PMC:4927924 / 20681-22870 JSONTXT

{"project":"TEST0","denotations":[{"id":"26485429-209-215-1671250","span":{"begin":386,"end":388},"obj":"[\"21387382\"]"},{"id":"26485429-202-208-1671251","span":{"begin":593,"end":595},"obj":"[\"19877238\"]"},{"id":"26485429-87-93-1671252","span":{"begin":685,"end":687},"obj":"[\"21287185\"]"},{"id":"26485429-113-119-1671253","span":{"begin":711,"end":713},"obj":"[\"21287185\"]"},{"id":"26485429-129-135-1671254","span":{"begin":727,"end":729},"obj":"[\"20669268\"]"},{"id":"26485429-140-146-1671255","span":{"begin":983,"end":985},"obj":"[\"19129507\"]"},{"id":"26485429-181-187-1671256","span":{"begin":1024,"end":1026},"obj":"[\"21287185\"]"},{"id":"26485429-205-211-1671257","span":{"begin":1234,"end":1236},"obj":"[\"23843466\"]"},{"id":"26485429-187-193-1671258","span":{"begin":1496,"end":1498},"obj":"[\"24710392\"]"},{"id":"26485429-232-238-1671259","span":{"begin":1584,"end":1586},"obj":"[\"25773707\"]"},{"id":"26485429-230-236-1671260","span":{"begin":1974,"end":1976},"obj":"[\"25773707\"]"}],"text":"Magnetic resonance imaging\nThere is limited information as to the potential of magnetic resonance imaging (MRI) to detect brain changes associated with PD risk or prodromal PD. Two studies in patients with idiopathic RBD found alterations in diffusivity measures in the tegmentum of the midbrain and the pontine reticular formation, regions involved in the generation of REM sleep [73, 74]. In a functional MRI study, asymptomatic subjects with a heterozygous Parkin and PINK1 mutation exhibited additional recruitment of supplementary motor areas as an expression of compensatory mechanisms [34]. In early PD significant alterations in various MRI diffusivity measures in the SN [75, 76], olfactory tract [75, 77] and cortex [78] were found compared with healthy controls at a field strength of 1.5 T and at a higher field strength of 3.0 T. Two studies reported a complete separation of early PD patients from controls using fractional anisotropy values in the caudal SN at 3.0 T [76] and in the olfactory tract at 1.5 T [75].\nUsing T2 *-weighted 7T MRI, a recent study described a hyperintense ovoid area within the dorsolateral border of the otherwise hypointense SN pars compacta consistent with nigrosome 1 in healthy controls [79]. The absence of this feature was highly sensitive and specific for PD. Intriguingly, the presence of this feature assessed with susceptibility weighted imaging (SWI) at 3T distinguished PD patients from healthy controls in another dataset of the same group [80] as well as in our own large cohort of patients with neurodegenerative parkinsonism [81], with a sensitivity and specificity of \u003e90% , respectively (Fig. 1). In the latter study also all included patients with MSA and PSP exhibited this imaging feature (i.e. sensitivity of 100%), indicating that visual assessment of dorsolateral nigral hyperintensity on high-field SWI scans may serve as a new simple diagnostic imaging marker for neurodegenerative parkinsonian disorders [81]. Future studies will have to elucidate whether these or other changes in MRI measures can be visualized in subjects exhibiting other PD risk markers and serve as biomarkers for the premotor stage of the illness."}

{"project":"2_test","denotations":[{"id":"26485429-21387382-64047479","span":{"begin":386,"end":388},"obj":"21387382"},{"id":"26485429-19877238-64047480","span":{"begin":593,"end":595},"obj":"19877238"},{"id":"26485429-21287185-64047481","span":{"begin":685,"end":687},"obj":"21287185"},{"id":"26485429-21287185-64047482","span":{"begin":711,"end":713},"obj":"21287185"},{"id":"26485429-20669268-64047483","span":{"begin":727,"end":729},"obj":"20669268"},{"id":"26485429-19129507-64047484","span":{"begin":983,"end":985},"obj":"19129507"},{"id":"26485429-21287185-64047485","span":{"begin":1024,"end":1026},"obj":"21287185"},{"id":"26485429-23843466-64047486","span":{"begin":1234,"end":1236},"obj":"23843466"},{"id":"26485429-24710392-64047487","span":{"begin":1496,"end":1498},"obj":"24710392"},{"id":"26485429-25773707-64047488","span":{"begin":1584,"end":1586},"obj":"25773707"},{"id":"26485429-25773707-64047489","span":{"begin":1974,"end":1976},"obj":"25773707"}],"text":"Magnetic resonance imaging\nThere is limited information as to the potential of magnetic resonance imaging (MRI) to detect brain changes associated with PD risk or prodromal PD. Two studies in patients with idiopathic RBD found alterations in diffusivity measures in the tegmentum of the midbrain and the pontine reticular formation, regions involved in the generation of REM sleep [73, 74]. In a functional MRI study, asymptomatic subjects with a heterozygous Parkin and PINK1 mutation exhibited additional recruitment of supplementary motor areas as an expression of compensatory mechanisms [34]. In early PD significant alterations in various MRI diffusivity measures in the SN [75, 76], olfactory tract [75, 77] and cortex [78] were found compared with healthy controls at a field strength of 1.5 T and at a higher field strength of 3.0 T. Two studies reported a complete separation of early PD patients from controls using fractional anisotropy values in the caudal SN at 3.0 T [76] and in the olfactory tract at 1.5 T [75].\nUsing T2 *-weighted 7T MRI, a recent study described a hyperintense ovoid area within the dorsolateral border of the otherwise hypointense SN pars compacta consistent with nigrosome 1 in healthy controls [79]. The absence of this feature was highly sensitive and specific for PD. Intriguingly, the presence of this feature assessed with susceptibility weighted imaging (SWI) at 3T distinguished PD patients from healthy controls in another dataset of the same group [80] as well as in our own large cohort of patients with neurodegenerative parkinsonism [81], with a sensitivity and specificity of \u003e90% , respectively (Fig. 1). In the latter study also all included patients with MSA and PSP exhibited this imaging feature (i.e. sensitivity of 100%), indicating that visual assessment of dorsolateral nigral hyperintensity on high-field SWI scans may serve as a new simple diagnostic imaging marker for neurodegenerative parkinsonian disorders [81]. Future studies will have to elucidate whether these or other changes in MRI measures can be visualized in subjects exhibiting other PD risk markers and serve as biomarkers for the premotor stage of the illness."}