Coronary Mask Guided Registration for Continuous Time 4D Cardiac CT Dataset Construction
Authors: Yuang Wang, Shuo Wang, Changyu Chen, Dufan Wu, Pengfei Jin, Yunqiang An, Yang Gao, Bin Lu, Dongrui Dai, Muge Du, Yan Yan, Dong Li, Liang Li, Li Zhang, Zhiqiang Chen
Organizations: Department of Engineering Physics, Tsinghua University, Beijing 100084, China · Department of Radiology, The Ohio State University, 2050 Kenny Rd, Columbus, OH 43221, Ohio, USA · Center for Advanced Medical Computing and Analysis, Massachusetts General Hospital and Harvard Medical School, 399 Revolution Dr, Somerville, 02145, Massachusetts, USA · Department of Radiology, Fuwai Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China · Department of Radiology, Tianjin Medical University General Hospital, Tianjin, China
Objective: Clinical cardiac CT multiphase reconstructions generally provide acceptable image quality in end-diastole (ED) or end-systole (ES) phases, but in other phases may exhibit motion artifacts, especially in the right coronary artery (RCA). This limits ground-truth availability in 4D cardiac CT imaging research. We aim to construct a 4D cardiac CT dataset that is generally suitable to serve as pseudo ground truth. Methods: We propose Coronary Mask Guided Registration (CMGR) to produce a motion-preserved, artifact-reduced, and continuous-time 4D cardiac CT sequence from the clinical multiphase reconstruction of each patient. For artifact reduction, CMGR uses the ED or ES phase as the reference phase and warps the reference volume with deformation fields to produce the sequence. For motion preservation, CMGR registers the reference phase to each non-reference phase of the multiphase reconstruction. To capture the motion of both the RCA and other cardiac structures in each registration, CMGR regularizes RCA masks and incorporates them into image-domain registration. Time-continuity is achieved by interpolating the deformation fields for non-reference phases to arbitrary times. Results: CMGR outperformed representative image-domain registration methods in capturing RCA motion and providing reasonable RCA shape, and showed competitive performance in capturing whole-heart motion. Additionally, CMGR reduced motion artifacts from clinical multiphase reconstructions, and intermediate CMGR frames generally provided plausible transitions between discrete cardiac phases. Conclusion: CMGR provides an effective approach for constructing continuous-time 4D cardiac CT datasets. Significance: The dataset can be used in system design simulations and in reconstruction algorithm development, thereby facilitating advances in cardiac CT imaging.
Figures & tables
Fig. 1: CMGR framework. CMGR is designed to produce a motion-preserved, artifact-reduced, and continuous-time 4D cardiac CT sequence from a clinical multiphase reconstruction. CMGR uses the cardiac phase with minimal motion artifacts as the reference phase and registers the reference phase to each non-reference phase. The two yellow boxes labeled “Multi-Resolution Registration” in Stages 1 and 2 represent the same registration strategy applied to different inputs. Specifically, the non-reference RCA mask in Stage 2 is the RCA mask produced after geometry propagation.
Original Cardiac Phases
10 × Denser Cardiac Phases
RCA
Entire Volume
RCA
Entire Volume
Method
Dice ↑
HD ↓
MSD ↓
RMSE ↓
SSIM ↑
LPIPS ↓
Dice ↑
HD ↓
MSD ↓
RMSE ↓
SSIM ↑
LPIPS ↓
FFD
0.48 ± 0.33
9.30 ± 7.64
2.99 ± 2.84
36.3 ±4.1
0.91 ± 0.01
0.20 ± 0.03
0.48 ± 0.33
9.17 ± 7.40
2.95 ± 2.76
35.9 ± 4.2
0.91 ± 0.01
0.19 ± 0.02
DARTEL
0.55 ± 0.31
8.65 ± 8.46
2.48 ± 2.78
35.4 ± 3.3
0.91 ± 0.01
0.20 ± 0.03
0.56 ± 0.31
8.59 ± 8.19
2.43 ± 2.68
34.9 ± 3.3
0.91 ± 0.01
0.19 ± 0.02
UGICON
0.75 ± 0.15
3.39 ± 3.41
0.54 ± 0.66
34.9 ± 2.3
0.91 ±0.01
0.18 ± 0.02
0.78 ± 0.14
3.30 ± 3.20
0.48 ± 0.60
34.1 ± 2.1
0.91 ± 0.01
0.18 ± 0.02
Ours
0.78 ± 0.11
1.91 ± 0.86
0.34 ± 0.16
34.4 ± 2.1
0.91 ± 0.01
0.18 ± 0.01
0.82 ± 0.08
1.77 ± 0.76
0.28 ± 0.12
33.0 ± 1.6
0.91 ± 0.01
0.18 ± 0.01
TABLE I: Quantitative results in XCAT simulations. HD and MSD are in mm, and RMSE in HU. STD was computed across cardiac phases for each case and then averaged across cases. Bold : best; underlined : second best.
Fig. 2: Visualization results for XCAT simulations. The cardiac phases close to the reference phase (45%) were omitted from the visualization. The regions enclosed by blue, green and yellow boxes are magnified for visual clarity. The box positions may vary across cardiac phases and are fixed across the original multiphase reconstruction, all tested methods, and the ground truth. The display window is [-250, 450] HU.
