Korean J Radiol.  2012 Feb;13(1):20-26. 10.3348/kjr.2012.13.1.20.

High-Definition Computed Tomography for Coronary Artery Stent Imaging: a Phantom Study

• Yang WJ
• Chen KM
• Pang LF
• Guo Y
• Li JY
• Zhang H
• Pan ZL

• KMID: 1058789
• DOI: http://doi.org/10.3348/kjr.2012.13.1.20

Abstract

OBJECTIVE
To assess the performance of a high-definition CT (HDCT) for imaging small caliber coronary stents (< or = 3 mm) by comparing different scan modes of a conventional 64-row standard-definition CT (SDCT).
MATERIALS AND METHODS
A cardiac phantom with twelve stents (2.5 mm and 3.0 mm in diameter) was scanned by HDCT and SDCT. The scan modes were retrospective electrocardiography (ECG)-gated helical and prospective ECG-triggered axial with tube voltages of 120 kVp and 100 kVp, respectively. The inner stent diameters (ISD) and the in-stent attenuation value (AVin-stent) and the in-vessel extra-stent attenuation value (AVin-vessel) were measured by two observers. The artificial lumen narrowing (ALN = [ISD - ISDmeasured]/ISD) and artificial attenuation increase between in-stent and in-vessel (AAI = AVin-stent - AVin-vessel) were calculated. All data was analyzed by intraclass correlation and ANOVA-test.
RESULTS
The correlation coefficient of ISD, AVin-vessel and AVin-stent between the two observers was good. The ALNs of HDCT were statistically lower than that of SDCT (30 +/- 5.7% versus 35 +/- 5.4%, p < 0.05). HDCT had statistically lower AAI values than SDCT (15.7 +/- 81.4 HU versus 71.4 +/- 90.5 HU, p < 0.05). The prospective axial dataset demonstrated smaller ALN than the retrospective helical dataset on both HDCT and SDCT (p < 0.05). Additionally, there were no differences in ALN between the 120 kVp and 100 kVp tube voltages on HDCT (p = 0.05).
CONCLUSION
High-definition CT helps improve measurement accuracy for imaging coronary stents compared to SDCT. HDCT with 100 kVp and the prospective ECG-triggered axial technique, with a lower radiation dose than 120 kVp application, may be advantageous in evaluating coronary stents with smaller calibers (< or = 3 mm).

Keyword

Stent; Coronary artery; Phantom; CTA

MeSH Terms

Analysis of Variance
Cardiac-Gated Imaging Techniques/methods
Coronary Disease/*radiography/*therapy
Humans
Phantoms, Imaging
Radiation Dosage
Radiographic Image Interpretation, Computer-Assisted
*Stents
Tomography, Spiral Computed/*methods

Figure

• 

  Fig. 1 Coronary artery models and stents. A. Closed at both ends, coronary artery models are fixed by plastic cement plate with long axis of model corresponding to z-axis. B. Models with expanded stents are positioned in plastic container filled with water. C. Transaxial and reconstructed sagittal images of all 12 stents on high-definition CT scanned with 120 kVp, 450 mA of phantom. Stent characteristics are listed in Table 1.

• 

  Fig. 2 Coronal and axial images of stent No 6 (S670, Medtronic) acquired with 120 kVp and 450 mA on high-definition CT (A, B) and standard-definition CT (C, D), respectively. Stent lumen on images of high-definition CT is better observed when combined with better lumen measurement.

• 

  Fig. 3 For tube voltages of 100 kVp and 120 kVp, no difference in artificial lumen narrowing on high-definition CT (A) and significant difference of artificial lumen narrowing (ALN) on standard-definition CT (B) is found.

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