High-Intensity Focused Ultrasound Surgery for Tumor Ablation: A Review of Current Applications

The management of cancer with alternative approaches is a matter of clinical interest worldwide. High-intensity focused ultrasound (HIFU) surgery is a noninvasive technique performed under US or MRI guidance. The most studied therapeutic uses of HIFU involve thermal tissue ablation, demonstrating both palliative and curative potential. However, concurrent mechanical bioeffects also provide opportunities in terms of augmented drug delivery and immunosensitization. The safety and efficacy of HIFU integration with current cancer treatment strategies are being actively investigated in managing primary and secondary tumors, including cancers of the breast, prostate, pancreas, liver, kidney, and bone. Current primary HIFU indications are pain palliation, complete ablation of localized earlystage tumors, or debulking of unresectable late-stage cancers. This review presents the latest HIFU applications, from investigational to clinically approved, in the field of tumor ablation. Keywords: Ultrasound, Ultrasound-High Intensity Focused (HIFU), Interventional-MSK, Interventional-Body, Oncology, Technology Assessment, Tumor Response, MR Imaging © RSNA, 2023.

Intraoperative Ultrasound-Guided Conserving Surgery for Breast Cancer: No More Time for Blind Surgery

BACKGROUND

Breast-conserving surgery (BCS) still remains a blind surgery despite all available tumor localization methods. Intraoperative ultrasound (IOUS) allows real-time visualization during all resection phases.

METHODS

This was a prospective observational cohort study conducted at the Veneto Institute of Oncology between January 2021 and June 2022. Patients with ductal carcinoma in situ, T1-2 invasive cancer, or post-neoadjuvant tumors, suitable for BCS, were recruited. All breast cancer lesion types were included, i.e. solid palpable, solid non-palpable, non-solid non-palpable, and post-neoadjuvant treatment residual lesions. Eligible participants were randomly assigned to either IOUS or traditional surgery (TS) in a 1:1 ratio. The main outcomes were surgical margin involvement, reoperation rate, closest margin width, main specimen and cavity shaving margin volumes, excess healthy tissue removal, and calculated resection ratio (CRR).

RESULTS

Overall, 160 patients were enrolled: 80 patients were allocated to the TS group and 80 to the IOUS group. IOUS significantly reduced specimen volumes (16.8 cm3 [10.5-28.9] vs. 24.3 cm3 [15.0-41.3]; p = 0.015), with wider closest resection margin width (2.0 mm [1.0-4.0] vs. 1.0 mm [0.5-2.0] after TS; p < 0.001). Tumor volume to specimen volume ratio was significantly higher after IOUS (4.7% [2.5-9.1] vs. 2.9% [0.8-5.2]; p < 0.001). IOUS yielded significantly better CRR (84.5% [46-120.8] vs. 114% [81.8-193.2] after TS; p < 0.001), lower involved margin rate (2.5 vs. 15%; p = 0.009) and reduced re-excision rate (2.5 vs. 12.5%; p = 0.032).

CONCLUSIONS

IOUS allows real-time resection margin visualization and continuous control during BCS. It showed clear superiority over TS in both oncological and surgical outcomes for all breast cancer lesion types. These results disfavor the paradigm of blind breast surgery.

A Systematic Review Comparing Focused Ultrasound Surgery With Radiosurgery for Essential Tremor

BACKGROUND

Focused ultrasound (FUS-T) and stereotactic radiosurgery thalamotomy (SRS-T) targeting the ventral intermediate nucleus are effective incisionless surgeries for essential tremor (ET). However, their efficacy for tremor reduction and, importantly, adverse event incidence have not been directly compared.

OBJECTIVE

To present a comprehensive systematic review with network meta-analysis examining both efficacy and adverse events (AEs) of FUS-T vs SRS-T for treating medically refractory ET.

