Therapeutic response assessment of high intensity focused ultrasound therapy for uterine fibroid: utility of contrast-enhanced ultrasonography

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.

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.

Clinical significance of performing Sonazoid-based contrast-enhanced ultrasonography before ablation of uterine fibroids by high-intensity focused ultrasound: A preliminary cohort study

High-intensity focused ultrasound (HIFU) is effective for the ablation of uterine fibroids. However, no research has indicated whether HIFU ablation of uterine fibroids might be improved by application of contrast-enhanced ultrasonography (CEUS) with Sonazoid as a contrast agent. This study aimed to assess the clinical significance of Sonazoid-based CEUS 30 minute before HIFU ablation of uterine fibroids.This retrospective cohort study included Asian patients with solitary uterine fibroids who were treated with HIFU at Seoul HICARE Clinic (South Korea; n = 34) and the Second Affiliated Hospital of Chongqing Medical University (China; n = 30) between August 1, 2017, and October 31, 2017. The patients in Seoul underwent Sonazoid-based CEUS 30 minute before HIFU. All the patients received contrast-enhanced magnetic resonance imaging to diagnose uterine fibroids. The ablation results were evaluated 1 day after HIFU by contrast-enhanced magnetic resonance imaging or Sonazoid-based CEUS.All the patients were successfully treated with HIFU. The CEUS+HIFU group had lower values for sonication power, treatment time, sonication time, total energy applied, and energy efficiency factor compared with HIFU alone group (P < .001). There were no major adverse events after ablation therapy in either group. The incidence of post-procedure sacrococcygeal pain was lower in the CEUS+HIFU group than that in the HIFU alone group (P = .045), while the incidences of all other intraoperative and postoperative adverse events were similar between the 2 groups.Our findings suggest that Sonazoid-based CEUS before HIFU may enhance the ablation of uterine fibroids.

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.

Disappearance of the blood supply to a giant uterine myoma due to childbirth: A CARE-compliant article

RATIONALE

Giant uterine myomas may be life-threatening due to pressure effects on the lungs and other contiguous organs.

PATIENT CONCERNS

A 32-year-old pregnant Asian woman was admitted to our hospital early in her pregnancy with a pre-pregnancy history of multiple uterine myomas.

DIAGNOSIS

She was diagnosed with multiple giant uterine myomas in pregnancy.

INTERVENTIONS

No intervention was performed on the woman.

OUTCOMES

A reduction in tumor size and disappearance of tumor blood supply were seen on conventional and contrast-enhanced ultrasounds (CEUS) on postpartum day 34. Mass volume gradually decreased and no blood flow signals were seen on CEUS during postpartum follow-up.

LESSONS

Childbirth can block the blood supply of giant uterine myomas and reduce mass size. In such cases, childbirth may be considered therapeutic.

Contrast-enhanced ultrasound in the diagnosis of endometrial carcinoma: A meta-analysis

The present study evaluated the diagnostic value of contrast-enhanced ultrasound (CEUS) in endometrial carcinoma (EC). Articles published until 31 January 2017 were retrieved from PubMed, EMBASE, Elsevier, Springer and Google scholar, with the following inclusion criteria: i) The accuracy (sensitivity and specificity) of CEUS in the diagnosis of EC was evaluated; ii) a gold standard was adopted to treat and confirm EC, including surgery, histopathology and appropriate follow-up (as included in the meta-analysis); iii) the data allowed for construction of a 2×2 table of positives, false-positives, negatives and false-negatives. Pooled estimates of sensitivity, specificity, risk ratios and diagnostic odds ratios (DOR) were calculated in the present meta-analysis of the accuracy of CEUS in diagnosing EC. The summary receiver-operating characteristics (sROC) curve was also constructed. Among the 93 relevant articles, 7 studies were finally selected according to the inclusion criteria with a sample size of n=275. The pooled sensitivity of CEUS in the diagnosis of EC was 84% [95% confidence interval (CI), 0.78-0.88], while the pooled specificity was 90% (95% CI, 0.86-0.92). The positive likelihood ratio (+LR) of CEUS was 8.0 (95% CI, 5.9-10.8) and the negative likelihood ratio (-LR) was 0.18 (95% CI, 0.13-0.25). The DOR was 44 (95% CI, 26-77). The area under the sROC curve was 0.93 with specificity of 0.90 (0.86-0.92) and sensitivity of 0.84 (0.78-0.88) for the summary operating point. Moderate heterogeneity was observed for sensitivity, specificity and DOR with I² values of 32.56, 34.68 and 41.2%, respectively. No significant publication bias was observed for the DOR of CEUS. In conclusion, the present meta-analysis indicates that CEUS is valuable in the diagnosis of EC. Additional clinical data and studies are still required to confirm these results and to further develop the diagnostic application of CEUS in EC.

Contrast-Enhanced Transrectal Ultrasound in Focal Therapy for Prostate Cancer

PURPOSE OF REVIEW

Contrast-enhanced transrectal ultrasound (CeTRUS) is an emerging imaging technique in prostate cancer (PCa) diagnosis and treatment. We review the utility and implications of CeTRUS in PCa focal therapy (FT).

