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Radiopharmaceuticals for Diagnostics
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
Jim Ballinger, Jacek Koziorowski
The function of the dopamine transporter is reuptake of dopamine released into the synapse into vesicles in the presynaptic nerve terminal. The dopamine transporter can be imaged with an 123I-labelled analogue of cocaine, ioflupane (fluoropropyl carbomethoxy iodophenyl nortropane, FP-CIT, Datscan, Striascan). Ioflupane binds to the transporter to give an indication of the density of presynaptic nerve terminals. SPECT imaging is performed at a fixed time, 3-6 h after injection [16]. In normal individuals there is bilateral homogeneous accumulation of activity in the basal ganglia (striatum; caudate nucleus and putamen). Parkinson’s disease involves degeneration of the nigrostriatal pathway with loss of dopaminergic nerve terminals. Thus, dopamine transporter imaging can be used to diagnose Parkinson’s disease and to differentiate it from other causes of Parkinsonian tremor, such as essential tremor (i.e. non-degenerative) or that caused by certain neuroleptic drugs. In early Parkinson’s disease there tends to be asymmetry, particularly in the putamen, while in advanced disease there is bilateral degeneration. Ioflupane is also useful in diagnosis of Lewy body disease [17].
Iodine is needed to maintain health
Published in Tatsuo Kaiho, Iodine Made Simple, 2017
Typical radioactive iodine isotopes include iodine 123, iodine 125, and iodine 131 (see the table). There are 15 radioactive iodine drugs, constituting one-third of all radioactive drugs. Iodine 123 has a half-life (13.2 hours) and γ ray (159 keV) energy suitable for diagnostic imaging. Iodine 123 is used for 12 diagnostic radiopharmaceuticals including ioflupane [123I]. Iodine 125 has a long half-life of 59.4 days and emits weak γ ray energy (27.5 keV), and is suitable for radiation treatment. For example, an iodine 125 seed (125I encapsulated in a 5 mm long, 1 mm diameter titanium capsule) is sold commercially. It is embedded into the focus of a prostate cancer patient using a dedicated needle.
Posterior cortical atrophy: clinical, neuroimaging, and neuropathological features
Published in Expert Review of Neurotherapeutics, 2023
John Best, Marianne Chapleau, Gil D. Rabinovici
Amyloid PET imaging can detect Aβ plaques in patients with PCA (Figure 2), supporting a diagnosis of underlying AD (though not excluding DLB which frequently also features amyloid deposition). Patterns of amyloid PET in individuals with PCA are similar to those seen in typical amnestic forms of Alzheimer’s disease, with widespread deposition of tracer throughout frontal, parietal, temporal, and cingulate cortices (Figure 2). At a group level, patients with PCA show higher occipital binding compared with patients presenting with amnestic or language-predominant AD [48,49]. Patterns of tau PET retention are more closely linked to clinical symptoms and neurodegenerative patterns, with PCA patients showing higher occipital retention compared to other AD phenotypes, and similarly elevated uptake in temporo-parietal cortices (Figure 2) [23]. When Lewy body dementia is a diagnostic consideration, dopamine transporter imaging with 123I-Ioflupane SPECT can be used to evaluate for nigrostriatal denervation [50].
The diagnosis of progressive supranuclear palsy: current opinions and challenges
Published in Expert Review of Neurotherapeutics, 2018
Dopamine active transporter (DAT) imaging quantifies striatal presynaptic dopamine binding using ligands such as [123I]-FP-CIT/[123I]-ioflupane SPECT and [18F]FP-CIT-PET. Binding is reduced in PD as well as other degenerative Parkinsonian conditions such as MSA and PSP, hence there has been interest in whether DAT imaging can help distinguish between them [106]. DAT binding is reduced to a greater extent and appears more symmetrical in PSP-RS as compared to PD and MSA [107,108]. Regional patterns of DAT binding using ratios of caudate to ventral striatum, caudate to putamen, and anterior–posterior putamen show that the caudate nucleus is affected to a greater extent in PSP-RS, whereas posterior putamen is most affected in MSA and PD [108–110]. Among different phenotypes of PSP, DAT binding is reduced in a similar pattern in PSP-P and PSP-PGF but findings may be more severe in PSP-RS [111,112]. Although DAT binding can be helpful in identifying PSP-RS, it has limited utility-identifying variant PSP syndromes, and definitively distinguishing alternate Parkinsonian conditions.
Investigating ioflupane I123 injection and single photon emission tomography as an imaging biomarker for long-term sequelae following mild traumatic brain injury
Published in Brain Injury, 2018
Nicole Reams, Julie Anderson, Reid Perlman, Wei Li, Shaun Walters, Samuel Tideman, Chi Wang, Kelly Simon, Roberta Frigerio, Demetrius M. Maraganore
Because aging may compound the effect of mTBI on the development of PD, decades may pass between mTBI and the clinical onset of PD (3). Ioflupane I123 injection (DaTscan) and single photon emission tomography (SPECT) has been approved by the FDA as an aid to the diagnosis of early PD (18,19). Ioflupane I123 is a radiopharmaceutical agent that is injected into the vein of subjects and binds to dopamine transporters on nigrostriatal neurons. This agent emits gamma radiation and allows for assessment of the dopaminergic system with SPECT scan (which uses a gamma camera to gather 3D information) in subjects and has been shown to have 79% sensitivity, 97% specificity and 98% positive predictive value in studies of patients with early parkinsonian symptoms (19). The software enables visual evaluation and quantification of ioflupane 123I images relative to normal population databases of DaTscan images. In patients with PD, there is reduced DaTscan uptake that is typically more pronounced in the putamen than in the caudate regions of the striatum, and that is asymmetric between left and right sides of the brain. Previous longitudinal data also supports the utility of DaTscan in supplementing clinical assessment when diagnosis is uncertain, and our prior studies suggested that DaTscan imaging might also detect preclinical PD (20,21).