Omoumi Patrick, Verdun Francis R, Ben Salah Yosr, Vande Berg Bruno C, Lecouvet Frederic E, Malghem Jacques, Ott Julien G, Meuli Reto, Becce Fabio
Department of Radiology, Cliniques Universitaires Saint-Luc, Université Catholique Louvain, IREC-IMAG, Brussels, Belgium.
Acta Radiol. 2014 Apr;55(3):335-44. doi: 10.1177/0284185113494981. Epub 2013 Jul 29.
Iterative reconstruction (IR) techniques reduce image noise in multidetector computed tomography (MDCT) imaging. They can therefore be used to reduce radiation dose while maintaining diagnostic image quality nearly constant. However, CT manufacturers offer several strength levels of IR to choose from.
To determine the optimal strength level of IR in low-dose MDCT of the cervical spine.
Thirty consecutive patients investigated by low-dose cervical spine MDCT were prospectively studied. Raw data were reconstructed using filtered back-projection and sinogram-affirmed IR (SAFIRE, strength levels 1 to 5) techniques. Image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were measured at C3-C4 and C6-C7 levels. Two radiologists independently and blindly evaluated various anatomical structures (both dense and soft tissues) using a 4-point scale. They also rated the overall diagnostic image quality using a 10-point scale.
As IR strength levels increased, image noise decreased linearly, while SNR and CNR both increased linearly at C3-C4 and C6-C7 levels (P < 0.001). For the intervertebral discs, the content of neural foramina and dural sac, and for the ligaments, subjective image quality scores increased linearly with increasing IR strength level (P ≤ 0.03). Conversely, for the soft tissues and trabecular bone, the scores decreased linearly with increasing IR strength level (P < 0.001). Finally, the overall diagnostic image quality scores increased linearly with increasing IR strength level (P < 0.001).
The optimal strength level of IR in low-dose cervical spine MDCT depends on the anatomical structure to be analyzed. For the intervertebral discs and the content of neural foramina, high strength levels of IR are recommended.
迭代重建（IR）技术可降低多排螺旋计算机断层扫描（MDCT）成像中的图像噪声。因此，它们可用于降低辐射剂量，同时使诊断图像质量几乎保持不变。然而，CT制造商提供了几种强度水平的IR供选择。
确定颈椎低剂量MDCT中IR的最佳强度水平。
对连续30例接受颈椎低剂量MDCT检查的患者进行前瞻性研究。原始数据采用滤波反投影和正弦图确认迭代重建（SAFIRE，强度水平1至5）技术进行重建。在C3-C4和C6-C7水平测量图像噪声、信噪比（SNR）和对比噪声比（CNR）。两名放射科医生独立且盲法使用4分制对各种解剖结构（包括致密组织和软组织）进行评估。他们还使用10分制对整体诊断图像质量进行评分。
随着IR强度水平的增加，图像噪声呈线性下降，而在C3-C4和C6-C7水平，SNR和CNR均呈线性增加（P<0.001）。对于椎间盘、神经孔内容物和硬脊膜囊，以及韧带，主观图像质量评分随IR强度水平的增加而线性增加（P≤0.03）。相反，对于软组织和骨小梁，评分随IR强度水平的增加而线性下降（P<0.001）。最后，整体诊断图像质量评分随IR强度水平的增加而线性增加（P<0.001）。
颈椎低剂量MDCT中IR的最佳强度水平取决于要分析的解剖结构。对于椎间盘和神经孔内容物，建议使用高强度水平的IR。
