Over the past two decades, advances in surgical techniques have led to the development of innovative and less invasive options for the local management of tumors. The principal driving force behind this is to reduce the perioperative morbidity and mortality rates associated with invasive procedures. Minimally invasive keyhole and laproscopic surgeries have replaced open surgeries and are the order of the day.
Percutaneous procedures such as radiofrequency ablation and cryoablation are newer alternative approaches to tumour management, though they still require the insertion of probes and are not truly non-invasive by definition. By definition, “MR-guided high-intensity focused ultrasound (MRI-HIFU)” is a truly non-invasive procedure without skin penetration and is used for the precise and targeted therapeutic management of tumours.
What are uterine fibroids?
Fibroids are benign tumours of the uterine wall that affect approximately 20-25 per cent of women in the childbearing age group. Fibroids can go unnoticed during a lifetime.
However, these can be very disconcerting also, and can cause excessive bleeding (menorrhagia), pain during the menstrual cycle (dysmenorrhea), a combination of both and often an inability to conceive.
What are the available treatment options for fibroids?
In the pre-menopausal age group, traditional management techniques range from medical therapy to hysterectomy. The gap between these two techniques is immense, and this can be extremely discouraging for the patient. At present, fibroids are the most common indication for hysterectomy in India. Laproscopic or hysteroscopic myomectomies are restricted to small tumours in certain locations. Uterine artery embolisation is a less invasive technique, in which a percutaneous puncture of a vessel in the groin is performed and the artery supplying the fibroid is blocked. However, this technique may be complicated by severe post-procedural pain and a post-embolisation syndrome. MRI-HIFU is the new kid on the block — it has been used for the treatment of uterine fibroids in the United States since 2004.
Who is an ideal candidate for MRI-HIFU?
Women in the pre-menopausal age group, interested in conserving the uterus are ideal candidates for MRI-HIFU of uterine fibroids.
How does MRI-HIFU work in treating uterine fibroids?
Real-time, MRI guidance allows the radiologist to target the fibroid with a high-intensity focused ultrasound (HIFU) energy beam. This process is called sonication. The therapeutic HIFU beam is delivered to the target, at which point the sound energy in the beam is converted to heat energy. This technique of ablation relies on heat-induced tissue necrosis (coagulative), which is achieved when the target is heated to a temperature at or beyond 57 C. Importantly, this technique leaves the normal uterine muscle intact.
How is it performed?
The patient has a light snack, six hours prior to the procedure and fasts till the scheduled appointment time. A nurse cannulates her vein and inserts a catheter into the urinary bladder. The patient’s abdominal wall is in contact with the treatment interface embedded in the MRI table. During the sonication procedure, real-time MRI images are obtained and are processed online, allowing the radiologist to precisely target, optimise and modify beam dosage. The patient is awake and aware throughout the entire procedure. After a post-procedural clinical assessment, the urinary catheter and intravenous cannula are removed.
What are the side effects?
Post-procedural symptoms may include lower abdominal pain, superficial tenderness or a low-grade fever, which may persist for a few days. These symptoms are often self-limiting and may be controlled using medications. An uncommon side effect includes sciatic neuralgia.
What are the advantages?
In a comparative study between MRI-HIFU and hysterectomy, MRI-HIFU treatment of fibroids led to clinical improvement with fewer significant clinical complications and serious adverse events compared to hysterectomy at half-yearly follow-ups. All MRI-HIFU patients were treated on an outpatient basis, with significantly faster recovery, earlier resumption of work and a reduced economical impact.
What are the disadvantages?
The principal aim of MRI-HIFU is symptomatic improvement in the patient’s quality of life. However, it is important to note that the fibroid is not completely removed /ablated, but only an adequate volume is targeted and ablated.
What are the other indications of MRI-HIFU?
MRI-HIFU is now being used to provide pain relief in painful bone metastases. It is also being used in research studies in cancer of the prostate and may in the future find applications in pancreatic and breast cancer and some brain lesions.
(The author is a consultant radiologist at SRL Diagnostics-Jhankaria Imaging)