Quantitative T(1) mapping of hepatic encephalopathy using magnetic resonance imaging

Changes are shown in the spin-lattice (T(1)) relaxation time caused by the putative deposition of manganese in various brain regions of hepatic encephalopathy (HE) patients using a novel and fast magnetic resonance imaging (MRI) method for quantitative relaxation time mapping. A new method, T(1) mapping with partial inversion recovery (TAPIR), was used to obtain a series of T(1)-weighted images to produce T(1) maps. Imaging of 15 control subjects and 11 patients was performed on a 1.5T MRI scanner. The measurement time per patient with this technique, including adjustments, was similar to5 minutes. Regions of interest in the globus pallidus, the caudate nucleus, the posterior and anterior limbs of the internal capsule, the putamen, the frontal and occipital white matter, the white matter of the corona radiata, the occipital visual and frontal cortices, and the thalamus were interactively defined in the left hemisphere and analyzed with respect to their T(1) values. T(1) changes in the brains of HE patients can be determined quantitatively with TAPIR in short, clinically relevant measurement times. Significant correlations between the change in T(1) and HE severity have been shown in the globus pallidus, the caudate nucleus, and the posterior limb of the internal capsule. No significant correlation of T(1) with grade of HE was found in the putamen, frontal white matter, white matter of the corona radiata, white matter in the occipital lobe, the anterior limb of the internal capsule, visual cortex, thalamus, or frontal cortex. In conclusion, these measurements show that T(1) mapping is feasible in short, clinically relevant acquisition times.