METHODS

We conducted a systematic review and network meta-analysis according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, using the PubMed and Embase databases. We included all primary FUS-T/SRS-T studies with approximately 1-year follow-up, with unilateral Fahn-Tolosa-Marin Tremor Rating Scale or Clinical Rating Scale for Tremor scores prethalamotomy/post-thalamotomy and/or AEs. The primary efficacy outcome was Fahn-Tolosa-Marin Tremor Rating Scale A+B score reduction. AEs were reported as an estimated incidence.

RESULTS

Fifteen studies of 464 patients and 3 studies of 62 patients met inclusion criteria for FUS-T/SRS-T efficacy comparison, respectively. Network meta-analysis demonstrated similar tremor reduction between modalities (absolute tremor reduction: FUS-T: -11.6 (95% CI: -13.3, -9.9); SRS-T: -10.3 (95% CI: -14.2, -6.0). FUS-T had a greater 1-year adverse event rate, particularly imbalance and gait disturbances (10.5%) and sensory disturbances (8.3%). Contralateral hemiparesis (2.7%) often accompanied by speech impairment (2.4%) were most common after SRS-T. There was no correlation between efficacy and lesion volume.

CONCLUSION

Our systematic review found similar efficacy between FUS-T and SRS-T for ET, with trend toward higher efficacy yet greater adverse event incidence with FUS-T. Smaller lesion volumes could mitigate FUS-T off-target effects for greater safety.

Magnetic Resonance Imaging-guided Focused Ultrasound Surgery in a Swine Adenomyosis Model

RATIONALE AND OBJECTIVES

The purpose of this study was to explore the feasibility of magnetic resonance imaging-guided focused ultrasound surgery (MRgFUS) for the treatment of an adenomyosis model of Bama pigs and the changes in the level of oxytocin receptor (OTR), vascular endothelial growth factor (VEGF), and cyclooxygenase-2 (COX-2) in the myometrium tissues of Bama pigs after MRgFUS.

MATERIALS AND METHODS

Three Bama pig models of adenomyosis were established by autologous endometrial implantation and evaluated by magnetic resonance imaging, computed tomography, and hematoxylin-eosin (H&E) staining. After the successful construction of the model, the pigs underwent MRgFUS. Before the modeling surgery, three months after the modeling, and two months after ablation, the myometrium tissues were clipped, then embedded and H&E stained for immunohistochemical examination. The average optical density of OTR, VEGF, and COX-2 were semi-quantitatively analyzed.

RESULTS

The adenomyosis models were established in all Bama pigs and confirmed by magnetic resonance imaging, computed tomography and H&E staining. Magnetic resonance imaging and computed tomography examination showed that the uterine wall at the modeling site was significantly thickened with uneven enhancement after contrast injection. All Bama pigs with adenomyosis lesions underwent MRgFUS without complications. The expression level of OTR and COX-2 in the myometrium increased three months after modeling surgery and decreased two months after MRgFUS. The expression level of VEGF decreased two months after MRgFUS.

CONCLUSION

Autologous endometrial implantation is effective in establishing the adenomyosis model of Bama pigs. It is feasible to treat adenomyosis in the Bama pig model with MRgFUS. The levels of OTR, COX-2 and VEGF in the local myometrium decreased after MRgFUS, which may be associated with symptom relief after treatment.

Clinic efficacy and safety of ultrasound-guided Mammotome-assisted surgery for patients with breast benign tumors

OBJECTIVE

The aim of this study was to assess the efficacy of ultrasound-guided Mammotome-assisted resection vs. conventional open surgery for benign breast tumors.

PATIENTS AND METHODS

From July 2019 to December 2020, 134 suitable patients with benign breast cancers treated at our institution (Breast Surgery Department) were recruited and randomly allocated (1:1) to receive either Mammotome-assisted tumor excision (observation group) or open surgery (control group). The primary endpoint was clinical effectiveness, with surgical outcomes, complications, and satisfaction as secondary endpoints.

