What is MR Guided Focused Ultrasound (MRgFUS) and what is its role in the management of fibroids?

MRgFUS offers a new and exciting options for women who have symptoms attributable to fibroids, who require surgical intervention and who wish to retain their uterus.

In this article, the technology is described and its relative merits to other treatment options are explored.

What are fibroids?

  • Uterine fibroids (leiomyomas) are benign tumors that grow within the muscular wall of the uterus. 
  • They are the most common pelvic tumors in women, with a prevalence of 20-40% during middle reproductive age. 
  • Prevalence of 70% of all women by age 50.
  • 20% of gynaecological consultations relate to fibroids.
  • They are more common in women of African-Caribbean origin. 
  • USA $6.5 billion for cesarean sections and $2.0 billion for fibroid surgery in 2004.

Fibroid Symptoms

Many women are unaware that they have fibroids but others have reduced quality of life because of:-

  • Heavy periods
  • Pelvic pain or pressure
  • Pressure on the bladder leading to increased need to urinate
  • Pressure on the bowel which can lead to constipation and/or bloating
  • An enlarged abdomen which is sometimes mistaken for pregnancy
  • Fertility Problems

Treatment options for fibroids

There are several treatment options to relieve symptoms associated with fibroids including:

  • MR Guided Focused Ultrasound - NEW TREATMENT
  • Medical - see below
  • Surgical - see below

MR Guided Focused Ultrasound (MRgFUS)

A brief history of focused ultrasound

  • 1926 - high intensity ultrasound can induce effects in animal tissues.
  • 1935 - ultrasound can be focused.
  • 1942 focused ultrasound found to have therapeutic effects.
  • 1957 pioneering work on delivering focused ultrasound beams.
  • 1959 focused ultrasound applications to cause necrosis (tissue death) in brain conditions including Parkinson's disease but discontinued as accurate targeting technology inadequate.
  • 1970s early work on treating breast cancer.
  • 1980s technological improvement with focusing.
  • 1990s focused lesions demonstrated in animal models but application by ultrasound guidance with sub-optimal vision and no feedback.
  • 1993 MRI guided focused ultrasound proposed to enhance visualization and record effect in real time.
  • 1997 MR focused ultrasound successfully treats benign prostatic hyperplasia (enlargement).
  • 2001 benign tumors of breast treated as pre-cursor to breast cancer studies.
  • 2003 first reported treatment of breast cancer.0301 "Thermal coagulation of small breast tumors by means of MR imaging-guided focused US appears to be a promising noninvasive ablation procedure."
  • 2003 first reported treatment of uterine fibroids.0302 "MR imaging-guided focused ultrasound causes thermocoagulation and necrosis in uterine leiomyomas and is feasible and safe, without serious consequences."
  • 2004 FDA approval for MRgFUS of fibroids.
  • 2006 GnRH pre-treatment for fibroids > 10cm - successful MRgFUS treatment.0601
  • 2007 National Institute of Clinical Excellence - approval for fibroids.2007
  • 2008 Good pregnancy outcomes reported after MRg Focused Ultrasound reported.0801
  • 2008 MRg Focused Ultrasound reported. Is likely to be cost-effective.0802
  • Studies to evaluate the potential of MRgFUS in bone metastases, liver tumours, brain tumours and some strokes are being inititiated.

The combination of Magnetic Resonance imaging and Focused Ultrasound offers non-invasive treatment of tumors inside the body without the need for incisions and is currently in use around the world in over 60 sites.(2008).MR Guided Focused Ultrasound (MRgFUS)

An ultrasound transducer converts electrical energy into ultrasound energy.  The ultrasound waves are directed from a transducer into a small focal volume. Ultrasound is a form of sound energy that passes through skin, muscle, fat and other soft tissues.  High intensity  ultrasound energy, when focused on a small target volume, provides a therapeutic effect by heating the target area high enough to destroy it. This can be compared to the sun's rays igniting paper when focused by a magnifying glass.


The cone-shaped ultrasound beam penetrates through soft tissue and produces well defined regions of protein denaturation, irreversible cell damage, and coagulative necrosis, at specific targeted locations. Tight focusing is designed to limit the ablation to this targeted location. Treatments consist of multiple exposures of focused energy or sonications.

Magnetic Resonance imaging is ideal for safely directing the energy because of excellent resolution, high differentiation between treated and untreated tissue, and the ability to create real time temperature "maps" during the treatment.

Therapeutic Ultrasound

Therapeutic ultrasound in physical therapy is an alternating compression and rarefaction of sound waves with a frequency of moe than 20 thousand cycles/second. The therapeutic ultrasound frequency used is set at 0.7 to 3.3 MHz. Maximum energy absorption in soft tissue is 2 to 5 cm. Intensity falls as the waves penetrate deeper.

Therapeutic ultrasound may have two types of benefit: Thermal effects and non thermal effects.