RECENT FINDINGS

CeTRUS utilizes intravenous injection of ultrasound-enhancing agents followed by high-resolution ultrasound to evaluate tissue microvasculature and differentiate between benign tissue and PCa, with the latter demonstrating increased enhancement. The potential utility of CeTRUS in FT for PCa extends to pre-, intra- and post-operative settings. CeTRUS may detect PCa, facilitate targeted biopsy and aid surgical planning prior to FT. During FT, the treated area can be visualized as a well-demarcated non-enhancing zone and continuous real-time assessment allows immediate re-treatment if necessary. Following FT, the changes on CeTRUS are immediate and consistent, thus facilitating repeat imaging for comparison during follow-up. Areas suspicious for recurrence may be detected and target-biopsied. Enhancement can be quantified using time-intensity curves allowing objective assessment and comparison. Based on encouraging early outcomes, CeTRUS may become an alternative imaging modality in prostate cancer FT. Further study with larger cohorts and longer follow-up are needed.

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

Contrast-enhanced ultrasound (CEUS) is an innovative ultrasound technique capable of visualizing both the macro- and microvasculature of tissues. In this prospective pilot study, we evaluated the feasibility of using CEUS to visualize the microvasculature of uterine fibroids and compared CEUS with conventional ultrasound. Four women with fibroids underwent gray-scale ultrasound, sonoelastography and power/color Doppler scans followed by CEUS examination. Analysis of CEUS images revealed initial perfusion of the peripheral rim, that is, a pseudo-capsule, followed by enhancement of the entire lesion through vessels traveling from the exterior to the interior of the fibroid. The pseudo-capsules exhibited slight hyper-enhancement, making a clear delineation of the fibroids possible. The centers of three fibroids exhibited areas lacking vascularization, information not obtainable with the other imaging techniques. CEUS is a feasible technique for imaging and quantifying the microvasculature of fibroids. In comparison with conventional ultrasound imaging modalities, CEUS can provide additional diagnostic information based on the microvasculature.

Ultrasound-Guided Intratumoral Radiofrequency Ablation Coagulation to Facilitate Meningioma Resection: Preliminary Experience

OBJECTIVES

This study aimed to explore the feasibility and safety of intratumoral radiofrequency ablation (RFA) in meningioma resection.

METHODS

This study was approved by the Xijing Ethics Committee, and informed consent was obtained from all of the patients. Thirteen patients with meningiomas were recruited in the Neurosurgery Department of Xijing Hospital. These patients were treated with intratumoral RFA and surgery. We also chose 13 patients with meningiomas treated with traditional surgery as the control group. Two-dimensional ultrasound, color Doppler flow imaging, contrast-enhanced ultrasound, and magnetic resonance imaging were used to identify the location, border, and blood supply of the meningiomas preoperatively and to assess the therapeutic effect intraoperatively. Finally, the meningiomas were dissected and removed by surgery.

RESULTS

All procedures were technically successful without serious complications. Intraoperative ultrasound was able to provide a clear display of the location, shape, size, and boundary of the tumor and its relationship with other tissues and reveal the vascular distribution in and around the tumors. With intratumoral RFA, coagulative necrosis was induced, and the meningiomas became hard in texture with a decreased blood supply. Blood loss was significantly lower in the RFA group versus control group (320.0 ± 24.8 versus 390.4 ± 36.8 mL; P < .001). The RFA group spent fewer days in the hospital (6.0 ± 0.9 versus 7.0 ± 1.2 days; P = .022). However, the surgical time of the RFA group was relatively longer (3.5 ± 0.5 versus 3.0 ± 0.3 hours, P = .007).

CONCLUSIONS

The application of intratumoral RFA in meningioma resection is effective and safe. It may be a useful adjunct for meningioma treatment.

Effects of a microbubble ultrasound contrast agent on high-intensity focused ultrasound for uterine fibroids: a randomised controlled trial

OBJECTIVE

To investigate the effects of a microbubble ultrasound contrast agent on high-intensity focused ultrasound (HIFU) treatment of uterine fibroids.

METHODS

A total of 120 patients with solitary uterine fibroid were randomly assigned into Groups A, B, C and D. Patients in Groups A and B received 1.5 ml of SonoVue, Groups C and D received 1.5 ml of saline before HIFU ablation. HIFU sonication started at 6 min after administration of SonoVue or saline in Groups A and C, whereas it started at 10 min in Groups B and D. On day 1 after HIFU, magnetic resonance imaging was performed. Patients were followed up via phone or clinic visit during the first week after HIFU.

RESULTS

No significant difference was observed in terms of age, fibroid location, diameter of fibroids, signal intensity on T2-weighted imaging, or tumour volume among the four groups (p > 0.05). The use of SonoVue significantly shortened the treatment time and sonication time. The sonication start time of 6 min, relative to 10 min, had significant effects on the treatment time and sonication time. The use of intravenous SonoVue followed by HIFU ablation 6 min later significantly increased the rate of significant grey-scale changes (55.9%) and the non-perfused volume ratio (94.2% ± 10.6%). No significant differences were observed in the incidence of intra-procedure and post-HIFU adverse effects among the four groups (p > 0.05).

CONCLUSIONS

SonoVue could be safely used to enhance the ablation effects of HIFU treatment of uterine fibroids.

