Yan WANG1, Yuli HUANG2, Haiyang DONG3, and Li ZHU3
1Department of Radiology, People’s Hospital of Xinjiang Uygur Autonomous Region, Urumqi, China, 2MR, Philips Healthcare (Suzhou) Co., Ltd, SUZHOU, China, 3Radiology, Shanghai Chest Hospital, Shanghai JiaoTong University, Shanghai, China
Synopsis
The Time-Spatial Labeling Inversion Pulses (Time-SLIP) technique was
used to perform non-contrast enhanced hepatic portal vein imaging using 3D
TRANCE and 3D Balanced FFE methods respectively, and the image quality obtained
by the two imaging methods and the number of branches of hepatic portal vein were
compared specifically. Both 3D TRANCE and 3D Balanced FFE imaging methods with
Time-SLIP can be used for hepatic portal vein imaging. The image quality of
hepatic portal vein obtained by 3D TRANCE was generally better than 3D Balanced
FFE.
INTRODUCTION
Anatomical structure of portal vein, which plays an
important role in liver surgery, mostly relies on imaging techniques, such as
computed tomography angiography (CTA), digital subtraction angiography (DSA) and
contrast enhanced magnetic resonance angiography (CE-MRA). Recently, non-contrast
enhanced MRA sequence has been developed for observing structure and branches
of portal vein1-3. Time-spatial labeling inversion pulse (Time-SLIP)
assists in morphological diagnosis via selectively observing the target region4,5.
In the present study, we investigated the performance of non-contrast enhanced
angiography (TRANCE) without ECG triggered and 3D balanced fast field echo (3D
bFFE) using Time-SLIP on abdominal MRI for portal vein6-9.METOHDS
Study sample: Eleven male and fourteen female healthy controls (mean age, 38.3 ± 12.8
years) without any contraindication to MR scanning underwent abdominal MR
imaging. All the parts of this study were approved by local institutional
review board and written consent form was obtained from each subject. MR
imaging: Abdominal MR imaging was acquired on a 1.5 Tesla MR
scanner (Achieva, Philips Hearthcare) with an 8-channel abdominal coil (Figure 1). A 2D balanced FFE (bFFE) scan with sequential phases was performed with
breath-hold to calculate optimized inverse time delay (TI delay) (Figure 2). The
TRANCE sequence was executed with following parameters: repetition time
2000-3000ms, echo time 144ms, inversion time 160ms, field of view 420×420mm2,
flip angle 90°, slice thickness 3.0mm. The 3D balanced FFE was executed using
following parameters: repetition time 5.6-6.0 ms, echo time 1.86 ms, inversion
time 160ms, field of view 420×420mm2, flip angle 85°, slice
thickness 3.0mm. Data Analysis: Abdominal MR images were reviewed by two
radiologists with >10 years` experience blinded to each other. Each reviewer
drew seven regions of interest (ROIs) >50mm2 in main portal vein
(MPV), superior mesenteric vein (SMV), splenic vein (SV), and left, and right
portal vein (LPV, RPV), respectively. Signal-to-noise ratio (SNR) and contrast-to-noise
ratio (CNR) were calculated in MPV, SMV, SV, LPV and RPV with following
equation:
SNR=Svessel/SD(Snoise)
CNR=(Svessel-Sliver)/SD(Snoise)
where Svessel,
Sliver represented the
mean value of signal in MPV and its branches, signal of hepatic parenchymal tissue, respectively. Besides, each
reviewer also counted the number of PV branches in different orders and
evaluated the image quality with 1 to 4 score. The mean values of measurements
from two reviewers were recorded. Statistical Analysis: The SNR
and CNR were compared between the ROI in TRANCE and 3D bFFE using an
independent t test. The amounts of
branches in different orders were compared between TRANCE and bFFE via
performing Kruskai-Wallis Test. A p<0.05 was considered as statistically
significantly and all statistical analysis was conducted with SPSS 25.0 (IBM
Inc., USA).RESULTS
Compared to 3D bFFE, TRANCE showed a higher SNR (MPV: 227± 118 vs. 140 ±
59, SMV: 218 ± 103 vs. 130 ± 53, SV: 209 ± 104 vs. 135 ± 62, LPV:
207 ± 110 vs. 124 ± 53, RPV: 220 ± 113 vs. 140 ± 61) and CNR (MPV: 203 ± 105
vs. 103 ± 48, SMV: 195 ± 91 vs. 92 ± 40, SV: 186 ± 92 vs. 97
± 51, LPV: 184 ± 98 vs. 86 ± 40, RPV: 197 ± 100 vs. 102 ± 47), more branch
count in left (order 2: 5.0 ± 1.6 vs. 4.2 ± 1.5, order 3: 2.4 ± 2.7 vs. 1.4 ±
1.9, order 4: 0.2 ± 0.5 vs. 0.1 ± 0.2 ) and right branch (order 2: 7.5 ± 2.0
vs. 7.1 ± 2.2,order 3: 11.8 ± 5.0 vs. 9.8 ± 5.3, order 4: 4.6 ± 3.4 vs. 2.5 ±
2.2) and better image quality (3.6 ± 0.5 vs. 3.0 ± 0.8). (Table 1) DISCUSSION
The TRANCE sequence was a turbo spin echo sequence which could
obtain clear structure of portal vein using optimized background and fat
suppression. Compared to 3D bFFE, TRANCE was less sensitive to susceptibility
and exhibited better illustration of portal vein branches. Thus, TRANCE with
Time-SLIP could provide a distinct structure in abdominal MRI for portal vein.
(Figure 3)CONCLUSION
Compared to 3D bFFE, TRANCE was validated to be a better technique
in portal vein imaging in the present study via exhibiting higher SNR and CNR,
more branch count and better image quality.Acknowledgements
No acknowledgement found.References
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