Zsolt Szucs-Farkas MD, PhD, Presenter: Nothing to Disclose

Luzia Kurmann, Abstract Co-Author: Nothing to Disclose

Tamara Strautz MD, Abstract Co-Author: Nothing to Disclose

Michael A. Patak MD, Abstract Co-Author: Nothing to Disclose

Peter Vock MD, Abstract Co-Author: Nothing to Disclose

Sebastian Tobias Schindera MD, Abstract Co-Author: Nothing to Disclose

To compare patient exposure and image quality for two low-dose pulmonary CT angiography (CTA) protocols in patients with suspected pulmonary embolism.

This retrospective study was approved by the institutional review board. Ninety patients weighing less than 100 kg were examined by a pulmonary CTA protocol using either 100 kVp (group A) or 80 kVp (group B). Volume and flow rate of contrast medium were reduced in group B (75 mL at 3 mL/s) compared to group A (100 mL at 4 mL/s). Attenuation was measured in the central and peripheral pulmonary arteries, and the contrast-to-noise ratios (CNR) were calculated. Quantitative image parameters and estimated effective dose in both groups were compared by the t-test. Arterial enhancement, noise, and overall quality were independently assessed by three radiologists, and results were compared between the groups using non-parametric tests.

Mean attenuation in the pulmonary arteries in group B (427.6±116 HU) was significantly higher than in group A (342.1±87.7 HU, p< 0.001), while CNR showed no difference (group A, 20.6 ± 7.3 and group B, 22.2 ± 7.1, p= 0.302). Effective dose was lower by more than 40% with 80 kVp (1.68 ± 0.23 mSv) compared to 100 kVp (2.87 ± 0.88 mSv) (p<0.001). Image quality did not differ significantly between the groups (p= 0.151).

 Using 80 kVp in pulmonary CTA permits reduced patient exposure by 40% and CM volume by 25% compared to 100 kVp without deterioration of image quality in patients weighing less than 100 kg.

Reduced patient exposure and iodine load is possible at pulmonary CT angiography using 80 kVp in patients weighing up to 100 kg without impairment of objective or subjective image quality.

Szucs-Farkas, Z, Kurmann, L, Strautz, T, Patak, M, Vock, P, Schindera, S, Patient Exposure and Image Quality of Low-dose Pulmonary CT Angiography: Comparison of 100 and 80 kVp Protocols.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6008388.html