Department of Radiology, Koç University School of Medicine, İstanbul, Turkey.
Department of General Surgery, Koç University School of Medicine, İstanbul, Turkey.
Diagn Interv Radiol. 2020 Mar;26(2):87-94. doi: 10.5152/dir.2019.19127.
In this study, we aimed to analyze the repeatability of quantitative multiparametric rectal magnetic resonance imaging (MRI) parameters with different measurement techniques.
All examinations were performed with 3 T MRI system. In addition to routine sequences for rectal cancer imaging protocol, small field-of-view diffusion-weighted imaging and perfusion sequences were acquired in each patient. Apparent diffusion coefficient (ADC) was used for diffusion analysis and ktrans was used for perfusion analysis. Three different methods were used in measurement of these parameters; measurements were performed twice by one radiologist for intraobserver and separately by three radiologists for interobserver variability analysis. ADC was measured by the lowest value, the value at maximum wall thickness, and freehand techniques. Ktrans was measured at the slice with maximum wall thickness, by freehand drawn region of interest (ROI), and at the dark red spot with maximum value.
A total of 30 patients with biopsy-proven rectal adenocarcinoma were included in the study. The mean values of the parameters measured by the first radiologist on the first and second measurements were as follows: mean lowest ADC, 721.31±147.18 mm2/s and 718.96±135.71 mm2/s; mean ADC value on the slice with maximum wall thickness, 829.90±144.24 mm2/s and 829.48±149.23 mm2/s; mean ADC value measured by freehand ROI on the slice with maximum wall thickness, 846.56±136.31 mm2/s and 848.23±144.15 mm2/s; mean ktrans value on the slice with maximum wall thickness, 0.219±0.080 and 0.214±0.074; mean ktrans by freehand ROI technique (including as much tumoral tissue as possible), 0.208±0.074 and 0.207±0.069; mean ktrans measured from the dark red foci, 0.308±0.109 and 0.311±0.105. Intraobserver agreement was very good among diffusion and perfusion parameters obtained with all three measurement techniques. Interobserver agreement was very good, except for one of the measurement techniques. As far as interobserver variability is considered, only ADC value measured on the slice with maximum wall thickness differed significantly.
Multiparametric MRI of rectum, using ADC as the diffusion and ktrans as the perfusion parameter is a repeatable technique. This technique may potentially be used in prediction and evaluation of neoadjuvant treatment response. New studies with larger patient groups are needed to validate the role of multiparametric MRI.
本研究旨在分析不同测量技术下定量多参数直肠磁共振成像（MRI）参数的可重复性。
所有检查均在 3 T MRI 系统上进行。除直肠癌成像方案的常规序列外，每位患者还采集小视野弥散加权成像和灌注序列。表观弥散系数（ADC）用于扩散分析，ktrans 用于灌注分析。这些参数的测量使用了三种不同的方法；观察者内变异分析由同一位放射科医生进行两次测量，观察者间变异分析由三位放射科医生分别进行测量。ADC 通过最低值、最大壁厚度处的值和徒手技术进行测量。ktrans 在最大壁厚度的层面上测量，通过徒手绘制的感兴趣区（ROI）测量，在最大强度的暗红色点上测量。
本研究共纳入 30 例经活检证实的直肠腺癌患者。第一位放射科医生在第一次和第二次测量中测量的参数的平均值如下：最低 ADC 的平均值分别为 721.31±147.18 mm2/s 和 718.96±135.71 mm2/s；最大壁厚度层面的 ADC 值的平均值为 829.90±144.24 mm2/s 和 829.48±149.23 mm2/s；最大壁厚度层面徒手 ROI 测量的 ADC 值的平均值为 846.56±136.31 mm2/s 和 848.23±144.15 mm2/s；最大壁厚度层面的 ktrans 值的平均值为 0.219±0.080 和 0.214±0.074；包括尽可能多的肿瘤组织的徒手 ROI 技术的 ktrans 值的平均值为 0.208±0.074 和 0.207±0.069；暗红色焦点处测量的 ktrans 值的平均值为 0.308±0.109 和 0.311±0.105。三种测量技术获得的扩散和灌注参数的观察者内一致性均非常好。观察者间一致性很好，除了一种测量技术外。就观察者间变异性而言，只有最大壁厚度层面测量的 ADC 值差异显著。
直肠多参数 MRI 采用 ADC 作为扩散参数，ktrans 作为灌注参数，是一种可重复的技术。该技术可能有潜力用于预测和评估新辅助治疗反应。需要更大的患者群体的新研究来验证多参数 MRI 的作用。
