Image quality, contrast enhancement, and radiation dose of ECG-triggered high-pitch CT versus non-ECG-triggered standard-pitch CT of the thoracoabdominal aorta

AJR Am J Roentgenol. 2012 Apr;198(4):931-8. doi: 10.2214/AJR.11.6921.


Objective: We sought to compare image quality, contrast enhancement, and radiation dose in patients undergoing ECG-triggered high-pitch helical CT or non-ECG-synchronized helical CT of the thoracoabdominal aorta.

Materials and methods: We retrospectively assessed data from 101 consecutive patients (81 men, 20 women; mean age, 71 ± 11 [SD] years) undergoing clinically indicated CT angiography (CTA) of the thoracoabdominal aorta on a dual-source scanner using either the ECG-triggered high-pitch helical mode (group 1, n = 52) or non-ECG-synchronized standard-pitch helical mode (group 2, n = 49) during the arterial phase. Two independent readers assessed image quality, noise, and contrast enhancement throughout the thoracoabdominal aorta. Scanner-reported dose-length product values were used to estimate effective dose values.

Results: Image quality at the root-proximal ascending level was higher in group 1 (mean ± SD, 2.81 ± 0.40) than in group 2 (1.22 ± 0.47; p < 0.0001), with similar quality for both groups noted at other levels. Group 1 scans displayed higher image noise at all levels. The groups received a similar volume of contrast material (p = 0.77), and similar percentages of cases with acceptable contrast enhancement (> 250 HU) were noted in the two groups. The estimated radiation burden was significantly lower in group 1 (mean ± SD, 5.4 ± 1.8 mSv) than in group 2 (14.4 ± 5.1 mSv; p < 0.0001).

Conclusion: Imaging of the thoracoabdominal aorta with ECG-triggered high-pitch CTA provides higher quality images of the aortic root and ascending aorta with sufficient contrast enhancement and decreased estimated radiation dose compared with non-ECG-synchronized standard-pitch helical CT.

Publication types

  • Comparative Study

MeSH terms

  • Aged
  • Angiography / methods*
  • Aortic Diseases / diagnostic imaging*
  • Cardiac-Gated Imaging Techniques / methods*
  • Contrast Media
  • Electrocardiography
  • Female
  • Humans
  • Iohexol / analogs & derivatives
  • Male
  • Radiation Dosage
  • Retrospective Studies
  • Tomography, Spiral Computed / methods*


  • Contrast Media
  • Iohexol
  • iopromide