Magnetic resonance texture parameters are associated with ablation efficiency in MR-guided high-intensity focussed ultrasound treatment of uterine fibroids

Objectives: The objective of this study is to assess the association between texture parameter analysis derived from T2-weighted images and efficiency of magnetic resonance-guided focussed ultrasound (MRgFUS) ablation for the treatment of uterine fibroids.

Materials and methods: Fifty-five women treated by MRgFUS were included in this retrospective analysis. Texture parameters were calculated using three 2D regions of interest placed on three consecutive slices on the same sagittal 3D T2-weighted images obtained at the beginning of MRgFUS ablation. Using uni- and multi-variate linear regression, texture parameters, fibroids/muscular T2W ratio (T2Wr), Funaki type, and fibroid depth were correlated with ablation efficiency, defined as the ratio of non-perfused volume (NPV) on post-treatment contrast-enhanced MRI by total volume of treatment-cell sizes used. Inter-rater reproducibility for texture analysis was assessed using variation coefficients.

Results: The mean total treatment cell volume was 49.5 (±30) ml, corresponding to a mean NPV of 57.2 (±57) ml (28%). The mean ablation efficiency was 1.14 (±0.7), with a range of 0.03–3.6. In addition to fibroid/muscular T2Wr, seven of the 14 texture parameters were significantly correlated with ablation efficiency: mean signal intensity (p?=?.047); Skewness (p?=?.03); Kurtosis (p?=?.015); mean uniformity (p?=?.052); mean sum of square (p?=?.045); mean sum entropy (p?=?.021) and mean entropy (p?=?.051). In multivariate linear regression, fibroid/muscular T2Wr and sum of entropy were associated with ablation efficiency. The inter-rater coefficient of variation for sum entropy was 2.6%.

Conclusions: Uterine fibroid texture parameters provide complementary information to T2Wr, and are associated with MRgFUS efficiency.

• Key points

• Mean sum entropy is negatively correlated with MRgFUS efficiency (ρ?=??0.307, p?=?.021).

• Fibroids/muscular T2-weighted ratio and entropy are associated with MRgFUS efficiency.

• Texture parameters are better predictors of MRgFUS efficiency than Funaki type.

• Fibroid MR texture analysis can improve patient selection for MRgFUS.

     

Establishment of a scoring system for predicting the difficulty level of high-intensity focussed ultrasound ablation of uterine fibroids

Purpose: To establish a scoring system that predicts the difficulty level of high-intensity focussed ultrasound (HIFU) ablation of uterine fibroids.

Materials and methods: Four hundred and twenty-two patients with fibroids were enrolled. The energy efficiency factor (EEF) and sonication time were set as dependent variables, with factors possibly affecting EEF and sonication time including age, body mass index (BMI), the volume of fibroids, the location of the uterus, the type of fibroids, the signal intensity on the T2-weighted imaging (T2WI), the enhancement type, the thickness of the rectus abdominis and the subcutaneous fat layer, the distance from the anterior/posterior surface of the fibroid to the skin, and the abdominal wall scars were set as predictors for building optimal scaling regression models.

Results: The volume of the fibroids, the location of the uterus, the signal intensity on T2WI, enhancement type, rectus abdominis thickness, subcutaneous fat thickness, and distance from the anterior surface of fibroid to the skin were related to EEF. Signal intensity on T2WI, the volume of fibroids, distance from the posterior surface of fibroid to the skin, and enhancement type were related to sonication time. Models that can predict the difficulty level of HIFU for fibroids have been established: for EEF, y?′?=?0.338X?′₁???0.231X?′₂+0.156X?′₃+0.167X?′₄?; for sonication time, y?=?0.227X₁+0.321X₂+0.157X₃+0.194X₄.

Conclusions: A scoring system for predicting the difficulty level of HIFU treatment for uterine fibroids has been established and it can be used to help select patients and to predict the sonication time for a given fibroid.     

