statdx/docs_md/articles/parkinsonian-syndromes_2b99b31a-ec1a-4dce-bb63-2a101fe9f044.md

---
title: "Parkinsonian Syndromes"
docid: "2b99b31a-ec1a-4dce-bb63-2a101fe9f044"
authors:
  - key: "9d40c5b1-57d2-442c-9daf-8d8d9d53e24b"
    value: "Akiva Mintz, MD, PhD, MHA, CFA"
  - key: "cfdbf358-617e-410b-994f-8b48b03fdb8c"
    value: "Jongho Kim, MD, PhD, FACNM"
  - key: "1f262abe-db83-4f18-99af-00bd3045cd4d"
    value: "Marc Benayoun, MD, PhD"
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lastUpdated: "06/06/25"
pageDescription: "Parkinsonian Syndromes"
pageKeywords: "Nuclear Medicine, Central Nervous System, Neurodegeneration, Parkinsonian Syndromes"
pageTitle: "Parkinsonian Syndromes | STATdx"
enhancedTitle: "Parkinsonian Syndromes"
type: "DX"
references: true
breadcrumbs:
  - "Nuclear Medicine"
  - "Central Nervous System"
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  - "Parkinsonian Syndromes"
---
# KEY FACTS

- ## Terminology
  
  
    - Chronic, progressive brain disorder characterized by loss of dopaminergic neurons that leads to tremors at rest, rigidity, slowed movements, and shuffling gait
- ## Imaging
  
  
    - Dopamine transporters typically decreased for all Parkinson syndromes [Parkinson disease (PD) and atypical parkinsonism syndromes (APS)]
    - Loss of dopaminergic neurons visualized on I-123 ioflupane (DaT) SPECT and F-18 fluorodopa (FDOPA) PET
    - **I-123 ioflupane (DaT, FP-CIT) SPECT**
          - Molecular imaging agent that binds to dopamine transporters located on presynaptic nigrostriatal axons
    - **F-18 FDOPA PET**
          - F-18 FDOPA is decarboxylated by amino acid decarboxylase to F-18 fluorodopamine and stored in presynaptic vesicles in dopaminergic nerve terminals
    - Sensitivity > 90% for differentiating PD and essential tremor
    - Normal DaT and FDOPA scans demonstrate comma-shaped uptake on axial images
    - Abnormal scans demonstrate 
          - Asymmetric putamen activity
          - Symmetrically decreased or absent putamen activity with preservation of caudate
          - Decreased or absent putamen activity with significantly decreased/absent caudate uptake
    - Patient should be off all interfering dopaminergic medications
- ## Top Differential Diagnoses
  
  
    - PD
    - Multiple system atrophy
    - Progressive supranuclear palsy
    - Dementia with Lewy bodies
    - Corticobasal degeneration

# TERMINOLOGY

- ## Definitions
  
  
    - **Parkinsonian syndrome (PS)**
          - Clinical syndrome presenting with any combination of bradykinesia, resting tremor, rigidity, and autonomic instability
    - **Parkinson disease** **(****PD**) **(α-synucleinopathy)**
          - Chronic progressive disorder caused by degenerative loss of dopaminergic neurons
          - Classically present with bradykinesia and at least 1 of (i) tremor &/or (ii) rigidity
          - Normal DaT scan considered essentially exclusionary for diagnosis
    - **Atypical PS (APS)**
          - Characterized by more rapid progression and poorer prognosis than PD
          - Includes progressive supranuclear palsy (PSP; 4R-tauopathy), multiple system atrophy (MSA; α-synucleinopathy), and corticobasal degeneration (CBD; 4R-tauopathy)
    - **Dementia with Lewy bodies (DLB) (****α****-synucleinopathy)**
          - Dementia + visual hallucinations, parkinsonism, cognitive fluctuations, dysautonomia, sleep disorders, and neuroleptic sensitivity
    - **Drug-induced parkinsonism (DIP**)
          - Secondary parkinsonism, usually reversible
    - **Vascular parkinsonism (VP)**
          - Small vessel disease, multiple lacunar infarcts in basal ganglia
    - **Essential tremor (ET)**
          - Most common cause of action tremor in adults
          - Slow, gradual progression

