如何在sharepoint 2010 c#中获取任务列表相关内容的值

我们知道，工作流的任务列表有一列名为Related content。如何获取特定任务项的Related Content值?我已按下列方法试过了，但不成功。

var campaignTaskList = currentWeb.Lists["CampaignTask"].Items;
var currentUserTaskList = (from SPListItem taskItem in campaignTaskList
                            let assignTo = new SPFieldUserValue(taskItem.Web, taskItem["Assigned To"].ToString())
                             where assignTo.User.Name == currentWeb.CurrentUser.Name
                             select taskItem).ToList();
     foreach (SPListItem workflowTaskItem in currentUserTaskList)
          {
             var item =  workflowTaskItem["Related Content"].ToString();
          }

<Field ID="{58DDDA52-C2A3-4650-9178-3BBC1F6E36DA}"
    Name="WorkflowLink"
    SourceID="http://schemas.microsoft.com/sharepoint/v3"
    StaticName="WorkflowLink"
    Group="_Hidden"
    Type="URL"
    DisplayName="$Resources:core,LinkField;"
    ReadOnly="TRUE"
    Sealed="TRUE">
</Field>

var relContent = item[SPBuiltInFieldId.WorkflowLink];

var relContent = item["WorkflowLink"];