Known or suspected lung cancer — staging

NICE NG122; ACR AC Noninvasive Clinical Staging of Primary Lung Cancer (2019)

Staging is a coverage-and-phase problem. A contrast-enhanced chest CT extended to include the liver, adrenals and lower neck comes first, before any biopsy; FDG PET-CT follows for everyone who might be treated with curative intent; brain imaging is added by histology and stage rather than by symptoms.

A mass or suspicious lesion on chest radiograph or CT, or a new histological diagnosis of lung cancer, where the treatment decision depends on stage.

Referenced decision support — confirm against your local protocol.

Decision support, not a directive. Protocols and timings shown are typical published ones — your local protocol takes precedence, and the vetting radiologist decides.

The request in front of you

Everything is optional. Leave a field alone and the answer assumes nothing — the verdict updates as you go.

Study requested

What the referrer actually asked for. It is evidence of intent, not a constraint on the right answer.

Contrast as written

What the request form says, not what it should say.

Age

Pick a band, or type an exact age if it matters.

years

Pregnancy status

Renal risk factors

The question a vetter can actually answer from the request. An explicit “none known” is a real answer, and it removes checks rather than deferring them.

Previous contrast reaction

The pathway — tap anything already done

Marking a study complete moves the answer on. A patient arrives partway through a pathway far more often than at the start of one.

Accept as requested

CT Chest — Contrast-Enhanced (Venous Phase)

CT Chest

What we'd amend, and why

Nodal and pleural disease is a soft-tissue contrast problem, and soft tissue only separates from vessel once the systemic venous phase has equilibrated at around 60 seconds. An arterial-timed acquisition leaves mediastinal nodes isodense with unopacified vessels and under-calls them; an unenhanced study cannot assess mediastinal or chest wall invasion at all. The coverage is part of the protocol rather than an extra: the liver and adrenals are the two commonest sites of silent metastasis in lung cancer and cost nothing to include, and the lower neck captures supraclavicular nodes that change the nodal stage.

Nothing needs resolving before this goes ahead. Routine checks below are owned downstream.

How was this decided?

pathwayadult — Adults
rulerule-contrast-reaction-premed — Prior contrast reaction and elective premedication; checked by Nurse before the scan
rulerule-metformin — Metformin and iodinated contrast; checked by Radiographer at the scanner
rulerule-paeds-dose — Child-sized technique and contrast dose; checked by Radiographer at the scanner
rulerule-pregnancy-ionising — Pregnancy status before an ionising exposure; checked by Radiographer at the scanner
rulerule-renal-iodinated — Kidney function and intravenous iodinated contrast; checked by Radiographer at the scanner
rulerule-iv-access — Intravenous access adequate for the planned injection; checked by Radiographer at the scanner

Decision support only. Local protocol takes precedence.

Handled at the scanner(4)nothing for you to do

Settled and owned downstream. Each returns to a radiologist only on the stated trigger.

Metformin and iodinated contrast
Confirm whether the patient takes metformin or a metformin-containing combination, and if so whether ACR Category II applies (eGFR below 30, known or suspected AKI, or an arterial catheter study likely to cause renal embolisation). If Category I — that is, no AKI and eGFR at or above 30 — no action of any kind is needed.
Radiographer at the scannerAt the scanner
Flags back if: The patient takes metformin AND meets ACR Category II — eGFR below 30 mL/min/1.73 m2, known or suspected acute kidney injury, or an arterial catheter procedure with likely renal arterial embolisation. Metformin plus a normal or mildly reduced eGFR is explicitly NOT a flag-back: there is no need to stop metformin before or after intravenous iodinated contrast in Category I patients, and no need to re-check creatinine afterwards.
Child-sized technique and contrast dose
Confirm that a size- or weight-based protocol is selected — child-sized kV and mAs against size-based diagnostic reference ranges — and that contrast volume is calculated by weight rather than taken from an adult default. Weight-based iodinated contrast volumes of roughly 1.5–2.0 mL/kg are widely used in paediatric CT.
Radiographer at the scannerAt the scanner
Flags back if: No paediatric or size-based protocol exists on the scanner for the requested examination, or the requested coverage or number of phases exceeds what the clinical question needs — for example a multiphase study where a single phase answers it, or whole-body coverage for a focal question.
Pregnancy status before an ionising exposure
Make the pregnancy enquiry immediately before the exposure and record the answer. In the UK this is a statutory operator duty discharged at the time of exposure under the employer’s written procedures required by IR(ME)R 2017 — it is not something the vetting radiologist can perform or pre-empt, and a request is complete without it.
Radiographer at the scannerAt the scanner
Flags back if: The patient states that she is, or may be, pregnant AND the uterus is in or near the primary beam. The exposure is then paused for re-justification by the IR(ME)R practitioner before it proceeds.
Intravenous access adequate for the planned injection
Site and test a cannula that supports the protocol flow rate, preferring an antecubital or large forearm vein, and observe the injection for extravasation. A 20-gauge or larger cannula is preferred for flow rates of 3 mL/s or more.
Radiographer at the scannerAt the scanner
Flags back if: No cannula can be sited that supports the protocol flow rate — for example only a 22-gauge hand or foot cannula for a CT angiogram needing 4–5 mL/s; or the only available access is a central line or port that is not labelled power-injectable; or an extravasation occurs.

