Objective: We investigated the diagnostic accuracy of nigrosome using susceptibility map-weighted imaging (SMwI) in distinguishing tremor-dominant Parkinson’s disease (PD) and essential tremor (ET).
Background: Tremor is a commonly observed hyperkinetic movements, which is a characteristic symptom of PD and ET. Although resting tremor is typically found in PD, postural or kinetic tremor can also be present in PD, making it difficult to differentiate it from ET. Dopaminergic positron emission tomography (PET) such as 18F-N-(3-fluoropropyl)-2β-carboxymethoxy-3β-(4-iodophenyl)nortropane (FP–CIT) PET could confirm the diagnosis of PD, but its use is limited due to high cost and the use of radioactive isotopes. Recent studies showed that patients with PD shows loss of nigrosome from brain magnetic resonance image. Especially, new imaging technology such as SMwI increased the resolution of the nigrosome.
Method: We retrospectively investigated patients who visited the Movement Disorder Clinic, Asan Medical Center, due to tremor, from July 2021 to August 2022. We included patients with tremor-dominant PD and ET, who underwent brain MRI including SWI. We excluded the patients with symptomatic stroke or brain tumor. After SWI acquisition, SMwI was generated to enhance the visibility of the nigrosome 1. We compared loss of nigrosome 1 using SMwI between PD and ET groups. The primary outcome of the study was the diagnostic accuracy of SMwI for differentiating tremor-dominant PD from ET.
Results: There were 146 tremor-dominant PD and 139 ET. All patients with tremor-dominant PD (100%) showed unilateral or bilateral loss of nigrosome. Among 139 patients with ET, 133 (95.7%) had intact bilateral nigrosomes, 1 (0.7%) had unilateral nigrosome loss, and 5 (3.6%) had bilateral nigrosome loss. The specificity was 95.7% and the sensitivity was 100%. 18F-FP-CIT PET was performed on all 6 ET patients with false positive results: 5 showed normal findings, and one showed vascular lesions of the putamen in MRI. Among 146 patients with tremor-dominant PD, 137 patients underwent 18F-FP-CIT PET, and among them, 5 patients showed loss of unilateral presynaptic dopaminergic neurons. All of 5 patients also showed unilateral loss of the nigrosome.
Conclusion: In this study, we found that nigrosome loss through SMwI showed high diagnostic accuracy for the differential diagnosis between ET and tremor-dominant PD.
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To cite this abstract in AMA style:MK. Yoon, S. Jo, S. Lee, J. Lee, CH. Suh, SJ. Chung. Diagnostic accuracy of susceptibility map-weighted MRI for discriminating tremor-dominant Parkinson’s disease and essential tremor [abstract]. Mov Disord. 2023; 38 (suppl 1). https://www.mdsabstracts.org/abstract/diagnostic-accuracy-of-susceptibility-map-weighted-mri-for-discriminating-tremor-dominant-parkinsons-disease-and-essential-tremor/. Accessed September 21, 2023.
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