Service d'imagerie medicale, CHU Nimes, Univ Montpellier, Medical Imaging Group Nimes, EA 2415, Bd Prof Robert Debré, 30029, Nîmes Cedex 9, France.
Department of Diagnostic and Interventional Radiology, Lausanne University Hospital and University of Lausanne, Bugnon 41, 1011, Lausanne, Switzerland.
Eur Radiol. 2020 Feb;30(2):1075-1078. doi: 10.1007/s00330-019-06425-z. Epub 2019 Sep 10.
OBJECTIVES: To determine the best compromise between low radiation dose and suitable image quality for the detection of lytic and sclerotic bone lesions of the lumbar spine and pelvis. METHODS: A phantom was scanned using the routine protocol (STD, 13 mGy) and six decreasing dose levels. Raw data were reconstructed using level 3 of iterative reconstruction (IR3) with 1-mm slice thickness for the STD protocol and highest IR levels with 3-mm slice thickness for the others. CTDI was used for radiation dose assessment. Quantitative criteria (noise power spectrum [NPS], task-based transfer function [TTF], and the detectability index [d']), as well as qualitative analysis, were used to compare protocols. NPS and TTF were computed using specific software (imQuest). d' was computed for two imaging tasks: lytic and sclerotic bone lesions. A subjective analysis was performed to validate the image quality obtained on the anthropomorphic phantom with the different dose values. RESULTS: Similar d' values were found for CTDI from 3 to 4 mGy with IR4 and from 1 to 2 mGy for IR5 compared with d' values using the STD protocol. Image quality was validated subjectively for IR4 but rejected for IR5 (image smoothing). Finally, for the same d', the dose was reduced by 74% compared with the STD protocol, with the CTDI being 3.4 mGy for the lumbar spine and for the pelvis. CONCLUSION: A dose level as low as 3.4 mGy, in association with high levels of IR, provides suitable image quality for the detection of lytic and sclerotic bone lesions of the lumbar spine and pelvis. KEY POINTS: • A CTDI of 3.4 mGy, in association with high iterative reconstruction level, provides suitable image quality for the detection of lytic and sclerotic bone lesions, both at objective and subjective analysis. • Compared with the standard protocol, radiation dose can be reduced up to 74% for the lumbar spine and pelvis. • A task-based image quality assessment using the detectability index represents an objective method for the assessment of image quality and bridges the gap between complex physical metrics and subjective image analysis.
目的：确定腰椎和骨盆溶骨性和硬化性骨病变检测中低剂量与合适图像质量之间的最佳折衷方案。
方法：使用常规方案（STD，13 mGy）和六个降低剂量水平对体模进行扫描。使用迭代重建 3 级（IR3）对 STD 方案以 1-mm 层厚重建原始数据，并对其他方案以最高 IR 级别和 3-mm 层厚重建原始数据。使用 CTDI 评估辐射剂量。使用定量标准（噪声功率谱[NPS]、基于任务的传递函数[TTF]和检测指数[d']）以及定性分析比较方案。使用特定软件（imQuest）计算 NPS 和 TTF。为两种成像任务（溶骨性和硬化性骨病变）计算 d'。使用不同剂量值对人体模型进行主观分析，以验证获得的图像质量。
结果：与 STD 方案相比，使用 IR4 的 CTDI 为 3 至 4 mGy 和 IR5 的 CTDI 为 1 至 2 mGy 时，d'值相似。IR4 的图像质量在主观上得到验证，但 IR5 的图像质量（图像平滑）未得到验证。最后，对于相同的 d'，与 STD 方案相比，剂量降低了 74%，腰椎和骨盆的 CTDI 分别为 3.4 mGy。
结论：低至 3.4 mGy 的剂量水平，结合高水平的 IR，可提供适用于腰椎和骨盆溶骨性和硬化性骨病变检测的图像质量。
关键要点：
Diagn Interv Imaging. 2020-5
Eur Radiol. 2019-7-29
Bioengineering (Basel). 2024-12-18
Diagnostics (Basel). 2023-1-26
Eur Radiol. 2018-4-10
Diagn Interv Imaging. 2018-2-1
Semin Musculoskelet Radiol. 2015-12
Diagn Interv Imaging. 2015-10-27
Zotero 插件