Simultaneous achievement of accurate CT number and image quality improvement for myocardial perfusion CT at 320-MDCT volume scanning. Issue 7 (November 2015) - Funama, Yoshinori
Abstract: Purpose: To investigate differences in image-to-image variations between full- and half-scan reconstruction on myocardial CT perfusion (CTP) study. Methods: Using a cardiac phantom we performed ECG-gated myocardial CTP on a second-generation 320-multidetector CT volume scanner. The heart rate was set at 60 bpm; once per second for a total of 24 s were performed. CT images were acquired at 80- and 120 kVp and subjected to full- and half-scan reconstruction. On images acquired at the same slice level we then measured image-to-image variations, coefficients of variance (CV), and image noise. Results: The image-to-image variations with full- and half-scan reconstruction were 1.3 HU vs. 27.2 HU at 80 kVp (p < 0.001) and 0.70 HU vs. 9.3 HU at 120 kVp (p < 0.001) even though the mean HU value was almost the same for both reconstruction methods. The CV of 80- and 120-kVp images of the left ventricular cavity decreased by 0.16% and 0.17%, respectively, with full-scan reconstruction; with half-scan reconstruction it decreased by 3.34% and 2.30%, respectively. Compared with half-scan reconstruction, the image noise was reduced by 27.2% at 80 kVp and by 28.0% at 120 kVp with full-scan reconstruction. Conclusion: Myocardial CTP with full-scan reconstruction substantially decreased image-to-image variations and provided accurate CT attenuation. Highlights: Image-to-image variations were lower with full-than half-scan reconstruction. Image noise and X-ray dose were lower with full-than half-scan reconstruction. Myocardial CTP imaging yields better contrast resolution at a lower tube voltage.