scholarly journals Dopamine transporter imaging in clinically unclear cases of parkinsonism and the importance of Scans Without Evidence of Dopaminergic Deficit (SWEDDs)

2012 ◽  
Vol 70 (9) ◽  
pp. 667-673 ◽  
Author(s):  
Marco A. T. Utiumi ◽  
André C. Felício ◽  
Conrado R. Borges ◽  
Vera L. Braatz ◽  
Sheyla A. S. Rezende ◽  
...  
Keyword(s):  
Dopamine Transporter ◽  
Single Photon ◽  
Imaging Techniques ◽  
Photon Emission ◽  
Cost Effective ◽  
Emission Computed Tomography ◽  
Parkinsonian Syndromes ◽  
Cost Effective Technique ◽  
Dat Spect

The clinical diagnosis of Parkinson's disease (PD) is susceptible to misdiagnosis, especially in the earlier stages of the disease. Recently, in vivo imaging techniques assessing the presynaptic dopamine transporter (DAT) have emerged as a useful tool in PD diagnosis, improving its accuracy. OBJECTIVE: It was to illustrate the clinical usefulness of a brain single-photon emission computed tomography (SPECT) DAT ligand, and highlight relevant aspects of scans without evidence of dopaminergic deficit (SWEDDs) in this context. CASES: We described four representative patients with clinically unclear parkinsonian syndromes who underwent [99mTc]-TRODAT-1 SPECT and reviewed the clinical implications. CONCLUSION: DAT-SPECT is an important, cost-effective, technique for the differential diagnosis of parkinsonian syndromes. Additionally, SWEDD cases present clinical and paraclinical peculiarities that may retrospectively identify them as essential/dystonic tremor. The lack of histopathological data limits further conclusions.

scholarly journals Dopamine transporter imaging in neurodegenerative movement disorders: PET vs. SPECT

2020 ◽  
Vol 8 (5) ◽  
pp. 349-356
Author(s):  
Vera S. Kerstens ◽  
A. Varrone
Keyword(s):  
Dopamine Transporter ◽  
Pet Imaging ◽  
Single Photon ◽  
Relevant Literature ◽  
Photon Emission ◽  
Active Role ◽  
Emission Computed Tomography ◽  
Parkinsonian Syndromes ◽  
Dat Spect

Abstract Purpose The dopamine transporter (DAT) serves as biomarker for parkinsonian syndromes. DAT can be measured in vivo with single-photon emission computed tomography (SPECT) and positron emission tomography (PET). DAT-SPECT is the current clinical molecular imaging standard. However, PET has advantages over SPECT measurements, and PET radioligands with the necessary properties for clinical applications are on the rise. Therefore, it is time to review the role of DAT imaging with SPECT compared to PET. Methods PubMed and Web of Science were searched for relevant literature of the previous 10 years. Four topics for comparison were used: diagnostic accuracy, quantitative accuracy, logistics, and flexibility. Results There are a few studies directly comparing DAT-PET and DAT-SPECT. PET and SPECT both perform well in discriminating neurodegenerative from non-neurodegenerative parkinsonism. Clinical DAT-PET imaging seems feasible only recently, thanks to simplified DAT assessments and better availability of PET radioligands and systems. The higher resolution of PET makes more comprehensive assessments of disease progression in the basal ganglia possible. Additionally, it has the possibility of multimodal target assessment. Conclusion DAT-SPECT is established for differentiating degenerative from non-degenerative parkinsonism. For further differentiation within neurodegenerative Parkinsonian syndromes, DAT-PET has essential benefits. Nowadays, because of wider availability of PET systems and radioligand production centers, and the possibility to use simplified quantification methods, DAT-PET imaging is feasible for clinical use. Therefore, DAT-PET needs to be considered for a more active role in the clinic to take a step forward to a more comprehensive understanding and assessment of Parkinson’s disease.

scholarly journals Molecular Imaging of the Dopamine Transporter

Cells ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 872 ◽  
Author(s):  
Palermo ◽  
Ceravolo
Keyword(s):  
Dopamine Transporter ◽  
Single Photon ◽  
Photon Emission ◽  
Surrogate Marker ◽  
Neuronal Loss ◽  
Drug Induced ◽  
Regulatory Changes ◽  
Quantitative Measurements ◽  
Dat Spect