Thermal effects are due to the absorption of the sound waves.

Non thermal effects of therapeutic ultrasound are from cavitation, microstreaming and acoustic streaming. Cavitational effects result from the vibration of the tissue causing microscopic air bubbles to form, which transmit vibrations in a way that stimulates cell membranes. This physical stimulation appears to enhance the cell-repair effects of the inflammatory response.

Therapeutic ultrasound is sometimes recommended for muscle as well as joint pain.

 

Follow up for 24 months of patients treated my magnetic resonance-guided focused ultrasound surgery confirms that it is effective treatment for uterine leiomyomata and results in sustained symptomatic relief.0701

There is early evidence that magnetic resonance-guided focused ultrasound surgery my be beneficial for some patients with adenomyosis.0602

ExAblateŽ 2000 MR guided focused ultrasound

ExAblateŽ 2000 uses MR guided focused ultrasound technology combining high intensity focused ultrasound beam that heats and destroys targeted tissue, non-invasively and Magnetic Resonance Imaging system (MRI) which visualizes patient anatomy, and controls the treatment by monitoring the tissue effect in real time.MR Guided Focused Ultrasound (MRgFUS)

The operator console is located in the control room next to the MRI workstation. It is the main control mechanism and all treatment planning, registration, and treatment is conducted from this console.  The equipment cabinet includes the interface electronics to the patient table, to the MR scanner and to the operator console. and is located in the adjacent MR equipment room.

The detachable patient table is docked to the MR scanner.  It incorporates a transducer immersed in a sealed water bath, with an automated positioning system that generates the focused ultrasound energy beams.

The relative tissue temperatures are displayed as a color map superimposed on an MR image. This allows the physician to observe temperature changes in real time during treatment. Based on these observed temperature changes, treatment parameters can be adjusted to ensure safe and effective thermal ablation. MR images with Gadolinium contrast allow the physician to monitor treatment and determine which regions are no longer perfused (ablated).

MR Guided Focused Ultrasound (MRgFUS)

During treatment for fibroids, the woman lies prone to allow focused ultrasound treatment.

Fibroid Treatment - MR Guided Focused Ultrasound

MR Guided Focused Ultrasound - Fibroid treatment

 

Fibroid treatment:- Suitability for MR Guided Focused Ultrasound

  • Symptoms attributable to fibroids.
  • Uterine size no more than 24 weeks size - (just above umbilicus).
  • Window of access to the targeted fibroids required. Posterior wall fibroids may not be treatable.
  • Pedunculated fibroids (on a stalk) are a contraindication.
  • Obesity (>100Kg) is a contraindication - this seems to be a limitation of the MR table.
  • A negative pregnancy test may be required.
  • No skin scar over area of treatment.

MR guided focused ultrasound - The procedure

  • Full discussion explaining the procedure to the patient is essential.
  • The patient must lie still within the MR machine for 3-4 hours. Clostraphobia is therefore a contraindication although the patient's head is outside the MRI scanner.
  • The patient is fasted for 6 hours before the procedure and a catheter is introduced to allow emptying or filling of the bladder.
  • The patient receives light sedation and is awake during the procedure.
  • During treatment, it is essential that the patient lies still.
  • Following the procedure, the patient can go home after two hours when the sedation has worn off.
  • The majority of patients experience no after effects and can return to work in one or two days.
  • Driving should be avoided for at least 48 hours.
  • The first period following MR guided focused ultrasound tends to be heavier than usual.
  • Patients should ensure that they do not conceive for at least three months.

MRI v Ultrasound Imaging

  • Both ultrasound and magnetic resonance imaging (MRI) are safe. Neither involve radiation.
  • Ultrasound has the advantage of being relatively simple to use and many machines are portable and can be used in clinics. When used for diagnostic imaging the low intensity ultrasound waves have virtually no biologic effect on cells or tissues.
  • MRI is far more expensive and is not portable and is not for the average clinician even with special training.

Pelvic Ultrasound

Pelvic Ultrasound

Modern ultrasound provides excellent quality images although it does not compete with MRI - see images above.

A Comparison of MR Guided Focused Ultrasound (MRgFUS) with other surgical modalities

  Description Advantages Disadvantages Efficacy Retreatment
Hysterectomy Removal of the uterus No recurrence of fibroids Fertility lost Only guaranteed method for non-recurrence 0%
Myomectomy Removal of the fibroids Uterus conserved Heavy bleeding. Risk for hysterectomy 80%. 2-35%
Uterine Artery Embolization Arterial Catheter introduced via groin - fine particles block blood supply to the fibroids Minimally Invasive. Radiation. Ovarian Failure (Menopause may be induced). 90% for bleeding 85% pain relief.  2-16%
MRgFUS As Above Out-patient procedure Low Risk 92% significant improvement. 14%

 

MRgFUS Uterine Artery Embolization
Non-Invasive Minimally Invasive
Out-Patient Overnight Stay
Almost Painless Pain ++ Requires Morphine
Individual Fibroids Targetable Can target more than one fibroid
Obesity (<100Kg) - Contraindication Obesity not a problem
Clostraphobia - Contraindication No Clostraphobia Problem
Beware of Skin Scars Skin scars not an issue
10-50% volume reduction 20-90% volume reduction
80% symptomatic Improvement 80% Symptomatic Improvement
Ovarian Failure unlikely. Ovarian Failure can occur.

