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Image-based interventional therapies for benign uterine neoplasms
Key points
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Uterine leiomyomata are common benign neoplasms that may cause symptoms related either to tissue bulk or bleeding for many women.
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Triage to the ideal treatment depends not only on fibroid characteristics and location within the uterus but also the patient’s fertility goals, nature of presenting symptoms, and consideration of potential complications.
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In addition to watchful waiting and traditional treatment, including medication for symptomatic relief, hormonal therapy, and surgical excision, patients now have the option of minimally invasive, image-guided procedures: uterine artery embolization (UAE) and many forms of thermal ablation (radiofrequency ablation and high-intensity focused ultrasound [HIFU]).
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UAE, associated with significant fibroid volume reduction and symptom relief, as well as less major adverse events and a shorter recovery as compared with hysterectomy, is also shown to lead to the need for reintervention in almost one third of patients, negating the cost-effectiveness at 5 years posttreatment.
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HIFU, especially when guided by MR imaging, has shown to be clinically effective in reducing fibroid volume and reducing symptoms, with fewer major complications and less lifetime total costs compared to currently available treatments.
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Clinical outcomes for minimally invasive, image-guided procedures are improving with improved technical skill and greater treatment volumes, but randomized trials analyzing longer-term outcomes (>5 years) and postprocedure fertility outcomes have not been reported to date.
Introduction
Uterine leiomyomas (fibroids) are benign, hormonally driven, well-encapsulated neoplasms originating from uterine smooth muscle, affecting an estimated 20%–35% of all reproductive-age women; some studies report that a cumulative lifetime incidence of leiomyomas occurs in 70% of U.S. white and 80% of African American women. Risk factors include African or African American background, family history, early menarche, nulliparity, obesity, hypertension, and polycystic ovary syndrome. Although the majority of women with uterine leiomyomas are asymptomatic, approximately 20%–30% of women have related symptoms, typically presenting in the fifth decade of life and lasting into menopause, with subsequent decrease in symptoms. Uterine fibroid-related symptoms are secondary to either mass effect (bulk) or excessive endometrial effect (bleeding). Bulk-related symptoms include back and pelvic pain, pelvic pressure, urinary frequency, dyspareunia, and defecation disorders. Bleeding-related symptoms include menorrhagia, metrorrhagia, menometrorrhagia, and dysmenorrhea, and the associated anemia. Submucosal fibroids, or those that significantly distort the endometrial cavity, are also thought to contribute to mass-related infertility. Leiomyoma-related symptoms, among the most common of all gynecologic disorders, are thought to be responsible for more than 360,000 hysterectomies in the United States annually, with an overall estimated annual cost of care exceeding $2 billion.
Imaging characteristics of uterine leiomyomas
Leiomyomas are readily detectable on pelvic ultrasonography, typically appearing as solid, hypoechoic masses originating from the uterine myometrium with varying degrees of echogenicity depending on fibrous, calcified, and degenerating components. There is no interruption of the endometrium (unless submucosal in location, which may cause adjacent cavity distortion), differentiating these lesions from endometrial polyps or more concerning endometrial carcinoma. Although ultrasonography most commonly identifies fibroids, MR imaging offers superior soft tissue contrast and tissue characterization of individual fibroids, multiplanar imaging, and characterization of perfusion, which helps triage patients to one or more therapeutic options, including surgical resection, uterine artery embolization (UAE), and high-intensity focused ultrasound (HIFU) ablation. It is also superior in diagnosing concomitant adenomyosis, which may contribute to UAE treatment failure. Based on MR imaging and enhancement patterns, individual leiomyomas can be classified as classical, hypercellular, or degenerating. Classical fibroids appear hypointense on T2-weighted sequences and enhance on gadolinium-enhanced T1-weighted sequences ( Figure 19-1 , A ). Hypercellular fibroids, which are T2 hyperintense, enhance avidly on gadolinium-enhanced T1-weighted sequences. Degenerating fibroids have variable T1 and T2 signal and do not exhibit contrast enhancement. The tissue characterization of these different subtypes of fibroids can help determine the best choice of treatment, as classical fibroids have been found to respond better to HIFU than hypercellular fibroids, while degenerating fibroids respond poorly to both HIFU and UAE.
Location of uterine leiomyomas
Leiomyomata are also described in terms of their location in the uterus, and these subtypes can display varying responses to specific treatments as well. Intramural leiomyomas, completely contained within the uterine wall, are most common and mostly asymptomatic, but if large, may cause bulk symptoms. Subserosal lesions are found along the outer contour of the uterus, and when large, can also cause bulk symptoms. Fibroids abutting or extending into the endometrial cavity are termed submucosal, and even small lesions can cause uterine bleeding. This subtype can potentially become intracavitary following UAE, predisposing to fibroid expulsion and postprocedure complications, the risk for which can best be gauged by preprocedure magnetic resonance imaging (MRI), with assessment of fibroid size to endometrial interface. Intracavitary leiomyomas grow into the endometrial cavity on a fibrovascular stalk and commonly result in bleeding symptoms. Those growing outside the uterus on a fibrovascular stalk are termed pedunculated and can cause mass effect on adjacent organs, and voiding or defecation symptoms.
Traditional treatment of uterine leiomyoma
Traditional options for therapy of uterine leiomyoma-related symptoms may be divided into medical, surgical, or watchful waiting/alternative therapy. Medical treatments, like nonsteroidal anti-inflammatory drugs (NSAIDs) or contraceptive steroids, or alternative therapies, such as acupuncture or herbal therapies, may be effective in the short term or for bridging perimenopausal patients whose fibroids may still spontaneously involute, but most symptomatic patients progress over time, requiring more durable treatment. Hormone therapy, namely gonadotrophin-releasing hormone (GnRH) agonists, are also used and act by suppressing circulating estradiol and progesterone levels via the pituitary–ovarian axis. This results in significant fibroid shrinkage, but long-term use of these compounds is not recommended because of the side effects of bone loss. Surgical therapy, including laparoscopic, hysteroscopic, robotic-assisted, or open hysterectomy, is the standard of care and is considered the definitive therapy for fibroid-related bulk symptoms, bleeding, and infertility. Although these are extremely common and safe surgical procedures, there is a major complication rate (such as hemorrhage requiring transfusion, urinary tract, and bowel damage) of 8.9% for abdominal, 14% for vaginal, and 19% for laparoscopic hysterectomy (the latter including the risk of conversion to laparotomy). Removal of the uterus and surrounding attachments also has been thought to increase a woman’s postmenopausal risk of pelvic floor disorders (pelvic prolapse and laxity). , For women who desire the option of future fertility or who wish to retain their uterus, open or laparoscopic surgical resection of individual leiomyomas (myomectomy) is performed. Although generally safe, the most frequent complications include perioperative blood loss requiring transfusion, fever, and ileus. There is a postoperative recurrence of up to 51% over time, and 10%–25% of patients will require a major surgery after the first myomectomy.
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