title: CTCA image quality improvement by using snapshot freeze technique under prospective and retrospective electrocardiographic gating.
abstract: BACKGROUND
  Although coronary computed tomography angiography (CCTA) can detect coronary artery disease, limited temporal resolution of computed tomographic scanners may allow for motion artifacts, which may result in nonevaluable coronary segments.
  
  
  OBJECTIVE
  This study aimed to assess Snapshot Freeze (SSF) Motion Correction algorithm for its effect on image quality of CCTA.
  
  
  RESULTS
  Thirty patients underwent prospective electrocardiographic (ECG)-gating CCTA and 30 patients underwent retrospective ECG gating. In prospective ECG-gating group, SSF showed higher interpretability than standard (STD) on per-artery [97.8% (88/90) vs 87.8% (79/90), P = 0.004] and per-segment level [99.1% (427/431) vs 96.1% (414/431), P = 0.000]. Image quality was higher with SSF than STD on per-patient [3.5 (0.9) vs 2.9 (1.2), P = 0.004], per-artery [3.5 (0.8) vs 3.1 (1.0), P = 0.000], and per-segment levels [3.7 (0.8) vs 3.4 (1.0), P = 0.000]. In retrospective ECG-gating group, SSF showed higher interpretability than STD on per-patient [80.0% (24/30) vs 53.3% (16/30), P = 0.039], per-artery [90.0% (81/90) vs 71.1% (64/90), P = 0.000], and per-segment levels [98.1% (413/421) vs 90.7% (382/421), P = 0.000] of 45% R-R interval images. Snapshot freeze showed higher interpretability than STD on per-artery [70.0% (63/90) vs 55.6% (50/90), P = 0.02] and per-segment levels [82.7% (348/421) vs 78.4% (330/421), P = 0.018]. Image quality was higher with SSF than STD on per-patient [2.8 (1.0) vs 2.1 (1.2), P = 0.013] [2.1 (1.2) vs 1.6 (1.0), P = 0.026], per-artery [3.0 (0.9) vs 2.4 (1.0), P = 0.000] [2.6 (1.2) vs 2.2 (1.2), P = 0.000], and per-segment levels [3.3 (0.9) vs 2.9 (1.0), P = 0.000] [2.9 (1.2) vs 2.7 (1.1), P = 0.000] of 45% and 75% R-R interval images.
  
  
  CONCLUSIONS
  Snapshot freeze could improve the image quality and interpretability of CCTA with prospective and retrospective ECG gating. Especially, SSF could improve the image quality on right coronary artery by using the 45% R-R interval as the central phase with retrospective ECG gating.
authors.affiliation: From the Department of Radiology, Cardiovascular Clinical Institute of Tianjin Medical University, TEDA International Cardiovascular Hospital, Tianjin, China.
authors.forename: Lijuan
authors.initials: L
authors.lastname: Fan
authors.forename: Jiwang
authors.initials: J
authors.lastname: Zhang
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Xu
authors.forename: Zhi
authors.initials: Z
authors.lastname: Dong
authors.forename: Xu
authors.initials: X
authors.lastname: Li
authors.forename: Liren
authors.initials: L
authors.lastname: Zhang
mesh_terms: D000465:Algorithms; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D017023:Coronary Angiography / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D007089:Image Enhancement; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014057:Tomography, X-Ray Computed