PMC:4927924 / 18406-20679
Annnotations
{"target":"https://pubannotation.org/docs/sourcedb/PMC/sourceid/4927924","sourcedb":"PMC","sourceid":"4927924","source_url":"https://www.ncbi.nlm.nih.gov/pmc/4927924","text":"Radiotracer imaging\nAmong various imaging techniques, radiotracer-based functional imaging currently offers the highest degree of accuracy in the diagnostic work-up of patients with early PD [29]. Decreased nigrostriatal dopaminergic function is associated with nonmotor symptoms known to precede PD. In a prospective study of first-degree relatives of PD patients, individuals with an olfactory dysfunction showed a faster decline of DAT binding compared to individuals with normal olfactory function [69]. Moreover, 10% of hyposmic individuals, who also had abnormal DAT binding at baseline, developed PD at 2 years and this figure rose to 12.5% at 5 years of follow-up [49]. Another recent prospective study showed that idiopathic RBD patients exhibited decreased DAT binding and faster rates of DAT-binding decline compared to healthy controls [70]. After 3 years of follow-up, 15% of RBD patients, who also had the lowest DAT binding at baseline, had developed PD. As DAT imaging is invasive, time consuming, and expensive, it would not lend itself for primary screening purposes but rather as a secondary screen in enriched populations, such as those with nonmotor symptoms. A recent report on sequential biomarker assessment of population-based hyposmia screening in a first and DAT imaging in a second step - the Parkinson At-Risk Syndrome (PARS) study -reported decreased radiotracer binding using DAT-SPECT to be present in 11% of hyposmic compared with 1% of normosmic participants [71]. Also male sex and constipation were predictive for a DAT-deficit such that combining these three factors increased the percentage of subjects with a DAT deficit to 40% [71]. In contrast to DAT imaging assessing nigrostriatal function, which is an established imaging method in neurodegenerative parkinsonism, direct visualisation of the neuropathologic process i.e. α-synuclein deposition and related neurodegeneration is not yet possible. In analogy to the Pittsburgh compound-B, an in vivo Aβ ligand labeling amyloid depositions in Alzheimer’s dementia, PET radiotracers specific for α-synuclein are beeing developed [72]. Longitudinal imaging of α-synuclein could particularly be relevant in the context of clinical neuroprotection-trials and serve as a surrogat outcome.","divisions":[{"label":"Title","span":{"begin":0,"end":19}}],"tracks":[{"project":"TEST0","denotations":[{"id":"26485429-172-178-1671243","span":{"begin":192,"end":194},"obj":"[\"22508281\"]"},{"id":"26485429-202-208-1671244","span":{"begin":503,"end":505},"obj":"[\"15293269\"]"},{"id":"26485429-165-171-1671245","span":{"begin":673,"end":675},"obj":"[\"19965851\"]"},{"id":"26485429-171-177-1671246","span":{"begin":849,"end":851},"obj":"[\"21802993\"]"},{"id":"26485429-233-239-1671247","span":{"begin":1494,"end":1496},"obj":"[\"25298306\"]"},{"id":"26485429-169-175-1671248","span":{"begin":1668,"end":1670},"obj":"[\"25298306\"]"},{"id":"26485429-180-186-1671249","span":{"begin":2119,"end":2121},"obj":"[\"24192754\"]"}],"attributes":[{"subj":"26485429-172-178-1671243","pred":"source","obj":"TEST0"},{"subj":"26485429-202-208-1671244","pred":"source","obj":"TEST0"},{"subj":"26485429-165-171-1671245","pred":"source","obj":"TEST0"},{"subj":"26485429-171-177-1671246","pred":"source","obj":"TEST0"},{"subj":"26485429-233-239-1671247","pred":"source","obj":"TEST0"},{"subj":"26485429-169-175-1671248","pred":"source","obj":"TEST0"},{"subj":"26485429-180-186-1671249","pred":"source","obj":"TEST0"}]},{"project":"2_test","denotations":[{"id":"26485429-22508281-64047472","span":{"begin":192,"end":194},"obj":"22508281"},{"id":"26485429-15293269-64047473","span":{"begin":503,"end":505},"obj":"15293269"},{"id":"26485429-19965851-64047474","span":{"begin":673,"end":675},"obj":"19965851"},{"id":"26485429-21802993-64047475","span":{"begin":849,"end":851},"obj":"21802993"},{"id":"26485429-25298306-64047476","span":{"begin":1494,"end":1496},"obj":"25298306"},{"id":"26485429-25298306-64047477","span":{"begin":1668,"end":1670},"obj":"25298306"},{"id":"26485429-24192754-64047478","span":{"begin":2119,"end":2121},"obj":"24192754"}],"attributes":[{"subj":"26485429-22508281-64047472","pred":"source","obj":"2_test"},{"subj":"26485429-15293269-64047473","pred":"source","obj":"2_test"},{"subj":"26485429-19965851-64047474","pred":"source","obj":"2_test"},{"subj":"26485429-21802993-64047475","pred":"source","obj":"2_test"},{"subj":"26485429-25298306-64047476","pred":"source","obj":"2_test"},{"subj":"26485429-25298306-64047477","pred":"source","obj":"2_test"},{"subj":"26485429-24192754-64047478","pred":"source","obj":"2_test"}]}],"config":{"attribute types":[{"pred":"source","value type":"selection","values":[{"id":"TEST0","color":"#93abec","default":true},{"id":"2_test","color":"#c5ec93"}]}]}}