Determining the Degree of Dopaminergic Denervation Based on the Loss of Nigral Hyperintensity on SMWI in Parkinsonism

BACKGROUND AND PURPOSE: Nigrostriatal dopaminergic function in patients with Parkinson disease can be assessed using I-123-2?-carbomethoxy-3?-(4-iodophenyl)-N-(3-fluoropropyl)-nortropan dopamine transporter (I-123-FP-CIT) SPECT, and a good correlation has been demonstrated between nigral status on SWI and dopaminergic denervation on I-123-FP-CIT SPECT. Here, we aim to correlate quantified dopamine transporter attenuation on I-123-FP-CIT SPECT with nigrosome-1 status using susceptibility map-weighted imaging (SMWI). MATERIALS AND METHODS: Between May 2017 and January 2018, consecutive patients with idiopathic Parkinson disease (n?=?109) and control participants (n?=?29) who underwent I-123-FP-CIT SPECT with concurrent 3T SWI were included. SMWI was generated from SWI. Two neuroradiologists evaluated nigral hyperintensity from nigrosome-1 on each side of the substantia nigra. Using consensus reading, we compared the I-123-FP-CIT?specific binding ratio according to nigral hyperintensity status and the I-123-FP-CIT specific binding ratio threshold to confirm the loss of nigral hyperintensity was determined using receiver operating characteristic curve analysis. RESULTS: The concordance rate between SMWI and I-123-FP-CIT SPECT was 65.9%. The I-123-FP-CIT?specific binding ratios in the striatum, caudate nucleus, and putamen were significantly lower when nigral hyperintensity in the ipsilateral substantia nigra was absent than when present (all, P?

Automated summary

This study aimed to investigate the correlation between nigrostriatal dopaminergic function and nigrosome-1 status, and found a concordance rate of 65.9% between I-123-FP-CIT SPECT and SMWI. The specific binding ratios of dopamine transporter were significantly lower in the absence of nigral hyperintensity.