Littooij Annemieke S, Humphries Paul D, Olsen Øystein E
Department of Radiology, University Medical Centre Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands.
Department of Radiology, Great Ormond Street Hospital for Children, London, UK.
Pediatr Radiol. 2015 Oct;45(11):1651-60. doi: 10.1007/s00247-015-3354-4. Epub 2015 May 8.
The apparent diffusion coefficient (ADC) is potentially useful for assessing treatment response in nephroblastoma (Wilms tumour). However the precision of ADC measurements in these heterogeneous lesions is unknown.
To assess intra- and interobserver variability of whole-tumour ADC measurements in viable parts of nephroblastomas at diagnosis and after preoperative chemotherapy.
We included children with histopathologically proven nephroblastoma who had undergone MRI with diffusion-weighted imaging before and after preoperative chemotherapy. Three independent observers performed whole-tumour ADC measurements of all lesions, excluding non-enhancing areas. One observer evaluated all lesions on two occasions. We performed analyses using Bland-Altman plots and concordance correlation coefficient (CCC) calculations with 95% limits of agreement for median ADC, difference between pre- and post-chemotherapy median ADC (ADC shift) and percentage of pixels with ADC values <1.0 × 10(-3) mm(2)/s.
In 22 lesions (13 pretreatment and 9 post-treatment) in 10 children the interobserver variability in median ADC and ADC shift were within the interval of approximately ±0.1 × 10(-3) mm(2)/s (limits of agreement for median ADC ranged -0.08-0.11 × 10(-3) mm(2)/s and for ADC-shift -0.11-0.09 × 10(-3) mm(2)/s). The interobserver variability for percentage of low-ADC pixels was larger and also biased. The calculated CCC confirmed good intra- and interobserver agreement (ρ-c ranging from 0.968 to 0.996).
Measurements of whole-tumour ADC values excluding necrotic areas seem to be sufficiently precise for detection of chemotherapy-related change.
表观扩散系数（ADC）可能有助于评估肾母细胞瘤（威尔姆斯瘤）的治疗反应。然而，这些异质性病变中ADC测量的精度尚不清楚。
评估诊断时及术前化疗后肾母细胞瘤存活部分全肿瘤ADC测量的观察者内和观察者间变异性。
我们纳入了经组织病理学证实为肾母细胞瘤且在术前化疗前后均接受过磁共振成像（MRI）及扩散加权成像检查的儿童。三名独立观察者对所有病变进行全肿瘤ADC测量，不包括无强化区域。一名观察者在两个不同时间点评估所有病变。我们使用Bland-Altman图和一致性相关系数（CCC）计算进行分析，给出中位数ADC的95%一致性界限、化疗前后中位数ADC的差值（ADC变化）以及ADC值<1.0×10(-3) mm(2)/s的像素百分比。
10名儿童的22个病变（13个治疗前病变和9个治疗后病变）中，中位数ADC和ADC变化的观察者间变异性在约±0.1×10(-3) mm(2)/s范围内（中位数ADC的一致性界限为-0.08 - 0.11×10(-3) mm(2)/s，ADC变化的一致性界限为-0.11 - 0.09×10(-3) mm(2)/s）。低ADC像素百分比的观察者间变异性更大且存在偏差。计算得到的CCC证实了良好的观察者内和观察者间一致性（ρ-c范围为0.968至0.996）。
排除坏死区域的全肿瘤ADC值测量对于检测化疗相关变化似乎足够精确。
