/// <summary>
/// Loads DICOM annotations from file,
/// changes the text of text annotations,
/// saves DICOM annotation back to the source file.
/// </summary>
/// <param name="presentationStateFilePath">The path to a presentation state file.</param>
/// <param name="textValue">The value of text annotations.</param>
public static void ChangeTextAnnotations(string presentationStateFilePath, string textValue)
{
    // load presentation state file
    using (Vintasoft.Imaging.Codecs.ImageFiles.Dicom.DicomFile dicomFile = 
        new Vintasoft.Imaging.Codecs.ImageFiles.Dicom.DicomFile(presentationStateFilePath, false))
    {
        // create codec of DICOM annotations
        Vintasoft.Imaging.Annotation.Dicom.DicomAnnotationCodec annotationCodec = 
            new Vintasoft.Imaging.Annotation.Dicom.DicomAnnotationCodec();
        // get annotations from the presentation state file
        Vintasoft.Imaging.Annotation.Dicom.DicomAnnotationDataCollection[] annotationDataCollections = 
            annotationCodec.Decode(dicomFile.Annotations);

        // for each annotation collection
        foreach (Vintasoft.Imaging.Annotation.Dicom.DicomAnnotationDataCollection annotationDataCollection in annotationDataCollections)
        {
            // for each annotation in annotation collection
            foreach (Vintasoft.Imaging.Annotation.Dicom.DicomAnnotationData annotationData in annotationDataCollection)
            {
                // if annotation is text annotation
                if (annotationData is Vintasoft.Imaging.Annotation.Dicom.DicomTextAnnotationData)
                {
                    // get text annotation data
                    Vintasoft.Imaging.Annotation.Dicom.DicomTextAnnotationData textAnnotationData = 
                        (Vintasoft.Imaging.Annotation.Dicom.DicomTextAnnotationData)annotationData;
                    // change text of text annotation
                    textAnnotationData.UnformattedTextValue = textValue;
                }
            }
        }

        // save annotations in the source presentation state file
        annotationCodec.Encode(dicomFile.Annotations, annotationDataCollections);

        // save changes in DICOM file
        dicomFile.SaveChanges();
    }
}

''' <summary>
''' Loads DICOM annotations from file,
''' changes the text of text annotations,
''' saves DICOM annotation back to the source file.
''' </summary>
''' <param name="presentationStateFilePath">The path to a presentation state file.</param>
''' <param name="textValue">The value of text annotations.</param>
Public Shared Sub ChangeTextAnnotations(presentationStateFilePath As String, textValue As String)
    ' load presentation state file
    Using dicomFile As New Vintasoft.Imaging.Codecs.ImageFiles.Dicom.DicomFile(presentationStateFilePath, False)
        ' create codec of DICOM annotations
        Dim annotationCodec As New Vintasoft.Imaging.Annotation.Dicom.DicomAnnotationCodec()
        ' get annotations from the presentation state file
        Dim annotationDataCollections As Vintasoft.Imaging.Annotation.Dicom.DicomAnnotationDataCollection() = annotationCodec.Decode(dicomFile.Annotations)

        ' for each annotation collection
        For Each annotationDataCollection As Vintasoft.Imaging.Annotation.Dicom.DicomAnnotationDataCollection In annotationDataCollections
            ' for each annotation in annotation collection
            For Each annotationData As Vintasoft.Imaging.Annotation.Dicom.DicomAnnotationData In annotationDataCollection
                ' if annotation is text annotation
                If TypeOf annotationData Is Vintasoft.Imaging.Annotation.Dicom.DicomTextAnnotationData Then
                    ' get text annotation data
                    Dim textAnnotationData As Vintasoft.Imaging.Annotation.Dicom.DicomTextAnnotationData = DirectCast(annotationData, Vintasoft.Imaging.Annotation.Dicom.DicomTextAnnotationData)
                    ' change text of text annotation
                    textAnnotationData.UnformattedTextValue = textValue
                End If
            Next
        Next

        ' save annotations in the source presentation state file
        annotationCodec.Encode(dicomFile.Annotations, annotationDataCollections)

        ' save changes in DICOM file
        dicomFile.SaveChanges()
    End Using
End Sub