Dopamine transporter SPECT

A report skeleton for [123I]FP-CIT (ioflupane) SPECT that follows the reporting elements of the joint EANM/SNMMI 2020 dopaminergic imaging guideline. It records a visual read, semiquantification against a matched normal database, and a conclusion stating whether a presynaptic dopaminergic deficit is present.

Based on: EANM practice guideline/SNMMI procedure standard for dopaminergic imaging in Parkinsonian syndromes 1.0 (Morbelli 2020)

DOPAMINE TRANSPORTER SPECT ([123I]FP-CIT)

CLINICAL INDICATION:
  [Parkinsonism or tremor: degenerative parkinsonism versus essential tremor / drug-induced / psychogenic; dementia: dementia with Lewy bodies versus Alzheimer disease; other]
  Clinical question: [ ]
  Symptoms and side: [ ]; duration [ ]
  Medication reviewed: [none interfering / [drug], stopped [ ] days before (about 5 half-lives) / not stopped]
  Prior CT / MRI brain: [date; vascular or structural lesion in basal ganglia: yes / no]

TECHNIQUE:
  [123I]FP-CIT [ ] MBq IV at [time]; thyroid blockade: [potassium iodide / perchlorate / none]
  Acquisition started [ ] h after injection (department standard [3] h); camera [ ]; duration [ ] min
  Reconstruction: [method; attenuation and scatter correction], matched to the normal database
  Sedation: [none / drug and dose]
  Scan quality: [good / suboptimal because of [motion / head tilt / extravasation / low counts]]

COMPARISON:
  [Prior DAT SPECT dated [ ] / none]

FINDINGS:
  Visual assessment (all striatal slices reviewed, head alignment checked):
    Right striatum: [normal comma shape / reduced putaminal uptake (dot shape) / reduced putamen and caudate]
    Left striatum: [ ]
    Symmetry: [symmetrical / asymmetrical, lower on the [right / left]]
    Gradient: [posterior putamen most affected / uniform (balanced) loss / focal punched-out defect]
    Background and extra-striatal activity: [ ]
  Semiquantification (software [ ]; normal database [ ], age-matched):
    Specific binding ratio: R caudate [ ], R putamen [ ], L caudate [ ], L putamen [ ]
    Reference range or z-scores: [ ]
    Putamen-to-caudate ratio: R [ ], L [ ]; left-right asymmetry: [ ]%
  Concordance of visual and semiquantitative results: [concordant / discordant: [ ]]

IMPRESSION:
  1. Presynaptic dopaminergic deficit: [ABSENT / PRESENT, [mild / moderate / severe], [asymmetrical, [side] putamen most affected / symmetrical]]
  2. [Answer to the clinical question, e.g. normal study: argues against a neurodegenerative parkinsonian syndrome; consistent with essential tremor, drug-induced or psychogenic parkinsonism if clinically appropriate / abnormal study: supports a neurodegenerative parkinsonian syndrome or dementia with Lewy bodies]
  3. Limitations: [drug interference / motion / none]

Before you sign

• A presynaptic scan cannot separate Parkinson disease or dementia with Lewy bodies from MSA, PSP or CBD. Say so, and do not suggest a subtype from the pattern alone.
• Uptake is normal in essential tremor, drug-induced parkinsonism and psychogenic parkinsonism. In vascular parkinsonism it is normal or slightly reduced, unless an infarct involves the striatum and gives a punched-out defect.
• For dementia: striatal binding is usually normal or only mildly reduced in Alzheimer disease and significantly reduced in dementia with Lewy bodies. About 10% of pathologically proven DLB scans are normal at diagnosis. Reduced basal ganglia DAT uptake is an indicative biomarker in the 2017 DLB consortium criteria, but probable DLB is never diagnosed on biomarkers alone.
• Levodopa, dopamine agonists, MAO-B inhibitors, amantadine and COMT inhibitors do not interfere. Cocaine, amphetamines, methylphenidate, modafinil, bupropion and some anaesthetics and opioids do, so stop them for about 5 half-lives where possible. SSRIs raise binding slightly but should not change a visual read.
• Tilt in the coronal plane can cause false left-right asymmetry. Check head alignment and review the prior CT or MRI, which the guideline asks for to exclude structural and vascular lesions.
• Semiquantification supports the visual read and does not replace it. It is valid only against a normal database built with the same camera and reconstruction, and there are no universal cut-offs.
• A very low global signal in a mildly affected patient should prompt a check for tracer extravasation.

Sources

1. Morbelli S, Esposito G, Arbizu J, et al. EANM practice guideline/SNMMI procedure standard for dopaminergic imaging in Parkinsonian syndromes 1.0. Eur J Nucl Med Mol Imaging. 2020;47:1885–1912.
2. McKeith IG, Boeve BF, Dickson DW, et al. Diagnosis and management of dementia with Lewy bodies: fourth consensus report of the DLB Consortium. Neurology. 2017;89:88–100.