Acquisition Parameters: PET
Representative adult activity, uptake time, and acquisition by PET tracer
Quick Answer
This is a representative adult PET-acquisition reference — tracer, typical activity, uptake time, and acquisition notes. For PET the parameters that most affect the result are the uptake time (fixed and consistent for quantitation), patient preparation (glucose for FDG; suppression vs promotion for cardiac), and reconstruction/uptake-time matching for serial SUV. Modern TOF scanners allow lower activities.
⚠️ Representative values for orientation — verify against SNMMI/EANM procedure standards and local protocol. Activity given in mCi (MBq); weight-based schemes (e.g. ~3–4 MBq/kg FDG) are increasingly standard.
Oncology & General
| Tracer | Activity | Uptake time | Acquisition / prep |
|---|---|---|---|
| ¹⁸F-FDG (oncology) | ~10–15 mCi (or ~3–4 MBq/kg; lower with TOF) | ~60 min (55–75) | Fast 4–6 h, glucose < ~150–200; skull base→mid-thigh; ~1.5–3 min/bed (or continuous-bed) |
| ¹⁸F-FDG (brain) | ~5–10 mCi | ~30–40 min | Quiet, dim room; dedicated brain acquisition |
| ¹⁸F-FES (breast, ER) | ~6 mCi (222 MBq) | ~60–80 min | Hold ER-blocking therapy (false-negative) |
| ¹⁸F-NaF (bone) | ~5–10 mCi | ~30–60 min | Low background; hydrate/void |
| ⁶⁸Ga/¹⁸F-FAPI | agent-specific | ~10–60 min | Low liver/brain background |
Prostate & Neuroendocrine
| Tracer | Activity | Uptake time | Notes |
|---|---|---|---|
| ⁶⁸Ga-PSMA-11 | ~1.8–2.2 mCi (~2 MBq/kg) | ~50–100 min | Furosemide/hydration to clear bladder for pelvic reads |
| ¹⁸F-DCFPyL (piflufolastat) | ~9 mCi (333 MBq) | ~60 min | Sharper images; batch distribution |
| ¹⁸F-rhPSMA-7.3 | agent-specific | ~60 min | Low urinary excretion |
| ⁶⁸Ga-DOTATATE | ~3–5 mCi (or weight-based) | ~45–90 min | Coordinate with somatostatin-analog timing |
| ⁶⁴Cu-DOTATATE | ~4 mCi (148 MBq) | ~45–90 min | Longer half-life; delayed/centralized |
Cardiac PET
| Study | Tracer | Activity | Acquisition / prep |
|---|---|---|---|
| Perfusion | ⁸²Rb | ~30–60 mCi per rest/stress | Dynamic list-mode (~76 s half-life); pharmacologic stress; MBF/MFR |
| Perfusion | ¹³N-ammonia | ~10–20 mCi | Dynamic; cyclotron; permits limited exercise |
| Viability | ¹⁸F-FDG | ~10 mCi | Promote myocardial glucose (glucose ± insulin/clamp) + rest perfusion |
| Sarcoid | ¹⁸F-FDG | ~10 mCi | Suppress myocardial glucose (high-fat/very-low-carb, fast, ± heparin) + rest perfusion |
Neuro (Dementia)
| Tracer | Activity | Uptake time | Notes |
|---|---|---|---|
| Amyloid (florbetapir/florbetaben/flutemetamol) | ~10 mCi (370 MBq) | ~30–90 min (agent-specific) | Read by approved visual criteria (gray–white) |
| Tau (flortaucipir) | ~10 mCi | ~80 min | Regional/Braak-like distribution |
| ¹⁸F-FDG (dementia) | ~5–10 mCi | ~30–40 min | Hypometabolism pattern |
Cross-Cutting PET Principles
- Uptake time must be fixed and consistent across serial scans — it strongly affects SUV (and PERCIST comparisons).
- Reconstruction (OSEM iterations/subsets, PSF, TOF) changes SUV — use matched or EARL-harmonized reconstructions for cross-site/serial work.
- Cross-calibration (scanner ↔ dose calibrator ↔ clock) must be current for quantitative SUV.
- Preparation is disease-specific for cardiac FDG (suppress for sarcoid, promote for viability) and glucose-dependent for oncology FDG.
Board-Level Synthesis
For PET, uptake time (fixed ~60 min for FDG; agent-specific otherwise), preparation (glucose/fasting; suppress-vs-promote for cardiac FDG), and reconstruction/uptake-time matching are what determine a valid, comparable SUV. Modern TOF scanners permit lower injected activities.
Two cardiac FDG preparations are opposite: suppress myocardial glucose for sarcoid, promote it for viability. PSMA pelvic reads benefit from hydration/furosemide to clear bladder activity; DOTATATE timing is coordinated with somatostatin-analog dosing.
Activities are representative and guideline-dependent and increasingly weight-based (e.g. ~3–4 MBq/kg FDG, ~2 MBq/kg Ga-68-PSMA). Cross-site/serial SUV requires matched or EARL-harmonized reconstruction and current cross-calibration; uptake-time drift is a common, avoidable source of spurious SUV change.
Related Pages
- Reference: Acquisition parameters — SPECT & planar, FDG-PET preparation & physiologic uptake, quantitative thresholds & decision cutoffs, SUV harmonization (EARL).
- Physics: PET & SPECT performance & reconstruction.
Figure / Diagram Suggestions
- A tracer → activity → uptake-time → prep PET protocol grid.
- A cardiac-FDG suppress-vs-promote side-by-side.
Self-Check
Q1. Why must FDG uptake time be fixed across serial oncologic scans?
Answer: SUV rises with uptake time; an inconsistent interval produces spurious SUV change and invalidates PERCIST-type comparison — keep ~60 min consistent.
Q2. How does cardiac FDG preparation differ between a sarcoid and a viability study?
Answer: Suppress myocardial glucose for sarcoid (high-fat/very-low-carb, fast, ± heparin); promote it for viability (glucose ± insulin/clamp).
Q3. What acquisition mode does Rb-82 cardiac PET require, and why?
Answer: Dynamic list-mode imaging begun immediately after infusion — because of Rb-82's ~76-second half-life and to derive MBF/MFR.
Q4. What technique improves PSMA-PET pelvic evaluation, and why?
Answer: Hydration/furosemide to clear urinary bladder activity that would otherwise obscure pelvic disease/nodes.
Evidence & sources
https://nuc.med/acquisition-parameters-pet/ Report an issue