Performance of dual source versus 256-slice multi-slice CT in the evaluation of 16 coronary artery stents

Introduction: Invasive coronary angiography is the reference method for identification of in-stent restenosis (ISR) bearing the disadvantages of high costs and invasiveness. New approaches like dual-source CT (DSCT) and 256-multi-slice CT (256-MSCT) may potentially be the future methods of choice to reliably exclude ISR in patients with low or intermediate risk of restenosis. We sought to compare the performance of DSCT and 256-MSCT for the in vitro assessment of stent lumen diameter and basic scan parameters in stents of various diameters and designs.

Materials and methods: In 16 coronary artery stents we evaluated relative in-stent lumen diameter, attenuation, noise, attenuation-/signal-to-noise ratio (ANR/SNR) and radiation dose (CTDIvol) in an acknowledged coronary vessel in vitro phantom (iodine-filled plastic tubes) with DSCT (Siemens, SOMATOM Definition, collimation=2×64×0.6mm, pitch=0.26, current=400mAs/rot, voltage=120kV, tube-rotation-time=330ms) and 256-MSCT (Philips Brilliance, iCT, tube collimation=2×128×0.625mm, pitch=0.18, current=800mAseff, voltage=120kV, tube-rotation-time=270ms). Diameter analysis was conducted with the observer-independent full-width-at-half-maximum (FWHM) technique.

Results: DSCT and 256-MSCT revealed similar stent lumen diameters (50.7±7.2% vs. 50.8±7.4%, p=0.98). Attenuation (-19±25HU vs. 54±29HU), ANR (-0.9±1.2 vs. 2.9±1.8) and SNR (12.1±2.4 vs. 17.4±1.9) were better in the DSCT (all p<0.001) at the expense of significantly higher radiation doses (CTDIvol=87 vs. 51mGy, p<0.01). Noise was comparable (21±2HU vs. 20±2HU, p=n.s.). Only stents with a diameter >3mm allowed sufficient stent lumen assessment in both scanners and showed a relative lumen diameter of 60-66%.

Conclusions: The measured stent lumen diameter and image noise were similar in both scanners. Yet the DSCT offered a more truthful stent lumen visualization at the cost of higher radiation dose. Applying the FWHM approach only stents with a diameter >3mm offered sufficient stent lumen assessment.