Sebastian Tobias Schindera MD, Abstract Co-Author: Research grant, Siemens AG

Patricia Graca MS, Abstract Co-Author: Nothing to Disclose

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

Susanne Abderhalden, Abstract Co-Author: Nothing to Disclose

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

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

To compare image quality and radiation dose of thoracoabdominal CT angiography (CTA) at 80 kVp and 100 kVp and to assess the feasibility of reducing contrast medium volume to 45 mL at 80 kVp.

This retrospective study had IRB approval. The study cohort comprised of three groups each consisting of 25 patients who had undergone thoracoabdominal 64-slice CTA (Siemens Somatom). Group A (mean weight, 77.5 kg; weight range, 48-143 kg) was acquired with 100 kVp, group B (mean weight, 84.2 kg; weight range, 62-130 kg) and C (mean weight, 75.1 kg; weight range, 53-110 kg) with 80 kVp. Automatic tube current modulation was applied using reference mAs setting of 160 for group A and 260 for groups B and C. Group A and B received 60 mL of contrast medium (iodine concentration, 370 mg/mL) at 4 mL/sec, group C 45 mL of contrast medium (iodine concentration, 370 mg/mL) at 3 mL/sec. Mean aortoiliac attenuation, image noise, and contrast-to-noise ratio (CNR) were assessed. The effective dose was estimated based on the dose-length product. Three independent readers assessed the diagnostic image quality.

Mean aortoiliac attenuation for group B (621.1 HU ± 90.5) was significantly greater than for groups A and C (485.2 HU ± 110.5 and 483.1 HU ± 119.8; respectively; P<.001). Mean image noise was significantly higher for groups B and C than for group A (P<.05). The CNR did not significantly differ between the groups (group A, 35.0 ± 13.8; group B, 31.7 ± 10.1; group C, 27.3 ± 11.5; P=.08). Mean estimated effective doses in groups B and C (5.7 mSv ± .5 and 5.3 mSv ± .4, respectively) were reduced by 23.4% and 28.9%, respectively, compared to group A (7.9 mSv ± 1.3; P<.001). The average overall diagnostic image quality for the three groups was graded as good or better. The image quality score for group A was significantly higher than that for group C (P<.01), no difference was seen between group A and B (P=.92).

Reduction of tube voltage from 100 kVp to 80 kVp for thoracoabdominal CTA significantly reduces radiation dose without compromising image quality. Reduction of contrast medium volume to 45 mL at 80 kVp resulted in lower but still diagnostically acceptable image quality.

80-kVp thoracoabdominal CTA with 45 mL of contrast medium might be an alternative to MRA in patients with impaired renal function who are at increased risk of developing nephrogenic systemic fibrosis.

Schindera, S, Graca, P, Patak, M, Abderhalden, S, Vock, P, Szucs-Farkas, Z, Thoracoabdominal-Aortoiliac Multidetector Row CT Angiography at 80 kVp with Reduced Contrast Medium Volume: Assessment of Image Quality and Radiation Dose.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8006564.html