MRI Pancreas — dynamic contrast-enhanced with MRCP
Whole pancreas, peripancreatic vessels and the biliary tree; portal venous phase extended to include the liver for metastases.
Timings, volumes and delays here are representative values drawn from published guidance. Scanner generation, injector, cardiac output and local preference all move them. Confirm against your department's own protocol before you rely on a number.
When to use it
- Characterisation and surveillance of pancreatic cystic lesions, where duct communication and mural nodules decide management.
- Suspected small pancreatic neuroendocrine tumour, which is often conspicuous only on the early enhanced phase.
- Suspected ductal adenocarcinoma where CT is equivocal, especially for small isoattenuating tumours.
- Suspected autoimmune pancreatitis, where the delayed enhancement pattern and capsule-like rim are characteristic.
- Chronic pancreatitis assessment including duct morphology and parenchymal signal.
Technique
- Unenhanced fat-suppressed T1 gradient-echo is the sequence in which normal pancreas is brightest and a tumour is most conspicuous; it must not be skipped.
- Axial and coronal T2, diffusion with low and high b values, and a 3D MRCP acquisition.
- Dynamic fat-suppressed 3D T1 in early (pancreatic parenchymal) and portal venous phases, then a delayed acquisition. The pancreatic parenchymal phase sits between conventional arterial and portal venous timings, at roughly 35-45 seconds, and centres differ on how they label it.
- Thin sections and small field of view are needed to resolve a mural nodule from mucin or debris.
Where it goes wrong
- Skipping the unenhanced fat-suppressed T1, on which a small tumour may be the only visible abnormality.
- Only acquiring a portal venous phase, so a hypervascular neuroendocrine tumour has already equilibrated with parenchyma.
- Slice thickness too great to distinguish a genuine enhancing mural nodule from non-enhancing mucin.
- Not repeating the same phases and planes on surveillance studies, making small interval change uninterpretable.
- Relying on MRCP alone for a solid-lesion question.
Clinical questions that reach this study
Contrast
Extracellular macrocyclic gadolinium agent at a typical single dose of about 0.1 mmol/kg by power injector with saline chaser, timed by bolus tracking or test bolus.
Acquisition
- Breathing
- End-expiratory breath-holds for the dynamic phases; respiratory triggering for the 3D MRCP acquisition.
- Preparation
- Fasting as for MRCP; the ductal sequences are part of the study. For cyst surveillance, supply the date and measurements of the previous study so the same phases and planes can be matched. Contrast is needed for mural nodule and solid-lesion questions but not for pure duct-morphology follow-up.
Phases
Each phase is authored once and shared across every protocol that uses it, so the physiology below is the same wherever you meet it.
- Non-contrast (unenhanced)No injection. Acquired before any contrast is given.
Shows intrinsic tissue attenuation, and nothing else. The transferable principle is that contrast is anti-signal for anything that is already dense: calcification, acute haemorrhage, urinary and biliary calculi, iodine-containing or haemorrhagic fluid, and intrinsic fat all lose conspicuity, or become uninterpretable, once surrounding tissue enhances. It is also the only baseline against which enhancement can be measured, so any protocol that quantifies enhancement or washout (a lesion "enhances by X HU", adrenal absolute washout, renal mass characterisation) is arithmetically impossible without it. Conversely, an unenhanced series adds dose and no information whenever the question is purely about vascularity or perfusion.
- Late arterial phase (arterial-dominant)Typically ~30–40 s after the start of injection. Confirm locally.
Arteries are still dense and solid organs supplied by arteries have begun to enhance, but the portal vein has not yet delivered its load to the liver. The transferable principle is that HYPERVASCULAR lesions peak here and are maximally conspicuous against a still-dark background: this is where arterially hyperenhancing tumours, hypervascular metastases and vascular malformations declare themselves. The window is narrow and cardiac-output dependent — mistiming by ten seconds in either direction converts a diagnostic study into a non-diagnostic one, which is why bolus tracking rather than a fixed delay is preferred whenever the clinical question is hypervascularity.
- Portal venous phaseTypically ~60–90 s after the start of injection. Confirm locally.
The portal vein and hepatic veins are opacified and the liver is at maximum parenchymal enhancement; bowel wall, mesentery, spleen and peritoneum are all well enhanced. The transferable principle is that HYPOVASCULAR lesions are most conspicuous when the BACKGROUND peaks, so this is the single most productive general-purpose abdominal phase and the correct default when the question is "what is wrong in this abdomen?". Its corollary is the classic error: a hypervascular lesion that was obvious 30 s earlier can become isodense and invisible here, so a normal portal venous study never excludes hypervascular disease.
- Delayed / equilibrium (washout) phaseQuestion-dependent: ~3–5 min for hepatic equilibrium/washout, ~15 min for adrenal absolute-washout calculations. Confirm locally.
Intravascular and interstitial compartments have equilibrated and contrast is being cleared, so most normal tissue is falling in attenuation. The transferable principle is that the diagnostic information is now in the RATE OF CHANGE rather than in the absolute density: tissues with rapid capillary exchange and a small interstitium wash out quickly, whereas fibrous, myxoid or otherwise expanded interstitial spaces retain contrast and become relatively dense. That single mechanism underlies delayed enhancement of scar and fibrosis, retained enhancement in cholangiocarcinoma and haemangioma fill-in, and the arithmetic of adrenal washout — all of which require a matched earlier acquisition to be interpretable at all.
Safety checks this protocol carries
Derived from the contrast agent and phases above, not authored here — which is why they cannot drift apart from what the protocol actually does.
- Prior contrast reaction and elective premedication· nurse pre scan
- Kidney function and gadolinium-based contrast· radiographer at scan
- Intravenous access adequate for the planned injection· radiographer at scan
- Metformin and iodinated contrast· radiographer at scan
- MR safety screening for implants and foreign bodies· radiographer at scan
- Kidney function and intravenous iodinated contrast· radiographer at scan