Use of Contrast-Enhanced Ultrasound in the Assessment of Uterine Fibroids: A Feasibility Study

Clinical signs and diagnosis of fibroids from adolescence to menopause

The aim of this review was to provide an updated assessment of the present diagnostic tools and clinical symptoms and signs to evaluate uterine fibroids (UFs) on the basis of current guidelines, recent scientific evidence, and a PubMed and Google Scholar search for peer-reviewed original and review articles related to clinical signs and diagnosis of UFs. Approximately 50%-75% of UFs are considered nonclinically relevant. When present, the most common symptoms are abnormal uterine bleeding, pelvic pain and/or bulk symptoms, and reproductive failure. Transvaginal ultrasound is recommended as the initial diagnostic modality because of its accessibility and high sensitivity, although magnetic resonance imaging appears to be the most accurate diagnostic tool to date in certain cases. Other emerging techniques, such as saline infusion sonohysterography, elastography, and contrast-enhanced ultrasonography, may contribute to improving diagnostic accuracy in selected cases. Moreover, artificial intelligence has begun to demonstrate its ability as a complementary tool to improve the efficiency of UF diagnosis. Therefore, it is critical to standardize descriptions of transvaginal ultrasound images according to updated classifications and to individualize the use of the different complementary diagnostic tools available to achieve precise uterine mapping that can lead to targeted therapeutic approaches according to the clinical context of each patient.

Evaluation of Uterine Fibroid Vascularity Using Contrast-Enhanced Ultrasound in Comparison with Contrast-Enhanced Magnetic Resonance Imaging

OBJECTIVE

The aim of the work described here was to assess uterine fibroid vascularity using contrast-enhanced ultrasound (CEUS) as compared with magnetic resonance imaging (MRI).

METHODS

Forty women diagnosed with symptomatic uterine fibroids scheduled for uterine artery embolization (UAE) were enrolled in this institutional review board-approved study. Before UAE, participants underwent CEUS examination with an Aplio i800 scanner (Canon Medical Systems, Tustin, CA, USA) with curvilinear array (8C1). CEUS was performed using 2.0 mL of the ultrasound contrast agent Lumason (Bracco, Milan, Italy) administered intravenously. Digital CEUS clips were acquired and randomized offline, and fibroids were characterized as hyper- or hypovascular. MRI was used as reference standard for fibroid vascularity and compared with CEUS. Results were analyzed using McNemar's test.

RESULTS

Forty participants were enrolled in the trial. One patient did not proceed with the UAE procedure and one patient refused pre-procedure MRI because of claustrophobia. Therefore, 38 participants underwent CEUS and MRI examinations before UAE. Hypervascular fibroids were seen on MRI and CEUS in 24 and 26 participants, respectively. Hypovascular fibroids were seen with MRI and CEUS in 14 and 12 participants, respectively. Fibroids characterized as hypovascular in two participants by MRI were characterized as hypervascular by CEUS. CEUS and MRI findings were similar in 36 of 38 participants, corresponding to an accuracy of 95% (p = 0.62).

CONCLUSION

Contrast-enhanced ultrasound can accurately assess uterine fibroid vascularity, serving as a potential alternative to MRI in determination of the vascularity of uterine fibroids.

Added Value of Contrast-enhanced US for Evaluation of Female Pelvic Disease

Since the first application of contrast-enhanced US (CEUS) in the late 1960s, the use of US contrast agents has grown tremendously, and this examination has proved to be a valuable adjunct to diagnostic US for detection and characterization of disease. Also, CEUS has emerged as an excellent option for evaluation of indeterminate lesions that require additional imaging, given its excellent safety profile, including that in patients with end-stage renal disease or allergies to contrast material who are unable to undergo contrast-enhanced CT or MRI. US traditionally has been considered the imaging modality of choice for evaluation of the female pelvis, followed by MRI and rarely fluoroscopy, CT, PET, or angiography. CEUS has the potential to add significant value in imaging gynecologic disease, and indications for its use in the female pelvis are expected to continue evolving. It can aid in evaluation of nonvascular structures, such as assessment of tubal patency, uterine cavity morphology, and pelvic fistulas. CEUS can help characterize poorly vascularized gynecologic tumors or tissues with slow flow by using qualitative and quantitative parameters and aid in image-guided interventions or biopsies by facilitating visualization of lesions that are difficult to see with other imaging modalities. The authors provide an overview of current applications of US contrast agents in the female pelvis and discuss associated factors such as technique, interpretation, and image optimization. They also discuss the limitations of CEUS and describe its utility in the evaluation of female pelvic disease by using an organ system case-based approach. © RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Contrast-Enhanced Ultrasound and High Sensitive Doppler for Monitoring Outcomes of Uterine Artery Embolization

