Hara Amy K, Paden Robert G, Silva Alvin C, Kujak Jennifer L, Lawder Holly J, Pavlicek William
Department of Diagnostic Radiology, Mayo Clinic Arizona, 13400 E Shea Blvd., Scottsdale, AZ 85259, USA.
AJR Am J Roentgenol. 2009 Sep;193(3):764-71. doi: 10.2214/AJR.09.2397.
The purpose of this study was to evaluate the image noise, low-contrast resolution, image quality, and spatial resolution of adaptive statistical iterative reconstruction in low-dose body CT.
Adaptive statistical iterative reconstruction was used to scan the American College of Radiology phantom at the American College of Radiology reference value and at one-half that value (12.5 mGy). Test objects in low- and high-contrast and uniformity modules were evaluated. Low-dose CT with adaptive statistical iterative reconstruction was then tested on 12 patients (seven men, five women; average age, 67.5 years) who had previously undergone routine-dose CT. Two radiologists blinded to scanning technique evaluated images of the same patients obtained with routine-dose CT and low-dose CT with and without adaptive statistical iterative reconstruction. Image noise, low-contrast resolution, image quality, and spatial resolution were graded on a scale of 1 (best) to 4 (worst). Quantitative noise measurements were made on clinical images.
In the phantom, low- and high-contrast and uniformity assessments showed no significant difference between routine-dose imaging and low-dose CT with adaptive statistical iterative reconstruction. In patients, low-dose CT with adaptive statistical iterative reconstruction was associated with CT dose index reductions of 32-65% compared with routine imaging and had the least noise both quantitatively and qualitatively (p < 0.05). Low-dose CT with adaptive statistical iterative reconstruction and routine-dose CT had identical results for low-contrast resolution and nearly identical results for overall image quality (grade 2.1-2.2). Spatial resolution was better with routine-dose CT (p = 0.004).
These preliminary results support body CT dose index reductions of 32-65% when adaptive statistical iterative reconstruction is used. Studies with larger statistical samples are needed to confirm these findings.
本研究旨在评估自适应统计迭代重建技术在低剂量体部CT中的图像噪声、低对比度分辨率、图像质量和空间分辨率。
采用自适应统计迭代重建技术，在美国放射学会（ACR）参考值及该值的一半（12.5 mGy）条件下扫描ACR体模。对低对比度和高对比度以及均匀性模块中的测试物体进行评估。然后，对12例（7名男性，5名女性；平均年龄67.5岁）此前接受过常规剂量CT检查的患者进行低剂量CT自适应统计迭代重建测试。两名对扫描技术不知情的放射科医生对同一批患者分别采用常规剂量CT以及有无自适应统计迭代重建技术的低剂量CT所获得的图像进行评估。图像噪声、低对比度分辨率、图像质量和空间分辨率按1（最佳）至4（最差）进行分级。对临床图像进行定量噪声测量。
在体模中，常规剂量成像与采用自适应统计迭代重建技术的低剂量CT在低对比度和高对比度以及均匀性评估方面无显著差异。在患者中，与常规成像相比，采用自适应统计迭代重建技术的低剂量CT的CT剂量指数降低了32% - 65%，并且在定量和定性方面噪声均最小（p < 0.05）。采用自适应统计迭代重建技术的低剂量CT与常规剂量CT在低对比度分辨率方面结果相同，在整体图像质量方面结果相近（2.1 - 2.2级）。常规剂量CT的空间分辨率更佳（p = 0.004）。
这些初步结果支持在使用自适应统计迭代重建技术时，体部CT剂量指数可降低32% - 65%。需要更大样本量的研究来证实这些发现。
