Esther Pompe MD, Presenter: Nothing to Disclose

Martin J. Willemink MD, Abstract Co-Author: Nothing to Disclose

Gawein Reinout Dijkhuis MD, Abstract Co-Author: Nothing to Disclose

Harald Verhaar, Abstract Co-Author: Nothing to Disclose

Firdaus Mohamed Hoesein MD, Abstract Co-Author: Nothing to Disclose

Pim A. De Jong MD, PhD, Abstract Co-Author: Nothing to Disclose

Osteoporosis could be detected by determining the bone density (BD) in a region of interest (ROI) within a lumbar vertebra on CT. The effect of intravenous contrast media on BD measurements on computed tomography (CT) examinations performed for other indications was evaluated. 

152 subjects (99 without and 53 with malignant renal neoplasm) who underwent both un-enhanced and two contrast-enhanced (arterial and portal venous phase) abdominal CT exams in a single session between June 2011 and July 2013 were included. BD was evaluated on the three exams as CT-attenuation values in Hounsfield Units (HU) in the first lumbar vertebra (L1).

Subjects were stratified based on the presence of malignancies, because BD measurements were significantly higher in the group without malignancies. Mean ± standard deviation (SD) differences in BD measurements were 27.5±56.4 HU (p<0.01) in the un-enhanced phase, 23.6±59.9 HU in the arterial phase (p<0.01) and 19.8±56.5HU (p<0.01) in the portal phase. CT-attenuation values were significantly higher in contrast-enhanced phases, compared to the un-enhanced phase (p<0.01). In patients without malignancies, 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 thresholds of ≤110 HU, ≤135 HU, ≤160 HU to define osteoporosis, measurements in the arterial phase and portal phase resulted in 7-25% false negatives. 

Our study showed that intravenous contrast injection substantially affects BD-assessment on CT and taking this into account it may improve opportunistic screening for osteoporosis. 

An overestimation of bone density due to contrast injection in clinical CT scans could lead to false negative results if used in a screening setting for osteoporosis. 

Pompe, E, Willemink, M, Dijkhuis, G, Verhaar, H, Mohamed Hoesein, F, De Jong, P, Osteoporosis Screening with Computed Tomography: Contrast Media Significantly Affects Bone Signal.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045573.html