Yuan QU1, Yan WANG1, Yuli HUANG2, Li ZHU3, and Haiyang DONG3
1Radiology, 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 pulmonary artery imaging using 3D TRANCE and
3D Balanced FFE respectively, and the image quality obtained by the two imaging
methods and the number of branches of pulmonary artery were compared specifically. Both 3D TRANCE and
3D Balanced FFE imaging methods with Time-SLIP can be used for pulmonary artery imaging. The image quality of
pulmonary artery obtained by 3D TRANCE is generally better than 3D Balanced
FFE.
INTRODUCTION
Pulmonary
angiography mostly relies on techniques such as computed tomography angiography
(CTA), digital subtraction angiography (DSA) and contrast-enhanced magnetic resonance angiography (CE-MRA).1,2 Alternatively, non-contrast enhanced MRA (NCE-MRA) sequences have been
developed for characterizing structure of pulmonary artery.3 Time-spatial
labeling inversion pulses (Time-SLIP) assist in morphological diagnosis via
selectively observing the target vessels.4-6 In the present study, we
investigated the performance of non-contrast enhanced 3D TRANCE without ECG
triggered and 3D balanced FFE (3D-bFFE) using Time-SLIP on pulmonary artery
imaging. METHODS
Study Sample: Twenty-three healthy subjects (10 males and 13
females, mean age 41.08 ± 13.67 years) were recruited for the study. This study was approved by local
institutional review board and written consent form was obtained from each
subject. MR Imaging: All pulmonary artery images were acquired on a 1.5
Tesla MR scanner (Achieva, Philips Healthcare) with an 8-channel abdominal coil. Each subject underwent NCE-MRA using 3D TRANCE and 3D-bFFE with Time-SLIP. 3D TRANCE sequence
was performed with following parameters: repetition time 2000-3000ms,
echo time 138ms, flip angle 90°, field of view 320x360mm2, slice
number 60, slice thickness 3.0mm. 3D-bFFE sequence was performed with following parameters: repetition
time 3.8ms, echo time 1.87ms, flip angle 65°, field of view 320x360mm2,
slice number 60, slice thickness 3.0mm. Two kinds of spatial selective inversion labeling methods were used in
this study: blood in superior and inferior vena cava, and blood in right
ventricular and right atrium (Figure 1). The inversion time was set to 1200ms empirically.
Data
analysis: Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR)
in different regions of interest (ROIs) in the branches of pulmonary arteries
were calculated using standard deviation in muscular tissue as noise. Additionally,
the number of pulmonary artery and its branches was counted and the image
quality was evaluated with 1 to 4 score (Figure 2). Image quality review was performed
by two observers with >10 years’ experience in the department of radiology blinded
to each other and the mean value of their outcome were used for further
statistical analysis. Statistical analysis: The SNR and
CNR were compared between 3D TRANCE and 3D-bFFE using a paired t-test. The
Spearman`s rank sum test was performed to compare the subjective scores of
image quality and the count of distinct branches of different orders. All statistical
analyses were conducted with SPSS 25.0 (IBM Inc., USA).RESULTS
SNR
and CNR of the pulmonary trunk, left and right pulmonary arteries, and their branches
in Time-SLIP 3D TRANCE images were significantly better than those in Time-SLIP
3D-BFFE images (p<0.05). With 3D TRANCE, the count of order 3 and order 4
branches of left and right pulmonary arteries were statistically significantly
more than 3D-bFFE (P<0.05). As for the results of image quality evaluation of
pulmonary artery, 3D TRANCE was also significantly better than 3D-bFFE
(P<0.05) (Table 1). When using 3D TRANCE, different positions of spatial
selective inversion labelling band affected the visualization of pulmonary
artery branches, such as the inferior branch of the left pulmonary artery and
the inferior branch of the right pulmonary artery. DISCUSSION
TRANCE
was a turbo spin echo sequence which acquires data with optimized suppression
of background tissue and fat, resulting in better structure
visualization of pulmonary artery. Compared to 3D-bFFE, TRANCE was insensitive
to susceptibility and obtained better illustration of pulmonary artery and its branches.
Thus, TRANCE with Time-SLIP could provide a distinct vascular structure in chest MRI for pulmonary artery (Figure 3). CONCLUSION
Time-spatial
labeling inversion pulse (Time-SLIP) technique can be used for selective,
non-enhanced magnetic resonance imaging of the pulmonary artery. Image quality
and diagnostic value are greater with Time-SLIP in combination with the 3D
TRANCE sequences based on TSE than in combination with 3D-bFFE. Different inversion labeling band positions have
a larger impact on visualization of pulmonary artery branches in Time-SLIP with
3D TRANCE than with 3D-bFFE. Acknowledgements
No acknowledgement found.References
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