Cavitation enhances coagulated size during pulsed high-intensity focussed ultrasound ablation in an isolated liver perfusion system

Purpose: To investigate whether cavitation enhances the degree of coagulation during pulsed high-intensity focussed ultrasound (HIFU) in an isolated liver perfusion system.

Methods: Isolated liver was treated by pulsed HIFU or continuous-wave HIFU with different portal vein flow rates. The cavitation emission during exposure was recorded, and real-time ultrasound images were used to observe changes in the grey scale. The coagulation size was measured and calculated.

Results: HIFU treatment led to complete coagulation necrosis and total cell destruction in the target regions. Compared to exposure at a duty cycle (DC) of 100%, the mean volumes of lesions induced by 6?s exposure at DCs of 50% and 10% were significantly larger (P?01) but were smaller at a DC of 5%. The necrosis volume was negatively related to the perfusion rate in the pulsed HIFU at a DC of 50% for exposure durations of 4 and 6?s, while the perfusion flow rate did not affect the necrosis volume for exposure durations of 1, 2 and 3?s. For increased perfusion flow rates, there was no significant decrease in the cavitation activity for the pulsed-HIFU (P?>?.05). For continuous-wave HIFU exposure, there was a significant decrease in the necrosis volume and cavitation activity for exposure times of 1, 2, 3, 4, and 6?s with increasing portal perfusion rates.

Conclusion: Perfusion flow rates negatively influence cavitation activity and coagulation volume. Ablation is significantly enhanced during pulsed HIFU exposure compared with continuous-wave HIFU.     

A retrospective study of ultrasound-guided high intensity focussed ultrasound ablation for multiple uterine fibroids in South Africa

Objective: To evaluate the shrinkage rate, symptom relief and improvement of the quality of life following ultrasound-guided high intensity focussed ultrasound (USgHIFU) for multiple uterine fibroids.

Methods: From October 2015 to November 2016, 81 black women with multiple symptomatic fibroids underwent USgHIFU. The number of the fibroids ranged from 3 to 9. The shrinkage rate of fibroids, symptom severity score and quality of life were evaluated following USgHIFU. Magnetic resonance imaging (MRI), the uterine fibroid symptom and quality of life (UFS-QOL) questionnaire were used for evaluation.

Results: The mean age of patients was 35.3?±?5.9 years. The average weight of these patients was 68.4?±?11.4?kg, with the median abdominal subcutaneous fat thickness of 38.0?±?11.4?mm. The median fibroid volume was 36.0 (range: 1.8–1220.1) cm³. During HIFU, 60.5% of the patients reported lower abdominal pain, 43.2% sciatic/buttock pain, 60.5% skin “burning” sensation, 6.2% abnormal vaginal discharge and 13.6% transient leg pain. No severe complications were observed. The average volume reduction rate of fibroids in 21 patients who completed the follow-up was 32.5?±?24.0, 42.3?±?32.2 and 52.5?±?36.3% 1, 3 and 6 months after HIFU, respectively. The UFS score decreased and the QOL values significantly increased during the follow-up period. Re-intervention treatment occurred in two of the 21 patients 6 months after HIFU. One patient conceived 3 months after HIFU, and she had a term vaginal delivery without any obstetrical complications.

Conclusions: Based on our results, USgHIFU is safe and effective in treating patients with multiple uterine fibroids.     

Reasons for different therapeutic effects of high-intensity focused ultrasound ablation on excised uterine fibroids with different signal intensities on T2-weighted MRI: a study of histopathological characteristics

Objective: The objective of this study was to explore the correlations between the therapeutic effect of high intensity focused ultrasound (HIFU) and histopathological characteristics of excised uterine fibroids with different signal intensities as visualized on T2-weighted magnetic resonance imaging (MRI).