# IMAGING

- ## General Features
  
  
    - Loss of dopaminergic neurons on I-123 ioflupane (DaT) SPECT or F-18 fluorodopa (FDOPA) PET
    - Relatively normal F-18 FDG PET/CT
          - Distinct abnormal patterns in APS
- ## Imaging Recommendations
  
  
    - ### Best imaging tool
      
      
          - **I-123 ioflupane (DaT, FP-CIT) SPECT**
                  - Molecular imaging agent that binds to dopamine (DA) transporters located on presynaptic nigrostriatal axons
                  - DA transporters typically decreased for all Parkinson syndromes (PD and APSs)
                  - DA transporters are located in putamen and caudate nuclei
                  - Demonstrates loss of dopaminergic neurons
                  - Sensitivity > 90% for differentiating PD and ET
                  - May be symmetric or asymmetric
                  - Differentiates PD and APS from ET and DIP
                  - PD and APS demonstrate decreased activity in putamen and caudate
                  - Does **not** differentiate PD from APS or between APSs
                  - Image interpretation
                            - Normal scans demonstrate comma-shaped uptake on axial images
                            - Abnormal scans demonstrate period-shaped uptake on axial images indicating more pronounced loss of uptake in putamen
                            - Abnormal uptake may be initially detected in contralateral putamen relative to clinical symptoms
                            - Abnormal patterns
                                        - Asymmetric putamen activity
                                        - Symmetrically decreased or absent putamen activity with preservation of caudate
                                        - Decreased or absent putamen activity with significantly decreased/absent caudate uptake
          - **F-18 FDOPA PET**
                  - F-18 FDOPA is decarboxylated by amino acid decarboxylase to F-18 fluorodopamine and stored in presynaptic vesicles in dopaminergic nerve terminals
                  - Accumulation of F-18 fluorodopamine in striatum is visually detected on PET
                  - Similar uptake pattern as I-123 ioflupane in normal and disease states but benefits from better quality of PET
                  - Normal scan: Comma-shaped uptake on axial images visualizing caudate and putamen
                  - Abnormal scan: Asymmetric or decreased putamen activity with normal or decreased caudate activity
          - **F-18 FDG PET/CT**
                  - Typically normal in PD
                            - Preserved F-18 FDG PET/CT in basal ganglia differentiates PD from PS
          - **MIBG cardiac SPECT**
                  - Absent myocardial tracer binding in PD and LBD
                  - Typically preserved in APDs, DIP, VP, ET
    - ### Protocol advice
      
      
          - **I-123 ioflupane**
                  - Patient should be off all interfering dopaminergic medications
                            - Cocaine, amphetamines, and methylphenidate severely decrease binding
                            - Ephedrine and phentermine may decrease binding
                            - Bupropion, fentanyl, and some anesthetics may decrease binding
                  - Patient preparation
                            - Pretreat with thyroid blocker (400 mg of oral potassium solution or single dose of Lugol solution) 1 hour before tracer injection
                            - Pregnancy category C: Unknown whether I-123 can cause fetal damage or early termination of pregnancy
                  - Radiopharmaceutical: I-123 ioflupane
                  - Dose: 3-5 mCi (111-185 MBq) intravenously
                  - Dosimetry: Striata receives highest radiation exposure, followed by bladder, bowel, and lungs (assuming thyroid is blocked)
                  - Image acquisition: 3-6 hours after injection
                            - SPECT or SPECT/CT acceptable but attenuation correction is recommended
                            - Photopeak should be set to 159 keV ± 10%
                            - Low-energy, high-resolution collimator
                            - 128 x 128 matrix is recommended
                            - 30-second projection time (120 projections)
          - **F-18 FDOPA**
                  - Patient preparation 
                            - Premedicate with 150 mg of carbidopa orally at least 60 minutes (and no longer than 120 minutes) prior to administration of F-18 FDOPA injection
                            - Carbidopa blocks systemic/peripheral decarboxylation of F-18 FDOPA to increase uptake in brain
                  - Patient should be off all interfering dopaminergic medications for at least 12 hours prior to F-18 FDOPA injection 
                            - Aromatic L-amino acid decarboxylase (AADC) inhibitors (e.g., carbidopa, benserazide, etc.)
                            - DA agonists, DA reuptake inhibitors, DA-releasing agents (DRAs), such as psychostimulants of amphetamine class, peripheral catechol-O-methyltransferase (COMT) inhibitors, and monoamine oxidase (MAO) inhibitors
                  - Radiopharmaceutical: F-18 FDOPA
                  - Dose: 5 mCi (185 MBq) intravenously
                  - Image acquisition: 80-100 minutes after injection
                            - PET attenuation correction CT
                  - Dosimetry: Critical organ is bladder wall
          - F-18 FDG PET/CT
                  - Patient preparation
                            - Patient should fast, stop IV fluids containing dextrose, stop parenteral feeding for 4-6 hours
                            - Blood sugar should be 150-200 mg/dL
                            - Patient should be placed in quiet, dimly lit room prior to and after injection for 30 minutes
                  - Radiopharmaceutical: F-18 FDG
                  - Dose: 5-20 mCi (185-740 MBq)
                  - Dosimetry: Urinary bladder receives largest dose
                  - Image acquisition: 30-60 minutes after injection
- ## Artifacts and Quality Control
  
