Keywords:
Arteries / Aorta, CT-Angiography, Computer Applications-Detection, diagnosis, Dissection
Authors:
N. Kamei, N. Hongo, M. Nakahara, H. Kiyosue, S. Miyamoto, R. Shuto, S. Ide, S. Matsumoto, H. Mori; Oita/JP
DOI:
10.1594/ecr2013/C-2080
Purpose
Aortic dissections (AD) are serious fatal aortic conditions.
Their treatment strategies largely depend on the extent of the dissection. Cases with aortic dissection involving the ascending aorta are fundamentally treated by prompt open surgical replacement of the ascending aorta or the aortic arch because of the high mortality rate during the onset of the disease.
Dissection of the descending aorta without complication has a relatively lower initial mortality rate,
with classical disease management being stand-alone medical therapy such as antihypertensive therapy.
However,
the mortality rate becomes higher once complicated by rupture,
aneurysmal dilatation or malperfusion.
The reported incidence of developing such complications is around 50% of medically-treated patients(1).
Malperfusion is a serious and fatal condition wherein the dissected false lumen compresses the true lumen,
resulting in flow impairment in the distal part of the true lumen.
While it is well known that the collapse of the true lumen occurs under the dynamic motion of the intimal flap,
assessment of its movement throughout the dissected aorta has been difficult on any modality,
and thus,
its kinetics and the mechanics of a collapse were not fully recognized.
The recent invention of retrospective electrocardiographically (ECG)-gated CT enables 4D image acquisition of the whole dissected aorta and clear visualization of the dissected intima by eliminating the influence of motion artifacts due to pulsation.
Furthermore,
we have developed dedicated software for the 4D analysis of the aorta in cooperation with a software maker (AZE,
Tokyo,
Japan),
whereby qualitative or quantitative assessment of the motion of the aorta on curved multiplanar reconstruction or cross-sectional images is possible.
Meanwhile,
endovascular entry closure using stent-grafts has become an attractive alternative to stand-alone medical therapy or invasive open surgery for complicated AD in the descending aorta(2-4).
In stent-graft placement,
detailed analysis of the anatomy is a prerequisite and includes determination of proximal and distal aortic diameters to achieve precise stent-graft sizing and exact planning of its landing part.
The current standard measurement is based on non-gated CTA,
which impairs image and measurement quality in AD because of intimal motion.
The purpose of this study is to analyze the images of the intimal flap in AD of the descending aorta on retrospective ECG-gated CT using cine curved planar reformation (CPR) and cross-sectional multiplanar reformation (CSMPR) and to characterize and define the kinetics of the intimal flap in acute or chronic aortic dissection.