Role of Neuroimaging on Differentiation of Parkinson’s Disease and Its Related Diseases

An accurate diagnosis of Parkinson’s disease (PD) is a prerequisite for therapeutic management. In spite of recent advances in the diagnosis of parkinsonian disorders, PD is misdiagnosed in between 6 and 25% of patients, even in specialized movement disorder centers. Although the gold standard for the diagnosis of PD is a neuropathological assessment, neuroimaging has been playing an important role in the differential diagnosis of PD and is used for clinical diagnostic criteria. In clinical practice, differential diagnoses of PD include atypical parkinsonian syndromes such as dementia with Lewy bodies, multiple system atrophy, progressive supranuclear palsy, corticobasal degeneration, caused by a striatal dopamine deficiency following nigrostrial degeneration. PD may also be mimicked by syndromes not associated with a striatal dopamine deficiency such as essential tremor, drug-induced parkinsonism, and vascular parkinsonism. Moreover, difficulties are associated with the clinical differentiation of patients with parkinsonism from those with Alzheimer’s disease. In this review, we summarize the typical imaging findings of PD and its related diseases described above using morphological imaging modalities (conventional MR imaging and neuromelanin MR imaging) and functional imaging modalities (99mTc-ethyl cysteinate dimer perfusion single photon emission computed tomography, 123I-metaiodobenzylguanidine myocardial scintigraphy, and 123I-FP-CIT dopamine transporter single photon emission computed tomography) that are clinically available in most hospitals. We also attempt to provide a diagnostic approach for the differential diagnosis of PD and its related diseases in clinical practice

Imaging evaluation after neuroendovascular therapy using fast kV switching dual energy CT

The efficacy and safety of neuroendovascular therapy is globally recognized due to the positive results of recent randomised control trials on mechanical thrombectomy for acute embolic stroke, on carotid arterial stenting for carotid artery stenosis, on coil embolization for intracranial aneurysm, and on embolization for arteriovenous malformation or dural arteriovenous fistula. In parallel, neuroradiologists frequently encounter difficulties in the interpretation of postinterventional non-contrast enhanced CT images, as they often have high attenuated areas derived from residual iodinated contrast media and metal artifacts caused by metallic devices such as platinum-coils, surgical clips, metallic stents, and liquid embolic agents such as Onyx®. Meanwhile, fast kV switching dual energy CT （gemstone spectral imaging: GSI） is one of the advanced imaging techniques that can overcome these obstacles. For instance, material decomposition using virtual monochromatic imaging （VMI） can generate an iodine map and water （virtual non-contrast） map, which enables residual iodinated contrast media and acute hemorrhage to be distinguished. Furthermore, the use of VMI with metal artifact reduction software, MARS, can suppress severe metal artifacts, resulting in improved image quality of surrounding vessels. In this review article, we demonstrate the utility of GSI after neuroendovascular therapy using representative clinical cases