  
    - Certain medications can significantly alter scan appearance and should be discontinued/documented
    - Ensure patient is off competing medications if activity is diffusely low

# DIFFERENTIAL DIAGNOSIS

- [Parkinson Disease](/document/parkinson-disease/0bc3188a-935b-416d-b1a0-25b2d52c6399)
    - I-123 ioflupane/F-18 FDOPA positive
    - Amyloid PET negative
    - F-18 FDG PET grossly normal, but PD-related metabolic pattern reported as increased pallidal, thalamic, and motor cortical metabolic activity associated with decreased lateral premotor and parietooccipital cortical activity
    - MR T2* can show loss of swallowtail sign in substantia nigra
- ## Atypical Parkinsonian Syndromes
  
  
    - [MSA](/document/multiple-system-atrophy/4fb9af00-e0bd-4164-8f61-4011ddc8bf9e)
          - Family of neurodegenerative disorders
          - Symptoms include parkinsonism, ataxia, and autonomic dysfunction
                  - Cerebellar dominant (MSA-C) and parkinsonian dominant (MSA-P)
          - F-18 FDG PET
                  - MSA-C shows decreased activity in cerebellum
                  - MSA-P shows decreased putamen activity
          - Amyloid PET negative
          - I-123 ioflupane/F-18 FDOPA positive
          - MR shows volume loss/T2 hyperintensity in cerebellum, middle cerebellar peduncles, and putamen
    - [PSP](/document/progressive-supranuclear-palsy/840ed321-c0ab-4069-a07e-ad416232f916)
          - Symptoms include parkinsonism, bradykinesia, rigidity, **vertical gaze palsy**, dysphagia, dysarthria
          - Amyloid PET negative
          - Ioflupane SPECT positive
          - Decreased F-18 FDG activity in basal ganglia, frontal lobes, anterior cingulate, midbrain
          - Volume loss in midbrain with relatively preserved pons, MR hummingbird sign or Mickey Mouse sign
    - [DLB](/document/lewy-body-dementia/f6a4382b-f0f7-4582-a703-7f695c65656f)
          - Symptoms include dementia, visual hallucinations, parkinsonism
          - I-123 ioflupane/F-18 FDOPA positive
          - Amyloid PET is positive in > 50% of patients
          - F-18 FDG PET/CT shows generalized reduced cortical uptake most pronounced in occipital region and sparing posterior cingulate gyrus cingulate island sign
    - [CBD](/document/corticobasal-degeneration/23f97d4e-8724-4229-b9f8-08f63906ebd8)
          - Cognitive/behavioral symptoms precede movement dysfunction
          - Symptoms include akinesia, rigidity, dystonia, apraxia, executive dysfunction, aphasia, "alien limb" phenomenon
          - Patients do not respond to levodopa
          - I-123 ioflupane/F-18 FDOPA positive, typically asymmetric and decreased contralateral to symptoms
          - Amyloid PET negative
          - F-18 FDG PET/CT relative decreased activity in contralateral cortex and basal ganglia
                  - May be caused by increased ipsilateral uptake
- ## Benign Essential Tremor
  