Dopamine transporter (DAT) single-photon emission tomography (SPECT) with (123)Ioflupane is a widely used diagnostic tool for patients with suspected parkinsonian syndromes, as it assists with differentiating between Parkinson’s disease (PD) or atypical parkinsonisms and conditions without a presynaptic dopaminergic deficit such as essential tremor, vascular and drug-induced parkinsonisms. Recent evidence supports its utility as in vivo proof of degenerative parkinsonisms, and DAT imaging has been proposed as a potential surrogate marker for dopaminergic nigrostriatal neurons. However, the interpretation of DAT-SPECT imaging may be challenged by several factors including the loss of DAT receptor density with age and the effect of certain drugs on dopamine uptake. Furthermore, a clear, direct relationship between nigral loss and DAT decrease has been controversial so far. Striatal DAT uptake could reflect nigral neuronal loss once the loss exceeds 50%. Indeed, reduction of DAT binding seems to be already present in the prodromal stage of PD, suggesting both an early synaptic dysfunction and the activation of compensatory changes to delay the onset of symptoms. Despite a weak correlation with PD severity and progression, quantitative measurements of DAT binding at baseline could be used to predict the emergence of late-disease motor fluctuations and dyskinesias. This review addresses the possibilities and limitations of DAT-SPECT in PD and, focusing specifically on regulatory changes of DAT in surviving DA neurons, we investigate its role in diagnosis and its prognostic value for motor complications as disease progresses.

scholarly journals Ocular Biodistribution Studies Using Molecular Imaging

Pharmaceutics ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 237 ◽  
Author(s):  
Ana Castro-Balado ◽  
Cristina Mondelo-García ◽  
Miguel González-Barcia ◽  
Irene Zarra-Ferro ◽  
Francisco J Otero-Espinar ◽  
...  
Keyword(s):  
Molecular Imaging ◽  
Single Photon ◽  
Imaging Techniques ◽  
Photon Emission ◽  
High Sensitivity ◽  
New Drugs ◽  
Emission Computed Tomography ◽  
Pharmacokinetic Data ◽  
Biodistribution Studies

Classical methodologies used in ocular pharmacokinetics studies have difficulties to obtain information about topical and intraocular distribution and clearance of drugs and formulations. This is associated with multiple factors related to ophthalmic physiology, as well as the complexity and invasiveness intrinsic to the sampling. Molecular imaging is a new diagnostic discipline for in vivo imaging, which is emerging and spreading rapidly. Recent developments in molecular imaging techniques, such as positron emission tomography (PET), single-photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI), allow obtaining reliable pharmacokinetic data, which can be translated into improving the permanence of the ophthalmic drugs in its action site, leading to dosage optimisation. They can be used to study either topical or intraocular administration. With these techniques it is possible to obtain real-time visualisation, localisation, characterisation and quantification of the compounds after their administration, all in a reliable, safe and non-invasive way. None of these novel techniques presents simultaneously high sensitivity and specificity, but it is possible to study biological procedures with the information provided when the techniques are combined. With the results obtained, it is possible to assume that molecular imaging techniques are postulated as a resource with great potential for the research and development of new drugs and ophthalmic delivery systems.

Reduced in vivo binding to the serotonin transporter in the cerebral cortex of MDMA (‘ecstasy’) users

1999 ◽  
Vol 175 (1) ◽  
pp. 63-69 ◽  
Author(s):  
David M. Semple ◽  
Klaus P. Ebmeier ◽  
Michael F. Glabus ◽  
Ronan E. O'Carroll ◽  
Eve C. Johnstone
Keyword(s):  
Dopamine Transporter ◽  
Serotonin Transporter ◽  
Single Photon ◽  
Psychiatric Morbidity ◽  
Photon Emission ◽  
Emission Computed Tomography ◽  
Cross Sectional ◽  
Lenticular Nuclei

