Head and neck cancer — staging and post-treatment surveillance

ACR AC Head and Neck Cancer (2023); ACR NI-RADS

Two related questions with different answers. Staging needs high-resolution local imaging matched to the subsite plus nodal and thoracic assessment. Surveillance needs a baseline at the right interval after treatment — too early and treatment change masquerades as residual tumour.

Newly diagnosed mucosal head and neck carcinoma requiring staging, or a treated patient under surveillance with suspected residual or recurrent disease.

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 Neck — Contrast-Enhanced Soft Tissue

CT Neck (Soft Tissues)

What we'd amend, and why

Contrast-enhanced neck CT separates node from vessel, shows nodal necrosis and extranodal extension, and demonstrates cartilage and cortical bone better than MRI. Acquisition is fast enough that swallowing and respiratory motion do not degrade it, which matters in a symptomatic patient with a compromised airway. Timing is the technical decision: too early and nodes and vessels are equally dense, defeating nodal staging.

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

How was this decided?

pathwaystandard — Adults — staging and surveillance
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-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(3)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.
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 — staging and surveillance

Matches your inputsDefault

Role	Study & protocol	Why this answers the question
First line	CT Neck (Soft Tissues) CT Neck — Contrast-Enhanced Soft Tissue usually appropriate	Contrast-enhanced neck CT separates node from vessel, shows nodal necrosis and extranodal extension, and demonstrates cartilage and cortical bone better than MRI. Acquisition is fast enough that swallowing and respiratory motion do not degrade it, which matters in a symptomatic patient with a compromised airway. Timing is the technical decision: too early and nodes and vessels are equally dense, defeating nodal staging.
Reasonable alternative	MRI Head and Neck (Soft Tissue Neck) MRI Neck — head and neck cancer staging	The better local staging test wherever soft-tissue extent decides the operation: tongue and floor of mouth, tonsil and tongue base, nasopharynx, and any tumour that may be tracking along a named cranial nerve. Mandibular and skull base marrow invasion is an MRI diagnosis, and coronal fat-suppressed post-contrast imaging is the plane in which it is made.
Second line	FDG PET-CT FDG PET-CT — skull base to mid-thigh	The workhorse of post-treatment assessment: performed at around 12 weeks it distinguishes residual viable tumour from post-radiotherapy change with high negative predictive value, and simultaneously screens for distant metastases and synchronous primaries, which are common enough in this population to change management.
First line	CT Chest CT Chest — Contrast-Enhanced (Venous Phase)	Thoracic imaging is part of staging in this group both for metastatic disease and for a synchronous lung primary, which shares the same smoking and alcohol risk profile.

Pitfalls

Imaging too soon after chemoradiotherapy. Before roughly 12 weeks, treatment-related enhancement and FDG uptake produce false positives and unnecessary biopsies.
Using one large field of view for both the primary and the nodes on MRI, so the primary is under-resolved exactly where the deep margin matters.
Accepting a plain CT for a tongue base or nasopharyngeal primary, where dental amalgam streak and poor soft-tissue contrast hide the tumour.
Missing perineural spread because coronal post-contrast imaging through the skull base foramina was not acquired.
Scanning with the arms up, driving shoulder streak through the lower neck and supraclavicular nodal stations.

Priors — what to pull first

The pre-treatment study is the essential comparator for every surveillance scan; without it, post-treatment distortion cannot be separated from residual disease.
Record the radiotherapy fields and the completion date. Enhancement and oedema within a treated field have a predictable time course.

What makes a good request

Subsite decides modality. Larynx and hypopharynx are well served by contrast-enhanced CT, which is fast and immune to swallowing motion; oral cavity, oropharynx, nasopharynx and sinonasal disease need MRI for marrow invasion, deep muscular extent and perineural spread.
The first post-treatment study is conventionally performed around 12 weeks after completion of chemoradiotherapy. Earlier imaging is dominated by oedema and inflammatory enhancement and generates false positives that lead to unnecessary biopsy.
Structured reporting of surveillance studies links an imaging category to a management recommendation, which is why the baseline and follow-up should be performed on the same modality and protocol.

Scoring this once it is done

The classification and risk tools this question ends in.

NI-RADS (Head & Neck Surveillance)

How these studies are acquired

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

CT Neck — Contrast-Enhanced Soft Tissue MRI Neck — head and neck cancer staging FDG PET-CT — skull base to mid-thigh CT Chest — Contrast-Enhanced (Venous Phase)

Confirm locally

CT Neck — Contrast-Enhanced Soft Tissue: 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.