Hi Olga!
In the University of Valencia we use Respondus to carry out test in format IMS QTI and to import them to assessment.
The URL of help pages is:
http://pizarra.uv.es/global/HELP/manualrespondus/respondus.htm
In this link your donwload one example
http://www.uv.es/avirtual/Ejemplo_test_respuestas_alternativas.zip.
Recently we have found a software open source that exports in format QTI (http://www.tecn.upf.es/gti/leteos/newnavs/jqtilite.html) but not work with assessment.
Greetings