Takeshi Nakaura MD, Presenter: Nothing to Disclose

Haruhiko Nakatake, Abstract Co-Author: Nothing to Disclose

Takaaki Ogata, Abstract Co-Author: Nothing to Disclose

Shouzaburou Uemura, Abstract Co-Author: Nothing to Disclose

Kazunori Harada, Abstract Co-Author: Nothing to Disclose

Yasuyuki Yamashita MD, Abstract Co-Author: Nothing to Disclose

Low contrast dose protocol for cardiac CT is important, because patients with chronic kidney disease (CKD)　often associates with cardiovascular disease (CVD). The purpose of this study was to evaluate the feasibility of 20 percent reduced contrast dose protocol in cardiac CT using 100 kVp and high tube current-time product technique at 256-row CT.

This prospective study received institutional review board approval; prior informed consent to participate was obtained from all patients. Eighty four patients were enrolled in this study. We assigned patients to 2 protocols according to the  estimated glomerular filtration rate (eGFR). For patients with eGFR above or equal to 60 ml/min/1.73m2, they were scanned at our conventional protocol with 120kVp, 669 mA, helical pitch 0.14, and the contrast material (370 mgI/kg body weight) delivered over 15 sec. For patients with eGFR 30 to 60 ml/min/1.73m2, they were scanned at low contrast dose protocol with 100 kVp, 827 mA, helical pitch 0.10, and the contrast material (296 mgI/kg body weight) delivered over 15 sec. We evaluated effective dose (ED), CT attenuation, image noise and contrast-to-noise ratio (CNR) of the ascending aorta. Two independent readers assessed image noise, vessel enhancement and overall image quality by using a 4-point scale. The 2 protocols were compared with Student t-test and two-sided Mann-Whitney’s U-test test.

Forty nine patients were scanned with 120 kVp protocol and 35 patients were scanned with 100 kVp protocol. There is no significant difference in ED between 100 kVp and 120 kVp protocol (21.1 mSv ± 1.8 vs 22.6 mSv ± 1.6, p > 0.05). There were no significant differences in image noise, CT attenuation and CNR between 100 kVp and 120 kVp protocol (435.6 HU ± 60.3 vs 459.1 HU ± 55.3; 24.8 ± 3.9 vs 26.5 ± 3.6; 18.0 ± 3.9 vs 17.5 ± 2.3, p > 0.05). There were no significant differences in the visual score of all qualitative analysis between at 100 kVp and at 120kVp protocol.

For cardiac CT of patients with renal dysfunction at 256-row CT, the setting of 100 kVp and a high tube current-time product offers almost the same image quality under 20% reduced contrast media as compared with standard-voltage and standard-contrast-dose CT.

The contrast dose can be 20% reduced at cardiac CT using 100 kVp setting at 256-row CT without the deterioration of image quality.

Nakaura, T, Nakatake, H, Ogata, T, Uemura, S, Harada, K, Yamashita, Y, Cardiac CT in Patients with Renal Dysfunction: Twenty Percent Contrast Dose Reduction Using 100 kVp and High Tube Current Time Setting at 256-Row Computed Tomography.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11034660.html