Contrast-enhanced ultrasound is better than magnetic resonance imaging in evaluating the short-term results of microwave ablation treatment of uterine fibroids

Contrast-enhanced ultrasound (CEUS) and magnetic resonance imaging (MRI) were compared in evaluating the short-term effects of microwave ablation (MWA) on uterine fibroids. A total of 60 patients with uterine fibroids treated by MWA were enrolled in the experimental group during their two-year follow-up period according to the inclusion criteria. Conventional two-dimensional US, MRI and CEUS were performed to determine the volume reduction and the fibroid residue by displaying the size, echo and signal intensity of fibroids prior to and after MWA treatment. As the control group, 60 consecutive patients were recruited on their follow-up visit at least two years after MWA treatment of uterine fibroids. Significant differences were observed in the wash-in rate (WiR) of the fibroid tissue, start time difference, rise time ratio (RTR) and WiR ratio between the experimental and control groups (P<0.05). However, the WiR of fibroid vessel, total area under the curve of fibroid vessel and tissue, and rise time difference (RTD) between fibroid vessel and tissue did not display any significant differences between the two groups. Fibroids were either reduced in volume or cured by MWA therapy in patients with uterine fibroids. The reductions in volume of hypointense, isointense and hyperintense fibroids were 62.42±18.13, 53.27±10.05 and 47.43±9.56%, respectively, on T1-weighted imaging (T1WI). On T2WI, the corresponding reductions were 67.32±32.63, 59.36±19.36 and 42.63±10.37%, respectively. The higher the signal intensity on T1WI and T2WI, the lower the reduction in volume. It is indicative that different blood supply to fibroids results in different ablation. CEUS was proved to be more effective than MRI in evaluating the effects of MWA on uterine fibroids during the first postoperative year.

Materials Chemistry of Nanoultrasonic Biomedicine

As a special cross-disciplinary research frontier, nanoultrasonic biomedicine refers to the design and synthesis of nanomaterials to solve some critical issues of ultrasound (US)-based biomedicine. The concept of nanoultrasonic biomedicine can also overcome the drawbacks of traditional microbubbles and promote the generation of novel US-based contrast agents or synergistic agents for US theranostics. Here, we discuss the recent developments of material chemistry in advancing the nanoultrasonic biomedicine for diverse US-based bio-applications. We initially introduce the design principles of novel nanoplatforms for serving the nanoultrasonic biomedicine, from the viewpoint of synthetic material chemistry. Based on these principles and diverse US-based bio-application backgrounds, the representative proof-of-concept paradigms on this topic are clarified in detail, including nanodroplet vaporization for intelligent/responsive US imaging, multifunctional nano-contrast agents for US-based multi-modality imaging, activatable synergistic agents for US-based therapy, US-triggered on-demand drug releasing, US-enhanced gene transfection, US-based synergistic therapy on combating the cancer and potential toxicity issue of screening various nanosystems suitable for nanoultrasonic biomedicine. It is highly expected that this novel nanoultrasonic biomedicine and corresponding high performance in US imaging and therapy can significantly promote the generation of new sub-discipline of US-based biomedicine by rationally integrating material chemistry and theranostic nanomedicine with clinical US-based biomedicine.

Clinical application of high-intensity focused ultrasound ablation for uterine fibroids

HIFU (high-intensity focused ultrasound) ablation is an emerging therapeutic modality that induces thermal coagulative necrosis of biological tissues by focusing high-energy ultrasound waves onto one small spot. This technique is at various stages of clinical applications in several organs. However, it has increasingly been used in the treatment of symptomatic uterine fibroids, a common condition affecting women. Since its first clinical use for symptomatic uterine fibroids, this technique has been recognized for safety, satisfactory therapeutic efficacy in symptom control, uterus-preserving ability, radiation-free nature, and because of the fact that it does not require hospitalization. Owing to its numerous benefits, HIFU ablation is currently one of the major therapeutic options for symptomatic uterine fibroids. In this review, several aspects ranging from the physical principle of HIFU to the long-term outcomes are summarized from the perspective of the clinical application for uterine fibroids.

Effectiveness of ultrasound-guided percutaneous microwave ablation for symptomatic uterine fibroids: a multicentre study in China

PURPOSE

To evaluate the clinical efficacy of ultrasound-guided percutaneous microwave ablation (PMWA) therapy for symptomatic uterine fibroids in a multicentre study.

MATERIALS AND METHODS

Patients with symptomatic uterine fibroids who underwent PMWA at multiple treatment centres in China between January 2013 and August 2015 were prospectively studied to compare the reduction rate of uterine fibroids, haemoglobin level and uterine fibroid symptom and health-related quality of life questionnaire (UFS-QOL) scores before and at 3, 6 and 12 months after ablation.

