Elsevier

Clinical Imaging

Volume 31, Issue 1, January–February 2007, Pages 11-17
Clinical Imaging

Original article
How image quality can be improved: our experience with multidetector computed tomography coronary angiography

https://doi.org/10.1016/j.clinimag.2006.10.003Get rights and content

Abstract

Purpose

The objective of this study was to investigate the factors that may influence image quality on multidetector computed tomography (MDCT) coronary angiography (CA).

Materials and Methods

Two hundred twenty-four consecutive patients (161 men and 63 women; mean age, 52 years; age range, 34–76 years) evaluated with MDCT CA were included in the study. The evaluation of the quality of the patients' images was mainly based on the contrast material phase (early phase, optimal phase, or late phase) and the level of stepladder artifact (none, acceptable, or unacceptable). In addition, factors such as patient selection, patient preparation, scanning, processing, and steps of analysis, which may be affecting the quality of a final image, were examined independently.

Results

Patients who could not achieve sufficient breath-holding despite multiple breath exercises, those with a calcium score of 500 or higher, those with a heart rate greater than 90 bpm after metoprolol administration (because of shortening of the diastolic phase in the most still period), and those whose scanning was not completed were excluded from the study. The results for the remaining 224 patients were evaluated. Based on the contrast phase, there were 66 (29.5%) patients in the first group (early), 93 (41.5%) in the second group (optimal), and 65 (29%) in the third group (late). Among the 224 patients, the images of 152 (67.9%) had no stepladder artifact, those of 67 (29.9%) were of acceptable image quality, and those of 5 (2.2%) were of unacceptable image quality.

Conclusion

It is important to obtain high-quality images to achieve correct interpretation with coronary artery CT angiography. This study aimed to describe a technique performed on 224 patients based on an array of factors ranging from patient selection to postprocessing. The results show that patient selection, cooperation with the patient, and breath-holding exercises play a very important role in obtaining the best images. In addition, a proper scanning technique (e.g., placement of electrocardiographic electrodes and contrast material phase) and postprocessing (e.g., reconstruction interval) may also contribute to obtaining high-quality images.

Introduction

Coronary artery disease is the leading cause of death in the world [1]. Catheter coronary angiography (CA) is the gold standard in diagnosing coronary artery disease; however, because of its disadvantages (e.g., mortality, morbidity, and cost), noninvasive alternatives are highly needed [2], [3]. Electron beam computed tomography (CT), magnetic resonance imaging, and multidetector CT (MDCT) are noninvasive alternatives that provide direct visualization of the coronary vessels.

The availability of 16-detector row CT with rapid image acquisition and improved temporal and spatial resolutions has allowed for accurate imaging of the heart and coronary vessels. Although CT scanners with more detector rows are now available, 16-detector row CT is more commonly used. Similarly, in this study, 16-detector row CT was used. Because patient selection, patient preparation, speed of contrast agent administration, scanning delay between the start of contrast injection and that of the scan, scanning protocol, and postprocessing have remained to be controversial, this study aimed to define the parameters that may affect the quality of final images by evaluating the quality of the MDCT images of 224 patients.

Section snippets

Patient selection

The study included 224 consecutive patients (161 men and 63 women; mean age, 52 years; age range, 34–76 years) who were referred to our unit for coronary artery imaging owing to findings of typical or atypical angina pectoris or to abnormal results from noninvasive physiologic tests for ischemia. Multidetector CT angiography was not used on patients with sustained arrhythmia, known allergic reaction to contrast media, deteriorated renal function (serum creatinine >1.5 mg/dl), pregnancy,

Results

Two hundred twenty-four consecutive patients (161 men and 63 women; mean age, 52 years; age range, 34–76 years) were imaged. All CT scans were acquired without any complication.

The HRs of 17 (7.5%) patients were lower than 70 bpm; thus, they did not require metoprolol administration. In the remaining 207 (92.5%) patients, a mean dose of 13.9 mg (range, 5–20 mg) of metoprolol was required. The HRs of 14 (6.7%) patients remained between 70 and 90 bpm despite metoprolol administration of 20 mg.

The

Discussion

It is important to obtain high-quality images across a wide patient spectrum to attain a correct interpretation by coronary artery CT angiography. The quality of an image is a result of a combination of spatial, temporal, and contrast resolutions [5]. The small-sized and mobile coronary arteries place great demands on the spatial resolution that must be achieved for adequate imaging. At present, MDCT systems provide better image quality with higher temporal and spatial resolutions at a shorter

References (13)

  • F Cademartiri et al.

    Standard versus user-interactive assessment of significant coronary stenoses with multislice computed tomography coronary angiography

    Am J Cardiol

    (2004)
  • WG Austen et al.

    A reporting system on patients evaluated for coronary artery disease. Report of the Ad Hoc Committee for Grading of Coronary Artery Disease, Council on Cardiovascular Surgery, American Heart Association

    Circulation

    (1975)
  • LW Johnson et al.

    Cardiac catheterization 1991: a report of the Registry of the Society for Cardiac Angiography and Interventions (SCA&I)

    Cathet Cardiovasc Diagn

    (1993)
  • CH Janssen et al.

    Coronary artery calcification score by multislice computed tomography predicts the outcome of dobutamine cardiovascular magnetic resonance imaging

    Eur Radiol

    (2005)
There are more references available in the full text version of this article.

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