Sauter Andreas P, Kössinger Antonia, Beck Stefanie, Deniffel Dominik, Dapper Hendrik, Combs Stephanie E, Rummeny Ernst J, Pfeiffer Daniela
Department of Diagnostic and Interventional Radiology, School of Medicine, Technical University of Munich, Klinikum rechts der Isar, Munich, Germany.
Department of Radiation Oncology, School of Medicine, Technical University of Munich, Klinikum rechts der Isar, Munich, Germany.
Acta Radiol Open. 2020 Sep 17;9(9):2058460120945316. doi: 10.1177/2058460120945316. eCollection 2020 Sep.
Rectal cancer (RC) is a frequent malignancy for which magnetic resonance imaging (MRI) is the most common and accurate imaging. Iodine concentration (IC) can be quantified with spectral dual-layer computed tomography CT (DL-CT), which could improve imaging of RC, especially for evaluation of response to radiochemotherapy (RCT).
To compare a DL-CT system to MRI as the non-invasive imaging gold standard for imaging of RC to evaluate the possibility of a response evaluation with DL-CT.
Eleven patients who received DL-CT as well as MRI before and after RCT of RC were retrospectively included into this study. For each examination, a region of interest (ROI) was placed within the tumor. For MRI, the mean apparent diffusion coefficient (ADC) was assessed. For DL-CT, IC, z-effective, and Hounsfield Units (HU) were measured. IC, z-effective, and HU were normalized to the aorta. ADC was correlated to absolute and relative normalized IC, z-effective, and HU with Spearman's ρ. Differences before and after treatment were tested with Wilcoxon signed-rank test.
HU, IC, and Z-effective values in DL-CT images decreased significantly after RCT (<0.01 for each comparison). The mean ADC increased significantly after RCT. Spearman's ρ of the absolute IC difference and the absolute ADC (both before and after RCT) is high and significant (ρ = 0.73; = 0.01), whereas the ρ-value for z-effective (ρ = 0.56) or HU (ρ = 0.45) to ADC was lower and non-significant.
Response evaluation of RC after RCT could be possible with DL-CT via the measurement of IC.
直肠癌（RC）是一种常见的恶性肿瘤，磁共振成像（MRI）是其最常用且准确的成像方法。碘浓度（IC）可通过光谱双层计算机断层扫描CT（DL-CT）进行定量，这可能会改善直肠癌的成像，特别是在评估放化疗（RCT）反应方面。
将DL-CT系统与作为直肠癌成像无创性成像金标准的MRI进行比较，以评估用DL-CT进行反应评估的可能性。
本研究回顾性纳入了11例在直肠癌RCT前后接受DL-CT及MRI检查的患者。每次检查时，在肿瘤内放置感兴趣区域（ROI）。对于MRI，评估平均表观扩散系数（ADC）。对于DL-CT，测量IC、有效原子序数（z-effective）和亨氏单位（HU）。将IC、z-effective和HU标准化至主动脉。采用Spearman秩相关系数ρ分析ADC与绝对及相对标准化IC、z-effective和HU之间的相关性。用Wilcoxon符号秩检验检测治疗前后的差异。
RCT后，DL-CT图像中的HU、IC和Z-effective值显著降低（每次比较P<0.01）。RCT后平均ADC显著升高。绝对IC差值与绝对ADC（RCT前后）的Spearman秩相关系数ρ较高且具有显著性（ρ = 0.73；P = 0.01），而z-effective（ρ = 0.56）或HU（ρ = 0.45）与ADC的ρ值较低且无显著性。
通过测量IC，DL-CT有可能对直肠癌RCT后的反应进行评估。
