我如何获得outlook联系人的头像图像?

我正在尝试获取联系人的头像图像。

using Microsoft.Office.Interop.Outlook;
public sealed class OutlookAvatarFetcher
{
    private static void FetchAvatars()
    {
        var outlook = new Application();
        var folder = outlook.GetNamespace("MAPI").GetDefaultFolder(OlDefaultFolders.olFolderContacts);
        var items = folder.Items;
        for (var i = 0; i < items.Count; ++i)
        {
            var contact = items[i + 1] as ContactItem;
            if (contact == null)
                continue;

            if (contact.HasPicture)
            {
                // TODO store the picture somehow.
            }
        }
    }
}

但不幸的是我找不到图片访问器