BackgroundThe use of MDMA (‘ecstasy’) is common among young people in Western countries. Animal models of MDMA toxicity suggest a loss of serotonergic neurons, and potentially implicate it in the development of significant psychiatric morbidity in humans.AimsTo test whether long-term use of MDMA can produce abnormalities in cerebral serotonin, but not dopamine, transporter binding measured by single photon emission computed tomography (SPECT)MethodTen male regular ecstasy users and 10 well-matched controls recruited from the same community sources participated in SPECT with the serotonin transporter (SEPT) ligand [123I]-CIT. Dopamine transporter binding was determined from scans acquired 23 hours after injection of the tracer.ResultsEcstasy users showed a cortical reduction of SERT binding, particularly prominent in primary sensory-motor cortex, with normal dopamine transporter binding in lenticular nuclei.ConclusionsThis cross-sectional association study provides suggestive evidence for specific, at least temporary, serotonergic neurotoxicity of MDMA in humans.

scholarly journals Evaluating dopamine transporter imaging as an enrichment biomarker in a phase 2 Parkinson’s disease trial

BMC Neurology ◽  
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
R. Matthew Hutchison ◽  
Karleyton C. Evans ◽  
Tara Fox ◽  
Minhua Yang ◽  
Jerome Barakos ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Clinical Trial ◽  
Parkinson's Disease ◽  
Dopamine Transporter ◽  
Single Photon ◽  
Photon Emission ◽  
Alpha Synuclein ◽  
Emission Computed Tomography ◽  
Phase 2 ◽  
Dat Spect

Abstract Background Dopamine transporter single-photon emission computed tomography (DaT-SPECT) can quantify the functional integrity of the dopaminergic nerve terminals and has been suggested as an imaging modality to verify the clinical diagnosis of Parkinson’s disease (PD). Depending on the stage of progression, approximately 5–15% of participants clinically diagnosed with idiopathic PD have been observed in previous studies to have normal DaT-SPECT patterns. However, the utility of DaT-SPECT in enhancing early PD participant selection in a global, multicenter clinical trial of a potentially disease-modifying therapy is not well understood. Methods The SPARK clinical trial was a phase 2 trial of cinpanemab, a monoclonal antibody against alpha-synuclein, in participants with early PD. DaT-SPECT was performed at screening to select participants with DaT-SPECT patterns consistent with degenerative parkinsonism. Acquisition was harmonised across 82 sites. Images were reconstructed and qualitatively read at a central laboratory by blinded neuroradiologists for inclusion prior to automated quantitative analysis. Results In total, 482 unique participants were screened between January 2018 and May 2019; 3.8% (15/398) of imaged participants were excluded owing to negative DaT-SPECT findings (i.e., scans without evidence of dopaminergic deficit [SWEDD]). Conclusion A smaller proportion of SPARK participants were excluded owing to SWEDD status upon DaT-SPECT screening than has been reported in prior studies. Further research is needed to understand the reasons for the low SWEDD rate in this study and whether these results are generalisable to future studies. If supported, the radiation risks, imaging costs, and operational burden of DaT-SPECT for enrichment may be mitigated by clinical assessment and other study design aspects. Trial registration ClinicalTrials.gov identifier: NCT03318523. Date submitted: October 19, 2017. First Posted: October 24, 2017.

scholarly journals Practical Application of DaTQUANT with Optimal Threshold for Diagnostic Accuracy of Dopamine Transporter SPECT

Tomography ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 980-989
Author(s):  
Matthew Neill ◽  
Julia M. Fisher ◽  
Christine Brand ◽  
Hong Lei ◽  
Scott J. Sherman ◽  
...  
Keyword(s):  
Diagnostic Accuracy ◽  
Dopamine Transporter ◽  
Sensitivity And Specificity ◽  
Single Photon ◽  
Photon Emission ◽  
Study Groups ◽  
Emission Computed Tomography ◽  
Single Variable ◽  
Dat Spect ◽  
Photon Emission Computed Tomography

