Division of Abdominal Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Boston, MA, 02114, USA.
Abdom Radiol (NY). 2017 May;42(5):1298-1309. doi: 10.1007/s00261-016-0993-3.
To determine to what extent low-energy CT imaging affects attenuation of gastrointestinal tract (GIT) opacified with positive oral contrast media (OCM). Second, to establish optimal OCM concentrations for low-energy diagnostic CT exams.
One hundred patients (38 men and 62 women; age 62 ± 11 years; BMI 26 ± 5) with positive OCM-enhanced 120-kVp single-energy CT (SECT), and follow-up 100-kVp acquisitions (group A; n = 50), or 40-70-keV reconstructions from rapid kV switching-single-source dual-energy CT (ssDECT) (group B; n = 50) were included. Luminal attenuation from different GIT segments was compared between exams. Standard dose of three OCM and diluted solutions (75%, 50%, and 25% concentrations) were introduced serially in a gastrointestinal phantom and scanned using SECT (120, 100, and 80 kVp) and DECT (80/140 kVp) acquisitions on a ssDECT scanner. Luminal attenuation was obtained on SECT and DECT images (40-70 keV), and compared to 120-kVp scans with standard OCM concentrations.
Luminal attenuation was higher on 100-kVp (328 HU) and on 40-60-keV images (410-924 HU) in comparison to 120-kVp scans (298 HU) in groups A and B (p < 0.05). Phantom: There was an inverse correlation between luminal attenuation and X-ray energy, increasing up to 527 HU on low-kVp and 999 HU on low-keV images (p < 0.05). 25% and 50% diluted OCM solutions provided similar or higher attenuation than 120 kVp, at low kVp and keV, respectively.
Low-energy CT imaging increases the attenuation of GIT opacified with positive OCM, permitting reduction of 25%-75% OCM concentration.
确定低能量 CT 成像对口服阳性对比剂（OCM）增强胃肠道（GIT）衰减的影响程度。其次，确定低能量诊断 CT 检查的最佳 OCM 浓度。
100 例患者（38 名男性和 62 名女性；年龄 62±11 岁；BMI 26±5）行阳性 OCM 增强 120kV 单能 CT（SECT）检查，随后进行 100kV 采集（A 组，n=50），或快速千伏切换单源双能 CT（ssDECT）的 40-70keV 重建（B 组，n=50）。比较两组不同 GIT 段的管腔衰减。在胃肠道体模中依次引入标准剂量的三种 OCM 和稀释溶液（75%、50%和 25%浓度），并用 SECT（120、100 和 80kVp）和 ssDECT 扫描仪上的 DECT（80/140kVp）采集进行扫描。在 SECT 和 DECT 图像（40-70keV）上获得管腔衰减，并与标准 OCM 浓度的 120kVp 扫描进行比较。
与 A 组和 B 组的 120kVp 扫描（298HU）相比，100kVp（328HU）和 40-60keV 图像（410-924HU）的管腔衰减更高（p<0.05）。体模：管腔衰减与 X 射线能量呈负相关，在低千伏和低 keV 时分别增加至 527HU 和 999HU（p<0.05）。25%和 50%稀释的 OCM 溶液在低千伏和低 keV 时分别提供与 120kVp 相似或更高的衰减。
低能量 CT 成像增加了阳性 OCM 增强的 GIT 衰减，允许将 OCM 浓度降低 25%-75%。