Methods: We collected 47 specimens of uterine fibroids after surgical resection and classified them into four groups according to preoperative T2-weighted MRI hypo-intense, isointense, heterogeneous intense and homogeneous hyper-intense. Then, specimens in each group were irradiated by HIFU with the same parameters and the necrotic tissue volume was calculated. The smooth muscle cell (SMC) count and collagen fiber content were quantitatively measured and compared between different groups. We analyzed the correlation between the necrotic tissue volume and SMC count and the collagen fiber content.

Results: Necrotic tissue volume gradually decreased from the hypo-intense group to the homogeneous hyper-intense group (p?=?.008). The SMC count from the hypo-intense group to the homogeneous hyper-intense group was 215.6?±?59.3, 237.0(89.5), 232.3?±?72.5 and 330.5?±?30.9, respectively; collagen fiber content was 0.65?±?0.07, 0.64?±?0.10, 0.53?±?0.11 and 0.41?±?0.06, respectively. Comparison among the four groups showed that SMC count progressively increased (p?=?.001) but collagen fiber content progressively decreased (p?=?.000) from the hypo-intense group to the homogeneous hyper-intense group. Correlation analysis showed that necrotic tissue volume was negatively correlated with SMC count (R?=??0.488, p=.013) but positively correlated with collagen fiber content (R?=?0.534, p?=?.005).

Conclusions: Differences in histopathological characteristics may be one of the reasons for different therapeutic effects of HIFU ablation on uterine fibroids with different signal intensities on T2-weighted MRI.     

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.     

Local thyroid tissue ablation by high-intensity focused ultrasound: Effects on thyroid function and first human feasibility study with hot and cold thyroid nodules

Objective: The aim of this study was to assess whether high-intensity focused ultrasound (HIFU), a new and promising method for the treatment of benign hot and cold thyroid nodules using thermal ablation, has an impact on thyroid function, and to evaluate its feasibility in outpatient settings. Additionally, a possible difference in the treatment of solid and complex thyroid nodules was evaluated. Method: Ten patients with one thyroid nodule each (six cold and four hot nodules) underwent HIFU in January 2014. Four nodules were solid and six nodules were complex. Serum levels of triiodothyronine (T3), thyroxine (T4), thyrotropin (TSH), thyroglobulin (hTg) and additionally antibodies against hTg (TAK), TSH receptors (TRAK) and thyroid peroxidase (TPO) were measured at enrolment and 24?h after the HIFU treatment. The pre- and post-thyroglobulin reduction was measured to evaluate the scale of ablation. In addition, patients’ pain was recorded on a numeric rating scale from 0 to 10. Results: The HIFU treatment did not affect thyroid function, since hormone levels stayed stable (p?p?p?Conclusion: HIFU is a safe and effective method to treat benign, solid, complex, hot and cold thyroid nodules preserving thyroid function. Further developments of the system are needed to gain suitability for daily use.     

腹壁种植癌胸骨旁淋巴结转移临床意义初步观察一附17例报道

目的：观察腹壁种植癌胸骨旁淋巴结转移临床意义。方法：选取我院自2003年3月-2011年5月间收治的17例经手术和病理证实的腹部恶性肿瘤术后腹壁切口种植性转移癌患者。超声检查对每例患者两侧胸骨旁淋巴结进行检测。对所发现增大胸骨旁淋巴结实施穿刺病理活检并进行跟踪随访,随访期平均15个月。结果：17例患者有8例经穿刺病理活检证实存在胸骨旁淋巴转移（占47．1％）;无转移者9例。随访期内存在胸骨旁淋巴结转移患者5例局部复发、死亡6例（占75％）,无转移者局部复发4例、死亡2例（占22．2％）。结论：胸骨旁淋巴转移患者较无转移者存在较早发生转移和局部复发的风险;关注腹壁种植转移患者的胸骨旁淋巴结存在状态有一定临床价值。     

A randomised clinical trial of high-intensity focused ultrasound ablation for the treatment of patients with localised breast cancer

