HIFU for Bone Metastases and other Musculoskeletal Applications

Tissue Ablation: Applications and Perspectives

Tissue ablation techniques have emerged as a critical component of modern medical practice and biomedical research, offering versatile solutions for treating various diseases and disorders. Percutaneous ablation is minimally invasive and offers numerous advantages over traditional surgery, such as shorter recovery times, reduced hospital stays, and decreased healthcare costs. Intra-procedural imaging during ablation also allows precise visualization of the treated tissue while minimizing injury to the surrounding normal tissues, reducing the risk of complications. Here, the mechanisms of tissue ablation and innovative energy delivery systems are explored, highlighting recent advancements that have reshaped the landscape of clinical practice. Current clinical challenges related to tissue ablation are also discussed, underlining unmet clinical needs for more advanced material-based approaches to improve the delivery of energy and pharmacology-based therapeutics.

High-intensity focused ultrasound-a needleless management for osteoid osteoma: a systematic review

Osteoid osteoma is one of the most frequent benign musculoskeletal neoplasm. Radiofrequency ablation is the method of choice for non-conservative treatment of osteoid osteoma. Recently, high-intensity focused ultrasound (HIFU) has been proposed as a safer option. The objective of this study is to review the efficacy and side effects of HIFU in the management of osteoid osteoma. A comprehensive search was conducted in PubMed, Science Direct, and Clinical Key until June 30, 2022. Demographic data, baseline characteristics, success rates, pre- and post-procedure pain scores, recurrences, and complications were recorded. Eleven studies were included in this systematic review. Pooled analysis that involved 186 subjects resulted in an overall success rate of 91.94%. Recurrence was reported in two studies, in which it occurred in 4/177 (2.26%) subjects. Skin burn was found in 1 (0.54%) patients. No major or other complications were reported. Three studies compared the success rate of HIFU and RFA. Success rate was slightly higher in the RFA group with insignificant difference (p = 0.15). High-intensity focused ultrasound showed promising results. It offers a safer treatment approach for osteoid osteoma, especially in children, and can be considered for recalcitrant cases after RFA. Nonetheless, more studies are expected in the future.

Update on musculoskeletal applications of magnetic resonance-guided focused ultrasound

Magnetic resonance-guided focused ultrasound (MRgFUS) is a noninvasive, incisionless, radiation-free technology used to ablate tissue deep within the body. This technique has gained increased popularity following FDA approval for treatment of pain related to bone metastases and limited approval for treatment of osteoid osteoma. MRgFUS delivers superior visualization of soft tissue targets in unlimited imaging planes and precision in targeting and delivery of thermal dose which is all provided during real-time monitoring using MR thermometry. This paper provides an overview of the common musculoskeletal applications of MRgFUS along with updates on clinical outcomes and discussion of future applications.

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.

Innovative Experimental Ultrasound and US-Related Techniques Using the Murine Model in Pancreatic Ductal Adenocarcinoma: A Systematic Review

Pancreatic ductal adenocarcinoma (PDAC) is a cancer with one of the highest mortality rates in the world. Several studies have been conductedusing preclinical experiments in mice to find new therapeutic strategies. Experimental ultrasound, in expert hands, is a safe, multifaceted, and relatively not-expensive device that helps researchers in several ways. In this systematic review, we propose a summary of the applications of ultrasonography in a preclinical mouse model of PDAC. Eighty-eight studies met our inclusion criteria. The included studies could be divided into seven main topics: ultrasound in pancreatic cancer diagnosis and progression (n: 21); dynamic contrast-enhanced ultrasound (DCE-US) (n: 5); microbubble ultra-sound-mediated drug delivery; focused ultrasound (n: 23); sonodynamic therapy (SDT) (n: 7); harmonic motion elastography (HME) and shear wave elastography (SWE) (n: 6); ultrasound-guided procedures (n: 9). In six cases, the articles fit into two or more sections. In conclusion, ultrasound can be a really useful, eclectic, and ductile tool in different diagnostic areas, not only regarding diagnosis but also in therapy, pharmacological and interventional treatment, and follow-up. All these multiple possibilities of use certainly represent a good starting point for the effective and wide use of murine ultrasonography in the study and comprehensive evaluation of pancreatic cancer.

