Table 6.

Validation of magnetic resonance imaging lesion volumes as a surrogate outcome: explanations of possible discordance between clinical and surrogate lesion volume measures

If clinical endpoint shows a benefit but lesion volume does not:

Imaging methods are insensitive to neuroprotection

Clinical benefit not mediated by neuroprotection

If lesion volume shows a benefit but the clinical endpoint does not:

Trial design or clinical measures are insensitive to detecting a

clinical effect

Toxicity offsets neuroprotective effect