Korean J Radiol.  2009 Jun;10(3):217-226. 10.3348/kjr.2009.10.3.217.

Coronary Artery Stent Evaluation Using a Vascular Model at 64-Detector Row CT: Comparison between Prospective and Retrospective ECG-Gated Axial Scans

• Suzuki S
• Furui S
• Kuwahara S
• Mehta D
• Kaminaga T
• Miyazawa A
• Ueno Y
• Konno K

• KMID: 1779448
• DOI: http://doi.org/10.3348/kjr.2009.10.3.217

Abstract

OBJECTIVE
We wanted to evaluate the performance of prospective electrocardiogram (ECG)-gated axial scans for assessing coronary stents as compared with retrospective ECG-gated helical scans. MATERIALS AND METHODS: As for a vascular model of the coronary artery, a tube of approximately 2.5-mm inner diameter was adopted and as for stents, three (Bx-Velocity, Express2, and Micro Driver) different kinds of stents were inserted into the tube. Both patent and stenotic models of coronary artery were made by instillating different attenuation (396 vs. 79 Hounsfield unit [HU]) of contrast medium within the tube in tube model. The models were scanned with two types of scan methods with a simulated ECG of 60 beats per minute and using display field of views (FOVs) of 9 and 18 cm. We evaluated the in-stent stenosis visually, and we measured the attenuation values and the diameter of the patent stent lumen. RESULTS: The visualization of the stent lumen of the vascular models was improved with using the prospective ECG-gated axial scans and a 9-cm FOV. The inner diameters of the vascular models were underestimated with mean measurement errors of -1.10 to -1.36 mm. The measurement errors were smaller with using the prospective ECG-gated axial scans (Bx-Velocity and Express2, p < 0.0001; Micro Driver, p = 0.0004) and a 9-cm FOV (all stents: p < 0.0001), as compared with the other conditions, respectively. The luminal attenuation value was overestimated in each condition. For the luminal attenuation measurement, the use of prospective ECG-gated axial scans provided less measurement error compared with the retrospective ECG-gated helical scans (all stents: p < 0.0001), and the use of a 9-cm FOV tended to decrease the measurement error. CONCLUSION: The visualization of coronary stents is improved by the use of prospective ECG-gated axial scans and using a small FOV with reduced blooming artifacts and increased spatial resolution.

Keyword

Computed tomography (CT), angiography; Experimental studies; Stent; Multi-slice CT (MSCT)

MeSH Terms

Contrast Media
*Coronary Angiography
Coronary Stenosis
Coronary Vessels
Electrocardiography/*methods
Image Processing, Computer-Assisted/methods
*Models, Cardiovascular
Observer Variation
Phantoms, Imaging
Radiographic Image Enhancement/methods
*Stents
Tomography, Spiral Computed/*methods

Figure

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  Fig. 1 Vascular models of stenosis. A. Stent was implanted into tube and contrast material diluted to 396 HU was filled in stented tubes as "patent" model (upper model). In stenotic models, smaller tube filled with contrast material diluted to 396 HU was fixed in stented tube that was filled with contrast material diluted to 79 HU (lower model). B. Vascular model was fixed in polypropylene cylinder filled with salad oil in parallel with central axis of cylinder. Polypropylene cylinder was fixed in water-filled spherical styrol container, with their central axes overlapping.

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  Fig. 2 Longitudinal and cross-sectional reformations of patent models. Window setting was 1,400 HU width and 500 HU center. FOV = field of view

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  Fig. 3 Longitudinal and cross-sectional reformations of stenotic models. Window setting was 1,400 HU width and 500 HU center. FOV = field of view

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  Fig. 4 Magnified views of cross-sectional reformations of patent and stenotic models. A. Bx-Velocity, B. Express2, C. Micro Driver. Window setting was 1,400 HU width and 500 HU center. FOV = field of view

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  Fig. 5 CT attenuation profile on cross section of stenotic models with using axial scan with 18-cm field of view, and axial and helical scans with 9-cm field of view. A. Bx-Velocity, B. Express2, C. Micro Driver. Profile curve passes through center of vascular model. FOV = field of view

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