Inter- and intra-observer reproducibility of ADC measurements in esophageal carcinoma primary tumors

// Zhimin Ye 1, * , Jun Fang 1, * , Shujun Dai 2 , Tieming Xie 3 , Fangzheng Wang 1 , Zhun Wang 1 , Kai Li 3 , Zhenfu Fu 1 and Yuezhen Wang 1 1 Department of Radiation Oncology, Zhejiang Cancer Hospital, Hangzhou, China 2 Department of Intensive Care Unit, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China 3 Department of Radiology, Zhejiang Cancer Hospital, Hangzhou, China * These authors are considered as co-first authors Correspondence to: Zhun Wang, email: wangzhun007@hotmail.com Zhenfu Fu, email: fuzf1000@163.com Keywords: esophageal carcinoma, diffuse weighted imaging, apparent diffused coefficient, reproducibility Received: June 16, 2017      Accepted: August 17, 2017      Published: October 06, 2017 ABSTRACT The apparent diffuse coefficient (ADC) may correlate with the treatment response to chemotherapy/radiotherapy in solid tumors. Our aim was to determine the inter- and intra-observer reproducibility of ADC measurements in primary esophageal squamous cell carcinoma (ESCC). ADCs were blindly measured in 31 patients diagnosed with ESCC by two observers before treatment (pre-ADC) and after 5 th fraction radiotherapy (intra-ADC) twice with a 2-week interval. The mean pre-ADC of primary tumors was 1.25±0.22 and 1.27±0.23 (in 10 −3 mm 2 /s) from observer A for measurements 1 and 2, respectively, and the intra-observer measurements were -0.02 bias vs. -0.13-0.09 limits of agreement. From observer B, the mean pre-ADC varied between 1.25±0.23 and 1.27±0.23 (in 10 −3 mm 2 /s) for measurements 1 and 2, respectively, and intra-observer measurements were -0.02 bias vs. -0.17~0.16 limits of agreement. The mean pre-ADC of primary tumors was 1.26±0.24 (in 10 −3 mm 2 /s) from observers A and B, and inter-observer measurements were 0.01 bias vs. -0.09-0.09 limits of agreement, revealing a low inter-observer variance. Similar measurements of the intra-SD parameters showed that the pre- and intra-ADC of primary tumors differed significantly. Thus ADC measurements may have sufficient inter-observer and intra-observer reproducibility to measure primary tumor responses to treatment, and the ADCs before and during treatment differed.