RESULTS

A total of 311 patients (405 leiomyomas) from eight treatment centres underwent the treatment (age, 29-55 years; mean ± SD, 41 ± 5.11 years). The mean diameter of the myomas ranged from 2.03 to 12.50 cm (mean, 5.10 ± 1.28 cm) and the volume ranged from 4.40 to 1022.14 cm³ (mean, 95.01 ± 70.29 cm³). Forty-eight myomas were identified as FIGO type 1/2 fibroids, 256 as type 3/4 fibroids and 101 as type 5/6 fibroids. The mean ablation rate was 86.6% (54.0-100%). The mean reduction rate was 63.5%, 78.5% and 86.7% at 3, 6 and 12 months posttreatment, respectively. The haemoglobin level increased significantly from 88.84 ± 9.31 g/L before treatment to 107.14 ± 13.32, 116.05 ± 7.66 and 117.79 ± 6.51 g/L at 3, 6 and 12 months posttreatment, respectively (p = .000). The symptom severity score (SSS) and health-related quality of life (HRQL) scores were also significantly improved posttreatment compared with before treatment (p = .000).

CONCLUSION

PMWA is an effective, minimally invasive treatment for symptomatic leiomyomas that can significantly improve the quality of life of patients.

Ultrasound-guided transcervical radiofrequency ablation for symptomatic uterine adenomyosis

OBJECTIVE

To retrospectively evaluate the midterm outcomes of transvaginal ultrasound-guided radiofrequency ablation (RFA) for the treatment of symptomatic uterine adenomyosis.

METHODS

87 patients with symptomatic uterine adenomyosis, who met the inclusion criteria, were enrolled in our study from January 2013 to October 2015. All of the patients underwent transvaginal ultrasound-guided RFA and were followed up for 12 months. Assessment end points included uterus volume reduction rate, lesion regression rate, dysmenorrhoeal score, symptom severity score (SSS) and adverse events.

RESULTS

In all 87 patients, 81 patients fulfilled the follow-up evaluations post-ablation. The mean uterine volume reduction rate was 35.8% at 1 month, 40.8% at 6 months and 41.2% at 12 months post-ablation. Dysmenorrhoea and SSS statistically significantly declined. Reintervention rate was 18.5%. Two patients developed intrauterine adhesion after ablation. No serious complications including penetration or burn injuries of the nearby organs were observed.

CONCLUSION

Ultrasound-guided RFA might be a safe and effective minimally invasive alternative in the treatment of symptomatic adenomyosis. Advances in knowledge: This is the first study to evaluate the efficacy and safety of ultrasound-guided RFA for the treatment of adenomyosis to our knowledge. This is also the first study to provide various changes of intrauterine cavity after this treatment.

An MRI-conditional motion phantom for the evaluation of high-intensity focused ultrasound protocols

BACKGROUND

The respiratory motion of abdominal organs is a serious obstacle in high-intensity focused ultrasound (HIFU) treatment with magnetic resonance imaging (MRI) guidance. In this study, a two-dimensional (2D) MRI-conditional motion phantom device was developed in order to evaluate HIFU protocols in synchronized and non-synchronized ablation of moving targets.

MATERIALS AND METHODS

The 2D phantom device simulates the respiratory motion of moving organs in both the left-right and craniocaudal directions. The device consists of MR-conditional materials which have been produced by a three-dimensional (3D) printer.

RESULTS

The MRI compatibility of the motion phantom was tested successfully in an MRI scanner. In vitro experiments were carried out to evaluate HIFU ablation protocols that are minimally affected by target motion.

CONCLUSION

It was shown that only in synchronized mode does HIFU produce thermal lesions, as tested on a gel phantom mimicking the moving target. The MRI-conditional phantom device was shown to be functional for its purpose and can be used as an evaluation tool for testing HIFU protocols for moving targets in an MRI environment. Copyright © 2015 John Wiley & Sons, Ltd.

Ultrasound guided high intensity focused ultrasound (USgHIFU) ablation for uterine fibroids: Do we need the microbubbles?

PURPOSE

The aim of this study was to assess the safety and effectiveness of contrast-enhanced ultrasound (CEUS) on ultrasound guided high intensity focused ultrasound (USgHIFU) ablation of uterine fibroids.

METHODS

Thirty-three patients (37 fibroids) were randomly assigned to two groups: group A (17 patients, 20 fibroids) in which CEUS was used before, during and after HIFU treatment, and group B (16 patients, 17 fibroids) in which CEUS was not administered at all. Follow-up including contrast-enhanced magnetic resonance imaging (MRI) and a clinical questionnaire was performed, and technical success, ablation efficacy, volume reduction and complications were assessed.

RESULTS

Technical success was 100% in both groups. CEUS revealed residual enhancement in 40% of the patients in group A and the treatment was continued until the completion of ablation. MRI at 1 month after treatment revealed significant difference in the relative fibroid volume reduction rate between the two groups: 16.1% in group A versus 4.8%, in group B (p = 0.01). There was no statistically significant relative volume reduction rate for the results at 3, 6 and 12 months and no significant changes in the quality of life results or the complication rate.

CONCLUSIONS

CEUS was safe and effective in enhancing US guidance during HIFU ablation of uterine fibroids. Moreover, the use of CEUS during HIFU sonication increased the ablation efficacy, leading to a more relevant fibroid volume reduction at 1 and 3 months. This gap disappeared after 6 months, when there were no differences between the two groups of patients at MRI. However, in our experience, USgHIFU represented a very effective method for the treatment of uterine fibroids, and the use of CEUS during HIFU procedure reduced the treatment time and treatment repetitions for incomplete fibroid ablation.