High-intensity focused ultrasound (HIFU) is a noninvasive treatment that induces complete coagulative necrosis of a tumour at depth through the intact skin. This study was to explore the possibility of using HIFU for the treatment of patients with localised breast cancer in a controlled clinical trial. A total of 48 women with biopsy-proven breast cancer (T(1-2), N(0-2), M0) were randomised to the control group in which modified radical mastectomy was performed, and the HIFU group in which an extracorporeal HIFU ablation of breast cancer was followed by modified radical mastectomy. Short-term follow-up, pathologic and immunohistochemical stains were performed to assess the therapeutic effects on tumour and complications of HIFU. The results showed that no severe side effect was observed in the HIFU-treated patients. Pathologic findings revealed that HIFU-treated tumour cells underwent complete coagulative necrosis, and tumour vascular vessels were severely damaged. Immunohistochemical staining showed that no expression of PCNA, MMP-9, and CD44v6 was detected within the treated tumour cells in the HIFU group, indicating that the treated tumour cells lost the abilities of proliferation, invasion, and metastasis. It is concluded that, as a noninvasive therapy, HIFU could be effective, safe, and feasible in the extracorporeal treatment of localised breast cancer.     

Magnetic resonance-guided high-intensity focused ultrasound for uterine fibroids: Mid-term outcomes of 36 patients treated with the Sonalleve system

Abstract

Objectives: This study sought to assess the mid-term efficacy of magnetic resonance-guided high-intensity focused ultrasound (MRgFUS) (Sonalleve system) for uterine fibroids.

Methods: We retrospectively included patients treated by MRgFUS controlled by real-time MR-thermometry. Clinical efficacy was defined as the minimum reduction of ten points in the Transformed Symptom Severity Score (tSSS) without additional treatment. Fibroid volumes were assessed at 6 months, and patients were contacted to assess mid-term efficacy using tSSS.

Results: Thirty-six patients were included; 22 patients (61.1%) exhibited clinical efficacy with a mean follow-up duration of 21.4 (95%CI: 16.3–26.5) months. In addition, the tSSS mean decreased significantly from 42.8?±?16 to 25.4?±?18 (p?<?0.0001). MRgFUS exhibited a preferential effect on menorrhagia (p?=?0.001) and symptoms related to pelvic heaviness and swelling (p?=?0.004). The volume reduction was 27% (p?<?0.001) and was correlated with the non-perfused volume (NPV) after treatment (r?=?0.373; p?=?0.028). Cumulative re-intervention rates (surgery or uterine artery embolisation) at 12 months, 18 months and 24 months were 2.8%, 8.5% and 21.6%, respectively. No serious adverse events were reported. Two pregnancies occurred during the follow-up period.

Conclusions: Treatment of uterine fibroids by MRgFUS is efficient and results in low morbidity and satisfactory clinical efficacy with a mean follow-up of 21.4 months.     

The percentage of serum thyroglobulin rise in the first-week did not predict the eventual success of high-intensity focussed ablation (HIFU) for benign thyroid nodules

Abstract

Background: Given that high-intensity focussed ultrasound (HIFU) of benign thyroid nodules often causes a massive release of thyroglobulin (Tg) into the circulation, we hypothesised a greater initial Tg rise may result in a greater nodule shrinkage 6?months after ablation.

Methods: One hundred and five patients who underwent HIFU for symptomatic benign thyroid nodule from 2015 to 2016 were analysed. Serum Tg and anti-Tg autoantibody were checked on treatment day (baseline) and 4?d after treatment. The % of Tg rise?=?[serum Tg on day-4 – baseline serum Tg]/[baseline serum Tg] * 100 while the nodule shrinkage as measured by volume reduction ratio (VRR)?=?[baseline volume – volume at 6-month]/[baseline volume] * 100. Treatment success was defined as VRR?>50%.

