Yumi Yanaga MD, Presenter: Nothing to Disclose

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

Takeshi Nakaura MD, Abstract Co-Author: Nothing to Disclose

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

Kyongtae Tyler Bae MD, PhD, Abstract Co-Author: Patent agreement, Covidien AG, St Louis, MO Patent agreement, Bayer AG, Pittsburgh, PA Consultant, Otsuka Pharmaceutical Co, Ltd, Rockville, MD

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

Masanori Imuta MD, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

To compare the effect on aortic enhancement (AE) of iodine doses adjusted for the patient estimated lean- and total body weight (ELBW, TBW) at computed tomography angiography (CTA).

Using a 64-detector CT scanner, we performed CTA of the whole aorta 97 patients (mean age 67.4 years) with confirmed or suspected aortoiliac disease. Bolus tracking with the trigger threshold set at 150 HU of AE was used for the scanning delay. The patients were divided into a TBW (n=49) and an ELBW (n=48) group; each contrast injection protocol groups into a high- and low body mass index (BMI) group (BMI < 25 and BMI ≥ 25, respectively). ELBW was estimated from patient's weight (TBW) and height. TBW-group received 360 mgI/[kg of TBW] of contrast medium, while ELBW-group received 450 mgI/[kg of ELBW]. All contrast media were injected at a fixed duration of 15 sec. We compared mean AE in the 2 protocols and in the high- and low BMI groups.

Mean AE in the ELBW- and TBW group was 308.9 and 314.1 HU, respectively; the difference was not significant (t-test, p = 0.58). However, the standard deviation of AE was 42.8 in the ELBW- and 57.1 HU in the TBW group, indicating significantly lower inter-patient variability in the ELBW group (Levene test, p < 0.01). In the TBW group, mean AE was significantly greater in the high- than the low BMI group (355.2 vs. 304.6 HU, respectively; p = 0.007). In the ELBW group, AE for high- and low BMI patients was 311.3 and 297.9 HU, respectively, and not significantly different (p = 0.40).

Under the TBW protocol, AE in patients with a high BMI was excessive because 300 HU is considered to be sufficient enhancement at CTA. Under the ELBW protocol, almost consistent and sufficient AE was achieved irrespective of the BMI.

Contrast injection protocols with the iodine dose adjusted for ELBW can be used to deliver optimal iodine doses to obese patients while maintaining adequate AE at CTA.

Yanaga, Y, Awai, K, Nakaura, T, Oda, S, Bae, K, Yamashita, Y, Imuta, M, et al, , Aortic Enhancement at CT Angiography Using a 64-Detector CT Scanner: Effect of Contrast Injection Protocols with Dose Adjusted to Estimated Lean Patient Body Weight.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6009804.html