diff --git a/IRaCIS.Core.Application/Service/ReadingCalculate/RECIST1Point1CalculateService.cs b/IRaCIS.Core.Application/Service/ReadingCalculate/RECIST1Point1CalculateService.cs
index 78e7c2c79..fbe8e839e 100644
--- a/IRaCIS.Core.Application/Service/ReadingCalculate/RECIST1Point1CalculateService.cs
+++ b/IRaCIS.Core.Application/Service/ReadingCalculate/RECIST1Point1CalculateService.cs
@@ -62,6 +62,8 @@ namespace IRaCIS.Core.Application.Service.ReadingCalculate
         /// 获取Sod的值
         /// </summary>
         private decimal? sODData;
+
+        private string nAString = "NA";
         #endregion
 
         #region 删除病灶获取起始病灶序号
@@ -391,7 +393,7 @@ namespace IRaCIS.Core.Application.Service.ReadingCalculate
                                 }
                                 else
                                 {
-                                    item.Answer = string.Empty;
+                                    item.Answer = this.nAString;
 
                                 }