Evaluation of Parkinsonian Syndromes (PS) with Ioflupane iodine-123 dopamine transporter single photon emission computed tomography (DaT-SPECT), in conjunction with history and clinical examination, aids in diagnosis. FDA-approved, semi-quantitative software, DaTQUANTTM (GE Healthcare, Chicago, IL, USA) is available to assist in interpretation. This study aims to evaluate the optimal variables and thresholds of DaTQUANT to yield the optimal diagnostic accuracy. It is a retrospective review with three different patient populations. DaT-SPECT images from all three study groups were evaluated using DaTQUANTTM software, and both single and multi-variable logistic regression were used to model PS status. The optimal models were chosen via accuracy, sensitivity, and specificity, then evaluated on the other study groups. Among single variable models, the posterior putamen yielded the highest accuracy (84% to 95%), while balancing sensitivity and specificity. Multi-variable models did not substantially improve the accuracy. When the optimal single variable models for each group were used to evaluate the remaining two groups, comparable results were achieved. In typical utilization of DaT-SPECT for differentiation between nigrostriatal degenerative disease (NSDD) and non-NSDD, the posterior putamen was the single variable that yielded the highest accuracy across three different patient populations. The posterior putamen’s recommended thresholds for DaTQUANT are SBR ≤ 1.0, z-score of ≤−1.8 and percent deviation ≤ −0.34.

Recent Advances in Targeting Nuclear Molecular Imaging Driven by Tetrazine Bioorthogonal Chemistry

2020 ◽  
Vol 27 (23) ◽  
pp. 3924-3943 ◽  
Author(s):  
Ping Dong ◽  
Xueyi Wang ◽  
Junwei Zheng ◽  
Xiaoyang Zhang ◽  
Yiwen Li ◽  
...  
Keyword(s):  
Molecular Imaging ◽  
Single Photon ◽  
Imaging Techniques ◽  
Photon Emission ◽  
Emission Computed Tomography ◽  
Bioorthogonal Chemistry ◽  
Cellular Processes ◽  
Positron Emission ◽  
Diagnosis Of Cancer

Molecular imaging techniques apply sophisticated technologies to monitor, directly or indirectly, the spatiotemporal distribution of molecular or cellular processes for biomedical, diagnostic, or therapeutic purposes. For example, Single-Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) imaging, the most representative modalities of molecular imaging, enable earlier and more accurate diagnosis of cancer and cardiovascular diseases. New possibilities for noninvasive molecular imaging in vivo have emerged with advances in bioorthogonal chemistry. For example, tetrazine-related Inverse Electron Demand Diels-Alder (IEDDA) reactions can rapidly generate short-lived radioisotope probes in vivo that provide strong contrast for SPECT and PET. Here, we review pretargeting strategies for molecular imaging and novel radiotracers synthesized via tetrazine bioorthogonal chemistry. We systematically describe advances in direct radiolabeling and pretargeting approaches in SPECT and PET using metal and nonmetal radioisotopes based on tetrazine bioorthogonal reactions, and we discuss prospects for the future of such contrast agents.

Correlation between in vitro and in vivo Data of Radiolabeled Peptide for Tumor Targeting

2019 ◽  
Vol 19 (12) ◽  
pp. 950-960
Author(s):  
Soghra Farzipour ◽  
Seyed Jalal Hosseinimehr
Keyword(s):  
Tumor Targeting ◽  
Single Photon ◽  
Specific Binding ◽  
Specific Interaction ◽  
Photon Emission ◽  
Emission Computed Tomography ◽  
Mixed Effect ◽  
Radiolabeled Peptides

Tumor-targeting peptides have been generally developed for the overexpression of tumor specific receptors in cancer cells. The use of specific radiolabeled peptide allows tumor visualization by single photon emission computed tomography (SPECT) and positron emission tomography (PET) tools. The high affinity and specific binding of radiolabeled peptide are focusing on tumoral receptors. The character of the peptide itself, in particular, its complex molecular structure and behaviors influence on its specific interaction with receptors which are overexpressed in tumor. This review summarizes various strategies which are applied for the expansion of radiolabeled peptides for tumor targeting based on in vitro and in vivo specific tumor data and then their data were compared to find any correlation between these experiments. With a careful look at previous studies, it can be found that in vitro unblock-block ratio was unable to correlate the tumor to muscle ratio and the success of radiolabeled peptide for in vivo tumor targeting. The introduction of modifiers’ approaches, nature of peptides, and type of chelators and co-ligands have mixed effect on the in vitro and in vivo specificity of radiolabeled peptides.

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