Does slice thickness affect diagnostic performance of 64-slice CT coronary angiography in stable and unstable angina patients with a positive calcium score?

Abstract

BACKGROUND:

Coronary calcification can lead to over-estimation of the degree of coronary stenosis.

PURPOSE:

To evaluate whether thinner reconstruction thickness improves the diagnostic performance of 64-slice CT coronary angiography (CTCA) in angina patients with a positive calcium score.

MATERIAL AND METHODS:

We selected 20 scans from a clinical study comparing CTCA to conventional coronary angiography (CCA) in stable and unstable angina patients based on a low number of motion artifacts and a positive calcium score. All images were acquired at 64 x 0.625 mm and each CTCA scan was reconstructed at slice thickness/increment 0.67 mm/0.33 mm, 0.9 mm/0.45 mm, and 1.4 mm/0.7 mm. Two reviewers blinded for CCA results independently evaluated the scans for the presence of significant coronary artery disease (CAD) in three randomly composed series, with > or =2 weeks in between series. The diagnostic performance of CTCA was compared for the different slice thicknesses using a pooled analysis of both reviewers. Significant CAD was defined as >50% diameter narrowing on quantitative CCA. Image noise (standard deviation of CT numbers) was measured in all scans. Inter-observer variability was assessed with kappa.

RESULTS:

Significant CAD was present in 8% of 304 available segments. Median total Agatston calcium score was 181.8 (interquartile range 34.9-815.6). Sensitivity at 0.67 mm, 0.9 mm, and 1.4 mm slice thickness was 70% (95% confidence interval 57-83%), 74% (62-86%), and 70% (57-83%), respectively. Specificity was 85% (82-88%), 84% (81-87%), and 84% (81-87%), respectively. The positive predictive value was 30 (21-38%), 29 (21-37%), and 28 (20-36%), respectively. The negative predictive value was 97% (95-98%), 97% (96-99%), and 97% (96-99%), respectively. Kappa for inter-observer agreement was 0.56, 0.58, and 0.59. Noise decreased from 32.9 HU at 0.67 mm, to 23.2 HU at 1.4 mm (P<0.001).

CONCLUSION:

Diagnostic performance of CTCA in angina patients with a positive calcium score was not markedly affected by modest variations in reconstruction slice thickness.

• Authors: Matthijs F L Meijs, Jan J J de Vries, Annemarieke Rutten, Ricardo P J Budde, Alexander M de Vos, W Bob Meijboom, Maarten J Cramer, Pim J de Feyter, Pieter A Doevendans, Mathias Prokop
• Journal: Acta radiologica (Stockholm, Sweden : 1987) (Acta Radiol) Vol. 51 Issue 4 Pg. 427-30 (May 2010) ISSN: 1600-0455 [Electronic] England
• PMID: 20233143 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Contrast Media
• Iohexol
• iopromide

Topics

• Analysis of Variance
• Angina Pectoris (diagnostic imaging)
• Angina, Unstable (diagnostic imaging)
• Artifacts
• Calcinosis (diagnostic imaging)
• Chi-Square Distribution
• Contrast Media
• Coronary Angiography
• Humans
• Iohexol (analogs & derivatives)
• Predictive Value of Tests
• Radiographic Image Interpretation, Computer-Assisted (methods)
• Tomography, X-Ray Computed (methods)