Contribution of contrast-enhanced ultrasound with Sonovue to describe the microvascularization of uterine fibroid tumors before and after uterine artery embolization

OBJECTIVE

The principal objective of this study was to use contrast-enhanced ultrasonography to describe the characteristics of fibroid microvascularization before and after embolization.

STUDY DESIGN

Forty women had contrast-enhanced ultrasonography with Sonovue(®) injections before uterine artery embolization, the day afterwards, and at 6-12 months afterwards. An MRI was also performed before and after the procedure.

RESULTS

Two thirds of the fibroids took up the contrast product before the myometrium did, and 45.8% were vascularized along the peripheral rim of the fibroid, compared with 41.6% with a principal pedicle and from the center in three (12.6%). After embolization at day one (D1), the myometrium was fully enhanced, that is, perfusion of the myometrium was plainly visible, in 25 cases (69.4%; n=36), partially enhanced in eight (22.2%), and totally avascular in three (8.4%). Analysis of the failures according to imaging criteria the day after embolization (D1) showed failure in seven women, with partial enhancement for six, and total for one. In the imaging at 6 months (M6), contrast ultrasonography showed failure for three women, with enhancement of the largest fibroid. This enhancement was total in two cases and partial (40%) in one. There were five failures according to MRI at M6, with partial enhancement. Only two of these failures were simultaneously failures according to the contrast-enhanced ultrasonography. There were five clinical failures, two consistent with the imaging at 6 months and four predictable on D1.

CONCLUSION

Contrast-enhanced ultrasonography is feasible and useful to understand fibroid vascularization and for monitoring embolization; its correlation with MRI is good, its concordance less so.

High-intensity focused ultrasound ablation of myocardium in vivo and instantaneous biological response

OBJECTIVE

This study aimed to evaluate the instantaneous biological response of canine myocardium in vivo to high-intensity focused ultrasound (HIFU) ablation, and thereby determine the feasibility of this method.

METHODS

Left ventricle myocardium HIFU ablation was performed on six dogs at four levels of HIFU energy (acoustic intensity was 3000 W/cm2 ; ablation durations were 1.2, 2.4, 3.6, and 4.8 sec, respectively). Gross lesion volumes were confirmed and assessed by tetrazolium chloride (TTC) staining, hematoxylin-eosin (HE) staining, and electron microscopy. Global cardiac function and focal wall motion were evaluated by echocardiography. Blood enzymes and cardiac troponin T (CTnT) were tested after ablation. HIFU ablation was repeated on another set of six fresh canine hearts in vitro at the same four energy levels. Focal maximum temperatures were detected both in vivo and in vitro.

RESULTS

Different sizes of ablation via HIFU can be created in beating hearts using controlled energy emission. Focal maximum temperatures varied from 62 ± 4.8 °C to 81 ± 12.9 °C. The lesion sizes were significantly smaller in vivo than in vitro, as verified by TTC and HE staining. Focal wall motion immediately decreased after ablation (P < 0.05), although the ejection fraction (EF) and E/A ratio were unchanged (P > 0.05). Enzymes and CTnT immediately increased.

CONCLUSION

HIFU can be used for the controllable ablation of myocardial tissue, with instantly increased serum markers, decreased regional wall motion, and unaffected left ventricular global function.

Investigation of women with postmenopausal uterine bleeding: clinical practice recommendations

Postmenopausal uterine bleeding is defined as uterine bleeding after permanent cessation of menstruation resulting from loss of ovarian follicular activity. Bleeding can be spontaneous or related to ovarian hormone replacement therapy or to use of selective estrogen receptor modulators (eg, tamoxifen adjuvant therapy for breast carcinoma). Because anovulatory "cycles" with episodes of multimonth amenorrhea frequently precede menopause, no consensus exists regarding the appropriate interval of amenorrhea before an episode of bleeding that allows for the definition of postmenopausal bleeding. The clinician faces the possibility that an underlying malignancy exists, knowing that most often the bleeding comes from a benign source. Formerly, the gold-standard clinical investigation of postmenopausal uterine bleeding was institution-based dilation and curettage, but there now exist office-based methods for the evaluation of women with this complaint. Strategies designed to implement these diagnostic methods must be applied in a balanced way considering the resource utilization issues of overinvestigation and the risk of missing a malignancy with underinvestigation. Consequently, guidelines and recommendations were developed to consider these issues and the diverse spectrum of practitioners who evaluate women with postmenopausal bleeding. The guideline development group determined that, for initial management of spontaneous postmenopausal bleeding, primary assessment may be with either endometrial sampling or transvaginal ultrasonography, allowing patients with an endometrial echo complex thickness of 4 mm or less to be managed expectantly. Guidelines are also provided for patients receiving selective estrogen receptor modulators or hormone replacement therapy, and for an endometrial echo complex with findings consistent with fluid in the endometrial cavity.�

Efficacy and safety of daily repeated sonographically guided high-intensity focused ultrasound treatment of uterine fibroids: preliminary study

OBJECTIVES

To evaluate the efficacy and safety of repeated low-dose sonographically guided high-intensity focused ultrasound (HIFU) treatment of uterine fibroids.

