Correlation of 3D FLAIR and dopamine transporter imaging in patients with parkinsonism

Objective. The purpose of this study is to evaluate direct in vivo visualization of nigrosome-1 in substantia nigra (SN) with 3D FLAIR imaging and its diagnostic value in predicting the intactness of presynaptic dopaminergic function of the nigrostriatal pathway. MATERIALS AND METHODS. Forty-fve patients showing parkinsonism who underwent both 3D FLAIR and dopamine transporter (DAT) imaging were recruited. In total, 90 SNs were reviewed on axial 3D FLAIR images. We regarded oval or linear hyperintensities on the posterolateral side of SN as intact nigrosome-1. Two neuroradiologists independently evaluated the appearance of nigrosome-1, and disagreements were settled by consensus. Kappa values for interrater agreement were calculated. Diagnostic performances of the appearance of nigrosome-1 for predicting presynaptic dopaminergic function on DAT imaging and Parkinson disease (PD) were calculated. RESULTS. The diagnostic performances of a loss of nigrosome-1 on 3D FLAIR images were sensitivity of 85.7%, specifcity of 85.4%, positive predictive value (PPV) of 83.7%, and negative predictive value (NPV) of 87.2% for predicting impaired presynaptic dopaminergic function on DAT imaging, and sensitivity of 94.7%, specifcity of 76.9%, PPV of 85.7%, and NPV of 90.9% for predicting PD. When only oval hyperintensity was considered as intact nigrosome-1, its sensitivity and NPV were increased up to 95.2% and 91.7%, respectively, for predicting impaired presynaptic dopaminergic function on DAT imaging, and both increased to 100% for predicting PD. Interobserver agreement for the appearance of nigrosome-1 on 3D FLAIR images was substantial (κ = 0.625). CONCLUSION. Nigrosome-1 could be visualized on 3D FLAIR images, and its loss can be used to predict presynaptic dopaminergic function and to diagnose PD with high accuracy.