Discrepancy in T 1 and T 2 shortening of the globus pallidus in hepatic insufficiency: Evaluation by susceptibility-weighted imaging

Abstract

Purpose: We assessed the signal of the globus pallidus (GP) in cases of hepatic in-sufficiency, especially to evaluate the degree of discrepancy in paramagnetic effects on shortening of T 1 and T 2* using susceptibility-weighted images (SWI). Materials and Methods: Seven patients with hepatic insufficiency underwent magnetic resonance (MR) examinations that included T 1-weighted images (T 1WI), T 2-weighted images (T 2WI), and SWI on a 1.5-tesla MR imager, and we compared their results to those of controls. On T 1WI and T 2WI, we measured signal intensity in the GP and posterior segment of the putamen (Put) to obtain a signal ratio (GP/Put ratio), and on SWI, we classified signal intensity into 4 grades: A, higher than the cortex; B, lower than the cortex and higher than the cerebrospinal fluid (CSF); C, lower than the CSF and higher than the red nucleus; and D, lower than the red nucleus. Results: In the 7 patients with hepatic insufficiency, the mean GP/Put ratio was significantly higher on T 1WI and T 2WI than those values in controls. On SWI, we classified 2 cases each as Grade A, Grade B, and Grade C, and one as Grade D. Although the signal of the GP was elevated on T 1WI, there was no decrease in signal on T 2WI. On SWI, we obtained no low signal intensity. Conclusion: In patients with hepatic insufficiency, the globus pallidus did not show low signal intensity on either T 2WI or SWI. Hyperintensity of the GP on T 1WI without hypoin-tensity on T 2WI, or even SWI, suggests a discrepancy between paramagnetic effect on T 1 and T 2 shortening that reflects the accumulation of manganese and the presence of hepatic insufficiency.