If you have been told you have fibroids and the next conversation is about what to do about them, the single most useful thing you can hold in your hand is not another opinion. It is a proper MRI map of your uterus. Every treatment worth considering - uterine artery embolisation, HIFU, myomectomy, hysteroscopic resection, and yes, hysterectomy - is chosen or ruled out based on where your fibroids sit, how many there are, how large the biggest one is, whether they still have a blood supply, and whether adenomyosis is quietly sitting alongside them. Ultrasound can tell you that fibroids exist. Only MRI tells you enough to plan around them.
This piece is written for women who already know they have fibroids, and want to understand what a fibroid mapping MRI actually is, what it will show, what your treating team will do with it, and how quickly you can get one privately in the UK in 2026.
The one-line answer
A pelvic MRI with contrast, reported by a subspecialist gynae-radiologist, is the standard of care before choosing between uterine artery embolisation, HIFU, myomectomy or hysteroscopic resection - because it maps every fibroid by number, size, FIGO location and blood supply, and picks up adenomyosis that ultrasound routinely misses.
Why ultrasound is not enough for treatment planning
Pelvic ultrasound - either transabdominal or transvaginal - is the right first test. It is quick, cheap, uses no radiation, and reliably confirms whether fibroids are present. That is where its usefulness for treatment planning tends to stop.
Ultrasound routinely under-counts fibroids in a uterus that has more than four or five, because the acoustic shadow from the largest ones hides the smaller ones behind them. It struggles to measure a uterus much bigger than the size of a 14-week pregnancy - the biggest fibroid literally will not fit in the field of view of a single probe. It cannot reliably tell a submucosal fibroid (inside the cavity) from an intramural one (in the wall), and this distinction changes whether your treatment is a 40-minute hysteroscopic day case or an abdominal myomectomy. And it is famously poor at separating fibroids from adenomyosis, a different condition that behaves differently under treatment, and which sits alongside fibroids in roughly one in three cases.
For a diagnosis, ultrasound is fine. For deciding what to do next, it is not.
The pelvic MRI protocol for fibroid mapping
A proper fibroid mapping MRI is not the generic pelvic MRI most non-specialist centres run. It is a specific protocol, tuned for uterine tissue and for the questions your interventional radiologist or gynaecologist will ask afterwards. It has three parts.
High-resolution T2-weighted sequences in three planes. This is the anatomy scan - the images your treating team will spend most of their time looking at. T2 is where uterine zones (endometrium, junctional zone, myometrium) show up with proper contrast, where individual fibroids are counted and measured, and where adenomyosis reveals itself as a thickened junctional zone. Sagittal, axial and coronal planes together let the radiologist rebuild the uterus in three dimensions on the reporting screen.
Dynamic post-gadolinium contrast sequences. A small volume of gadolinium contrast is given through a cannula in your arm, and a rapid series of images is taken as it perfuses the uterus. This is the part that ultrasound cannot copy. Well-vascularised fibroids light up brightly - they are the ones most likely to shrink after uterine artery embolisation or HIFU. Fibroids that have already degenerated, calcified or lost their blood supply enhance poorly, and behave very differently under the same treatment. Without contrast, this information does not exist.
MR angiography of the uterine arteries (sometimes). If you are being planned for uterine artery embolisation specifically, some interventional radiologists ask for a short MRA sequence to map the anatomy of your uterine and ovarian arteries before the procedure. It is not always needed, but when it is, it makes the intervention itself safer and quicker.
What the map actually includes
A properly reported fibroid MRI is not a paragraph. It is a structured map, and a good gynae-radiologist will give you all of the following.
- Total fibroid count. Every fibroid over roughly 5 mm, listed. In a uterus with more than 10 fibroids, they may be grouped by region rather than listed individually, but you should still see a total number.
- FIGO classification 0 to 8 for each significant fibroid. This is the international system your gynaecologist uses to decide surgical route. Types 0 to 2 are submucosal (inside or bulging into the cavity, often resectable hysteroscopically). Types 3 to 5 are intramural. Types 6 to 7 are subserosal (on the outside). Type 8 is pedunculated or unusual. This one number changes which specialist you are sent to.
- Dominant fibroid size in three dimensions and a total uterine volume. Size matters for HIFU eligibility, for UAE technique, and for whether an open, laparoscopic or robotic myomectomy is feasible.
- Presence of any submucosal component. A submucosal fibroid is the most common cause of heavy bleeding and can often be treated with a single hysteroscopic day case. Missing it is a common reason women end up with the wrong treatment.
- Enhancement pattern after contrast. Which fibroids are alive and well perfused, and which have degenerated. The most honest predictor of UAE or HIFU success.
- Adenomyosis assessment. Junctional zone thickness, ill-defined myometrial changes, small cysts. Adenomyosis coexists with fibroids often, and responds differently. If it is there, the treatment plan changes.
- Ovaries and adnexa. Endometriomas, dermoids, hydrosalpinx and other pelvic findings that might change your surgical plan.
The treatment options that MRI decides between
This is the reason the scan matters. Once your map is on the table, five doors are open, and the MRI is what closes some and opens others.
Uterine artery embolisation (UAE). Minimally invasive, done by an interventional radiologist through a small artery in the wrist or groin, with a one to two night hospital stay. Works best on well-vascularised intramural fibroids, and on multiple fibroids at once. MRI predicts this by showing enhancement pattern and ruling out pedunculated subserosal fibroids where UAE is a poor choice.
MR-guided high intensity focused ultrasound (HIFU / MRgFUS). A non-invasive outpatient procedure that ablates fibroids from outside the body using focused ultrasound waves, guided in real time by MRI. Eligibility is strict - fibroid location, size, distance from bowel and bladder, and enhancement pattern all matter. Your mapping MRI is essentially the screening test for HIFU.
Laparoscopic or open myomectomy. Surgical removal of fibroids while preserving the uterus, usually for women wanting future pregnancy. MRI tells the surgeon exactly what they are walking into - how many fibroids, where they are, whether laparoscopic is realistic or whether open is safer.
Hysteroscopic resection. A day-case procedure through the vagina for FIGO type 0 to 2 submucosal fibroids. The whole plan hinges on whether MRI shows a submucosal component and how much of the fibroid sits inside the cavity.
Hysterectomy. Definitive treatment for women who have completed their family and want the problem gone permanently. MRI is still done beforehand to plan the surgical route (vaginal, laparoscopic, robotic or open) and to catch anything unexpected.
Post-treatment MRI to confirm response
The mapping MRI is not the last scan you will have. After UAE or HIFU, a follow-up MRI at three to six months is standard, and it is genuinely useful. It confirms that treated fibroids have lost their blood supply (non-enhancement is the sign of a successful UAE) and quantifies the reduction in uterine volume. If a fibroid is still enhancing, that is worth knowing early - a second treatment or a different plan is much easier to discuss with a clear picture than with symptoms alone.
For myomectomy patients planning pregnancy, a post-operative MRI at six months also gives your obstetrician a clear picture of the uterine wall before conception.
