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Procedures · Administration

Administration & Extravasation

Snapshot

Most radiopharmaceuticals are given intravenously through a reliable, flushed cannula. The activity is measured in a calibrated dose calibrator before injection and the residual afterwards, so that the net activity (and the SUV) is right. The main avoidable error is paravenous injection (extravasation). With diagnostic tracers it is common and usually harmless, but it lowers counts and SUV and can create a false draining-node focus. With therapy agents it needs a defined management protocol.

Good technique protects image quality, quantitation and the patient. Some studies need their own technique: MAA is given supine and slowly, without drawing back blood. Other routes have their own rules: interstitial for sentinel nodes, intrathecal for cisternography, oral or inhaled for gastric and ventilation studies.

≥10 mLSaline flush after FDG (EANM)
6.2%PET infiltration rate, 7 centres
20 GySkin ulceration threshold
Reference values
  • FDG (EANM v2.0): cannula in place ideally 10 min before injection; three-way tap; flush with ≥10 mL 0.9% saline; measure residual activity in the syringe and lines to derive net activity; record the injection time on synchronised clocks; automated injectors accurate to within 3%.
  • PET infiltration: 6.2% (range 2–16%) of 5,541 injections at 7 centres, cut from 8.9% to 4.6% by quality improvement (Wong 2019); 10.5% of 400 whole-body FDG scans, with 31% of them outside the usual skull-base-to-thigh field (Osman 2011).
  • MAA particles: about 400,000 usual (60,000 enough to show regional perfusion); 100,000–200,000 in pulmonary hypertension, right-to-left shunt, pneumonectomy or single-lung transplant (EANM 2019). SNM 2012: 200,000–700,000.
  • MAA activity: 140–160 MBq for perfusion SPECT (EANM 2019); 40–150 MBq (SNM 2012); pregnancy: perfusion-only on day 1 with 50 MBq.
  • Therapy extravasation: tissue doses of 6–10 Gy reported after ¹⁷⁷Lu, below the 20 Gy threshold for ulceration and permanent skin breakdown; clearance half-life from the arm 1.2–3 h (EANM Dosimetry Committee 2022).

Good practice

  • Measure the activity in a dose calibrator under a quality-control programme, then measure the syringe (and line) residual after injection. Record net activity, injection time and injection site; the SUV depends on the first two.
  • Use a free-flowing cannula, ideally placed about 10 min before FDG, and confirm patency with saline. A three-way tap separates tracer and flush; flush with at least 10 mL of saline afterwards (EANM FDG v2.0).
  • Inject on the side opposite the site of concern (SNMMI FDG guideline) — for example the arm opposite a breast cancer — so that any injection-site or nodal activity does not confuse the report.
  • Automated PET injectors lower finger dose to staff and must deliver the prescribed activity to within 3%.

Study-specific technique

  • ⁹⁹ᵐTc-MAA: shake the vial; inject with the patient supine, slowly over about 30 s (several breaths); never draw blood back into the syringe, because MAA aggregates with blood and gives artefactual hot spots; avoid lines with filters and Swan–Ganz catheters (EANM 2019; SNM 2012).
  • Reduce the MAA particle number to 100,000–200,000 in known pulmonary hypertension, right-to-left shunt, pneumonectomy or single-lung transplant, and by weight in children. In pregnancy the activity is reduced (perfusion-only with 50 MBq), not the particle number. See V/Q imaging.
  • Sentinel node mapping uses interstitial (for example peritumoural) injection. See sentinel node.
  • Cisternography needs a sterile intrathecal (lumbar) injection. See CSF imaging.

Extravasation of diagnostic tracers

  • It is common: 3–23% across published PET series and 6.2% in a 7-centre audit. Sites other than the antecubital fossa and higher injected activity carried more risk, and larger flush volumes less (Wong 2019).
  • Effects: less tracer reaches the circulation, so organ counts and SUVs fall (liver SUVmax 11.7% lower in paired studies; Osman 2011). Lymphatic drainage can make a focus in the axillary nodes on the injected side.
  • Include the injection site in the field or image it separately when infiltration is suspected; a limited skull-base-to-thigh field missed 31% of extravasations in one series.
  • No specific treatment is needed for ⁹⁹ᵐTc-, ¹²³I-, ¹⁸F- or ⁶⁸Ga-labelled tracers (van der Pol 2017). Record it in the report, and repeat the study if quantitation is essential and the SUV is compromised.

Extravasation of therapy agents

  • Stop the infusion at once and disconnect the line, but leave the cannula in place to try to aspirate the extravasate; do not aspirate directly from tissue (Gebruers 2025).
  • Mark the affected area on the skin, photograph it and inform the responsible physician.
  • Promote lymphatic drainage: elevate the arm, use gentle self-massage, a stress ball or hand-pumping exercise. Heat or cold is controversial; if used, heat is preferred.
  • Measure the dose rate over the site at least twice and image it (SPECT at about 2, 4 and 24 h is suggested for ¹⁷⁷Lu) to estimate retained activity, effective half-life and absorbed dose (EANM 2022).
  • Arrange clinical follow-up, and involve a surgeon if serious injury is suspected. Severe injuries have followed radiosynoviorthesis and large molecules such as ⁹⁰Y-ibritumomab tiuxetan. None have been reported after PRRT or PSMA radioligand therapy.