  
    - Negative I-123 ioflupane/F-18 FDOPA
- ## Vascular Parkinsonism
  
  
    - Negative I-123 ioflupane/F-18 FDOPA
- ## Drug-Induced Parkinsonism
  
  
    - Negative I-123 ioflupane/F-18 FDOPA

# PATHOLOGY

- ## General Features
  
  
    - PD accounts for > 70% of parkinsonian patients
    - α-synuclein skin biopsy shows high sensitivity for PD, MSA, and DLB
    - Loss of dopaminergic neurons
          - Affected neurons project from substantia nigra (midbrain) to putamen and caudate
          - Putamen typically affected earlier and more severely
          - Symptoms begin to show after ~ 50% of neurons are affected

# CLINICAL ISSUES

- ## Presentation
  
  
    - ### Most common signs/symptoms
      
      
          - Rigidity, tremor, bradykinesia, autonomic instability
- ## Demographics
  
  
    - Prevalence of ~ 1% in adults > 65 years

# DIAGNOSTIC CHECKLIST

- ## Image Interpretation Pearls
  
  
    - I-123 ioflupane SPECT/F-18 FDOPA each differentiate between diseases related to DA loss (PD and APS) and those that mimic them clinically (benign tremor and VP)
    - Cardiac MIBG may be helpful in diagnosing PD and DLB, though is typically normal in other PSs
- ## Reporting Tips
  
  
    - Reporting scheme in literature
          - Normal: 2 comma-shaped areas of uptake
          - Abnormal grade 1: Asymmetric uptake [normal (comma shape) on one side and abnormal (period shape) on other side]
          - Abnormal grade 2: Abnormal (period shape) reduced putamen activity bilaterally
          - Abnormal grade 3: Markedly reduced uptake bilaterally

 cc5405dd-1797-4f98-b1a1-127b9159f5f1

## References

# Selected References

1. [Jost WH et al: Neuroimaging in multiple system atrophy: clinical implications and novel developments. J Neural Transm (Vienna). ePub, 2025](http://www.ncbi.nlm.nih.gov/pubmed/?term=40214765%5Bpmid%5D)
1. [Hastings A et al: Neuropathologic validation and diagnostic accuracy of presynaptic dopaminergic imaging in the diagnosis of parkinsonism. Neurology. 102(11):e209453, 2024](http://www.ncbi.nlm.nih.gov/pubmed/?term=38759132%5Bpmid%5D)
1. [American College of Radiology: ACRE–ACNM–SNMMI practice parameter for the performance of dopamine transporter (DaT) single photon emission computed tomography (SPECT) imaging for movement disorders. Updated 2022. Accessed May 17, 2025. https://gravitas.acr.org/PPTS/DownloadPreviewDocument?DocId=134](https://gravitas.acr.org/PPTS/DownloadPreviewDocument?DocId=134)
1. [Pirtošek Z et al: Update on the management of Parkinson's disease for general neurologists. Parkinsons Dis. 2020:9131474, 2020](http://www.ncbi.nlm.nih.gov/pubmed/?term=32300476%5Bpmid%5D)
1. [Broski SM et al: Structural and functional imaging in parkinsonian syndromes. Radiographics. 34(5):1273-92, 2014](http://www.ncbi.nlm.nih.gov/pubmed/?term=25208280%5Bpmid%5D)
1. [Bajaj N et al: Clinical utility of dopamine transporter single photon emission CT (DaT-SPECT) with (123I) ioflupane in diagnosis of parkinsonian syndromes. J Neurol Neurosurg Psychiatry. 84(11):1288-95, 2013](http://www.ncbi.nlm.nih.gov/pubmed/?term=23486993%5Bpmid%5D)
1. [Djang DS et al: SNM practice guideline for dopamine transporter imaging with 123I-ioflupane SPECT 1.0. J Nucl Med. 53(1):154-63, 2012](http://www.ncbi.nlm.nih.gov/pubmed/?term=22159160%5Bpmid%5D)
1. [Access Data: FDA prescribing information for DaTscan website. Updated 2011. Accessed April 11, 2025. http://www.accessdata.fda.gov/drugsatfda_docs/nda/2011/022454sOrig1s000Lbl.pdf](http://www.accessdata.fda.gov/drugsatfda_docs/nda/2011/022454sOrig1s000Lbl.pdf)
1. [Tang CC et al: Differential diagnosis of parkinsonism: a metabolic imaging study using pattern analysis. Lancet Neurol. 9(2):149-58, 2010](http://www.ncbi.nlm.nih.gov/pubmed/?term=20061183%5Bpmid%5D)
1. [Booij J et al: Dopamine transporter imaging with [(123)I]FP-CIT SPECT: potential effects of drugs. Eur J Nucl Med Mol Imaging. 35(2):424-38, 2008](http://www.ncbi.nlm.nih.gov/pubmed/?term=17968545%5Bpmid%5D)
1. [Ibrahim N et al: The sensitivity and specificity of F-DOPA PET in a movement disorder clinic. Am J Nucl Med Mol Imaging. 6(1):102-9, 2016](http://www.ncbi.nlm.nih.gov/pubmed/?term=27069770%5Bpmid%5D)
1. [Eshuis SA et al: Comparison of FP-CIT SPECT with F-DOPA PET in patients with de novo and advanced Parkinson's disease. Eur J Nucl Med Mol Imaging. 33(2):200-9, 2006](http://www.ncbi.nlm.nih.gov/pubmed/?term=16228235%5Bpmid%5D)
1. [Dhawan V et al: Comparative analysis of striatal FDOPA uptake in Parkinson's disease: ratio method versus graphical approach. J Nucl Med. 43(10):1324-30, 2002](http://www.ncbi.nlm.nih.gov/pubmed/?term=12368370%5Bpmid%5D)
1. [Brooks DJ: Imaging approaches to Parkinson disease. J Nucl Med. 51(4):596-609, 2010](http://www.ncbi.nlm.nih.gov/pubmed/?term=20351351%5Bpmid%5D)
1. [Eckert T et al: FDG PET in the differential diagnosis of parkinsonian disorders. Neuroimage. 26(3):912-21, 2005](http://www.ncbi.nlm.nih.gov/pubmed/?term=15955501%5Bpmid%5D)
1. [Marek K et al: [123I.] Neurology. 57(11):2089-94, 2001](http://www.ncbi.nlm.nih.gov/pubmed/?term=11739831%5Bpmid%5D)


