Detection of a coronary artery vessel wall: performance of 0.3 mm fine-cell detector computed tomography--a phantom study.

The purpose of this study was to evaluate whether experimental fine-cell detector computed tomography with a 0.3125 mm cell (0.3 mm cell CT) can improve the detection of coronary vessel walls compared with conventional 64-slice computed tomography with a 0.625 mm cell (0.6 mm cell CT). A coronary vessel wall phantom was scanned using 0.6 mm cell CT and 0.3 mm cell CT. The data for 0.3 mm cell CT were obtained using four protocols: a radiation dose equal, double, triple or quadruple that were used in the 0.6 mm cell CT protocol. The detectable size of the vessel wall was assessed based on the first and second derivative functions, and the minimum measurable values were compared using a paired t-test. As a result, the minimum detectable wall thickness of 0.6 mm cell CT (1.5 mm) was significantly larger than that of 0.3 mm cell CT performed using the triple- and quadruple-dose protocols (0.9 mm) and the double-dose protocol (1.1 mm). The difference in the minimum detectable vessel wall thickness measured using 0.6 mm cell CT (1.5 ± 0.1 mm) and 0.3 mm cell CT (0.9 ± 0.1 mm, 1.1 ± 0.2 mm) was significant (p < 0.01). We concluded that 0.3 mm cell CT improved the detection of coronary vessel walls when a more than double-dose protocol was used compared with 0.6 mm cell CT.

Development and performance evaluation of an experimental fine pitch detector multislice CT scanner.

The authors have developed an experimental fine pitch detector multislice CT scanner with an ultrasmall focal spot x-ray tube and a high-density matrix detector through current CT technology. The latitudinal size of the x-ray tube focal spot was 0.4 mm. The detector dimension was 1824 channels (azimuthal direction) x 32 rows (longitudinal direction) at row width of 0.3125 mm, in which a thinner reflected separator surrounds each detector cell coupled with a large active area photodiode. They were mounted on a commercial 64-slice CT scanner gantry while the scan field of view (50 cm) and gantry rotation speed (0.35 s) can be maintained. The experimental CT scanner demonstrated the spatial resolution of 0.21-0.22 mm (23.8-22.7 lp/cm) with the acrylic slit phantom and in-plane 50%-MTF 9.0 lp/cm and 10%-MTF 22.0 lp/cm. In the longitudinal direction, it demonstrated the spatial resolution of 0.24 mm with the high-resolution insert of the CATPHAN phantom and 0.34 mm as the full width at half maximum of the slice sensitivity profile. In low-contrast detectability, 3 mm at 0.3% was visualized at the CTDI(vol) of 47.2 mGy. Two types of 2.75 mm diameter vessel phantoms with in-stent stenosis at 25%, 50%, and 75% stair steps were scanned, and the reconstructed images can clearly resolve the stenosis at each case. The experimental CT scanner provides high-resolution imaging while maintaining low-contrast detectability, demonstrating the potentiality for clinical applications demanding high spatial resolution, such as imaging of inner ear, lung, and bone, or low-contrast detectability, such as imaging of coronary artery.