Zhang Zhang, Presenter: Nothing to Disclose

Wenjia Zhang, Abstract Co-Author: Nothing to Disclose

Ningnannan Zhang PhD, Abstract Co-Author: Nothing to Disclose

Tielian Yu, Abstract Co-Author: Nothing to Disclose

Detection of in-stent re-stenosis using cardiac CTA is still challenging. One important obstacle is the beam hardening artifact from the high density stent, which may decrease the positive predictive value or even fail the examination. The cardiac gemstone spectral imaging (GSI) allows the synthesis of virtual monochromatic spectral (VMS) images, which may reduce the beam hardening artifact. The purpose of this study was to explore the reductions of beam hardening artifacts by using different energy levels of VMS at various heart rates.

Totally 5 different types of coronary stents (internal diameter: 3.10±0.55mm; strut thickness: 0.12±0.04mm) were placed in a pulsating cardiac phantom (ALPHA 1-VT PC, Fuyo Corporation, Japan). The cardiac GSI scans were acquired on a single-source dual-energy spectral CT scanner (Discovery CT750 HD CT FREEdom Edition scanner, GE Healthcare, Milwaukee, WI, USA). All the spectral imaging data were analyzed with GSI viewer to reconstruct the VMS images (40~140keV). The Artifact Index (AI) was measured for each keV level data set.

On stationary condition, the AI of the polychromatic axial scan with standard reconstruction was 115.92 ± 34.86, while the AIs of VMS were 62.07 ± 18.67, 42.29 ± 12.72, 35.33 ± 10.62, 27.95 ± 8.41, 17.87 ± 5.37, 8.12 ± 2.44, 5.73 ± 1.72 on 40~100keV by interval of 10 keV, respectively (ps<0.005). There were significant differences of AIs between the VMS and polychromatic images (ps<0.001). AIs above 80keV decreased significantly than the others (ps<0.005). Similar results were also found in the other heart rates (AI in 60bpm: 81.46 ± 24.46 for polychromatic images, 54.12 ± 16.29 in 40keV, 13.68 ± 4.11 in 80keV; AI in 70bpm: 19.34 ± 5.92 for polychromatic images, 59.55 ± 17.93 in 40keV, 6.33 ± 1.92 in 80keV).

VMS images with high en¬ergy level (i.e., >80keV) can apparently reduce the beam hardening artifacts for coronary stent in various heart rates.

The spectral CTA could effectively reduce the artifact, and may have the potential to show a clear inner- lumen for the patient with coronary stent in clinic.

Zhang, Z, Zhang, W, Zhang, N, Yu, T, Reduction of Beam Hardening Artifacts for Coronary Stent by using the Cardiac Spectral Imaging at Various Heart Rates: An In Vitro Study.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14046028.html