RESULTS

Mammotome-assisted surgery resulted in shorter operative time, scar length, and postoperative healing time and less intraoperative bleeding volume vs. open surgery (p<0.001). Mammotome-assisted surgery was associated with a significantly higher clinical efficacy vs. open surgery (p<0.05). Patients receiving Mammotome-assisted surgery had a lower incidence of complications vs. those given open surgery (p<0.05). A significantly higher satisfaction was observed in patients given Mammotome-assisted surgery vs. open surgery (p<0.05).

CONCLUSIONS

In comparison to standard open surgery, ultrasound-guided Mammotome-assisted surgery provides a viable alternative for breast benign tumor removal with superior efficacy, shorter operating time, less trauma, higher safety, fewer complications, and higher patient satisfaction.

Limits and Opportunities for Miniaturizing Ultrasonic Surgical Devices Based on a Langevin Transducer

Minimally invasive surgery offers opportunities for reduced morbidities, faster postoperative recovery, and reduced costs, and is a major focus of surgical device innovation. For ultrasonic surgical devices, which offer benefits of high precision, low force, and tissue selectivity in surgical procedures, there exist laparoscopic ultrasonic shears for minimally invasive surgeries that combine tissue cutting with vessel hemostasis and sealing functions. Another approach to laparoscopy that could enable new procedures, and increase the sites of surgeries that could be reached by an ultrasonic device, involves integrating a miniature ultrasonic tool with a flexible surgical robot. However, miniaturization presents challenges in delivering the ultrasonic vibrational energy required to cut hard and soft tissues, partly due to the concomitant small volume of piezoelectric material. This article aims to provide insights into the trade-offs between transducer size, volume of piezoceramic material, resonance frequency, and the achievable displacement amplitude of devices that, consistent with current ultrasonic surgical tools, are based on a bolted Langevin transducer (BLT) and tip. Different configurations of BLTs are studied, including a cascaded version, simple bar versions, and BLTs with different front mass geometries. Results show that a BLT with a larger number of piezoceramic rings exhibits a higher coupling coefficient [Formula: see text] but with the compromise of a lower mechanical Q and stronger nonlinear response at increasing excitation levels. Displacement amplitude is reduced considerably when a BLT is excited at a higher harmonic, where the PZT rings are maintained at a nodal plane, and the resonance frequency shift at increasing excitation levels increases significantly. The electromechanical and dynamic characteristics of a cascaded transducer excited in its third longitudinal mode (L3) are almost equivalent to a much shorter version of a BLT driven at the same frequency but in its first longitudinal mode (L1), showing that a cascaded BLT can be a realistic proxy for studying the dynamics of small BLT devices. A new figure of merit is proposed that is the product of Q , [Formula: see text], and gain, which [Formula: see text] accounts for the gain of cylindrical BLTs which is shown not to be unity. It also proves effective as it incorporates the key factors affecting the achievable displacement amplitude of a BLT, including for BLTs with gain profiles in the front mass. The order of highest to lowest amplitude of a series of six gain-profile BLTs matches the order estimated by the figure of merit. It is shown that a BLT with a stepped profile front mass can achieve displacement that has the potential to cut hard or soft tissue and exhibits the smallest shifts in resonance frequency at increasing excitation levels.

Revisiting Forel Field Surgery

BACKGROUND

Lesioning the Forel field or the subthalamic region is considered a possible treatment for tremoric patients with Parkinson disease, essential tremor, and other diseases. This surgical treatment was performed in the 1960s to 1970s and was an alternative to thalamotomy. Recently, there has been increasing interest in the reappraisal of stimulating and/or lesioning these targets, partly as a result of innovations in imaging and noninvasive ablative technologies, such as magnetic resonance-guided focused ultrasonography.

OBJECTIVE

We wanted to perform a thorough review of the subthalamic region, both from an anatomic and a surgical standpoint, to offer a comprehensive and updated analysis of the techniques and results reported for patients with tremor treated with different techniques.