RATIONALE AND OBJECTIVES

To monitor fibroid microvascularity using contrast-enhanced ultrasound (CEUS) and a new high-sensitive Doppler mode (SMI) for assessment of uterine artery embolization (UAE) outcomes.

MATERIALS AND METHODS

Forty women with symptomatic uterine fibroids scheduled for UAE were enrolled in this Institutional Review Board-approved study. Subjects underwent three examinations (day 0, 15, and 90 post-UAE) with Color Doppler (CDI), power Doppler (PDI), color and monochrome SMI (cSMI and mSMI), and CEUS imaging of the fibroids. Clips were assessed by two radiologists classifying fibroids based on their vascularity. Fibroid fractional vascularity (FV; % of enhanced pixels within the fibroid) and flow intensity (as mean brightness level of the enhanced pixels) were quantified. Results were analyzed using repeated measures ANOVA and nonparametric Wilcoxon sign rank tests. Inter-reader agreement was assessed with κ-values.

RESULTS

There was overall agreement between readers for all imaging modalities and examination times (P = .25; κ = 0.70). The FV analysis showed statistically significant differences between CEUS and the Doppler imaging modes (CDI, PDI, cSMI, and mSMI) for the three examination times were compared (P < .0001). The comparison using CDI, PDI, and cSMI showed no statistically significant difference (P = .53). The flow intensity analysis comparison between the Doppler imaging modes (CDI, PDI, cSMI and mSMI) and examination times showed statistically significant differences between all the Doppler imaging modalities (P = .02), except for the 90days post-UAE (P = .34). When the comparison was made for CDI, PDI, and cSMI there was no statistically significant differences (P < .47).

CONCLUSION

CEUS and SMI can accurately evaluate fibroid microvascularity, and therefore, can be a noninvasive and accurate method for monitoring outcomes following UAE treatment.

Contrast-Enhanced Ultrasonography (CEUS) in Imaging of the Reproductive System in Dogs: A Literature Review

The use of contrast-enhanced ultrasound (CEUS) has been widely reported for reproductive imaging in humans and animals. This review aims to analyze the utility of CEUS in characterizing canine reproductive physiology and pathologies. In September 2022, a search for articles about CEUS in canine testicles, prostate, uterus, placenta, and mammary glands was conducted on PubMed and Scopus from 1990 to 2022, showing 36 total results. CEUS differentiated testicular abnormalities and neoplastic lesions, but it could not characterize tumors. In prostatic diseases, CEUS in dogs was widely studied in animal models for prostatic cancer treatment. In veterinary medicine, this diagnostic tool could distinguish prostatic adenocarcinomas. In ovaries, CEUS differentiated the follicular phases. In CEH-pyometra syndrome, it showed a different enhancement between endometrium and cysts, and highlighted angiogenesis. CEUS was shown to be safe in pregnant dogs and was able to assess normal and abnormal fetal-maternal blood flow and placental dysfunction. In normal mammary glands, CEUS showed vascularization only in diestrus, with differences between mammary glands. CEUS was not specific for neoplastic versus non-neoplastic masses and for benign tumors, except for complex carcinomas and neoplastic vascularization. Works on CEUS showed its usefulness in a wide spectrum of pathologies of this non-invasive, reliable diagnostic procedure.