Results: At 6-month, the mean VRR was 62.2?±?25.0% and 59 (76.6%) patients had treatment success. The mean baseline Tg level increased from 292.8?±?672.7?ng/mL to 2022.7?±?1759.8?ng/mL in the first-week. The % of Tg rise did not significantly correlate with either 3-month or 6-month VRR (p?=?0.920 and p?=?0.699, respectively). The mean % of Tg rise in the first week was not different between those with and without 6-month treatment success (368.2% vs. 1068.7%, p?=?0.381). No clinical factors significantly correlated with treatment success.

Conclusions: There was an almost seven-fold increase in the mean Tg level 4?d after HIFU ablation. The % of Tg rise in the first week did not appear to correlate with the 6-month nodule shrinkage or treatment success.     

补片修补腹壁子宫内膜异位病灶切除术后腹壁缺损24例临床分析

目的:分析采用补片修补腹壁子宫内膜异位病灶切除术后腹壁缺损的疗效.方法:回顾性分析2007年至2014年中国医科大学附属盛京医院诊治的24例腹壁子宫内膜异位病灶切除术后采用补片修补腹壁缺损患者的临床资料.结果:24例患者腹壁包块最大径为3.5-15cm,平均5.4cm,病灶切除后腹壁缺损大且深,采用补片修补,切口均为Ⅰ期愈合,无感染,17例术后补充GnRH-a治疗,随访患者1-78个月,腹壁切口愈合良好,无复发,无腹壁疝形成,外形美观,患者感受良好.结论:腹壁子宫内膜异位症一旦发现应及早手术完全切除病灶,手术后较大腹壁缺损应用补片修补效果好.     

Synovial sarcoma of abdominal wall: a case report and study of tumor fine structure

A case of synovial sarcoma in the abdominal wall of a 50-year-old Iraqi woman is reported. The ultrastructure of the tumor has been studied. Eight other cases of synovial sarcoma in the abdominal wall reported in the English literature up to 1978 have been reviewed. Synovial sarcomas in the abdominal wall tend to occur with a much greater frequency in women, whereas such tumors occurring in the extremities or the neck are more common in men than woman. No ultrastructural studies of abdominal wall synovial sarcomas could be found in the English literature. The ultrastructural characters of this tumor are similar to those of such tumors arising in the usual sites and the neck. However, the present study has indicated that the light and dark cells reported by earlier workers are not limited solely to the epitheloid areas but are also present in the spindle cell zones.     

Combination of microbubbles and diagnostic ultrasound at a high mechanical index for the synergistic microwave ablation of tumours

Objectives: To determine whether combining microbubbles (MBs) with diagnostic ultrasound (US) at a high mechanical index (MI) could enhance the microwave (MW) ablation of tumours.

Materials and methods: Five therapeutic MW adjuvant protocols were studied: MW, MW?+?US, MW?+?US?+?MB, MW?+?US?+?NS (saline) and MW?+?MB. In 30 normal rabbit livers, the synergistic effects were evaluated via temperature, necrosis volume and histology. In 90 VX2 rabbit hepatic tumours, residual cells in the peripheral ablated tumours were examined via immunohistochemical assay and tumour growth. Additional 40 VX2 hepatic tumours were evaluated for ablation safety via blood assay and weight and for survival to 105 days. Results were compared using analysis of variance.

Results: Compared with the other protocols, the ablation volumes in normal rabbit livers were significantly larger using the MW?+?US?+?MB protocol (p?p?p?p?p?Conclusions: MBs in combination with diagnostic US at a high MI showed potential synergy in the MW ablation of tumours in rabbits.     

Synovial sarcoma of the abdominal wall: a case report and study of its fine structure

A case of synovial sarcoma in the abdominal wall of a 50-year-old Iraq female is reported. The ultrastructure of the tumor has been studied. Eight other cases of synovial sarcoma in the abdominal wall which reported in the English literature up to 1978 have been reviewed. Synovial sarcomas in the abdominal wall tend to occur with a much greater frequency in females in contrast to such tumors in the extremities or the neck which tend to occur with a much greater frequency in males. No ultrastructure studies of abdominal wall synovial sarcomas could be found in the English literature. Ultrastructure characteristics of this tumor were similar to those arising in the usual sites and in the neck. However, the present study has indicated that the light and dark cells reported by earlier workers are not solely limited to the epitheloid areas but are also present in the spindle cell zones.     