## Images


### Selected Images

![Axial graphic demonstrates brain anatomy and expected area of uptake (blue) in the head of the caudate <img src='img/arrows/BO.png'/> and putamen <img src='img/arrows/WS.png'/>.](images/app.statdx.com_image_thumbnail_17843f38-8102-416d-b40b-e43c4129deed_size_168_quality_85_9728a401_20251014T193526Z.jpg)
*Axial graphic demonstrates brain anatomy and expected area of uptake (blue) in the head of the caudate <img src='img/arrows/BO.png'/> and putamen <img src='img/arrows/WS.png'/>.*

![Axial graphic demonstrates brain anatomy and expected area of uptake (blue) in the head of the caudate <img src='img/arrows/BO.png'/> and putamen <img src='img/arrows/WS.png'/>.](images/app.statdx.com_image_thumbnail_17843f38-8102-416d-b40b-e43c4129deed_size_174_quality_85_095ac8b7_20251014T190917Z.jpg)
*Axial graphic demonstrates brain anatomy and expected area of uptake (blue) in the head of the caudate <img src='img/arrows/BO.png'/> and putamen <img src='img/arrows/WS.png'/>.*

![Axial graphic demonstrates brain anatomy and expected area of uptake (blue) in the head of the caudate <img src='img/arrows/BO.png'/> and putamen <img src='img/arrows/WS.png'/>.](images/app.statdx.com_image_thumbnail_17843f38-8102-416d-b40b-e43c4129deed_size_174_quality_85_40352aab_20251014T193347Z.jpg)
*Axial graphic demonstrates brain anatomy and expected area of uptake (blue) in the head of the caudate <img src='img/arrows/BO.png'/> and putamen <img src='img/arrows/WS.png'/>.*