A review of the development of histotripsy for extremity tumor ablation with a canine comparative oncology model to inform human treatments

Cancer is a devasting disease resulting in millions of deaths worldwide in both humans and companion animals, including dogs. Treatment of cancer is complex and challenging and therefore often multifaceted, as in the case of osteosarcoma (OS) and soft tissue sarcoma (STS). OS predominantly involves the appendicular skeleton and STS commonly develops in the extremities, resulting in treatment challenges due to the need to balance wide-margin resections to achieve local oncological control against the functional outcomes for the patient. To achieve wide tumor resection, invasive limb salvage surgery is often required, and the patient is at risk for numerous complications which can ultimately lead to impaired limb function and mobility. The advent of tumor ablation techniques offers the exciting potential of developing noninvasive or minimally invasive treatment options for extremity tumors. One promising innovative tumor ablation technique with strong potential to serve as a noninvasive limb salvage treatment for extremity tumor patients is histotripsy. Histotripsy is a novel, noninvasive, non-thermal, and non-ionizing focused ultrasound technique which uses controlled acoustic cavitation to mechanically disintegrate tissue with high precision. In this review, we present the ongoing development of histotripsy as a non-surgical alternative for extremity tumors and highlight the value of spontaneously occurring OS and STS in the pet dog as a comparative oncology research model to advance this field of histotripsy research.

MRI-guided focused ultrasound ablation of painful lumbar facet joints: a retrospective assessment of safety and tolerability in human subjects

OBJECTIVE

To evaluate the safety and tolerability of MRI-guided focused ultrasound (MRgFUS) for the treatment of facet joint-mediated pain in human subjects for whom conventional treatment had failed. Secondarily, to evaluate effectiveness of the procedure.

METHODS

Consecutive patients who underwent MRgFUS at our institution were retrospectively identified. Chart review was performed to obtain relevant clinical and technical data. All patients had chronic low back pain and positive comparative medial branch blocks.

RESULTS

Twenty-six MRgFUS treatments in 20 patients were included. Mean sonication energy was 1436.6 Joules. The procedure was technically successful in all patients. Of the treated patients, 29.6% experienced short-term worsening of low back pain immediately after the procedure, all by 1-4 points on a 0-10 scale. One patient (3.8%) reported temporary worsening of preexisting radicular symptoms after the procedure. Of 21 treatments with clinical follow-up of at least 3 months available, 12 (57.1%) had >3 months' pain relief, 2 (10%) had <3 months' benefit, 6 (30%) reported no benefit, and 1 (5%) patient was lost to follow-up. In patients who reported at least some benefit with prior conventional radiofrequency ablation, 8/10 (80%) benefited from the MRgFUS procedure.

CONCLUSION

The present study demonstrates that MRgFUS ablation of the lumbar facet joints is a safe and tolerable procedure in human subjects and could provide another option for patients for whom radiofrequency ablation had failed. More than half of all patients received significant durable pain relief, which jumped to 80% for patients who had experienced at least some benefit from prior radiofrequency ablations.

Ablative and Immunostimulatory Effects of Histotripsy Ablation in a Murine Osteosarcoma Model

Background: Osteosarcoma (OS) is the most frequently occurring malignant bone tumor in humans, primarily affecting children and adolescents. Significant advancements in treatment options for OS have not occurred in the last several decades, and the prognosis remains grim with only a 70% rate of 5-year survival. The objective of this study was to investigate the focused ultrasound technique of histotripsy as a novel, noninvasive treatment option for OS. Methods: We utilized a heterotopic OS murine model to establish the feasibility of ablating OS tumors with histotripsy in a preclinical setting. We investigated the local immune response within the tumor microenvironment (TME) via immune cell phenotyping and gene expression analysis. Findings: We established the feasibility of ablating heterotopic OS tumors with ablation characterized microscopically by loss of cellular architecture in targeted regions of tumors. We observed greater populations of macrophages and dendritic cells within treated tumors and the upregulation of immune activating genes 72 h after histotripsy ablation. Interpretation: This study was the first to investigate histotripsy ablation for OS in a preclinical murine model, with results suggesting local immunomodulation within the TME. Our results support the continued investigation of histotripsy as a novel noninvasive treatment option for OS patients to improve clinical outcomes and patient prognosis.