Needle track seeding after percutaneous radiofrequency ablation of hepatocellular carcinoma: 14-year experience at a single centre

Purpose: To determine the incidence, risk factors and prognosis associated with needle track seeding after percutaneous radiofrequency ablations (RFA) for hepatocellular carcinoma (HCC) with a long-term follow-up.

Materials and methods: A total of 741 HCC patients undergoing percutaneous RFA were retrospectively analysed. Mean follow-up interval was 34.3?±?26.8 months. All seeding neoplasms were diagnosed by imaging modalities with or without pathological evaluation. Risk factors, including Child–Pugh grading, tumour size, number, location, serum alpha-fetoprotein (AFP) level, track number, biopsy before RFA and electrode type were performed by univariate analysis. Further therapy and survival of seeding after RFA were assessed. Survival analysis was analysed by Kaplan–Meier method.

Results: Twelve patients (12 tumours) were diagnosed as seeding. It corresponds to an incidence of 1.6% (12/741) per patient and 0.9% (12/1341) per tumour. Seeding developed an average of 14.0?±?8.1 months (6–33 months). Significant risk factors included tumour >3?cm (p?=?0.031), subcapsular tumour (p?=?0.031), biopsy before RFA (p?=?0.001) and non-cool-tip electrode (p?=?0.034). Eight patients received local therapy and four cases only received systematic therapy for uncontrolled advanced hepatic tumour or distal metastasis. Of eight patients receiving local therapy, one patient had local recurrence 16 months later and other seven patients did not have local recurrence for 3–73 months. The cumulative survival rates after seeding were 55.6%, 27.8%, 9.3% at 1, 3 and 5 years, respectively.

Conclusion: Needle track seeding is a rare delayed complication after percutaneous RFA. Tumour >3?cm, subcapsular tumour, biopsy before RFA and non-cool-tip electrode are potential risk factors for seeding. Local therapies are effective methods for seeding patients.     

Surgical microwave ablation for multifocal non-resectable liver metastases: a single institution experience treating five or more liver lesions

BackgroundThermal ablation is an effective treatment for patients with metastatic colon and rectal cancer and allows surgeons to offer curative intent therapy to patients who are otherwise not candidates for resection. We aimed to report outcomes of a single institution experience using microwave ablation (MWA) with or without resection to treat five or more liver metastases.MethodsIn this retrospective cohort study, the University of Minnesota Division of Surgical Oncology liver surgery database was queried to identify all patients who underwent thermal ablation of five or more colorectal liver metastases (CRLM) between 2012–2018. We reviewed patient, disease, and tumor characteristics and measured local, intrahepatic, and extrahepatic recurrence (EHR) rates. We also calculated median overall survival (OS) and disease-free survival (DFS).ResultsTen patients identified had five or more (range, 5–18) tumors ablated with or without combined liver and bowel resection. Median age was 50, and most patients were male (70%) and Caucasian (90%). Four patients received ablation alone (5–12 lesions), while six had combined resection and ablation (5–18 lesions). Ablation was performed laparoscopically in six patients, and four had ablations without resection. All patients received pre- and post-operative chemotherapy. A median of 7 tumors were ablated per patient. Median follow-up was 2.3 years. Among 75 tumors ablated, ablation site recurrence (ASR) (within 1 cm of ablation site) was seen in three with a per-lesion recurrence rate of 4%. Intrahepatic recurrence (IHR) occurred in 6 (60%) patients and EHR in 1 (10%). Five patients underwent retreatment of IHR during follow-up. Median OS was 3 years and DFS was 7.1 months. At the time of last follow up, 6 patients were disease-free.ConclusionsThermal ablation can provide acceptable DFS and OS, even with high volume metastatic colorectal cancers. Future efforts should be focused on defining selection criteria for those most likely to benefit from this aggressive approach.     

