Takeshi Nakaura MD, Presenter: Nothing to Disclose

Kazuo Awai MD, Abstract Co-Author: Nothing to Disclose

Yumi Yanaga MD, Abstract Co-Author: Nothing to Disclose

Hiroyuki Uetani, Abstract Co-Author: Nothing to Disclose

Tomohiro Namimoto MD, Abstract Co-Author: Nothing to Disclose

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

Yoshinori Funama PhD, Abstract Co-Author: Nothing to Disclose

Seitaro Oda MD, Abstract Co-Author: Nothing to Disclose

Kazunori Harada, Abstract Co-Author: Nothing to Disclose

Shouzaburou Uemura, Abstract Co-Author: Nothing to Disclose

00030490-DMT et al, Abstract Co-Author: Nothing to Disclose

Indirect CT venography (CTV) provides high diagnostic accuracy, however, it has the disadvantages of increased contrast- and radiation doses. The use of low kilovoltage and high tube current techniques may overcome this disadvantage. We prospectively evaluated the effect of indirect multi-detector row CTV using a low kVp- with high tube current technique on image noise, contrast-to-noise ratio (CNR), and radiation dose.

This prospective study had institutional review board approval; informed consent was waived. Thirty patients underwent indirect multi-detector row CT (MDCT) venography of the lower extremity at 120 kVp with 170 mA and at 80 kVp with 426 mA on a 64-detector CT scanner. Attenuation of the femoral and popliteal vein, image noise, contrast-to-noise ratio and dose length product (DLP) were measured. Two independent readers assessed the diagnostic image quality for beam-hardening artifacts and vessel enhancement by using a 3-point scale. The two protocols were compared with the two-tailed Student t-test and the Wilcoxon signed rank test.

The attenuation of the femoral and popliteal veins was significantly greater at 80 kVp (138.8 HU ± 37.1 and 146.6 HU ± 27.0; respectively) than at 120 kVp (93.7 HU ± 20.1 and 105.5 HU ± 20.6; respectively) (P<0.01). Mean image noise was significantly higher at 80- than 120 kVp (P<0.05). The CNR was significantly higher at 80- (5.7 ± 2.9 and 9.6 ± 3.5; respectively) than 120 kVp (3.4 ± 4.2 and 6.8 ± 3.3; respectively) (P < .01). There was no significant difference in the visual score for image noise at 80- and 120kVp (P=0.37). The visual score of contrast enhancement was significantly higher at 80- than 120 kVp (P<0.01). The mean DLP was significantly smaller at 80- than 120 kVp (562.1 mGy x cm ± 72.0 vs 737.7 mGy x cm ± 94.1) (P<0.01).

At indirect CTV, 80 kVp and a high tube current setting significantly improved the image quality and reduced the radiation dose compared with 120 kVp.

At indirect CTV, low kilovoltage and high tube current setting is recommended to reduce the radiation dose and to improved the image quality.

Nakaura, T, Awai, K, Yanaga, Y, Uetani, H, Namimoto, T, Yamashita, Y, Funama, Y, Oda, S, Harada, K, Uemura, S, et al, 0, Improvement of Venous Enhancement and Radiation Dose Reduction in Indirect Multidetector Row CT Venography by Using a Low kVp with High Tube Current Technique: Initial Experience.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8011139.html