![Axial graphic demonstrates brain anatomy and expected area of uptake (blue) in the head of the caudate <img src='img/arrows/BO.png'/> and putamen <img src='img/arrows/WS.png'/>.](images/app.statdx.com_image_thumbnail_17843f38-8102-416d-b40b-e43c4129deed_size_174_quality_85_7e4274d9_20251014T185333Z.jpg)
*Axial graphic demonstrates brain anatomy and expected area of uptake (blue) in the head of the caudate <img src='img/arrows/BO.png'/> and putamen <img src='img/arrows/WS.png'/>.*

![Axial graphic demonstrates brain anatomy and expected area of uptake (blue) in the head of the caudate <img src='img/arrows/BO.png'/> and putamen <img src='img/arrows/WS.png'/>.](images/app.statdx.com_image_thumbnail_17843f38-8102-416d-b40b-e43c4129deed_size_174_quality_85_d08cdb15_20251014T204456Z.jpg)
*Axial graphic demonstrates brain anatomy and expected area of uptake (blue) in the head of the caudate <img src='img/arrows/BO.png'/> and putamen <img src='img/arrows/WS.png'/>.*

![Axial graphic shows normal uptake (orange) of I-123 ioflupane or F-18 FDOPA overlaid on the head of the caudate <img src='img/arrows/BO.png'/> and putamen <img src='img/arrows/WS.png'/>.](images/app.statdx.com_image_thumbnail_e0ed92cb-b3a1-48fa-ab99-e313afc78451_size_168_quality_85_558c0b20_20251014T193526Z.jpg)
*Axial graphic shows normal uptake (orange) of I-123 ioflupane or F-18 FDOPA overlaid on the head of the caudate <img src='img/arrows/BO.png'/> and putamen <img src='img/arrows/WS.png'/>.*

![Axial I-123 ioflupane SPECT shows normal putamen activity <img src='img/arrows/WS.png'/> and caudate activity <img src='img/arrows/WO.png'/>. These finding are not consistent with Parkinson disease (PD) or atypical parkinsonism syndromes (APS).](images/app.statdx.com_image_thumbnail_a52bfe74-abeb-477c-b71c-c25b9c95c3b1_size_168_quality_85_66dff809_20251014T193526Z.jpg)
*Axial I-123 ioflupane SPECT shows normal putamen activity <img src='img/arrows/WS.png'/> and caudate activity <img src='img/arrows/WO.png'/>. These finding are not consistent with Parkinson disease (PD) or atypical parkinsonism syndromes (APS).*

![Axial I-123 ioflupane SPECT shows absent left putamen activity <img src='img/arrows/WS.png'/>, preserved but decreased right putamen activity <img src='img/arrows/WC.png'/>, and preserved caudate activity <img src='img/arrows/WO.png'/>. These findings are consistent with PD or APS.](images/app.statdx.com_image_thumbnail_7743550b-7b1e-4eec-8159-e88bf5ffabe8_size_168_quality_85_4666d72c_20251014T193526Z.jpg)
*Axial I-123 ioflupane SPECT shows absent left putamen activity <img src='img/arrows/WS.png'/>, preserved but decreased right putamen activity <img src='img/arrows/WC.png'/>, and preserved caudate activity <img src='img/arrows/WO.png'/>. These findings are consistent with PD or APS.*

![Axial I-123 ioflupane SPECT shows absent bilateral putamen activity <img src='img/arrows/WS.png'/> and preserved caudate activity <img src='img/arrows/WO.png'/>. These finding are consistent with PD or APS.](images/app.statdx.com_image_thumbnail_b62ca27d-39ae-4715-a9a4-ded04d4f026c_size_168_quality_85_a3f667bd_20251014T193526Z.jpg)
*Axial I-123 ioflupane SPECT shows absent bilateral putamen activity <img src='img/arrows/WS.png'/> and preserved caudate activity <img src='img/arrows/WO.png'/>. These finding are consistent with PD or APS.*

![Axial I-123 ioflupane SPECT shows absent bilateral putamen activity and almost absent caudate activity. These findings are consistent with PD or APS if patient was not on any interfering medications.](images/app.statdx.com_image_thumbnail_05952069-bc51-4025-b0a6-007790451288_size_168_quality_85_7bd19dca_20251014T193526Z.jpg)
*Axial I-123 ioflupane SPECT shows absent bilateral putamen activity and almost absent caudate activity. These findings are consistent with PD or APS if patient was not on any interfering medications.*

