Count Pages PDF in vb.net

Public Function GetNoOfPagesPDF(ByVal FileName As String) As Integer
        Dim Count As Integer = 0
        If FileName <> "" Then
            'Open the file
            Dim fstream As New IO.FileStream(FileName, IO.FileMode.Open, IO.FileAccess.Read)
            Dim stream As New IO.StreamReader(fstream)        'Read the contents
            Dim strContents As String = stream.ReadToEnd()        'Count the Total page cound
            Dim reg As System.Text.RegularExpressions.Regex = _
            New System.Text.RegularExpressions.Regex("/Type\s*/Page[^s]")

            Dim mat As System.Text.RegularExpressions.MatchCollection = reg.Matches(strContents)
            Count = mat.Count
        End If

        Return Count
End Function