Diagnostic accuracy of diffusion tensor imaging in amyotrophic lateral sclerosis

Abstract

Objective To evaluate the diagnostic accuracy of diffusion tensor imaging (DTI) of corticospinal tract in amyotrophic lateral sclerosis (ALS) and find optimal testing strategies and optimal cut-off values of DTI indices for individual patient discrimination. Methods Thirty-three ALS patients and 34 healthy controls, collected at Peking Union Medical College Hospital from June 2004 through July 2005, undergoing brain DTI studies and fractional anisotropy (FA) examinations along the corticospinal tract, were analyzed by receiver operating characteristic (ROC) curves. Results Compared with the controls, ALS group had significantly decreased FA values in subcortical white matter of the precentral gyrus, the posterior limb of the internal capsule and the cerebral peduncle. In ROC analysis, the average FA value of the former two positions showed the best performance with an area under the curve of 0.917, an optimal cut-off value of 0.604, a sensitivity of 0.759 and a specificity of 0.912. The corresponding data for the average FA of all the three positions and each single position were listed as follows: average of three 0.914, 0.648, 0.759, 0.912; precentral gyrus 0.875, 0.509, 0.733, 0.824; internal capsule 0.845, 0.692, 0.656, 0.941; and cerebral peduncle 0.752, 0.742, 0.656, 0.735. Conclusions FA values of the corticospinal tract have a good accuracy in detecting upper motor neuron involvement in ALS. Precentral gyrus and posterior limb of the internal capsule and the average FA values of these two positions were suggested as the preferred testing places and DTI indices for clinical use. Key words: Amyotrophic lateral sclerosis; Diffusion tensor imaging; Pyramidal tracts; ROC curve