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Effect of Lower Tube Voltage on the Reproducibility of Right-to-Left Ventricular Diameter Ratio Measurements on Computed Tomographic Pulmonary Angiography Images

George, Elizabeth MBBS; Hunsaker, Andetta R. MD; Rybicki, Frank J. MD, PhD; Kumamaru, Kanako K. MD, PhD

Journal of Computer Assisted Tomography: September/October 2013 - Volume 37 - Issue 5 - p 737–742
doi: 10.1097/RCT.0b013e3182994f37
Thoracic and Cardiovascular Imaging

Objective: This study aimed to evaluate the interobserver variability of right-to-left ventricular (RV/LV) diameter ratios on computed tomographic pulmonary angiographies at reduced tube potential.

Methods: Consecutive computed tomographic pulmonary angiographies performed at 80 kVp for subjects weighing less than 80 kg (n = 40) and 100 kVp for those weighing 80 kg or greater (n = 40) were selected as the low peak kilovoltage cohort, with age- and sex-matched studies performed at 120 kVp forming the controls (n = 40 each). The interobserver variability in RV/LV diameter ratio on axial and 4-chamber images was evaluated.

Results: Interobserver correlation was excellent at both reduced tube voltages (correlation coefficients, 0.81–0.91; P < 0.001). Bland-Altman plots indicated higher variability at lower peak kilovoltage, confirmed only for axial measurements by multivariate regression adjusting for body weight and ventricular ratio (β coefficient = 0.04 and 0.03, P = 0.049 and 0.022, for 80 kVp and 100 kVp, respectively).

Conclusions: Lower tube voltage did not affect the reproducibility of RV/LV diameter ratio on 4-chamber images; for axial measurements, the increase in variability was 3% to 4% of the average ventricular ratio.

From the Applied Imaging Science Laboratory, Department of Radiology, Brigham and Women’s Hospital, Boston, MA.

Received for publication February 22, 2013; accepted April 27, 2013.

Reprints: Frank J. Rybicki, MD, PhD, Applied Imaging Science Laboratory, Department of Radiology, Brigham and Women’s Hospital & Harvard Medical School, 75 Francis St, Boston, MA 02115 (e-mail: frybicki@partners.org).

Conflicts of interest and source of funding: none.

© 2013 by Lippincott Williams & Wilkins