METHODS

We performed a systematic review of the literature, gathering articles that included patients who underwent ablative or stimulation surgical techniques, targeting the pallidothalamic pathways (pallidothalamic tractotomy), cerebellothalamic pathway (cerebellothalamic tractotomy), or subthalamic area.

RESULTS

Pallidothalamic tractotomy consists of a reduced area that includes pallidofugal pathways. It may be considered an interesting target, given the benefit/risk ratio and the clinical effect, which, compared with pallidotomy, involves a lower risk of injury or involvement of vital structures such as the internal capsule or optic tract. Cerebellothalamic tractotomy and/or posterior subthalamic area are other alternative targets to thalamic stimulation or ablative surgery.

CONCLUSIONS

Based on the significant breakthrough that magnetic resonance-guided focused ultrasonography has meant in the neurosurgical world, some classic targets such as the pallidothalamic tract, Forel field, and posterior subthalamic area may be reconsidered as surgical alternatives for patients with movement disorders.

Effects of Non-invasive, Targeted, Neuronal Lesions on Seizures in a Mouse Model of Temporal Lobe Epilepsy

Surgery to treat drug-resistant epilepsy can be quite effective but remains substantially underutilized. A pilot study was undertaken to test the feasibility of using a non-invasive, non-ablative, approach to produce focal neuronal loss to treat seizures in a rodent model of temporal lobe epilepsy. In this study, spontaneous, recurrent seizures were established in a mouse model of pilocarpine-induced status epilepticus. After post-status epilepticus stabilization, baseline behavioral seizures were monitored for 30 d. Non-invasive opening of the blood-brain barrier targeting the hippocampus was then produced by using magnetic resonance-guided, low-intensity focused ultrasound, through which a neurotoxin (quinolinic acid) administered intraperitoneally gained access to the brain parenchyma to produce focal neuronal loss. Behavioral seizures were then monitored for 30 d after this procedure, and brains were subsequently prepared for histologic analysis of the sites of neuronal loss. The average frequency of behavioral seizures in all animals (n = 11) was reduced by 21.2%. Histologic analyses along the longitudinal axis of the hippocampus revealed that most of the animals (n = 8) exhibited neuronal loss located primarily in the intermediate aspect of the hippocampus, while sparing the septal aspect. Two other animals with damage to the intermediate hippocampus also exhibited prominent bilateral damage to the septal aspect of the hippocampus. A final animal had negligible neuronal loss overall. Notably, the site of neuronal loss along the longitudinal axis of the hippocampus influenced seizure outcomes. Animals that did not have bilateral damage to the septal hippocampus displayed a mean decrease in seizure frequency of 27.7%, while those with bilateral damage to the septal hippocampus actually increased seizure frequency by 18.7%. The animal without neuronal loss exhibited an increase in seizure frequency of 19.6%. The findings indicate an overall decrease in seizure frequency in treated animals. And, the site of neuronal loss along the longitudinal axis of the hippocampus appears to play a key role in reducing seizure activity. These pilot data are promising, and they encourage additional and more comprehensive studies examining the effects of targeted, non-invasive, neuronal lesions for the treatment of epilepsy.

Endoscopy-Assisted Resection of Benign Lesions on the Base of the Tongue via the Transoral Approach Using a Harmonic Scalpel

PURPOSE

Surgical removal of lesions from the base of the tongue can be challenging for head and neck surgeons. This study evaluated the clinical outcomes of patients with benign lesions at the base of the tongue who underwent endoscopy-assisted resection through the transoral approach using an ultrasonic harmonic scalpel.

PATIENTS AND METHODS

This retrospective observational study was conducted from May 2013 to January 2016. Data collected for each patient included age, gender, chief complaints, clinical symptoms, diagnostic imaging, complications after resection, and reported outcomes of resection. Diagnoses were made based on patient complaints, clinical symptoms, and computed tomography or magnetic resonance imaging. Diagnoses were confirmed by permanent pathologic sections.

