Dual-source photon-counting computed tomography for coronary in-stent observation: influence of heart rate and virtual monoenergetic image.

To investigate the effect of heart rate and virtual monoenergetic image (VMI) on coronary stent imaging in dual-source photon-counting detector computed tomography (PCD-CT). A dynamic cardiac phantom was used to vary the heart rate at 50 beats per minute (bpm), 70 bpm, and 90 bpm. Five types of stents (4.0 mm, 3.5 mm, 3.0 mm, 2.75 mm, and 2.5 mm diameter) were scanned at three different locations and reconstructed VMI at 70 keV. In addition, 50% stenosis was assessed for 3.0 mm and 4.0 mm stents. To assess in-stent stenosis, 40 keV, 70 keV, and 100 keV images were compared. Measurable lumen and contrast to noise ratio (CNR) from lumen to stenosis were evaluated quantitatively. A-4-point scale was used for the qualitative image quality of in-stent stenosis. The measurable lumen had no significant differences among heart rates in patent stents (p = 0.55). In-stent stenosis, the residual lumen was significantly larger in 40 keV [27.5% (20.8-32.3%)] than in 70 keV [11.5% (10.0-23.0%), p < 0.05] and 100 keV [0% (0-5.2%), p < 0.05]. The CNR was higher in 40 keV [12.5 (7.5-18.2)] than in 70 keV [5.3 (2.9-7.7), p < 0.05] and 100 keV [1.3 (0.5-2.7), p < 0.05]. The image quality was better in 40 keV (3.4 ± 0.7) than in 70 keV [(2.6 ± 0.8), p < 0.05] and 100 keV [(1.3 ± 0.4), p < 0.05]. Dual-source PCD-CT maintains a measurable lumen even at high heart rates. Adjusting the VMI can be helpful in visualizing the in-stent stenosis.