Experimental study of HIFU incomplete ablation on the damage effect and prognosis of rabbit VX2 breast cancer model

PURPOSE

High-intensity focused ultrasound (HIFU) represents an emerging noninvasive modality for tumor treatment. While biological responses and immunological change associated with incomplete ablation have not been thoroughly investigated. This study aims to evaluate the damage effect of HIFU incomplete ablation via establishing animal model and further explore its possible mechanism to inhibit tumor growth.

METHODS

The rabbit VX2 breast cancer model was established and received HIFU treatment with complete ablation (100% tumor volume) and incomplete ablation (about 80% tumor volume) under real-time B-ultrasound monitoring. Histopathological alterations, dynamics of tumor cell apoptosis and proliferation, expression levels of VEGF, MMP-9, IL-2R, TGF-β1, HSP-70, IL-6, IL-8, and INF-γ, and the presence of circulating tumor cells (CTCs) were evaluated post-HIFU incomplete ablation.

RESULTS

For HIFU 80% ablation group, there was an 85.85% reduction in tumor volume 21 days post-intervention. A marked increase in tumor cell apoptosis and a concomitant decrease in proliferation were observed. Notably, distant tumor metastasis rates, CTC counts, and expression levels of VEGF, MMP-9, IL-2R, TGF-β1, IL-6, and IL-8 were significantly reduced. In contrast, INF-γ and HSP-70 expressions were notably elevated, aligning with findings from the 100% ablation group.

CONCLUSIONS

HIFU incomplete ablation, with an 80% tumor ablation rate, induces substantial tumor damage, augments tumor cell apoptosis, and triggers an anti-tumor immune response, curtailing metastasis. These insights may underpin further investigations into the therapeutic implications of HIFU incomplete ablation.

Current therapies and future prospective for locally aggressive mesenchymal tumors

Locally aggressive mesenchymal tumors comprise a heterogeneous group of soft tissue and bone tumors with intermediate histology, incompletely understood biology, and highly variable natural history. Despite having a limited to absent ability to metastasize and excellent survival prognosis, locally aggressive mesenchymal tumors can be symptomatic, require prolonged and repeat treatments including surgery and chemotherapy, and can severely impact patients' quality of life. The management of locally aggressive tumors has evolved over the years with a focus on minimizing morbid treatments. Extensive oncologic surgeries and radiation are pillars of care for high grade sarcomas, however, play a more limited role in management of locally aggressive mesenchymal tumors, due to propensity for local recurrence despite resection, and the risk of transformation to a higher-grade entity following radiation. Patients should ideally be evaluated in specialized sarcoma centers that can coordinate complex multimodal decision-making, taking into consideration the individual patient's clinical presentation and history, as well as any available prognostic factors into customizing therapy. In this review, we aim to discuss the biology, clinical management, and future treatment frontiers for three representative locally aggressive mesenchymal tumors: desmoid-type fibromatosis (DF), tenosynovial giant cell tumor (TSGCT) and giant cell tumor of bone (GCTB). These entities challenge clinicians with their unpredictable behavior and responses to treatment, and still lack a well-defined standard of care despite recent progress with newly approved or promising experimental drugs.

Immunomodulation and targeted drug delivery with high intensity focused ultrasound (HIFU): Principles and mechanisms

High intensity focused ultrasound (HIFU) is a non-invasive and non-ionizing sonic energy-based therapeutic technology for inducing thermal and non-thermal effects in tissues. Depending on the parameters, HIFU can ablate tissues by heating them to >55 °C to induce denaturation and coagulative necrosis, improve radio- and chemo-sensitizations and local drug delivery from nanoparticles at moderate hyperthermia (~41-43 °C), and mechanically fragment cells using acoustic cavitation (also known as histotripsy). HIFU has already emerged as an attractive modality for treating human prostate cancer, veterinary cancers, and neuromodulation. Herein, we comprehensively review the role of HIFU in enhancing drug delivery and immunotherapy in soft and calcified tissues. Specifically, the ability of HIFU to improve adjuvant treatments from various classes of drugs is described. These crucial insights highlight the opportunities and challenges of HIFU technology and its potential to support new clinical trials and translation to patients.

