Suspected pancreatic mass or painless obstructive jaundice

ACR AC Staging of Pancreatic Ductal Adenocarcinoma

The indication that most clearly proves the design point: the right body part imaged in the wrong phase is a wrong study. A routine portal-venous abdomen and a pancreas-protocol CT are both "CT abdomen with contrast", and only one of them shows the tumour.

Painless jaundice with weight loss, a mass or duct dilatation seen on ultrasound, or new-onset diabetes with weight loss in an older patient.

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 Pancreas — Dual Phase with Water Distension

CT Pancreas Protocol

What we'd amend, and why

Ductal adenocarcinoma is a desmoplastic, hypovascular tumour sitting in richly vascular parenchyma. In the pancreatic parenchymal phase the normal gland has reached peak enhancement while the fibrous tumour has not, so the attenuation difference between the two — the only thing that makes the tumour visible — is at its maximum. By the portal venous phase the parenchyma has fallen and the tumour has slowly accumulated contrast, the two converge, and a small tumour becomes isoattenuating and disappears. The same early acquisition is what shows arterial contact for resectability, while the venous acquisition shows portal and superior mesenteric vein involvement and liver metastases. Water rather than positive oral contrast is used so the duodenal wall and ampulla remain visible.

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 Pancreas Protocol CT Pancreas — Dual Phase with Water Distension usually appropriate	Ductal adenocarcinoma is a desmoplastic, hypovascular tumour sitting in richly vascular parenchyma. In the pancreatic parenchymal phase the normal gland has reached peak enhancement while the fibrous tumour has not, so the attenuation difference between the two — the only thing that makes the tumour visible — is at its maximum. By the portal venous phase the parenchyma has fallen and the tumour has slowly accumulated contrast, the two converge, and a small tumour becomes isoattenuating and disappears. The same early acquisition is what shows arterial contact for resectability, while the venous acquisition shows portal and superior mesenteric vein involvement and liver metastases. Water rather than positive oral contrast is used so the duodenal wall and ampulla remain visible.
Reasonable alternative	Ultrasound abdomen Ultrasound abdomen — full survey	Where the presentation is undifferentiated jaundice rather than a suspected mass, ultrasound is the appropriate opening move: it establishes that the obstruction is mechanical and often shows the level. It cannot stage, and a normal pancreas on ultrasound is weak evidence because bowel gas obscures the body and tail.
Problem solving	MRI Pancreas MRI Pancreas — dynamic contrast-enhanced with MRCP	When CT shows duct obstruction but no mass, MRI supplies contrast mechanisms CT does not have. On unenhanced fat-suppressed T1 the normal pancreas is intrinsically bright because of its acinar protein content, and a tumour is dark against it — a difference that persists even when the lesion is isoattenuating on CT. The integrated cholangiographic sequences map the duct at the same visit.
Second line	CT Chest CT Chest — Contrast-Enhanced (Venous Phase)	Thoracic imaging completes distant staging once a pancreatic tumour is confirmed, because pulmonary metastases change intent from curative to palliative and are outside the coverage of a dedicated pancreatic acquisition.

Pitfalls

Accepting a routine portal-venous CT abdomen and pelvis. It is the phase in which a small ductal adenocarcinoma is least visible, and a negative report from it is not reassurance.
Allowing positive oral contrast, which obscures the duodenum and ampulla and degrades vascular assessment.
Stopping at duct dilatation without a mass. An abrupt duct cut-off with upstream atrophy is a tumour until proven otherwise and needs MRI or endoscopic ultrasound.
Reporting resectability without describing the degree of circumferential arterial and venous contact, which is the number the surgeons act on.
Assuming every pancreatic mass is adenocarcinoma; a hypervascular lesion conspicuous in the early phase is more likely a neuroendocrine tumour and follows a different pathway.

Priors — what to pull first

Look back at any abdominal CT from the preceding two years for a subtle duct calibre change or a small cyst at the same site — pancreatic cancer is frequently visible in retrospect.
If a stent has been placed, compare with the pre-stent imaging, which usually shows the tumour more clearly.

What makes a good request

If a tumour is found, the report is a resectability document, not a detection document — arterial and venous contact, and the presence of metastases, decide whether the patient is offered surgery.
Where a biliary stent has already been placed, say so: stent-related duct changes and pneumobilia alter both the appearances and the timing of staging.

Scoring this once it is done

The classification and risk tools this question ends in.

eGFR (CKD-EPI 2021 Creatinine)RECIST 1.1 Tumor Response Lutathera Dose Modification for Adverse Reactions

How these studies are acquired

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

CT Pancreas — Dual Phase with Water Distension Ultrasound abdomen — full survey MRI Pancreas — dynamic contrast-enhanced with MRCP CT Chest — Contrast-Enhanced (Venous Phase)

Confirm locally

CT Pancreas — Dual Phase with Water Distension: 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.