RESULTS

Twelve patients with benign lesions on the base of the tongue were identified who had undergone endoscopy-assisted resection through the transoral approach using an ultrasonic harmonic scalpel. The patients had a mean age of 38.9 years. The benign lingual lesions consisted of lingual thyroid masses, squamous papillomas, schwannomas, pleomorphic adenomas, myoepithelioma, and lymphoid hyperplasia. Tumor size varied from 2.0 × 1.8 to 3.0 × 2.8 cm. All tumors were completely removed, and no complications occurred during or after surgery. The patients were followed for 6 to 30 months; 1 recurrence was found and was treated using a second endoscopy-assisted transoral resection.

CONCLUSIONS

Under endoscopic assistance, use of the harmonic scalpel through the transoral approach is a safe and feasible surgical technique for the removal of benign lesions at the base of the tongue.

Focused Ultrasound: An Emerging Therapeutic Modality for Neurologic Disease

Therapeutic ultrasound is only beginning to be applied to neurologic conditions, but the potential of this modality for a wide spectrum of brain applications is high. Engineering advances now allow sound waves to be targeted through the skull to a brain region selected with real time magnetic resonance imaging and thermography, using a commercial array of focused emitters. High intensities of sonic energy can create a coagulation lesion similar to that of older radiofrequency stereotactic methods, but without opening the skull. This has led to the recent Food and Drug Administration approval of focused ultrasound (FUS) thalamotomy for unilateral treatment of essential tremor. Clinical studies of stereotactic FUS for aspects of Parkinson's disease, chronic pain, and refractory psychiatric indications are underway, with promising results. Moderate-intensity FUS has the potential to safely open the blood-brain barrier for localized delivery of therapeutics, while low levels of sonic energy can be used as a form of neuromodulation.

[Salvage external beam radiation therapy for prostate cancer recurrence after high-intensity focused ultrasound ablation]

The article outlines oncological and functional outcomes of salvage external beam radiation therapy after HIFU-ablation in 49 patients. The study determined overall and relapse-free survival, compared the rates of adverse events stratified by CTCAE, erectile function and continence scores assessed by questionnaire survey. Univariate and multivariate analysis of risk factors for failure of salvage radiation therapy after prostate HIFU-ablation were conducted. In univariate analysis the level of prostate-specific antigen (PSA) prior to radiotherapy, the risk group, PSA nadir after radiotherapy, PSA nadir greater than 0.2 ng/mL and the time to nadir after salvage therapy were predictors of failure. There were no serious gastrointestinal side effects. The most frequent urinary adverse event was urgency. The difference in the rates of urinary incontinence before and 1 year after radiotherapy was not statistically significant. The study confirmed the appropriateness of radiotherapy after HIFU-ablation. Radiation therapy can be considered as a treatment option for prostate cancer recurrence after HIFU-ablation.

Focal therapy for prostate cancer: current status and future perspectives

Focal therapy is a relatively new and extremely attractive option of treatment for prostate cancer. It has been described as the "middle approach" between active surveillance and radical treatment, aiming to destroy the tumor itself or the region containing the tumor in order to preserve surrounding non-cancerous tissue. The goal is to maintain disease control at acceptable levels, while preserving erectile, urinary, and rectal function. While a lot of technologies have been described for delivering targeted therapy to the prostate, such as cryoablation, high intensity focused ultrasound, photodynamic therapy, irreversible electroporation and laser, the key point is the patient selection. Recent advances in mpMRI and the introduction of new biopsy techniques that use MR images as a guidance, have significantly improved localization of the tumor lesions and the detection rate, evolving prostate biopsy toward targeted rather than systematic biopsies. The future challenge to clinicians is to precisely risk-stratify patients to differentiate between those who would profit from focal treatment and who would not. Forthcoming research efforts should pursue to identify molecular, genetic, and imaging characteristics that distinguish aggressive prostate tumors from indolent lesions.