METHODS

Between April and December 2010, 24 consecutive premenopausal women with symptomatic uterine fibroids were enrolled in this study. The treatment was performed with an HIFU unit without anesthesia or sedative administration and Foley catheter insertion. The treatment was performed 40 to 70 min/d according to the tumor volume. The entire treatment was finished after 4 to 6 days of treatment. We assessed the differences in the symptom severity score, tumor volume, and contrast-enhanced volume at baseline and 1 and 3 months after treatment. The clinical success rates according to tumor volume and contrast-enhanced volume reductions and echogenicity and vascular flow changes were analyzed. The clinical success rates according to the baseline characteristics of fibroids were analyzed. We assessed adverse events during and after treatment.

RESULTS

The symptom severity score, tumor volume, and contrast-enhanced volume decreased significantly after repeated low-dose HIFU treatment (P < .05). There were significant correlations between tumor volume and contrast-enhanced volume reduction and the decrease in the symptom severity score. The clinical success rates were significantly different according to the tumor vascularity on color Doppler sonography and the degree of enhancement on magnetic resonance imaging. Skin burns and other serious adverse events did not develop.

CONCLUSIONS

Although this preliminary report had several limitations, daily repeated HIFU treatment of uterine fibroids may be a useful and safe method and can be used as a different option for HIFU treatment in patients who prefer treatment without anesthesia or sedation.

Heart ablation using a planar rectangular high intensity ultrasound transducer and MRI guidance

The aim of this study was to evaluate a flat rectangular (3×10mm(2)) MRI compatible transducer operating at 5MHz. The main task was to explore the feasibility of creating deep lesions in heart at a depth of at least 15mm. The size of thermal necrosis in heart tissue was estimated as a function of power and time using a simulation model. The system was then tested in an excised lamb heart. In this study, we were able to create lesions of 15mm deep with acoustic power of 6W for an exposure of approximately 1min. The contrast to noise ratio (CNR) between lesion and heart tissue was evaluated using fast spin echo (FSE). The CNR value was approximately 22 using T1W FSE. Maximum CNR was achieved with repetition time (TR) between 300 and 800ms. Using T2W FSE, the corresponding CNR was approximately 13 for the 14 in vivo experiments. The average lesion depth was 11.93mm with a standard deviation of 0.62mm. In vivo irradiation conditions were 6W for 60s. The size of the lesion in the other two dimensions was close to 3×10mm(2) (size of the transducer element).

Safety and efficacy of US-guided high-intensity focused ultrasound for treatment of submucosal fibroids

OBJECTIVES

To evaluate the safety and efficacy of US-guided high-intensity focused ultrasound (HIFU) ablation for the treatment of submucosal fibroids

METHODS

A total of 76 women with 78 submucosal uterine fibroids (68 type II fibroids, 10 type I fibroids) underwent US-guided HIFU ablation. The pretreatment fibroid diameter ranged from 2.4 to 13.5 cm (mean 5.7 ± 2.3 cm). The fibroids were ablated using a power output of 420-520 W. During follow-up, the volume shrinkage of the ablated fibroids was continuously observed on contrast-enhanced MR and/or contrast-enhanced ultrasound (CEUS). The change of symptoms was evaluated by using the symptom severity score questionnaire.

RESULTS

HIFU ablation was well tolerated in all patients. No major complications occurred. The mean nonperfused ablation ratio was 80 ± 12 % on CEUS. During follow-up, the ablated fibroids shrank significantly over time. The symptoms were alleviated significantly. No patients had amenorrhoea after treatment. Vaginal expulsion of necrotic tissue was seen in 58 % (44/76) of patients after HIFU ablation which disappeared after 2-4 menstrual cycles. Four patients received repeated HIFU ablation for enlarged residual fibroids.

CONCLUSIONS

US-guided HIFU ablation may be a safe and effective treatment for submucosal fibroids. Further studies are warranted to observe its influence on fertility.

KEY POINTS

• High-intensity focused ultrasound (HIFU) is a new minimally invasive therapeutic technique. • HIFU ablation may be safe and effective for treatment of submucosal fibroids • Treatment is minimally invasive and repeatable. • Vaginal expulsion of necrotic tissue is common after treatment.

A preclinical in vivo investigation of high-intensity focused ultrasound combined with radiotherapy

This study aims to perform an in vivo investigation evaluating the injury to the pancreas and adjacent tissue of swine resulting with high-intensity focused ultrasound (HIFU) combined with radiotherapy (RT). The protocol was approved by the animal ethics committee at the Peking University First Hospital. A total of 12 domestic swine were divided into four groups: control, HIFU only, RT only and HIFU + RT. The injury to the pancreas, adjacent tissue and tissue within the acoustic path of the HIFU beam was assessed based on gross and histologic findings. For the targeted region of the pancreas, the score of the combined group was higher than that of the HIFU group and there was significant difference. For the acoustic path tissue, there was no significant difference except between the control group and the other groups. HIFU combined with RT increased the injury to the targeted pancreas, without increased injury to tissue outside of the targeted region.

