Visual Basic.NET - Obtener la ruta con TreeView

¿Como ago para obtener la ruta en formato string?

Tengo un control TreeView para examinar solamente carpetas.
Quiero que el usuario busque una carpeta, la seleccione y que en un control TextBox aparesca la ruta completa de la carpeta que selecciono

Debe ser una linea nada mas, quisiera saber donde va, aca dejo el codigo:

Imports System.IO
Public Class ExaminarCarpetas

Private Sub ExaminarCarpetas_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
LlenarArbol()
End Sub

Private Sub LlenarArbol()
tvDirectorios.BeginUpdate()
tvDirectorios.Nodes.Clear()
Dim astrDrives As String() = Directory.GetLogicalDrives()
Dim strDrive As String
For Each strDrive In astrDrives
Dim tnDrive As New TreeNode(strDrive, 0, 0)
tvDirectorios.Nodes.Add(tnDrive)
AgregarDir(tnDrive)
' Drive C por defecto
If strDrive = "C:" Then
tvDirectorios.SelectedNode = tnDrive
End If
Next
tvDirectorios.EndUpdate()
End Sub

Private Sub AgregarDir(ByVal tn As TreeNode)
tn.Nodes.Clear()
Dim strPath As String = tn.FullPath
Dim diDirectory As New DirectoryInfo(strPath)
Dim aDir() As DirectoryInfo
Try
aDir = diDirectory.GetDirectories()
Catch exp As Exception
Exit Sub
End Try
Dim di As DirectoryInfo
For Each di In aDir
Dim tnDir As New TreeNode(di.Name, 1, 2)
tn.Nodes.Add(tnDir)
Next
End Sub

Private Sub tvDirectorios_BeforeExpand(ByVal sender As Object, ByVal e As System.Windows.Forms.TreeViewCancelEventArgs) Handles tvDirectorios.BeforeExpand
tvDirectorios.BeginUpdate()
Dim tn As TreeNode
For Each tn In e.Node.Nodes
AgregarDir(tn)
Next tn
tvDirectorios.EndUpdate()
End Sub
End Class