MRI Pelvis — endometrial cancer staging
Uterus and pelvis, extended superiorly to cover the para-aortic nodal station where nodal staging is required.
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.
Premedication
Given to make the acquisition work, not to treat the patient. Doses are typical — confirm against your local protocol and prescribe within your own governance.
Suppression of small bowel peristalsis over the pelvis. The measurement this study exists to make is the depth of myometrial invasion relative to the full myometrial thickness, judged on a thin oblique-axial T2 and on the equilibrium-phase enhanced image; motion of overlying bowel propagates ghosting across the uterus in the phase-encoding direction and blurs the junctional zone that the measurement is taken from.
- Dose and route
- Typically 20 mg intravenously, or about 20 mg intramuscularly. Glucagon roughly 0.25-1 mg intravenously where hyoscine is contraindicated or unavailable.
- When
- Immediately before the high-resolution oblique T2 and diffusion series. Where the enhanced acquisition is the decisive one locally, a repeat dose before the post-contrast series is the usual approach, as the effect does not last the length of the examination.
- Do not give if
- If glucagon is used instead of hyoscine, it carries its OWN absolute contraindications rather than inheriting a clean slate: phaeochromocytoma, where it provokes catecholamine release and hypertensive crisis, and insulinoma or glucagonoma, where it causes rebound hypoglycaemia. It also raises blood glucose transiently, which matters in diabetes, and commonly causes nausea and vomiting.
- MHRA Drug Safety Update (February 2017), issued after nine reported deaths mostly from cardiac arrest: in patients with cardiac disease, monitor the patient and ensure resuscitation equipment AND staff trained to use it are readily available before giving it. This is an availability requirement, not a caution to note and move past.
- Practice varies. ESUR technique recommendations support a spasmolytic for female pelvic MRI where it is available and not contraindicated, but it is not given in every department and should be read as the local protocol rather than a universal step.
- Contraindicated in untreated angle-closure glaucoma, myasthenia gravis, megacolon, and significant tachyarrhythmia.
- Caution in prostatic enlargement with urinary retention, and in significant cardiac disease.
- Warn the patient about transient blurred vision, and that they must not drive until it resolves.
- If unsuitable
- Proceed without it. Bowel motion can also be reduced by fasting for a few hours beforehand and by prone positioning or an abdominal binder where tolerated, and a repeated oblique-axial acquisition often recovers the plane that matters.
When to use it
- Newly diagnosed endometrial carcinoma requiring assessment of depth of myometrial invasion.
- Assessment of cervical stromal involvement, which changes surgical planning.
- Nodal staging and detection of extrauterine spread.
- Assessment before fertility-sparing management.
- Suspected recurrence in the pelvis.
Technique
- Sagittal T2 plus an oblique-axial T2 angled perpendicular to the endometrial cavity — the plane in which myometrial invasion depth is actually measurable.
- Oblique-coronal T2 along the cavity for the cornual regions.
- Diffusion-weighted imaging in the same oblique plane, which is now a core sequence for junctional-zone assessment.
- Dynamic or delayed contrast-enhanced T1: the tumour-myometrium contrast is maximal on the equilibrium-type image rather than on the earliest post-contrast acquisition.
Where it goes wrong
- Straight axial images rather than a plane perpendicular to the cavity, which systematically distorts the measurement of invasion depth.
- Using only an early post-contrast acquisition, when the discriminating contrast appears later.
- Coverage not extended for para-aortic nodes when nodal staging was the point of the request.
- Diffusion acquired in a different plane from the T2, preventing direct correlation.
- A markedly distended endometrial cavity or a large fibroid thinning the myometrium and producing an overcall of deep invasion.
Clinical questions that reach this study
Contrast
Macrocyclic gadolinium agent at a typical single dose of about 0.1 mmol/kg; the acquisition used to judge myometrial invasion is an equilibrium-type image obtained a couple of minutes after injection, when the contrast between tumour and enhancing myometrium is greatest.
Acquisition
- Breathing
- Free breathing with an antiperistaltic agent.
- Preparation
- Moderate bladder filling is wanted for most gynaecological protocols; an over-full bladder causes motion and an empty one loses anatomical separation. Fasting for a few hours plus an antiperistaltic agent reduces bowel motion for high-resolution sequences. Intrauterine devices are MR-conditional in general but must still be declared at screening.
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.
- Dynamic contrast-enhanced series (multiphase gadolinium)A late arterial acquisition timed to about 15–20 s after contrast reaches the target artery (fluoroscopically triggered or test-bolus timed), a portal venous/early venous acquisition roughly 15–30 s later, and a delayed or transitional acquisition at about 2–3 min. Confirm locally.
The same volume is imaged repeatedly across the passage of a gadolinium bolus, so enhancement is read as a curve rather than as a single value. The transferable principle is that MR sees T1 shortening rather than photon attenuation, which removes the dose penalty for repeating an acquisition and therefore makes the TEMPORAL PATTERN the primary datum: rapid arterial uptake followed by relative fall-off, progressive centripetal fill-in, and persistent late enhancement are three different diagnoses that can share an identical single-timepoint appearance. Because everything downstream depends on hitting the arterial peak within a few seconds, the phase is unusually sensitive to circulation time and to breath-hold failure, and a mistimed arterial acquisition cannot be recovered by post-processing.
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
- MR safety screening for implants and foreign bodies· radiographer at scan
- Gadolinium in known or possible pregnancy· radiographer at scan