Targeted MRI (tMRI) of Small Increases in the T<sub>1</sub> of Normal Appearing White Matter in Mild Traumatic Brain Injury (mTBI) Using a Divided Subtracted Inversion Recovery (dSIR) Sequence

Abstract

In modelling studies targeted MRI (tMRI) of small increases in the T<sub>1</sub> of tissues using divided Subtracted Inversion Recovery (dSIR) sequences show ten or more times the contrast seen with conventional IR sequences. This may be particularly useful in imaging normal appearing white matter where there may be small changes in T<sub>1</sub> and/or T<sub>2</sub> in disease but these changes may be insufficient to produce useful contrast with conventional T<sub>2</sub>-weighted spin echo (T<sub>2</sub>-wSE) and T<sub>2</sub>-FLuid Attenuated Inversion Recovery (T<sub>2</sub>-FLAIR) sequences. In a case of recurrent mild Traumatic Brain Injury (mTBI), very extensive high contrast abnormalities were seen in white matter using a dSIR sequence that targeted small increases in T<sub>1</sub> in areas where no abnormality was apparent with T<sub>2</sub>-wSE or T<sub>2</sub>-FLAIR sequences. The increases in T<sub>1</sub> may be due to neuroinflammation and/or degeneration which produces the abnormalities seen on the dSIR images. tMRI of normal appearing white matter may have widespread application in clinical MRI of the brain.