Ultrasound-guided percutaneous microwave ablation for uterine fibroids: mid-term local treatment efficiency and associated influencing factors

OBJECTIVE

To investigate the mid-term local treatment efficiency of ultrasound-guided percutaneous microwave ablation (MWA) for uterine fibroids (UFs) and the associated influencing factors.

METHODS

From July 2020 to October 2021, a total of 28 patients with 52 UFs who had undergone ultrasound-guided MWA were retrospectively included in this study. Pre-treatment clinical characteristics, conventional ultrasound and contrast-enhanced ultrasound (CEUS) features were analyzed to explore their correlation with volume reduction ratios (VRRs) of sufficient ablation (i.e. a VRR of at least 50% at the 3 month follow-up). The patients were assessed at 1-, 3-, 6 month follow-up after MWA treatment and the assessment included VRR, adverse events, uterine fibroid symptom (UFS) and quality of life (QoL) scores, and clinical symptoms.

RESULTS

The procedures of percutaneous MWA for UFs were tolerated well and no major complications occurred in all patients. At the 1-, 3-, 6 month follow-up, the median VRRs of UFs were 30.1%, 46.9%, and 65.8%, respectively. At the 3 month follow-up, 44.4% of fibroids obtained sufficient ablation while the remaining 55.6% obtained partial ablation (i.e. a VRR of <50%). Non-enhancing area during the early phase (i.e. within 30 s after injecting contrast agent) on pre-treatment CEUS was present in 22.2% UFs, which was associated with sufficient ablation at the 3 month follow-up (p < 0.05). In addition, the relevant clinical symptoms of all patients were alleviated or removed. The UFS and QoL score after MWA decreased significantly in comparison with those after MWA (p = 0.04 and p = 0.057, respectively), indicating a remarkable improvement of clinical symptom and QoL.

CONCLUSION

Ultrasound-guided MWA is an effective and safe method to treat patients with UFs. Non-enhancing area during the early phase on pretreatment CEUS is associated with mid-term local treatment efficiency, which might be used to predict treatment outcome.

ADVANCES IN KNOWLEDGE

Non-enhancing area during the early phase on pretreatment CEUS is an important factor associated with mid-term local treatment efficiency. This is the first study finding that CEUS feature can be used as a marker for the prediction of mid-term local treatment response.

A pictorial review of ultrasonography of the FIGO classification for uterine leiomyomas

Uterine leiomyomas are the most common gynecological and pelvic neoplasm, reported in up to 80 percent of women by age 50. While the majority are asymptomatic, uterine leiomyomas, depending on size, number, and location can result in bulk symptoms, abnormal uterine bleeding (AUB), infertility or recurrent pregnancy loss. Ultrasonography (USG) remains first-line for the diagnosis of leiomyomas and is the most appropriate imaging modality for the initial assessment of abnormal uterine bleeding. In an effort to standardize nomenclature and identify causes of AUB, the International Federation of Gynecology and Obstetrics (FIGO) developed a classification system based on the acronym PALM-COEIN (polyp; adenomyosis; leiomyoma; malignancy and hyperplasia; coagulopathy; ovulatory dysfunction; endometrial; iatrogenic; and not yet classified). For the L category of leiomyoma, when present, a secondary and tertiary subclassification system is described distinguishing submucosal masses from others and categorizing the relationship of the mass to the endometrium and serosa. With advancements in newer minimally to non-invasive techniques developed for the management of leiomyomas, uniform characterization, mapping, and classification of leiomyomas is necessary to decide the optimal therapeutic approach. While this classification system has recently been reviewed on MR, to our knowledge, it has not been reviewed on ultrasound in the radiology literature. We hereby present a pictorial review of USG images of all the FIGO categories of leiomyomas to provide a standard guide for radiology reporting.

Role of contrast-enhanced ultrasonography in MR-guided focused ultrasound ablation on uterus fibroids: lesion selection and assessment of ablative effects

OBJECTIVES

To determine whether contrast-enhanced ultrasonography (CEUS) can be used for selecting lesions and assessing the ablative effects of MRgFUS ablation on uterus fibroids, compared with MR imaging.