Pathways

Big forks are separate pathways; the first whose conditions match is the one used.

Adults

Matches your inputsDefault

Role	Study & protocol	Why this answers the question
First line	CT Chest CT Chest — Contrast-Enhanced (Venous Phase) usually appropriate	Nodal and pleural disease is a soft-tissue contrast problem, and soft tissue only separates from vessel once the systemic venous phase has equilibrated at around 60 seconds. An arterial-timed acquisition leaves mediastinal nodes isodense with unopacified vessels and under-calls them; an unenhanced study cannot assess mediastinal or chest wall invasion at all. The coverage is part of the protocol rather than an extra: the liver and adrenals are the two commonest sites of silent metastasis in lung cancer and cost nothing to include, and the lower neck captures supraclavicular nodes that change the nodal stage.
Second line	FDG PET-CT FDG PET-CT — skull base to mid-thigh usually appropriate	Metabolic staging finds the disease that anatomy misses — normal-sized but involved nodes, and unsuspected distant metastases that convert a planned resection into systemic treatment. It earns its place specifically in the group who could be treated with curative intent, because that is where a change in stage changes the operation. Its weakness is specificity: granulomatous and other inflammatory nodes are avid, so an isolated avid mediastinal node in a patient otherwise fit for surgery is a reason to sample, not a reason to abandon.
Problem solving	MRI Brain MRI Brain — with gadolinium	Contrast-enhanced brain MRI is the sensitive test for intracranial metastasis and finds lesions that CT does not, which is why it is applied by histology and stage rather than by neurological symptoms. The trigger belongs on the step rather than only in the notes: small cell disease earns brain imaging in every patient at diagnosis regardless of symptoms, and non-small cell disease earns it from stage II upwards in anyone being considered for treatment with curative intent — a meaningful minority of whom have occult intracranial disease that converts a planned resection into a different treatment altogether. FDG PET does not cover this: the normal cortex is intensely avid, so metastases are hidden in physiological background.

Pitfalls

Accepting a chest-only acquisition when the staging question needs the liver and adrenals — the repeat scan costs another cannula, another dose and a week of the pathway.
Requesting PET-CT before the diagnostic contrast CT. PET without a good anatomical staging study leaves the surgical planning questions unanswered and often has to be repeated.
Arterial-phase timing on a staging chest CT, which under-shows nodal and pleural enhancement.
Interpreting FDG avidity as proof of malignancy. Sarcoid, tuberculosis and other granulomatous nodes are avid, and in endemic populations mediastinal specificity falls substantially.
Omitting brain imaging in an asymptomatic small cell patient, where a meaningful proportion have occult intracranial disease at diagnosis.
Staging a superior sulcus tumour on CT alone. A Pancoast lesion is a T-stage question about the brachial plexus, the subclavian vessels, the vertebral body and the neural foramina, and every one of those is a soft-tissue boundary that MRI resolves and CT does not — so a CT that calls a superior sulcus tumour resectable has not answered the question the surgeon asked. The same applies to any tumour abutting the spine or the chest wall where the operative plan depends on the depth of invasion.
Treating an avid mediastinal node on PET as a staging conclusion. Nodal stage decides between resection and systemic treatment, so an isolated avid node in an otherwise operable patient is a reason for endobronchial ultrasound or mediastinoscopy — the commonest way a curable patient loses the operation is a nodal stage assigned from imaging alone.
Ignoring a pleural effusion in a staging study. A malignant effusion is M1a disease and takes resection off the table, and the way to establish it is sampling and a CT acquired before the fluid is drained — which is a different card and a sequencing decision this one should hand over rather than assume.

Priors — what to pull first

Find the study that first showed the lesion — an apparent T1 nodule that has been present and unchanged for three years is not the staging problem the request describes.
If a biopsy has already been performed, note the date: post-procedural change in the same lobe should not be staged as tumour extension.

What makes a good request

A good request states the working diagnosis, whether tissue has already been taken, and whether the patient is a candidate for treatment with curative intent — the last of these is what justifies PET-CT.
Sequence matters: the staging CT should precede biopsy, because post-biopsy haemorrhage, pneumothorax and reactive nodal enlargement all degrade the staging read.
Small cell and non-small cell disease diverge for brain imaging. Brain MRI is advised in all small cell patients regardless of symptoms, and in stage II and above non-small cell disease, because a substantial minority of asymptomatic patients have intracranial metastases.

Scoring this once it is done

The classification and risk tools this question ends in.

Lung Cancer TNM Staging (9th Edition)RECIST 1.1 Tumor Response PERCIST 1.0 PET Response eGFR (CKD-EPI 2021 Creatinine)Lung-RADS v2022 (Screening LDCT)

How these studies are acquired

Contrast, phases and timing for every study on the pathways above.

CT Chest — Contrast-Enhanced (Venous Phase)FDG PET-CT — skull base to mid-thigh MRI Brain — with gadolinium

Confirm locally

CT Chest — Contrast-Enhanced (Venous Phase): timings are typical — confirm against local protocol.
Timings, contrast volumes and rates above are typical published values. Your department's protocol, scanner and patient population decide the actual numbers.
Safety thresholds and premedication policy follow local policy where it differs from the cited guidance.

References

Implemented from the cited published sources. Educational and workflow support only; confirm against current guidelines and local policy before clinical use.