Intractable bone marrow edema syndrome of the hip

There is a need for an effective and noninvasive treatment for intractable bone marrow edema syndrome of the hip. Forty-six patients with intractable bone marrow edema syndrome of the hip were retrospectively studied to compare the short-term clinical effects of treatment with high-energy extracorporeal shock wave therapy vs femoral head core decompression. The postoperative visual analog scale score decreased significantly more in the extracorporeal shock wave therapy group compared with the femoral head core decompression group (P<.05). For unilateral lesions, postoperative Harris Hip Scores for all hips in the extracorporeal shock wave therapy group were more significantly improved than Harris Hip Scores for all hips in the femoral head core decompression group (P<.05). Patients who underwent extracorporeal shock wave therapy also resumed daily activities significantly earlier. Average overall operative time was similar in both groups. Symptoms disappeared significantly sooner in the extracorporeal shock wave therapy group in patients with both unilateral (P<.01) and bilateral lesions (P<.05). Hospital costs were significantly lower with extracorporeal shock wave therapy compared with femoral head core decompression. The intraoperative fluoroscopy radiation dose was lower in extracorporeal shock wave therapy than in femoral head core decompression for both unilateral (P<.05) and bilateral lesions (P<.01). On magnetic resonance imaging (MRI), bone marrow edema improved in all patients during the follow-up period. After extracorporeal shock wave therapy, all patients remained pain-free and had normal findings on posttreatment radiographs and MRI scans. Extracorporeal shock wave therapy appears to be a valid, reliable, and noninvasive tool for rapidly resolving intractable bone marrow edema syndrome of the hip, and it has a low complication rate and relatively low cost compared with other conservative and surgical treatment approaches.

"Knotless" laparoscopic extraperitoneal adenomectomy

INTRODUCTION

Laparoscopic adenomectomy is a feasible and effective surgical procedure. We have progressively simplified the procedure using barbed sutures and a technique we call "knotless" laparoscopic adenomectomy. We present a prospective, multicenter, descriptive study that reflects the efficacy and safety of this technique in an actual, reproducible clinical practice situation.

METHODS

A total of 26 patients with benign prostatic hyperplasia of considerable size (>80cc) underwent "knotless" laparoscopic adenomectomy. This is an extraperitoneal laparoscopic technique with 4 trocars based on the controlled and hemostatic enucleation of the adenoma using ultrasonic scalpels, precise urethral sectioning under direct vision assisted by a urethral plug, trigonization using barbed suture covering the posterior wall of the fascia, capsulorrhaphy with barbed suture and extraction of the morcellated adenoma through the umbilical incision.

RESULTS

The median patient age was 69 (54-83)years, the mean prostate volume was 127 (89-245)cc, the mean operative time was 136 (90-315)min, the mean estimated bleeding volume was 200 (120-500)cc and the hospital stay was 3 (2-6)days. All patients experienced improved function in terms of uroflowmetry and International Prostate Symptom Score and quality of life questionnaires. There were complications in 6 patients, 5 of which were minor.

CONCLUSIONS

"Knotless" laparoscopic adenomectomy is a procedure with low complexity that combines the advantages of open surgery (lasting functional results and complete extraction of the adenoma) with laparoscopic procedures (reduced bleeding and need for transfusions, shorter hospital stays and reduced morbidity and complications related to the abdominal wall). The use of ultrasonic scalpels and barbed sutures simplifies the procedure and enables a safe and hemostatic technique.

Laparoscopic partial resection for hemangioma in the third portion of the duodenum

Benign duodenal tumors are rare and less common than malignant tumors. Furthermore, vascular lesions of the duodenum, including hemangiomas, are rare causes of gastrointestinal bleeding. This report describes a case with bleeding hemangiomas in the third portion of the duodenum and jejunum and their successful treatment using a laparoscopic approach. There is no report of totally laparoscopic resection for tumor in the third portion of duodenum. After performing a laparoscopic Kocher maneuver, the location of the duodenal hemangioma was confirmed by endoscopic and laparoscopic observation. The lesion was excised using ultrasonic coagulating shears and the defect in the duodenal wall was sutured laparoscopically. The hemangioma of the jejunum was treated extracorporeally through a 3.0 cm umbilical incision. The operating time was 241 min and blood loss was negligible. The postoperative course was uneventful. For benign duodenal tumors in the third portion, if endoscopic resection is not adapted, this less invasive technique may be a standard treatment.

