Imaging Institute, Cleveland Clinic, OH 44195, USA.
AJR Am J Roentgenol. 2010 Aug;195(2):486-93. doi: 10.2214/AJR.09.3872.
The purpose of this study was to investigate replacing unenhanced and arterial single-energy CT acquisitions after endovascular aneurysm repair with one dual-energy CT arterial acquisition.
Thirty patients underwent arterial dual-energy CT (80 and 140 kVp) and venous single-energy CT (120 kVp) after endovascular aneurysm repair, and the radiation doses were compared with those of a standard triple-phase protocol. Both virtual unenhanced and arterial images were generated with dual-energy CT. Images were reviewed clinically for detection of endoleaks and evaluation of stent and calcium appearance. The aortic luminal attenuation on virtual unenhanced CT images was compared with that on previously acquired true unenhanced images. Virtual unenhanced, arterial, and venous images were compared for thrombus attenuation. Single-energy CT and dual-energy CT images were compared for noise.
Replacement of two (unenhanced, arterial) of three single-energy CT acquisitions with one dual-energy CT acquisition resulted in 31% radiation dose savings. All images were clinically interpretable. Thoracic (32 +/- 2 vs 35 +/- 4 HU) and abdominal (30 +/- 3 vs 35 +/- 5 HU) aortic attenuation was similar on virtual unenhanced and true unenhanced images. Thrombus attenuation was similar on virtual unenhanced (32 +/- 6 HU), arterial phase (33 +/- 7 HU), and venous phase (34 +/- 6 HU) images. Decreased stent and calcium attenuation was observed at some locations on virtual unenhanced images. Noise in the thoracic (10 +/- 1 HU) and abdominal (12 +/- 2 HU) aorta was lower on virtual unenhanced images than on true unenhanced images (13 +/- 4 HU, 19 +/- 5 HU). Noise was comparable for dual-energy and single-energy CT (thorax, 16 +/- 2 vs 13 +/- 2 HU; abdomen, 21 +/- 3 vs 23 +/- 5 HU).
Virtual unenhanced and arterial phase images derived from dual-energy CT can replace true unenhanced and arterial phase single-energy CT images in follow-up after endovascular aneurysm repair (except immediately after the procedure), providing comparable diagnostic information with substantial dose savings.
本研究旨在探讨在血管内动脉瘤修复后，用单能 CT 动脉期一次采集代替非增强和动脉期双能 CT 采集的可行性。
30 例患者在血管内动脉瘤修复后进行了动脉双能 CT（80 和 140kVp）和静脉单能 CT（120kVp）检查，比较了其与标准三时相方案的辐射剂量。双能 CT 生成虚拟非增强和动脉图像。临床评估内漏的检出情况和支架及钙的显示情况。比较虚拟非增强 CT 图像上主动脉管腔的衰减与之前获得的真实非增强图像上的衰减。比较单能 CT 和双能 CT 图像上血栓的衰减。比较单能 CT 和双能 CT 图像上的噪声。
用双能 CT 一次采集代替两个（非增强、动脉期）单能 CT 采集，可使辐射剂量降低 31%。所有图像均具有临床可解读性。虚拟非增强图像（32±2HU）和真实非增强图像（35±4HU）上的胸主动脉（32±2HU）和腹主动脉（30±3HU）衰减相似。虚拟非增强图像（32±6HU）、动脉期图像（33±7HU）和静脉期图像（34±6HU）上的血栓衰减相似。在一些部位的虚拟非增强图像上观察到支架和钙衰减降低。在胸（10±1HU）和腹（12±2HU）主动脉上，虚拟非增强图像上的噪声低于真实非增强图像（13±4HU，19±5HU）。双能 CT 和单能 CT 的噪声相当（胸部，16±2HU 比 13±2HU；腹部，21±3HU 比 23±5HU）。
血管内动脉瘤修复后，虚拟非增强和动脉期图像可替代真实非增强和动脉期单能 CT 图像进行随访，提供具有可比性的诊断信息，同时大幅降低辐射剂量。
