Matthew Jay Kruse MD, Presenter: Nothing to Disclose

Shadpour Demehri MD, Abstract Co-Author: Nothing to Disclose

John A. Carrino MD, MPH, Abstract Co-Author: Research Grant, Siemens AG Research Grant, Carestream Health, Inc Research Grant, Toshiba Corporation Consultant, BioClinica, Inc Consultant, Pfizer Inc Consultant, Medtronic, Inc Advisory Board, General Electric Company Advisory Board, Siemens AG Advisory Board, Carestream Health, Inc

Stanley S. Siegelman MD, Abstract Co-Author: Nothing to Disclose

There is increasing interest in the use of clinical CT exams as a tool to assess bone density. Our purpose was to evaluate the effect of intravenous contrast on attenuation measurements in the lumbar vertebrae.

Subjects were 200 patients (133 male, age 67 ± 11.7, range 30-97) undergoing unenhanced and multiple-phase contrast-enhanced abdominal CT exams (unenhanced, arterial, venous, and delayed acquisitions). The mean attenuation (HU) was recorded using an elliptical ROI placed over the trabecular bone of L1, L2, and L3 in a standardized fashion (central sagittal image of intended vertebrae). Mean attenuation was also measured in a 1 cm diameter ROI within the aorta at the level of the SMA take-off. Corrected vertebral attenuation values were calculated by multiplying by an adjustment factor, 250 HU/measured aortic HU (where 250 HU is considered standard attenuation of the arterial phase aorta). The correlation between arterial aorta and lumbar vertebrae attenuation values and the association of patient age/gender with attenuation values was assessed.

The absolute change in vertebral attenuation (compared to unenhanced) was 8 ± 8.6, 19 ± 8.8, and 7 ± 6.9 for the arterial, venous, and delayed acquisitions, respectively. The percent change in vertebral attenuation (compared to the unenhanced) was 8 ± 10.4, 18.7 ± 16.8, and 7.2 ± 9.7 for the arterial, venous, and delayed acquisitions, respectively. The corrected percent change in vertebral attenuation was 7.1 ± 9.8, 16.3 ± 14.8, and 6.2 ± 9 for the arterial, venous, and delayed acquisitions, respectively. Both absolute and percentage change in vertebral attenuation values were poorly correlated with the aortic attenuation value (r= 0.15-0.17). Increased patient age trended toward greater enhancement on delayed phase acquisition (p=0.12, Fisher’s Exact Test).

Administration of intravenous contrast is associated with only a modest increase in vertebral attenuation independent of attenuation values in the aorta.

Contrast-enhanced clinical CT examinations may be suitable for bone density assessment. Further investigation is needed to fully characterize the effect of contrast on vertebral attenuation values.

Kruse, M, Demehri, S, Carrino, J, Siegelman, S, Effect of Intravenous Contrast on Attenuation Measurements of the Lumbar Vertebrae on Clinical CT: Application to Bone Density Assessment.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13022523.html