Transurethral high-intensity ultrasound for treatment of stress urinary incontinence (SUI): simulation studies with patient-specific models

Background: Stress urinary incontinence (SUI) is prevalent in adult women, attributed to weakened endopelvic supporting tissues, and typically treated using drugs and invasive surgical procedures. The objective of this in silico study is to explore transurethral high-intensity ultrasound for delivery of precise thermal therapy to the endopelvic tissues adjacent to the mid-urethra, to induce thermal remodeling as a potential minimally invasive treatment alternative.

Methods: 3D acoustic (Rayleigh–Sommerfeld) and biothermal (Pennes bioheat) models of the ultrasound applicator and surrounding tissues were devised. Parametric studies over transducer configuration [frequency, radius-of-curvature (ROC)] and treatment settings (power, duration) were performed, and select cases on patient-specific models were used for further evaluation. Transient temperature and thermal dose distributions were calculated, and temperature and dose metrics reported.

Results: Configurations using a 5-MHz curvilinear transducer (3.5?×?10?mm, 28?mm ROC) with single 90?s sonication can create heated zones with 11?mm penetration (>50?°C) while sparing the inner 1.8?mm (<45?°C) radial depth of the urethral mucosa. Sequential and discrete applicator rotations can sweep out bilateral coagulation volumes (1.4?W power, 15° rotations, 600?s total time), produce large volumetric (1124?mm³ above 60 EM_43?°C) and wide angular (～50.5° per lateral sweep) coverage, with up to 15.6?mm thermal penetration and at least 1.6?mm radial urethral protection (<5?EM_43?°C).

Conclusion: Transurethral applicators with curvilinear ultrasound transducers can deliver spatially selective temperature elevations to lateral mid-urethral targets as a possible means to tighten the endopelvic fascia and adjacent tissues.     

Single-session high intensity focussed ablation (HIFU) versus open cervical hemithyroidectomy for benign thyroid nodule: analysis on early efficacy,safety and voice quality

Abstract

Background: High intensity focussed ultrasound (HIFU) is a promising non-surgical treatment for symptomatic benign thyroid nodule. We aimed to compare early efficacy, safety and voice quality between HIFU ablation and open thyroidectomy.

Methods: Consecutive patients who underwent single-session HIFU ablation or a hemithyroidectomy for symptomatic benign thyroid nodule were included. The 6-month extent of nodule shrinkage, symptom improvement score, thyroid function, hospital stay and cost were compared between the two procedures. Safety was defined by absence of major complications like recurrent laryngeal nerve injury and skin burn. Voice quality was assessed by a computerised multi-dimensional voice programme and a Voice Handicap Index (VHI) questionnaire 1-month after treatment.

Results: Altogether, 43 patients had HIFU and 103 patients had a hemithyroidectomy. In the HIFU group, the extent of nodule shrinkage at 6-month was 51.71?±?16.04%. No patients in the HIFU group suffered skin burn or hypothyroidism. The HIFU group had a significantly shorter length of hospital stay (0.3 vs. 1.0?day, p?<?0.001), lower incidence of subclinical hypothyroidism (1/43 vs. 21/103, p?=?0.008), higher symptom improvement score (p?=?0.009) and was less costly (USD 1923.1 vs. USD 5384.6). Relative to HIFU, pitch quality also worsen after surgery (p?<?0.05).

Conclusions: Relative to surgery, single HIFU ablation appeared efficacious and safe. Apart from shorter hospital stay, less subclinical hypothyroidism, being scar-less, lower cost and more symptom improvement, HIFU patients were less affected by a pitch problem in the first month. This study provides a strong argument for HIFU ablation as a treatment for symptomatic benign thyroid nodule.