Musculoskeletal oncology and thermal ablation: the current and emerging role of interventional radiology

The role of interventional radiology (IR) is expanding. With new techniques being developed and tested, this radiology subspecialty is taking a step forward in different clinical scenarios, especially in oncology. Musculoskeletal tumoral diseases would definitely benefit from a low-invasive approach that could reduce mortality and morbidity in particular. Thermal ablation through IR has already become important in the palliation and consolidation of bone metastases, oligometastatic disease, local recurrences, and treating specific benign tumors, with a more tailored approach, considering the characteristics of every patient. As image-guided ablation techniques lower their invasiveness and increase their efficacy while the collateral effects and complications decrease, they become more relevant and need to be considered in patient care pathways and clinical management, to improve outcomes. We present a literature review of the different percutaneous and non-invasive image-guided thermal ablation methods that are currently available and that could in the future become relevant to manage musculoskeletal oncologic diseases.

Combination of Focused Ultrasound, Immunotherapy, and Chemotherapy: New Perspectives in Breast Cancer Therapy

Focused ultrasound is a treatment modality increasingly used for diverse therapeutic applications, and currently approved for several indications, including prostate cancers and uterine fibroids. But what about breast cancer? Breast cancer is the most common and deadliest cancer in women worldwide. While there are different treatment strategies available, there is a need for development of more effective and personalized modalities, with fewer side effects. Therapeutic ultrasound is such an option, and this review summarizes the state of the art in their use for the treatment of breast cancer and evaluate potentials of novel treatment approaches combining therapeutic ultrasound, immuno- and chemo-therapies.

Factors Influencing the Adoption of Magnetic Resonance-Guided High-Intensity Focused Ultrasound for Painful Bone Metastases in Europe, A Group Concept Mapping Study

Magnetic resonance imaging-guided high-intensity focused ultrasound (MR-HIFU) is an innovative treatment for patients with painful bone metastases. The adoption of MR-HIFU will be influenced by several factors beyond its effectiveness. To identify contextual factors affecting the adoption of MR-HIFU, we conducted a group concept mapping (GCM) study in four European countries. The GCM was conducted in two phases. First, the participants brainstormed statements guided by the focus prompt "One factor that may influence the uptake of MR-HIFU in clinical practice is...". Second, the participants sorted statements into categories and rated the statements according to their importance and changeability. To generate a concept map, multidimensional scaling and cluster analysis were conducted, and average ratings for each (cluster of) factors were calculated. Forty-five participants contributed to phase I and/or II (56% overall participation rate). The resulting concept map comprises 49 factors, organized in 12 clusters: "competitive treatments", "physicians' attitudes", "alignment of resources", "logistics and workflow", "technical disadvantages", "radiotherapy as first-line therapy", "aggregating knowledge and improving awareness", "clinical effectiveness", "patients' preferences", "reimbursement", "cost-effectiveness" and "hospital costs". The factors identified echo those from the literature, but their relevance and interrelationship are case-specific. Besides evidence on clinical effectiveness, contextual factors from 10 other clusters should be addressed to support adoption of MR-HIFU.

Focused Ultrasound and RadioTHERapy for non-invasive palliative pain treatment in patients with bone metastasis: a study protocol for the three armed randomized controlled FURTHER trial

BACKGROUND

Cancer-induced bone pain (CIBP), caused by bone metastases, is a common complication of cancer and strongly impairs quality of life (QoL). External beam radiotherapy (EBRT) is the current standard of care for treatment of CIBP. However, approximately 45% of patients have no adequate pain response after EBRT. Magnetic resonance image-guided high-intensity focused ultrasound (MR-HIFU) may improve pain palliation in this patient population. The main objective of this trial was to compare MR-HIFU, EBRT, and MR-HIFU + EBRT for the palliative treatment of bone metastases.

METHODS/DESIGN

The FURTHER trial is an international multicenter, three-armed randomized controlled trial. A total of 216 patients with painful bone metastases will be randomized in a 1:1:1 ratio to receive EBRT only, MR-HIFU only, or combined treatment with EBRT followed by MR-HIFU. During a follow-up period of 6 months, patients will be contacted at eight time points to retrieve information about their level of pain, QoL, and the occurrence of (serious) adverse events. The primary outcome of the trial is pain response at 14 days after start of treatment. Secondary outcomes include pain response at 14 days after trial enrolment, pain scores (daily until the 21st day and at 4, 6, 12 and 24 weeks), toxicity, adverse events, QoL, and survival. Cost-effectiveness and cost-utility analysis will be conducted.

