Yoshinori Funama1, Daisuke Utsunomiya2, Seitaro Oda2, Toshiaki Shimonobo3, Takeshi Nakaura2, Toshifumi Mukunoki4, Masafumi Kidoh2, Hideaki Yuki2, Yasuyuki Yamashita2. 1. Department of Medical Physics, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan. Electronic address: funama@kumamoto-u.ac.jp. 2. Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan. 3. Department of Radiology, Kumamoto University Hospital, Kumamoto, Japan. 4. Department of Civil and Environmental Engineering, Graduate School of Science and Technology, Kumamoto University, Japan.
Abstract
PURPOSE: Transluminal-attenuation-gradient (TAG) may reflect patient characteristics and physiological parameters. Furthermore, TAG may be affected by factors such as the CT scanner speed, scanning method, scan timing after contrast-medium (CM) injection, and the injection methods. The purpose of our study was to investigate quantitative TAG at different scan timing points after CM injection for coronary CT angiography. MATERIALS AND METHODS: Using a CM flow phantom and two types of connecting tube mimicking 0% and 70% coronary artery stenosis, we performed 320-detector volume scanning. The heart rate was set at 60bpm and cardiac-output (CO) at 2.0 and 4.0 l/min, respectively. The acquisition time repeated at 0.5-s intervals for 40 and 25s at a CO of 2.0- and 4.0 l/min. We measured the CT number on the same slice level, calculated the time-density-curve (TDC) and the TAG at each time point. RESULTS: At COs of 2.0 and 4.0 l/min at 0% stenosis, TAG exhibited smaller variations (-3.02 to +0.55HU/cm at 2.0 l/min, -2.63 to +0.43HU/cm at 4.0 l/min) than at 70% stenosis at each time point along the TDC. Compared with a CO at 2.0 l/min with 70% stenosis, the TAG curve for a CO at 4.0 l/min gradually changed with time (-6.64 to +1.18HU/cm at 2.0 l/min vs. -3.46 to +2.75HU/cm at 4.0 l/min). CONCLUSION: The TAG value was affected by scan timing after CM injection and by CO although the size of the connecting tube with and without stenosis was identical. Copyright Â
PURPOSE: Transluminal-attenuation-gradient (TAG) may reflect patient characteristics and physiological parameters. Furthermore, TAG may be affected by factors such as the CT scanner speed, scanning method, scan timing after contrast-medium (CM) injection, and the injection methods. The purpose of our study was to investigate quantitative TAG at different scan timing points after CM injection for coronary CT angiography. MATERIALS AND METHODS: Using a CM flow phantom and two types of connecting tube mimicking 0% and 70% coronary artery stenosis, we performed 320-detector volume scanning. The heart rate was set at 60bpm and cardiac-output (CO) at 2.0 and 4.0 l/min, respectively. The acquisition time repeated at 0.5-s intervals for 40 and 25s at a CO of 2.0- and 4.0 l/min. We measured the CT number on the same slice level, calculated the time-density-curve (TDC) and the TAG at each time point. RESULTS: At COs of 2.0 and 4.0 l/min at 0% stenosis, TAG exhibited smaller variations (-3.02 to +0.55HU/cm at 2.0 l/min, -2.63 to +0.43HU/cm at 4.0 l/min) than at 70% stenosis at each time point along the TDC. Compared with a CO at 2.0 l/min with 70% stenosis, the TAG curve for a CO at 4.0 l/min gradually changed with time (-6.64 to +1.18HU/cm at 2.0 l/min vs. -3.46 to +2.75HU/cm at 4.0 l/min). CONCLUSION: The TAG value was affected by scan timing after CM injection and by CO although the size of the connecting tube with and without stenosis was identical. Copyright Â