My talk mainly focusses on imaging techniques in myeloma. I go through the fact that, of course, it is necessary to have imaging because of bone disease which is the main part of symptomatic myeloma and also because in the last ten years we have had a significant improvement in the use of imaging techniques, thanks to the availability of modern techniques that are often combining the morphological with the functional part. It was clearly stated three years ago by the International Myeloma Working Group that nowadays to demonstrate bone disease you should not wait for severe damage in the bone that is demonstrated by whole body X-ray, that is able to see only when at least 30-50% of the trabecular substance is lost. But you may have an earlier diagnosis and so you can use more sensitive techniques such as low dose CT, PET-CT or MRI. This, regarding the staging of the disease, we may say that it is an already accomplished point.
But also, thanks to the fact that two of these techniques, PET-CT and MRI, are functional so are able to show disease metabolism, you may also use them to evaluate response to treatment. This was done in several either retrospective or prospective trials and it was clearly demonstrated that the achievement of a negativisation of focal lesions has a significant impact on the prognosis of the patients. Formal recognition of this came two years ago when the International Myeloma Working Group redefined the response criteria in myeloma adding a subcategory which is named imaging minimal residual disease evaluation that should be done by functional imaging techniques. This was the formal recognition that we need to evaluate response to therapy, not only within the bone marrow with traditional techniques but also outside the bone marrow with imaging.
What are the current preferred techniques?
Regarding staging or restaging of the disease at eventual relapse phases, you mainly have three techniques – low dose CT, whole body low dose CT, PET-CT or whole body MRI. I may say that we cannot make a unique recommendation because the use of either of these techniques is related to the local practice, to the availability of these techniques, to the expertise and to the reimbursement. These, of course, are national rules so you may not recommend something too core. All three techniques are very sensitive and so they can be used.
Regarding the evaluation of response to therapy, the most robust data are coming from PET-CT. So nowadays the International Myeloma Working Group is recommending PET-CT. However, of course, PET-CT does have some pitfalls, like every technique, so there is rising interest in the use of functional MRI, diffusion weighted or dynamic contrast enhanced MRI. The experience is at the beginning so we do have several studies on a small number of patients showing interesting results. What is good is that all over Europe there are several prospective clinical trials using, in a prospective fashion, novel imaging techniques, some of them also comparing, for example, diffusion weighted MRI with PET-CT. So in two or three years from now we will have more answers to what nowadays are open questions.
What will we see developing over the next few years?
One effort going on now is to standardise the interpretation of the technique, like each technique, to be able to make a clear standard recommendation is very useful for routine clinical practice. So the standardisation process for PET-CT is ongoing. Regarding diffusion weighted MRI it’s a little bit more far to come, however I think it will. So the comparison of these techniques, one with the other. Thirdly the matching of imaging techniques with the bone marrow evaluation in the follow-up of the patients - we should, of course, understand how to incorporate these two different tools. As I said before, we have several prospective trials, including extensively all these tools. So we will be able to have some answers in some years from now.