Visual Basic.NET - Mostar una palabra letra por letra ascendente y descendente

Sub Main()

        Dim i As Integer

        Dim NCadena As String

        Console.WriteLine("Introduzca La Cadena")

        NCadena = Console.ReadLine()

        Console.WriteLine("--------------------")

        i = NCadena.Length

        While i > 1

            Console.WriteLine(NCadena.Substring(0, i))

            i -= 1

        End While

        While i <= NCadena.Length

            Console.WriteLine(NCadena.Substring(0, i))

            i += 1

        End While

        Console.WriteLine("--------------------")

        Console.WriteLine("Listo..")

        Console.ReadLine()    End Sub