METHODS

This retrospective study was approved by the institutional review board of our hospital. From April 2018 to November 2019, a total of 44 symptomatic fibroids in 38 patients who underwent MRgFUS ablation were included. The association between pre-ablation characteristics on CEUS/MR imaging and the non-perfusion volume (NPV) after ablation was analyzed using multivariable linear regression analysis. The area under the curve (AUC) of the receiver operating characteristic (ROC) curve values was compared between the CEUS and MR imaging regression models. NPV after ablation was compared between CEUS and enhanced MR imaging.

RESULTS

On CEUS, entangled branch vessels, fast-in, and fast-out patterns were significantly associated with NPV, with an AUC of 0.95 (95% CI; 0.88, 1.00). On MR imaging, hyper-intensity on T2-weighted images (T2WI), hyper-intense ring-like signal on T2WI images, and hyper-enhancement on contrast-enhanced T1WI images were correlated with NPV, with an AUC of 0.86 (95% CI; 0.70, 1.00). After ablation, no differences in NPV were noted between contrast-enhanced T1WI (84.13 ± 75.42 cm³) and CEUS (80.22 ± 76.49 cm³).

CONCLUSIONS

Some pre-ablation characteristics of uterine fibroids on CEUS were associated with NPV after MRgFUS. CEUS may contribute to the evaluation of ablative outcomes and patient selection, similar to MR imaging.

KEY POINTS

• Contrast-enhanced ultrasonography (CEUS) is effective for selecting the appropriate uterine fibroids before MR-guided focused ultrasound (MRgFUS) ablation and evaluating non-perfusion volumes (NPV) after ablation, as a potential alternative to MR imaging. • Before ablation, entangled branch vessels, fast-in, and fast-out patterns on CEUS were significantly associated with NPV after MRgFUS. • No significant differences in NPV were detected between contrast-enhanced T1WI and CEUS after ablation.

Uterine fibroid vascularization: from morphological evidence to clinical implications

Uterine fibroids are the most common cause of solid pelvic tumours, occurring in 20-30% of fertile women and presenting clinical complications that seriously affect women's health. They commonly cause severe symptoms, such as heavy, prolonged menstrual bleeding and anaemia. The study of microscopic and macroscopic vascular aspects of uterine fibroids is important for understanding the clinical manifestations of uterine fibroids, for predicting the effectiveness of alternative treatments to surgery, i.e. uterine artery embolization, for improving surgery outcomes and for carrying out a differential diagnosis with other benign conditions, e.g. adenomyosis, or malignancy, e.g. leiomyosarcoma, and to develop new therapeutic approaches. In this review, current knowledge of how the vascular network and angiogenesis are implied in the formation of uterine fibroids and in the pathogenesis of related symptoms is explored, and evidence on the role of ultrasound in evaluating fibroid vascularization is summarized. This review combines anatomical, morphological and biomolecular information related to angiogenic mechanisms with diagnostic and clinical information, highlighting the various interconnections. Uterine and fibroid vascularization need further investigation to gain a deeper understanding of the pathogenetic elements that lead to the formation of uterine fibroids and their clinical manifestations.

Contrast-Enhanced Ultrasound Imaging of Uterine Disorders: A Systematic Review

Uterine disorders are often presented with overlapping symptoms. The microvasculature holds specific information important for diagnosing uterine disorders. Conventional sonography is an established diagnostic technique in gynecology, but is limited by its inability to image the microvasculature. Contrast-enhanced ultrasound (CEUS), is capable of imaging the microvasculature by means of intravascular contrast agents; that is, gas-filled microbubbles. We provide a literature overview on the use of CEUS in diagnosing myometrial and endometrial disorders, that is, fibroids, adenomyosis, leiomyosarcomas and endometrial carcinomas, as well as for monitoring and enhancing the effectiveness of minimally invasive therapies. A systematic literature search with quality assessment was performed until December 2020. In total 34 studies were included, published between 2007 and 2020.The results entail a description of contrast-enhancement patterns obtained from healthy tissue and from malignant and benign tissue; providing a first base for potential diagnostic differentiation in gynecology. In addition it is also possible to determine the degree of myometrial invasion in case of endometrial carcinoma using CEUS. The effectiveness of minimally invasive therapies for uterine disorders can safely and accurately be assessed with CEUS. In conclusion, the abovementioned applications of CEUS are promising and it is worth further exploring its full potential for gynecology by designing innovative and methodologically high-quality clinical studies.

