chemical_list: D003287:Contrast Media