Pitfalls

  • A draining-node focus on the injected side misread as metastasis.
  • SUV underestimated because the residual or the paravenous dose was not accounted for.
  • MAA hot spots from blood drawn back into the syringe, or from an unflushed indwelling line.
  • A therapy infiltration found only on post-therapy imaging because the site was not checked during infusion.
In depth
  • Osman et al. found FDG extravasation in 42 of 400 true whole-body scans. The injection site was at or distal to the antecubital fossa in 97% of studies, and 13 of the 42 infiltrates lay outside the limited whole-body field. In 5 paired patients, mediastinal SUVmax was 9.3% lower with infiltration.
  • In an earlier FDG PET/CT series, 21% of 190 studies showed a visible injection-site focus. Most held ≤1% of the injected dose, but three held 3.0%, 7.7% and 17.5%, and SUVmax changed by 0–21% (Hall 2006).
  • A literature pool of 6 PET studies found infiltration in 425 of 2,804 patients (15.2%). The multicentre audit that reported 6.2% used topical sensors and was supported by the sensor manufacturer.
  • Of 3,016 reported diagnostic extravasations, only 3 caused symptoms, after ²⁰¹Tl and ¹³¹I-iodocholesterol. The same review advises surgical assessment, dispersive measures, dosimetry and follow-up for therapy extravasation, but no drug treatment.
  • Worst case for ¹⁷⁷Lu: 7.4 GBq retained without clearance in 100 cm³ of tissue would deliver about 1,400 Gy. Real infiltrates clear with half-lives of 1.2–3 h, and the basal epidermal layer dose in one case was about 3 Gy.
  • Fewer than about 100,000 MAA particles in an adult can give an inhomogeneous perfusion pattern. That is why the reduced range in pulmonary hypertension stops at 100,000–200,000 (SNM 2012).
  • In the US, extravasation has been excluded from medical-event reporting. An NRC rulemaking (proposed rule 2024) would make extravasations that need medical attention for suspected radiation injury reportable.

Sources: Osman 2011 (PMID 22655246) · Hall et al. J Nucl Med 2006;47 suppl 1:115P · Wong 2019 (PMID 31182666) · van der Pol 2017 (PMID 28303300) · EANM Dosimetry Committee 2022 (PMID 35284969) · SNM lung scintigraphy 4.0 (PMID 22282651) · NRC extravasation rulemaking (NRC-2022-0218)

Sources

  1. Boellaard R, Delgado-Bolton R, Oyen WJG, et al. FDG PET/CT: EANM procedure guidelines for tumour imaging: version 2.0. Eur J Nucl Med Mol Imaging. 2015;42:328–354.
  2. Bajc M, Schümichen C, Grüning T, et al. EANM guideline for ventilation/perfusion single-photon emission computed tomography (SPECT) for diagnosis of pulmonary embolism and beyond. Eur J Nucl Med Mol Imaging. 2019;46:2429–2451.
  3. Parker JA, Coleman RE, Grady E, et al. SNM practice guideline for lung scintigraphy 4.0. J Nucl Med Technol. 2012;40:57–65.
  4. van der Pol J, Vöö S, Bucerius J, Mottaghy FM. Consequences of radiopharmaceutical extravasation and therapeutic interventions: a systematic review. Eur J Nucl Med Mol Imaging. 2017;44:1234–1243.
  5. Wong TZ, Benefield T, Masters S, et al. Quality improvement initiatives to assess and improve PET/CT injection infiltration rates at multiple centers. J Nucl Med Technol. 2019;47:326–331.
  6. Osman MM, Muzaffar R, Altinyay ME, Teymouri C. FDG dose extravasations in PET/CT: frequency and impact on SUV measurements. Front Oncol. 2011;1:41.
  7. Sjögreen Gleisner K, Chouin N, Gabina PM, et al. EANM dosimetry committee recommendations for dosimetry of ¹⁷⁷Lu-labelled somatostatin-receptor- and PSMA-targeting ligands. Eur J Nucl Med Mol Imaging. 2022;49:1778–1809.
  8. Gebruers J, Terwinghe C, Graven LH, et al. Extravasation of therapeutic radiopharmaceuticals: a systematic review and management proposal. J Nucl Med. 2025;66:1948–1955.
  9. Delbeke D, Coleman RE, Guiberteau MJ, et al. Procedure guideline for tumor imaging with ¹⁸F-FDG PET/CT 1.0. J Nucl Med. 2006;47:885–895.
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