Contrast-enhanced ultrasound of the small organs in children

In pediatric and adult populations, intravenous contrast-enhanced ultrasound (CEUS) remains off-label for imaging of organs other than the liver and heart. This limited scope inhibits potential benefits of the new modality from a more widespread utilization. Yet, CEUS is potentially useful for imaging small organs such as the thyroid gland, lymph nodes, testes, ovaries and uterus, with all having locations and vasculature favorable for this type of examination. In the adult population, the utility of CEUS has been demonstrated in a growing number of studies for the evaluation of these small organs. The aim of this article is to present a review of pediatric CEUS of the thyroid gland, lymph nodes, testes, ovaries and uterus as well as to draw from the adult literature indications for possible applications in children.

Contrast-Enhanced Ultrasound for Monitoring Non-surgical Treatments of Uterine Fibroids: A Systematic Review

Non-surgical treatment options for uterine fibroids are uterine artery embolization (UAE), high-intensity focused ultrasound ablation (HIFUA), and percutaneous microwave ablation (PMWA). Magnetic resonance imaging (MRI) is the reference standard imaging method before and after these procedures. Contrast-enhanced ultrasound (CEUS) has been studied as an alternative to MRI for evaluating the fibroids' characteristics and responses to non-surgical treatments. PubMed, Ovid MEDLINE and Scopus databases were searched for literature published from January 2000 through June 7, 2020, that investigated the application of CEUS as an adjunct to monitor UAE, HIFUA or PMWA in human uterine fibroid treatments. Two independent reviewers analyzed 128 publications, out of which 17 were included. Based on this systematic review, CEUS provides detailed data about fibroid volume and vascularization prior, during and post UAE, and it helps determine the endpoint of the procedure. HIFUA with intra-procedural CEUS has faster volume shrinkage over a shorter time period with less needed energy and provides early detection of residual tissue after HIFUA. CEUS and contrast-enhanced MRI have sufficient agreement to be used interchangeably in the clinic to evaluate the therapeutic effect of PMWA and HIFUA on fibroids.

Clinical value of contrast-enhanced ultrasound for the differential diagnosis of specific subtypes of uterine leiomyomas

OBJECTIVE

To improve the accuracy of clinical diagnosis by analyzing different contrast-enhanced ultrasound (CEUS) imagines of specific subtypes of uterine leiomyomas.

METHODS

A total of 147 female patients received preoperative CEUS examination. The scanning plane of the biggest tumors for CEUS was found by common B-mode ultrasonographic scanning on pelvic cavity, then 1.5 mL SonoVue were injected into the median cubital vein. According to the CEUS images, the lesion enhanced time, enhanced level and enhanced morphology were recorded. The time-intensity curve was acquired and analyzed, meanwhile, the relevant parameters were calculated, including rise time (RT), peak intensity (PI), time to peak (TTP) and mean transit time (MTT).

RESULTS

In cellular uterine leiomyoma group, the percentage of high enhancement, early enhancement was higher, equal enhancement and synchronic enhancement were lower than those in the common uterine leiomyomas group. In hysteromyoma with hyaline degeneration group, the percentage of high enhancement, early enhancement was lower, while low enhancement and delayed enhancement were higher than those in the common uterine leiomyomas group. The ratio of PI in cellular uterine leiomyoma group was the highest, but the ratios of RT, TTP and MTT were the lowest of the three benign groups. The ratio of PI in hysteromyoma with hyaline degeneration group was the lowest, while the ratios of RT and TTP was the highest among the three benign groups.

CONCLUSION

Different pathological types of uterine leiomyomas have their own signal performance on CEUS. CEUS can be used to infer their pathological types and help differential diagnosis.