hao tang1, daoyu hu, xiaoyan meng, zi wang, zhen li, and yanchun wang
1Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
Synopsis
Unenhanced MR angiography with spatial labeling with
multiple inversion pulses (SLEEK) is a reliable method for depicting portal
vein system in patients with liver transplantation compared with computed
tomographic portography (CTP) results. In a study of 20 patients who underwent liver
transplantation, we found that there was excellent correlation between SLEEK and CTP in
presenting the diameter of portal vein. Unenhanced MRA using SLEEK is relatively inexpensive and
is not associated with renal complications. It can be as a good choice for
screening portal vein system in patients with liver transplantation, especially
in patients with renal insufficiency.
Objectives
The objective of this
study was to evaluate the diagnostic performance of unenhanced MR Angiography using
spatial labeling with multiple inversion pulses sequence (SLEEK) in comparison
with CT portography in the detection of Portal Vein System in patients with
liver transplantation.Introduction
Unenhanced
MR angiography with spatial labeling with multiple inversion pulses (SLEEK) sequence
(Fig. 1) has made substantial progress and is effectively used for
visualization of transplant renal
vascular anatomy and complications (1). Although SLEEK and routine inflow inversion
recovery renal MR angiography [2]were basically the same on the principle of
imaging, SLEEK technique is used to highlight the importance of the preparation
of multiple space selective inversion recovery pulses, with which blood flow
could be labeled in a more flexible way. The purpose of this prospective study
was to evaluate the ability to depict portal vein system with unenhanced MR
angiography by using SLEEK.Materials and Methods
22
patients, 21 men and 1 women (mean age 44.3 years; age range, 15–51 years).
Unenhanced MRA using SLEEK was performed on a 1.5-T MRI system for assessing
portal vein system in 22 patients with liver transplantation. Then all patients
underwent 16-slice CT portography within 1–4 days. The ability to present the
portal vein system and to reveal portal vein system disease with SLEEK was
evaluated by two experienced radiologists and was compared with CT portography
results using a joint reading performed in consensus.Results
22
patients with liver transplantation underwent SLEEK MRA. A total of 20 portal
veins were successful assessed, including 13 no significant stenoses (Fig. 2), 7
with significant stenoses (>50% narrowing) (Fig. 3). Nineteen of the 20 patients were performed end-to-end
anastomosis between the donor’s and recipient’s portal veins. One of the 20
patients was performed end-to-end anastomosis between the donor’s portal vein
and recipient’s inferior vena cave. There was excellent correlation between
SLEEK and CT portography in presenting the diameter of portal vein (R = 0.92; p
< 0.05) (Fig. 4). SLEEK was superior to CT portography in revealing the
third- and fourth-order segmental branches in the hepatic parenchyma (p <
0.05). SLEEK has the advantage of avoiding interference from ribs, arterial and
venous system enhancement.Discussion and conclusion
In
this study, the preliminary data from our study demonstrate that SLEEK sequence
was capable of displaying transplant portal vein system anatomy and
complications. Our results show that consistently high-quality images can be
obtained by using SLEEK, which enabled visualization of even small branches
within the transplant liver parenchyma. However, because the signal of the portal
vein depends on the cardiac output of the patient, a suboptimal
blood-suppression TI may lead to poor signal-to-noise ratio and vessel
depiction. We did not obtain an additional scout image, which may be helpful in
evaluating the flow velocity in the aorta to optimize the blood-suppression TI;
thus, a larger study for full comparative evaluation of diagnostic performance
is necessary. The SLEEK has a comparable ability in demonstrating portal vein
system in patients with liver transplantation as well as CT portography does.
It can provide helpful information for surgeons to make an accurate
postoperative assessment. Unenhanced MRA using SLEEK is relatively inexpensive
and is not associated with renal complications. It can be as a good choice for
screening portal vein system in patients with liver transplantation, especially
in patients with renal insufficiency.Acknowledgements
We thank ShaofaWang, Zhihui Wang, and Nan Wang, whose important contributions to this study were indispensableto its success.References
1. Tang H,
Wang Z, Wang L, Hu X, Wang Q, Li Z, Li J, Meng X, Wang Y, Hu D. Depiction of
Transplant Renal Vascular Anatomy and Complications: Unenhanced MR Angiography
by Using Spatial Labeling with Multiple Inversion Pulses. Radiology2014 Mar 3:131800.
2. Parienty
I, Rostoker G, Jouniaux F, Piotin M, Admiraal-Behloul F, Miyazaki M. Renal
artery stenosis evaluation in chronic kidney disease patients: nonenhanced
time-spatial labeling inversion-pulse three-dimensional MR angiography with
regulated breathing versus DSA. Radiology2011 May;259(2):592-601.