Magnetic resonance imaging (MRI) is a sensitive paraclinical test for diagnosis 
and assessment of disease progression in multiple sclerosis (MS) and is often 
used to evaluate therapeutic efficacy. The formation of new T2-hyperintense MRI 
lesions is commonly used to measure disease activity, but lacks specificity 
because edema, inflammation, gliosis, and axonal loss all contribute to T2 
lesion formation. As the role of neurodegeneration in the pathophysiology of MS 
has become more prominent, the formation and evolution of chronic or persistent 
Tl-hypointense lesions (black holes) have been used as markers of axonal loss 
and neuronal destruction to measure disease activity. Despite the use of various 
detection methods, including advanced imaging techniques such as magnetization 
transfer imaging and magnetic resonance spectroscopy, correlation of persistent 
black holes with clinical outcomes in patients with MS remains uncertain. 
Furthermore, although axonal loss and neuronal tissue destruction are known to 
contribute to irreversible disability in patients with MS, there are limited 
data on the effect of therapy on longitudinal change in Tl-hypointense lesion 
volume. Measurement of black holes in clinical studies may elucidate the 
underlying pathophysiology of MS and may be an additional method of evaluating 
therapeutic efficacy.