Hi Linh,
I agree, the roots are easy to observe and follow through the neck from their origins passing between the anterior and middle scalene muscles and towards the axilla.
I have never been able to demonstrate adhesions reliably with ultrasound so I would think the referral is not ideal with the MRI being more useful.
I have seen nerve sheath tumours, post radiotherapy fibrosis and post trauma changes in the brachial plexus but adhesions I have not.
The problem I have with brachial plexus ultrasound in my hands is that the process of following the anatomy is fun and easy but making a positive diagnosis with ultrasound of pathology is more difficult in my hands at least.
Others may have a different opinion,
Steve