Double inversion recovery (DIR) is a Magnetic Resonance Imaging (MRI) pulse sequence which suppresses signal from the CSF as well as from the white matter and hence enhances any inflammatory lesion. To obtain DIR sequence, two inversion times are required. TI-1 is used for suppression of CSF and TI-2 is used for suppression of white matter (upper image). At 1.5 Tesla, TI-1 is usually obtained at 2000-3500 msec and TI-2 at 310-450 msec. At 3 Tesla, TI-1 is usually obtained at 2000-3500 msec and TI-2 at 450 msec. Its main application is to delineate white matter plaques in multiple sclerosis, estimate lesion load, differentiate juxtacortical from mixed grey matter-white matter plaques and detect infratentorial or spinal cord lesions. The sequence is very useful in depicting cortical gray matter lesions, which are not well visible on the other sequences (down image).
