imagen default en MVC

        private static string imagenDefault = "/Content/imagenes/productos/default_box_art.jpg";

        public static string ImageOrDefault(this HtmlHelper helper, string urlImagen)
        {
            try
            {
                HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(urlImagen);
                request.Method = "HEAD";
                request.GetResponse();
                return urlImagen;
            }
            catch
            {
                return imagenDefault;
            }
        }