A novel approach to identify non-palpable breast lesions combining fluorescent liposomes and magnetic resonance-guided high intensity focused ultrasound-triggered release

The combination of fluorescein-containing liposomes (FCL) and magnetic resonance-guided high intensity focused ultrasound (MR-HIFU)-triggered release is a promising approach for lesion demarcation and more efficient removal of non-palpable breast lesions. Exposure of FCL to ablation temperatures (60 °C) using MR-HIFU would result in palpable, stained tumors, which are more easy to identify during surgical resection. In this study, proof-of-concept concerning fluorescent FCL for MR-HIFU-triggered release and tumor demarcation of non-palpable breast lesions is presented. Ex vivo experiments in human blood and porcine muscle tissue showed increased label release from the liposomes, clear fluorescence enhancement and diffusion of the released compound after heating to 60 °C. Next, fluorescein release of FCL was observed after MR-HIFU-mediated mild hyperthermia (42 °C) and ablation temperature (60 °C) for a short period (30s), which is in line with the clinically relevant MR-HIFU treatment parameters. These results indicate the potential of the FCL as a tool to improve tumor demarcation in patients by MR-HIFU-triggered release. Therefore, this method may offer a new tool for efficient surgical resection of non-palpable breast tumor lesions by enabling proper discrimination between tumor tissue and adjacent healthy tissue.

A rabbit bone tumor model for high-intensity focused ultrasound therapy

The incidence of malignant bone tumor increases every year. Because the application of high-intensity focused ultrasound (HIFU) for the treatment of bone tumors is still at a nascent stage, it is essential to study the effectiveness of this technique in ideal animal models in order to obtain a beneficial reference for imaging studies. In this study, we established a VX2 malignant bone tumor model and evaluated this model by contrast-enhanced sonography and magnetic resonance imaging (MRI). The results show that all tumors were enhanced after injection of SonoVue. A contrast-enhanced MRI scan revealed obvious enhancement within the tumors. Histological examination revealed the presence of a large number of tumor cells. The model can serve as an ideal experimental model for the study of HIFU therapy in the treatment of malignant bone tumors and as a reference for imaging studies during follow-ups.

Parametric perfusion imaging based on low-cost ultrasound platform

In this study, we attempted to implement parametric perfusion imaging to quantify blood perfusion based on modified low-cost ultrasound platform. A novel ultrasound contrast-specific imaging method called pulse-inversion harmonic sum-squared-differences (PIHSSD) was proposed for improving the sensitivity for detecting contrast agents and the accuracy of parametric perfusion imaging, which combined pulse-inversion harmonic (PIH) with pulse-inversion sum-squared-differences (PISSD) threshold-based decision. PIHSSD method just involved simple operations including addition and multiplication and was easy to realize. The sequences of contrast images without logarithmic compression were used to acquire time intensity curves (TICs) from numerous equal-sized regions-of-interest (ROI) covering the entire image plane. Parametric perfusion images were obtained based on the parameters extracted from the TICs, including peak value (PV), area under curve (AUC), mean transit time (MTT), peak value time (PVT), peak width (PW) and climbing rate (CR). Flow phantom was used for validation and the results suggested that PIHSSD method provided 9.6 to 20.3 dB higher contrast-to-tissue ratio (CTR) than PIH method. The results of the experiments of rabbit kidney also showed that the CTR of PIHSSD images was higher than that of PIH images, and the parametric perfusion images based on PIHSSD method provided more accurate quantification of blood perfusion compared with those based on PIH and PISSD methods. It demonstrated that the parametric perfusion imaging achieved good performance though implemented on low-cost ultrasound platform. (E-mail: mxwan@mail.xjtu.edu.cn).

Contrast-enhanced ultrasound: The evolving applications

Contrast-enhanced ultrasound (CEUS) is a major breakthrough for ultrasound imaging in recent years. By using a microbubble contrast agent and contrast-specific imaging software, CEUS is able to depict the micro- and macro-circulation of the targeted organ, which in turn leads to improved performance in diagnosis. Due to the special dual blood supply system in the liver, CEUS is particularly suitable for liver imaging. It is evident that CEUS facilitates improvement for characterization of focal liver lesions (FLLs), detection of liver malignancy, guidance for interventional procedures, and evaluation of treatment response after local therapies. CEUS has been demonstrated to be equal to contrast-enhanced computed tomography or magnetic resonance imaging for the characterization of FLLs. In addition, the applicability of CEUS has expanded to non-liver structures such as gallbladder, bile duct, pancreas, kidney, spleen, breast, thyroid, and prostate. The usefulness of CEUS in these applications is confirmed by extensive literature production. Novel applications include detecting bleeding sites and hematomas in patients with abdominal trauma, guiding percutaneous injection therapy and therefore achieving the goal of using interventional ultrasonography in managing splenic trauma, assessing the activity of Crohn’s disease, and detecting suspected endoleaks after endovascular abdominal aneurysm repair. Contrast-enhanced intraoperative ultrasound (US) and intracavitary use of CEUS have been developed and clinically studied. The potential use of CEUS involves sentinel lymph node detection, drug or gene delivery, and molecular imaging. In conclusion, the advent of CEUS has greatly enhanced the usefulness of US and even changed the status of US in clinical practice. The application of CEUS in the clinic is continuously evolving and it is expected that its use will be expanded further in the future.

