Many have been through a magnetic resonance imaging (MRI) process. The intention has been to see whether a blood vessel is resting/pumping on the trigeminal nerve. This is not a diagnostic tool because some people can have this situation and never feel pain or discomfort on the trigeminal nerve. In some cases, a blood vessel does not appear to be touching the nerve yet some people feel pain. The MRI is simply part of a broad information gathering process.
The following research paper, using specific medical language which may make reading a challenge, may be of interest because it examines the usefulness of MRIs.
Titled Predictive value of magnetic resonance imaging for identifying neurovascular compressions in trigeminal neuralgia, this research was published in the journal Neurología (English Edition) Volume 34, Issue 8, October 2019, Pages 510-519.