Brain PET and DaT SPECT

What it does

Brain PET and DaT SPECT reads the four neuro-nuclear exams that memory and movement-disorder clinics order: amyloid PET, tau PET, FDG brain PET and dopamine transporter (DaT) SPECT. Upload the reconstructed brain study; the tracer is identified from the DICOM radiopharmaceutical codes, the scan is spatially normalised (an MRI is optional) and the quantification that belongs to that tracer is returned.

Amyloid PET gets a Centiloid value, SUVR and a positive or negative classification with visual-read support. Tau PET gets CenTauRz, regional SUVR and a Braak-like stage. FDG PET gets regional z-score maps against a normal database and the probabilities of Alzheimer's, frontotemporal and Lewy-body patterns. DaT SPECT gets caudate and putamen striatal binding ratios with asymmetry. With a prior scan, the run reports the change, such as the fall in Centiloid during anti-amyloid therapy.

Intended use

Decision support where a number is part of the clinical question: amyloid status before anti-amyloid antibodies, amyloid clearance on treatment, an aetiological pattern in cognitive decline, presynaptic dopaminergic loss in parkinsonism. Atrophy, partial-volume effects, off-target tau binding, head motion and vascular lesions on DaT SPECT all affect the numbers, and the result shows the visual-read support beside each value.

Who it is for

Nuclear-medicine physicians and neuroradiologists who read brain PET and DaT SPECT, neurologists in memory and movement-disorder clinics who ask for a Centiloid or binding ratio, and research groups running longitudinal amyloid or tau cohorts.

Accepted input

• Brain PET: DICOM PET Image or Enhanced PET Image of an amyloid, tau or FDG study, reconstructed.
• DaT SPECT: DICOM NM tomographic reconstruction of a dopamine transporter study.
• T1-weighted MRI (optional): used for spatial normalisation when supplied; otherwise normalisation is PET-only.
• Prior study (optional, in prior_files): an earlier scan with the same tracer for the change section.

Requirements

Requirement	Why
Reconstructed tomographic data, not screenshots or summary pages	Spatial normalisation and regional quantification need the volume
Radiopharmaceutical code in the DICOM header	Selects tracer-specific reference regions and thresholds
Whole brain in the field of view	Tracer-specific reference regions for SUVR and binding ratios
Limited head motion	Motion blurs cortical and striatal uptake

Reference regions and positivity thresholds are tracer-specific, and the normal database used for z-scores is named with its version in the result.

Optional context

Age, sex, the clinical question (cognitive impairment, parkinsonism) and current anti-amyloid treatment can be passed in clinical_context; they shape the guidance, not the measured values.

The result

Section	Content
Amyloid PET (Centiloid)	Centiloid value, SUVR, amyloid positive or negative with visual-read support
Tau PET (CenTauRz)	CenTauRz, regional SUVR, Braak-like stage and visual-read pattern
FDG dementia patterns	Regional z-score maps against a normal database; Alzheimer's, frontotemporal and Lewy-body pattern probabilities
DaT SPECT striatal binding	Caudate and putamen striatal binding ratios, asymmetry and normal or abnormal probability
Change versus prior	Change in Centiloid, CenTauRz or FDG z-scores against the prior scan
Draft report	Opt-in (options.report): an English narrative that interprets the result for the reader (findings, impression, limitations); every number is checked against the findings

The sections that appear depend on the tracer: an amyloid study returns the amyloid section, and the change section appears only with a prior.

Standards

• Quantitative scales: the Centiloid scale for amyloid PET; CenTauR(z) and Braak-stage patterns for tau PET.
• Guidelines: SNMMI/EANM amyloid PET guideline 1.0 (2016); EANM/SNMMI DaT imaging guideline 1.0 (2020); SNMMI/EANM brain FDG PET guideline; AA/SNMMI appropriate use criteria for amyloid and tau PET (2025).
• DICOM: Parametric Map for SUVR and z-score maps; SR TID 1500 Measurement Report for regional values; Key Object Selection; Encapsulated PDF.

The Centiloid scale

Centiloid maps amyloid PET from different tracers and pipelines onto one scale anchored at 0 for young controls and 100 for typical Alzheimer's disease. That shared scale makes the change section meaningful during anti-amyloid therapy, where amyloid clearance is judged on the Centiloid value over time.