 

  Uterine Artery Embolization Myomectomy Hysterectomy MRgFUS
Days In Hospital 1  1 - 5  3 - 5  0
Procedure Time (Hours) 1 - 2  1 - 3  1 - 2  3 - 4
Return To Normal
Activity
10 days  28 - 56 days  28 - 56 days  1 - 2 days

Medical Treatment of Fibroids

  • Medical treatments used for other causes of heavy periods, including tranexamic acid may help reduce menstrual loss.
  • Mild analgesics may help if pain is not severe.
  • GnRH analogues may reduce the size of the periods and stop menstruation but this is usually indicated in the short term perhaps in preparation for surgery.
  • The Mirena IUS can be used to control period loss if the uterus is not particularly big.

Surgical Treatments of Fibroids

If medical treatment cannot suffice, then the two traditional options have been:

  • Hysterectomy

    For women who have completed their family, hysterectomy has been the treatment of choice.

  • Myomectomy

    For women who wish to conserve their uterus, usually because they wish to retain the possibility of increasing their family, removing the fibroid(s) has been performed for many years through an abdominal incision. As the muscle of the uterus is opened, bleeding occurs and this can be heavy; blood transfusion is often required. If bleeding becomes life-threatening the surgeon may have no choice but to proceed to hysterectomy. Patients undergoing myomectomy are consented for hysterectomy just in case.

    Minimally invasive procedures aim to provide surgical treatment options without major surgery. If their are fibroids affecting the cavity of the uterus, they may be visible at hysteroscopy and treated through this route - hysteroscopic myomectomy. If the uterus is not very big and there are fibroids near the outer surface of the uterus (sub-serosal), they may be amenable to laparoscopic myomectomy.

  • Radiological procedures.

Uterine Artery Embolization - a catheter is introduced into an artery in the groin and steered into the vessels supplying the offending fibroids.

Laser Ablation - Under MR guidance, needles are inserted into the centre of the targeted uterine fibroid through an area of skin that has been locally anaesthetised. Bare laser fibres are inserted down the centre of each of the needles into the targeted fibroid. Laser energy is then used to destroy the fibroid. This procedure has been replaced by MRgFUS.

Women's Health




Conclusions on MR Guided Focused Ultrasound (MRgFUS)

MRgFUS offers a new and exciting options for women who have symptoms attributable to fibroids, who require surgical intervention and who wish to retain their uterus.

Do you have an unanswered women's health question?

MR Guided Focused Ultrasound (MRgFUS)


Useful Links:

InSightec InSightec developed ExAblateŽ 2000– a product that integrates Magnetic Resonance Imaging (MRI) with focused ultrasound energy -- as a new treatment modality that can replace invasive procedures and provide therapeutic alternatives to millions of patients with serious diseases around the globe. 
FUS Organization The Focused Ultrasound Surgery Foundation (FUSF) was founded as a catalyst to compress the time between technology development and the treatment of patients, develop new applications and accelerate the worldwide adoption of MR-guided focused ultrasound surgery.
Fibroid Relief FibroidRelief is dedicated to supporting women suffering from uterine fibroids who seek non-invasive treatment alternatives. We are committed to raising awareness about the benefits of Focused Ultrasound (regardless of manufacturer) and will work tirelessly to promote patient access through educational and advocacy activities.
Birmingham Fibroid Clinic The Birmingham Fibroid Clinic is a pioneering clinic set up by Miss Shirin Irani, Consultant Gynaecologist and Consultant Interventional Radiologist, Dr. Paul Crowe. Between them they have years of experience of treating women with fibroids, one of the commonest gynaecological disorders that can cause pain, heavy periods, pressure symptoms and impaired fertility.
MR Therapy Centre St. Mary's London The MR Therapy Centre is a Limited Company established to enable Magnetic Resonance-guided Focused Ultrasound (MRgFUS) treatment of uterine fibroids to be offered as a clinical service, and to allow the continuation of our research programme into new applications using this innovative therapy. The MR Therapy Centre is the UK’s first, and most experienced, centre for MRgFUS.
Uterine Fibroids .org This well produced web site dedicated to the management of uterine fibroids provides a wealth of information including a regularly updated list of current providers of MRgFUS around the world.
Women's Health

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I do hope that you find the answers to your women's health questions in the patient information and medical advice provided.

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