![Quantitative analysis of I-123 ioflupane SPECT shows the bilateral caudates have abnormally low uptake <img src='img/arrows/CS.png'/> of radiotracer compared with normal controls. Note that this would be difficult to discern on visual analysis alone <img src='img/arrows/CO.png'/>.](images/app.statdx.com_image_thumbnail_f6560a81-923d-4104-88de-89d4996052fb_size_168_quality_85_950da1dd_20251014T193526Z.jpg)
*Quantitative analysis of I-123 ioflupane SPECT shows the bilateral caudates have abnormally low uptake <img src='img/arrows/CS.png'/> of radiotracer compared with normal controls. Note that this would be difficult to discern on visual analysis alone <img src='img/arrows/CO.png'/>.*

![Quantitative analysis of I-123 ioflupane SPECT in the same patient shows the bilateral posterior putamina have abnormally low uptake <img src='img/arrows/CS.png'/> of radiotracer compared with normal controls. Visual analysis of the putamina <img src='img/arrows/CO.png'/> supports the quantitative analysis.](images/app.statdx.com_image_thumbnail_6604908d-a9da-44fa-a20c-668d4311a4c8_size_168_quality_85_c8c3307a_20251014T193526Z.jpg)
*Quantitative analysis of I-123 ioflupane SPECT in the same patient shows the bilateral posterior putamina have abnormally low uptake <img src='img/arrows/CS.png'/> of radiotracer compared with normal controls. Visual analysis of the putamina <img src='img/arrows/CO.png'/> supports the quantitative analysis.*

![Axial I-123 ioflupane SPECT images in a patient with suspected PD show no significant uptake in the caudate or putamen <img src='img/arrows/CS.png'/>. After the scan, it was revealed that the patient was taking modafinil, which has been reported to bind to the dopamine transporter and inhibit dopamine reuptake.](images/app.statdx.com_image_thumbnail_49c79e7b-2a61-4abe-bcce-cae96d7ed7c1_size_168_quality_85_f8943437_20251014T193526Z.jpg)
*Axial I-123 ioflupane SPECT images in a patient with suspected PD show no significant uptake in the caudate or putamen <img src='img/arrows/CS.png'/>. After the scan, it was revealed that the patient was taking modafinil, which has been reported to bind to the dopamine transporter and inhibit dopamine reuptake.*

![Axial I-123 ioflupane SPECT images in the same patient after discontinuation of modafinil show significant uptake in the caudate <img src='img/arrows/CO.png'/> but decreased/absent uptake in the putamen <img src='img/arrows/CS.png'/>.](images/app.statdx.com_image_thumbnail_049e94bf-844c-4dfa-a565-ebc8c0f1ef01_size_168_quality_85_e65e58c1_20251014T193526Z.jpg)
*Axial I-123 ioflupane SPECT images in the same patient after discontinuation of modafinil show significant uptake in the caudate <img src='img/arrows/CO.png'/> but decreased/absent uptake in the putamen <img src='img/arrows/CS.png'/>.*


### Additional Images

![Axial I-123 ioflupane SPECT shows bilateral a comma-shaped appearance, consistent with a normal study. Note the slight asymmetry between sides, which may be secondary to head positioning.](images/app.statdx.com_image_thumbnail_0d7a795e-dc3a-42d0-84cb-1814033ddd39_size_168_quality_85_605f1414_20251014T193526Z.jpg)
*Axial I-123 ioflupane SPECT shows bilateral a comma-shaped appearance, consistent with a normal study. Note the slight asymmetry between sides, which may be secondary to head positioning.*

![Axial I-123 Ioflupane SPECT images of the same patient from superior <img src='img/arrows/CS.png'/> to inferior <img src='img/arrows/WS.png'/> demonstrate the full appearance of caudate heads and putamen.](images/app.statdx.com_image_thumbnail_3ea3c16e-9495-40eb-b4f5-63f9500eb818_size_168_quality_85_f12410fe_20251014T193526Z.jpg)
*Axial I-123 Ioflupane SPECT images of the same patient from superior <img src='img/arrows/CS.png'/> to inferior <img src='img/arrows/WS.png'/> demonstrate the full appearance of caudate heads and putamen.*