Safety and efficacy of high intensity focused ultrasound ablation therapy for adenomyosis

RATIONALE AND OBJECTIVES

In patients with adenomyosis, the severity of symptoms correlates roughly with the extent of adenomyosis. Thus, it was hypothesized that the ablation of enough volume of adenomyosis might alleviate symptoms. The aim of this study was to investigate the safety and efficacy of high-intensity focused ultrasound (HIFU) ablation for the treatment of adenomyosis.

MATERIALS AND METHODS

Phase I HIFU ablation of adenomyosis was performed on 12 patients. Three patients each were treated using four different acoustic intensities (290, 340, 380, and 420 W) step by step. Contrast-enhanced ultrasound was used to evaluate the necrotic region of treated adenomyosis. The efficacy of therapy was evaluated after 3 months of follow-up.

RESULTS

All patients in the four groups tolerated the therapy well, and no severe complications were found during follow-up. After treatment, nonenhanced necrotic regions were shown on contrast-enhanced ultrasound in all treated adenomyosis. The mean volumes of the nonenhanced regions were 72, 75, 68, and 124 cm(3) in the 290-W, 340-W, 380-W, and 420-W groups, respectively. At 3 months after therapy, the mean pain relief in the four groups was 25%, 58.3%, 66.7%, and 83.3%, respectively.

CONCLUSIONS

HIFU may be a safe and effective method to treat adenomyosis, and an acoustic intensity of 420 W may be able to produce larger volumes of necrosis and better pain relief.

Imaging techniques to evaluate the response to treatment in oncology: current standards and perspectives

Response evaluation in solid tumours currently uses radiological imaging techniques to measure changes under treatment. Imaging requires a well-defined anatomical lesion to be viewed and relies on the measurement of a reduction in tumour size during treatment as the basis for presumed clinical benefit. However, with the development of anti-angiogenesis agents, anatomical imaging has became inappropriate as certain tumours would not reduce in size. Functional studies are therefore necessary and dynamic contrast enhanced magnetic resonance imaging (DCE-MRI), DCE-computed tomography (CT) and DCE-ultrasonography (US) are currently being evaluated for monitoring treatments. Diffusion-weighted MR imaging (DW-MRI) and magnetic resonance spectroscopy (MRS) are also capable of detecting changes in cell density and metabolite content within tumours. In this article, we review anatomical and functional criteria currently used for monitoring therapy. We review the published data on DCE-MRI, DCE-CT, DCE-US, DW-MRI and MRS. This literature review covers the following area: basic principles of the technique, clinical studies, reproducibility and repeatability, limits and perspectives in monitoring therapy. Anatomical criteria such as response evaluation criteria in solid tumours (RECIST) will require adaptation to employ not only new tools but also different complementary techniques such as functional imaging in order to monitor therapeutic effects of conventional and new anti-cancer agents.

Hyperecho as the indicator of tissue necrosis during microbubble-assisted high intensity focused ultrasound: sensitivity, specificity and predictive value

The purpose of this study was to determine the sensitivity, specificity and predictive values of hyperecho in grayscale ultrasonic images as the indicator of tissue necrosis in microbubble-assisted high-intensity focused ultrasound (HIFU) exposure in vivo. Livers and kidneys of the rabbit were exposed to HIFU (control group) or microbubble-assisted HIFU (experimental group); a continuous line of ablation, viz. linear scan, was performed to destruct tissues. Tissue responses were evaluated macroscopically and microscopically 24 h after HIFU. The cases of positive (hyperecho occurred and tissue necrotized), false positive (tissue was unaffected although hyperecho appeared), negative (echo was not changed and tissue was intact) and false negative (tissue was destructed despite the lack of hyperecho) were counted, and then the sensitivity, specificity and positive and negative predictive values of hyperecho were calculated. The sensitivity, specificity, positive predictive value and negative predictive value were 49.25% vs. 79.63% (p < 0.001), 45.45% vs. 30.00%, 84.62% vs. 86.00% and 12.82% vs. 21.43% for liver and 76.06% vs. 81.25%, 26.53% vs. 41.67%, 60.00% vs. 82.28% (p = 0.002) and 43.33% vs. 40.00% for kidney, in control and experimental groups, respectively. Rates varied between tissue types in control group. These findings indicated that the use of microbubble during HIFU improved the sensitivity in liver and the positive predictive value in kidney. The specificity and negative predictive value were poor. Hyperecho could only be used as the indicator of tissue necrosis in some tissue types.

Focused ultrasound for treatment of uterine myoma: From experimental model to clinical practice

It is well known that focused ultrasound has a biologic effect on tissue. High intensity focused ultrasound (HIFU) on a small target area raises the temperature of the tissue enough to denaturate proteins and cause irreversible cell damage. The tight focus of the ultrasound energy allows delivery of the intended dose to a very precise location. The resulting coagulation necrosis is relatively painless. The application of this method in the human clinical setting has required pilot studies on an animal model. Although the treatment had a high success rate, there was a significant percentage of complications, mainly attributed to the technical drawbacks of the procedure. Therefore, this method has been modified for use in humans, and the HIFU is now guided, monitored and controlled by magnetic resonance imaging (MRI). In October 2004, Food and Drug Adiministration (FDA) approved MRI guided focused ultrasound treatment of uterine fibroids in humans. Since then, successful treatment of uterine myomas by HIFU has been performed in thousands of women.