Fig. 3: Visualization results for CMGR intermediate frames in XCAT simulations. The regions enclosed by blue and yellow boxes are magnified for visual clarity. The box positions are fixed for each view. The display window is [-250, 450] HU.
RCA
Entire Volume
Method
Dice ↑
HD ↓
MSD ↓
RMSE ↓
SSIM ↑
LPIPS ↓
FFD
0.30 ± 0.23
14.3 ± 4.1
3.44 ± 2.41
50.2 ±4.4
0.93 ± 0.02
0.17 ± 0.04
DARTEL
0.45 ± 0.28
13.4 ± 4.7
2.81 ± 2.55
49.7 ± 4.3
0.93 ± 0.02
0.17 ± 0.04
UGICON
0.73 ± 0.24
13.5 ± 4.1
1.99 ± 2.12
43.6 ± 5.8
0.94 ± 0.02
0.17 ± 0.04
Ours
0.83 ± 0.04
8.6 ± 3.4
0.33 ± 0.09
46.4 ± 4.6
0.93 ± 0.02
0.17 ± 0.04
TABLE II: Quantitative results on clinical high-quality ED and ES pairs. HD and MSD are in mm, and RMSE in HU. STD was computed across pairs. Bold : best; underlined : second best.
Original Cardiac Phases
10 × Denser Cardiac Phases
Method
FOR ↑
NC ↑
FOR ↑
NC ↑
FFD
0.74 ± 0.05
0.66 ± 0.09
0.75 ± 0.04
0.66 ± 0.08
DARTEL
0.75 ± 0.04
0.65 ± 0.07
0.76 ± 0.03
0.66 ± 0.07
UGICON
0.71 ± 0.10
0.61 ± 0.15
0.73 ± 0.08
0.63 ± 0.13
Ours
0.77 ± 0.02
0.70 ± 0.04
0.77 ± 0.02
0.69 ± 0.05
TABLE III: FOR and NC in clinical data evaluation. STD was computed across cardiac phases for each case and then averaged across cases. Bold : best; underlined : second best.
Fig. 4: Visualization results for the first representative clinical case. The cardiac phases close to the reference phase (75%) were omitted from the visualization. The regions enclosed by blue and yellow boxes are magnified for visual clarity. The box positions may vary across cardiac phases and are fixed across the original multiphase reconstruction and all tested methods. The display window is [-250, 450] HU.
Fig. 5: Visualization results for the second representative clinical case. The cardiac phases close to the reference phase (80%) were omitted from the visualization. The regions enclosed by blue and yellow boxes are magnified for visual clarity. The box positions may vary across cardiac phases and are fixed across the original multiphase reconstruction and all tested methods. The display window is [-250, 450] HU.
Fig. 6: Visualization results for CMGR intermediate frames in clinical data evaluation. The regions enclosed by blue and yellow boxes are magnified for visual clarity. The box positions are fixed for each view. The display window is [-250, 450] HU.
Fig. 7: Visualization results for non-RCA cardiac structures in clinical data evaluation. The regions enclosed by blue and green boxes are magnified for visual clarity. The box positions may vary across cardiac phases and are fixed across the original multiphase reconstruction and CMGR. The display window is [-250, 450] HU.
Rank Score ↑
Radiologists
Researchers
RCA
Chamber & Aorta
RCA
Chamber & Aorta
Method
Motion
Geometry
Motion
Structure
Motion
Geometry
Motion
Structure
DARTEL
2.00 ± 0.45
1.98 ± 0.42
2.08 ± 0.63
2.08 ± 0.56
1.75 ± 0.46
1.99 ± 0.38
1.69 ± 0.65
2.17 ± 0.64
UGICON
1.24 ± 0.59
1.14 ± 0.40
1.38 ± 0.60
1.40 ± 0.69
1.35 ± 0.60
1.09 ± 0.29
1.64 ± 0.79
1.21 ± 0.55
Ours
2.76 ± 0.55
2.88 ± 0.38
2.54 ± 0.75
2.52 ± 0.75
2.91 ± 0.33
2.92 ± 0.32
2.67 ± 0.52
2.61 ± 0.51
TABLE IV: Rank scores in the observer study. STD was computed across cases and observers. Bold : best; underlined : second best.
P-value
RCA
Chamber & Aorta
Statistical Test
Motion
Geometry
Motion
Structure
Friedman
<0.001
<0.001
<0.001
<0.001
Wilcoxon(Ours > DARTEL)
<0.001
<0.001
0.019
0.011
Wilcoxon(Ours > UGICON)
<0.001
<0.001
<0.001
<0.001
TABLE V: P-values in statistical tests of the observer study. Observer–case rank scores were used. Statistical tests were performed separately for radiologists and researchers, and larger p-values were reported.
Department of Biomedical Engineering, National University of Singapore, Singapore · School of Automation, Southeast University, Nanjing, China · Department of Medicine, National University of Singapore, Singapore +1
Department of Biomedical Engineering, National University of Singapore, Singapore · School of Automation, Southeast University, Nanjing, China · Department of Medicine, National University of Singapore, Singapore +1