Yike Diao, Presenter: Nothing to Disclose

Chun-Yan Lu, Abstract Co-Author: Nothing to Disclose

Xiaohui Zhang, Abstract Co-Author: Employee, Siemens AG

Zhenlin Li MD, Abstract Co-Author: Nothing to Disclose

To assess feasibility and additional diagnostic value of low dose multiphasic CT dynamic protocols (Shuttle mode and Flash-4D mode) in aortic dissection (AD) compared to a standard tri-phase protocol on a dual source CT (DSCT) scanner.

54 consecutive patients with known or suspected AD (age range：30-77 years) referred for aortic CTA were randomly, equally assigned into three groups and scanned on a DSCT scanner (SOMATOM Definition Flash, Siemens). For group A，a shuttle mode (Siemens) of multiphasic image acquisition (range: 48cm, time resolution 6s, 4 phase, 80kV, 125mAs/rot), for group B a high-pitch (pitch=3.0) mode of multiphasic image acquisition (range from the entrance of bony thorax to the plane of symphysis pubis, time resolution 12s, 4 phases, CARE kV, ref 80kV, 100mAs/rot) , for group C the standard tri-phasic acquisition (range from the entrance of bony thorax to the plane of symphysis pubis, 100kV, 210mAs/rot) was used. Radiation dose were recorded. One-way ANOVA was used for statistical analysis.

 In all 54 cases CTA can exactly display the true and false lumen, intimal flap, the entry tear and the involvement of branches of AD. Compared to standard tri-phasic protocol (un-enhanced, arterial and portal scans), additional diagnostic information was obtained by multiphasic CT dynamic protocols as followed: the enhancement delay between the true and false lumen (group A=18; group B=18); the degree of membrane oscillation (group A=8; group B=14); dynamic ejection of contrast material from the true into the false lumen (group A=6; group B=7). Mean effective radiation dose (group A: 8.08±0.12mSv, group B: 11.60±0.3mSv, group C: 23.86±1.31mSv) of the three groups were shown statistically different (P<0.05).Scan length range of Flash-4D CTA is approximately 62.63±4.44 cm, longer than shuttle mode (fixed 48cm).

Multiphasic dynamic CTA covering the entire aorta is feasible. Compared to standard tri-phasic protocol, both multiphasic scan protocols can provide more reveal pathological and anatomical features of AD with relative low radiation dose. In Flash-4D mode larger scan range can be provided, however, shuttle mode has a better time-resolution.

Multiphasic protocols can exactly reveal pathological and anatomical features of AD with relative low radiation dose and offer more diagnostic information for surgical operation.

Diao, Y, Lu, C, Zhang, X, Li, Z, To Assess the Feasibility and Value of Multiphasic Dynamic Scan Protocol in Aortic Dissection.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14017013.html