Moloney Fiachra, Twomey Maria, Fama Daniel, Balta Joy Y, James Karl, Kavanagh Richard G, Moore Niamh, Murphy Mary Jane, O'Mahony Siobhan M, Maher Michael M, Cryan John F, O'Connor Owen J
Department of Radiology, Cork University Hospital, Cork, Ireland.
Department of Anatomy and Neuroscience, College of Medicine and Health, University College Cork, Cork, Ireland.
J Med Imaging Radiat Oncol. 2018 Oct;62(5):625-633. doi: 10.1111/1754-9485.12733. Epub 2018 Apr 15.
Cadaveric studies provide a means of safely assessing new technologies and optimizing scanning prior to clinical validation. Reducing radiation exposure in a clinical setting can entail incremental dose reductions to avoid missing important clinical findings. The use of cadavers allows assessment of the impact of more substantial dose reductions on image quality. Our aim was to identify a suitable low-dose abdominopelvic CT protocol for subsequent clinical validation.
Five human cadavers were scanned at one conventional dose and three low-dose settings. All scans were reconstructed using three different reconstruction algorithms: filtered back projection (FBP), hybrid iterative reconstruction (60% FBP and 40% adaptive statistical iterative reconstruction (ASIR40)), and model-based iterative reconstruction (MBIR). Two readers rated the image quality both quantitatively and qualitatively.
Model-based iterative reconstruction images had significantly better objective image noise and higher qualitative scores compared with both FBP and ASIR40 images at all dose levels. The greatest absolute noise reduction, between MBIR and FBP, of 34.3 HU (equating to a 68% reduction) was at the lowest dose level. MBIR reduced image noise and improved image quality even in CT images acquired with a mean radiation dose reduction of 62% compared with conventional dose studies reconstructed with ASIR40, with lower levels of objective image noise, superior diagnostic acceptability and contrast resolution, and comparable subjective image noise and streak artefact scores.
This cadaveric study demonstrates that MBIR reduces image noise and improves image quality in abdominopelvic CT images acquired with dose reductions of up to 62%.
尸体研究提供了一种在临床验证之前安全评估新技术和优化扫描的方法。在临床环境中减少辐射暴露可能需要逐步降低剂量以避免遗漏重要的临床发现。使用尸体可以评估更大剂量降低对图像质量的影响。我们的目的是确定一种合适的低剂量腹部盆腔CT方案，用于后续的临床验证。
对五具人体尸体进行了一次常规剂量和三种低剂量设置的扫描。所有扫描均使用三种不同的重建算法进行重建：滤波反投影（FBP）、混合迭代重建（60% FBP和40%自适应统计迭代重建（ASIR40））以及基于模型的迭代重建（MBIR）。两名阅片者对图像质量进行了定量和定性评分。
在所有剂量水平下，与FBP和ASIR40图像相比，基于模型的迭代重建图像具有明显更好的客观图像噪声和更高的定性评分。在最低剂量水平下，MBIR与FBP之间最大的绝对噪声降低为34.3 HU（相当于降低68%）。与使用ASIR40重建的常规剂量研究相比，即使在平均辐射剂量降低62%的CT图像中，MBIR也能降低图像噪声并提高图像质量，具有更低的客观图像噪声水平、更好的诊断可接受性和对比度分辨率，以及相当的主观图像噪声和条纹伪影评分。
这项尸体研究表明，MBIR在腹部盆腔CT图像中，当剂量降低高达62%时，可降低图像噪声并提高图像质量。
