Bladder cancer — pretreatment staging

ACR AC Pretreatment Staging of MIBC; VI-RADS

Urothelial cancer is a field disease, so staging a bladder tumour means imaging the entire urothelium, not just the pelvis. A routine portal-venous CT abdomen and pelvis leaves the upper tracts unassessed and is explicitly not the staging study.

Bladder tumour identified at cystoscopy or on imaging, requiring assessment of local extent, upper tract synchronous disease and distant spread before treatment.

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 Urogram — Split Bolus

CT Urogram

What we'd amend, and why

The excretory acquisition is the point. Opacified urine outlines the calyces, renal pelves and ureters, so a synchronous upper tract tumour appears as a filling defect in a system that is otherwise invisible on a venous-phase scan. The same study stages the abdomen and pelvis for nodal and visceral disease. The split-bolus technique compresses nephrographic and excretory information into one acquisition, which matters in a population that will be imaged repeatedly for surveillance.

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

How was this decided?

pathwaystandard — Adults — pretreatment staging
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 — pretreatment staging

Matches your inputsDefault

Role	Study & protocol	Why this answers the question
First line	CT Urogram CT Urogram — Split Bolus usually appropriate	The excretory acquisition is the point. Opacified urine outlines the calyces, renal pelves and ureters, so a synchronous upper tract tumour appears as a filling defect in a system that is otherwise invisible on a venous-phase scan. The same study stages the abdomen and pelvis for nodal and visceral disease. The split-bolus technique compresses nephrographic and excretory information into one acquisition, which matters in a population that will be imaged repeatedly for surveillance.
Second line	MRI abdomen and pelvis MRI abdomen/pelvis — non-contrast rapid protocol	Local T-staging: the discriminator for muscle invasion is whether the low-signal muscularis propria line is interrupted, judged on high-resolution T2 with diffusion and an early dynamic series. A structured bladder MRI protocol is required for that assessment and should be specified locally, because the generic pelvic protocol referenced here omits the dynamic sequence on which the scoring depends.
First line	CT Chest CT Chest — Contrast-Enhanced (Venous Phase)	Thoracic assessment completes the metastatic survey; lung and mediastinal nodes are common sites and a chest radiograph is frequently adequate in low-stage disease but not once muscle invasion is established.
Problem solving	FDG PET-CT FDG PET-CT — skull base to mid-thigh	May add nodal and distant information where CT is equivocal and the finding would change between radical and systemic treatment. Its weakness here is anatomical rather than biological: excreted tracer fills the bladder and obscures the primary, which is why it supplements rather than replaces CT urography.

Pitfalls

Accepting a routine portal-venous CT abdomen and pelvis as a staging study. The upper tracts are not assessed and synchronous urothelial disease is missed.
Dense layering excreted contrast in the bladder concealing a tumour at the bladder base — a prone or supplementary delayed acquisition is often needed.
Reporting a non-opacified ureteric segment as normal. It is unassessed, not clear.
Local staging MRI performed too soon after resection, where oedema is over-called as muscle invasion.
Staging CT performed immediately after transurethral resection, where perivesical stranding and haemorrhage read as extravesical tumour and push the patient up a stage.
Relying on PET to assess the primary tumour when excreted tracer in the bladder makes that assessment unreliable.

Priors — what to pull first

Obtain the cystoscopy and resection findings: tumour site, size, number and whether muscle was present in the specimen determine what the imaging needs to add.
Note the date of the last resection — MRI local staging within about two weeks of resection is dominated by post-operative change.

What makes a good request

Pretreatment staging should cover the upper tract urothelium for synchronous lesions, the chest, abdomen and pelvis for metastases, and the bladder wall itself for local T-stage. Non-urogram CT of the abdomen and pelvis is rated as usually not appropriate for this purpose.
Local T-staging by multiparametric MRI of the bladder, scored with a structured system, predicts muscle invasion well enough to influence whether a repeat resection is needed. That bladder-specific MRI protocol has no node in this vocabulary; the generic pelvic MRI step below is a placeholder for it and the protocol must be specified locally.
Timing relative to resection matters, and it matters for the CT as well as the MRI. MRI is best performed before transurethral resection, or at least a couple of weeks afterwards, because post-resection oedema is indistinguishable from tumour in the bladder wall; the staging CT urogram has the same problem in a different tissue, since perivesical fat stranding and haemorrhage after resection cannot be told from extravesical tumour and systematically overstage local extent. Where the sequence can be arranged, both are better acquired before resection.
Bone scintigraphy and ultrasound have no routine role in pretreatment staging of muscle-invasive disease.

Scoring this once it is done

The classification and risk tools this question ends in.

VI-RADS (Bladder Cancer Muscle Invasion, mpMRI)AAST Bladder Injury Scale

How these studies are acquired

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

CT Urogram — Split Bolus MRI abdomen/pelvis — non-contrast rapid protocol CT Chest — Contrast-Enhanced (Venous Phase)FDG PET-CT — skull base to mid-thigh

Confirm locally

CT Urogram — Split Bolus: 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.