[Clinical introduction of the method of the abdominal cavity infiltrate dissection with saving of anatomic integrity and functional capacity of organs, included in the inflammatory process]

The results of application of the tissue dissection method and hemostasis performance while operation for the abdominal organs acute diseases were summarized. The proposed method introduction have permitted to reduce the intraoperative complications rate from 66.6%--in a control group to 12.2%--in the main group; postoperative complications--from 21.2 to 1.7%, postoperative lethality--from 7.4 to 1.7%.

[New technologies in partial nephrectomy]

OBJECTIVES

We aim to analyse the role of new technologies in management of small renal cancer.

METHODS

We perform a non-systematic review of the literature in Medline, Cochrane Database of Systematic Reviews between period 2000-2012, using following mesh terms: partial nephrectomy, renal ablative technologies, and renal cancer.

RESULTS

We don't review in this article ablative technologies such as cryotherapy, radiofrequency, as they are the subject of others manuscripts within this monographic issue. We focus on high intensity ultrasounds (HIFU) microwaves therapy, radiosurgery, laser and water jet dissection.

CONCLUSIONS

New technologies in partial nephrectomy are under constant and vertiginous evolution. Although efficacy has been demonstrated in short term and isolated studies, more studies, better designed, with bigger sample size and longer follow up are needed.

[Functional state of liver before and after its resection using various dissection methods]

Today a few randomized investigations have been accomplished, in which advantages and disadvantages of various methods of hepatic resection are compared. The investigation objective was to estimate the hepatic functional state before and after its resection, using various methods of parenchymal dissection. Randomized investigation was conducted in 90 patients, to whom hepatic resection, using scalpel, with its preliminary suturing by the block-like sutures with the Vycril thread, applying radiofrequency coagulator, "clamp crushing" procedure, ultrasonic (Sonoca 300) and a water-jet (Hydrojet) dissectors. The dissection was not combined with the hepatic vessels exclusion. Coefficient of elimination of indocyangreen and a speciphic coefficient of its elimination were estimated. There was established, that putting the block-like sutures and radiofrequency coagulation, concerning the hermetization peculiarities, causes the resection area ischemia, what is accompanied by persisting degradation of hepatocytes and hepatic functional reserve reduction as a result of its resection performance. While the extended hepatic resection conduction it is expedient to apply the methods of ultrasonographic, the jet-like dissection or a "clamp crushing", which guarantee minimization of risk of postoperative hepatic insufficiency occurrence.

[Minimally invasive video-assisted thyroidectomy for treatment of benign thyroid nodules]

OBJECTIVES

This study aims to evaluate patients who underwent minimally invasive video-assisted thyroidectomy (MIVAT) and to discuss the advantages and disadvantages of this technique in the light of literature data.

PATIENTS AND METHODS

Between May 2008 and February 2009, 20 patients (18 females, 2 males; mean age 44.5±13.6 years; range 23 to 68 years) who underwent MIVAT using a 4 mm and 30° rigid endoscope and ultrasonic scalpel for dissected the main thyroid vessels were included in the study. Inclusion criteria were benign thyroid nodules of <30 mm and ultrasonographically thyroid volume of <20 ml.

RESULTS

The mean length of incision was 2.6±0.5 cm, the mean operation time was 111.7±39.7 min and the mean amount of bleeding was 82.8±84.1 cc. A statistically significantly positive relationship was found between the operation time and the nodule size and the amount of bleeding and also between the length of the incision and cosmetic satisfaction scale scores (p<0.05). However, no statistically significant correlation was found between the operation time and postoperative pain and between the length of incision and postoperative pain (p>0.05). Although 30% of the patients had mild to moderate pain, 50% had moderate pain and 20% had severe pain in the early postoperative period, no patient had pain in the postoperative third day. No postoperative persistent vocal cord paralysis was observed in the patients.

CONCLUSION

Minimally invasive video-assisted thyroidectomy is a safe and useful approach in the treatment of the patients with benign thyroid nodules.

Extension of the angular spectrum method to calculate pressure from a spherically curved acoustic source

The angular spectrum method is an accurate and computationally efficient method for modeling acoustic wave propagation. The use of the typical 2D fast Fourier transform algorithm makes this a fast technique but it requires that the source pressure (or velocity) be specified on a plane. Here the angular spectrum method is extended to calculate pressure from a spherical transducer-as used extensively in applications such as magnetic resonance-guided focused ultrasound surgery-to a plane. The approach, called the Ring-Bessel technique, decomposes the curved source into circular rings of increasing radii, each ring a different distance from the intermediate plane, and calculates the angular spectrum of each ring using a Fourier series. Each angular spectrum is then propagated to the intermediate plane where all the propagated angular spectra are summed to obtain the pressure on the plane; subsequent plane-to-plane propagation can be achieved using the traditional angular spectrum method. Since the Ring-Bessel calculations are carried out in the frequency domain, it reduces calculation times by a factor of approximately 24 compared to the Rayleigh-Sommerfeld method and about 82 compared to the Field II technique, while maintaining accuracies of better than 96% as judged by those methods for cases of both solid and phased-array transducers.

An unique case of dyspareunia leading to the diagnosis of urachal cyst in a nulliparous 28-year-old woman

Urachal cysts are usually asymptomatic. Symptoms, when present, are usually acute abdominal pain, fever, midline hypogastric tenderness, palpable mass, evidence of urinary infection or haematuria due to infection of the cyst. We report an unique case of dyspareunia and "abdominal fluid flowing feeling" caused by an urachal cyst in a 28 year-old nulliparous woman. Diagnosis was achieved by US and MRI. Cystography excluded any cyst-bladder communication. Laparoscopic surgery was performed without perioperative complications. Patient obtained immediate relief of symptoms still continuing at a 24 months follow up.

[Development and clinical application of ultrasonic osteotomy in dentistry]

Ultrasonic osteotomy is a new technique for osseous surgery utilizing an innovative ultrasonic surgical apparatus. Oral surgeons have started using this newly developed ultrasonic bone scalpel when performing precise osteotomies. This technique is known as piezosurgery also and has found wide applications in dental and medical specialities. Numerous protocols including conventional diamond round bur, safe scraper, rongeur pliers and gouge shaped bone chisel have been proposed to simplify osteotomy and osteoplasty in bone surgery before this technique was created. But only ultrasonic osteotomy could reach high levels of precision and safety as compared to those instruments. Ultrasonic osteotomy device is characterized by piezoelectric ultrasonic vibrations of a frequency of 25-29 kHz and a range between 60-200 microm. Due to low-frequency ultrasonic vibration, the device precisely cuts bone without cutting soft tissue even in case of accidental contact. It also maintains a blood-free site during cutting bone. This technique was first used in sinus floor elevation for bony window osteotomy and sinus membrane elevation. After several years, this technique is utilized in more and more dental indications such as ridge expansion, maxillary sinus floor elevation, harvesting of bone graft, extraction and socket debridement for the installation of immediate-loaded implants, extraction of third molars, periodontal surgery, cyst exeresis and inferior alveolar nerve transposition. It's also reported in hand surgery, cranial osteoplasty and segmental maxillary Le Fort osteotomy. Ultrasonic osteotomy is different from the conventional techniques utilized and proved to be a safe and useful technique in bone surgery.