DISCUSSION

The FURTHER trial aims to evaluate the effectiveness and cost-effectiveness of MR-HIFU-alone or in combination with EBRT-compared to EBRT to relieve CIBP. The trial will be performed in six hospitals in four European countries, all of which are partners in the FURTHER consortium.

TRIAL REGISTRATION

The FURTHER trial is registered under the Netherlands Trials Register number NL71303.041.19 and ClinicalTrials.gov registration number NCT04307914. Date of trial registration is 13-01-2020.

Interventional Palliation of Painful Extraspinal Musculoskeletal Metastases

The musculoskeletal system is commonly involved by metastases, and skeletal-related events such as intractable pain due to direct osseous tumor involvement, pathologic fracture, and neurologic deficits as a result of nerve compression often adversely affect patient's quality of life. There have been substantial advances in percutaneous minimally invasive musculoskeletal oncologic interventions for the management of patients with musculoskeletal metastases including thermal ablations, cementation with or without osseous reinforcement via implants, osteosynthesis, neurolysis, and palliative injections which are progressively incorporated in clinical practice. These interventions are performed, in conjunction with or supplemented by adjuvant radiation therapy, systemic therapy, surgery, or analgesics, to achieve durable pain palliation, local tumor control, or cure. This article reviews minimally invasive percutaneous image-guided musculoskeletal oncologic interventions for the management of patients with extraspinal musculoskeletal metastases.

3-T magnetic resonance-guided high-intensity focused ultrasound (3 T-MR-HIFU) for the treatment of pain from bone metastases of solid tumors

INTRODUCTION

Bone metastases (BM) are still the main cause of morbidity and mortality in cancer patients, not only because of their complications, defined as skeletal-related events (SREs), but also because of the negative impact bone pain has on quality of life (QoL) and survival, especially when opioid analgesics and locoregional treatments fail.

MATERIALS AND METHODS

A single-center prospective study was carried out on 12 patients with symptomatic BM treated with MRI-guided focused ultrasound (MR-HIFU). The primary endpoint was the effectiveness of MR-HIFU in reducing current and breakthrough cancer pain (BTCP) scores. The main secondary aims were the evaluation of circulating markers at different time-points and their relation to pain and procedure efficacy. Other secondary objectives included temporal evolution of pain response, evaluation of QoL, and side effects of the treatment. Descriptive statistics were used to evaluate primary and secondary endpoints. Questionnaires on pain and QoL completed at baseline and at 30 days were compared using appropriate statistical tests with exploratory intent.

RESULTS

MR-HIFU was successfully completed in all 12 patients enrolled between September 2015 and December 2018. On day 30, 6 (50.0%) patients showed a complete response of current pain and 6 a partial response, while 5 (41.7%) obtained a complete BTCP response. A partial response of BM evaluated by MD Anderson criteria was obtained in 9 (81.8%) patients. Only one patient progressed in the target lesion after MR-HIFU. No treatment-related adverse events were recorded. Bone turnover markers CTX/RANK-L (P) do not demonstrate any significant change with the pain or BM response.

CONCLUSION

In our patients, targeted therapy of painful BM with MRI-guided focused ultrasound ablation was safe and showed encouraging early-onset and functional results.

Focused Ultrasound for Pediatric Diseases

Focused ultrasound (FUS) is a noninvasive therapeutic technology with multiple pediatric clinical applications. The ability of focused ultrasound to target tissues deep in the body without exposing children to the morbidities associated with conventional surgery, interventional procedures, or radiation offers significant advantages. In 2021, there are 10 clinical pediatric focused ultrasound studies evaluating various musculoskeletal, oncologic, neurologic, and vascular diseases of which 8 are actively recruiting and 2 are completed. Pediatric musculoskeletal applications of FUS include treatment of osteoid osteoma and bone metastases using thermal ablation and high-intensity FUS. Pediatric oncologic applications of FUS include treatment of soft tissue tumors including desmoid tumors, malignant sarcomas, and neuroblastoma with high-intensity FUS ablation alone, or in combination with targeted chemotherapy delivery. Pediatric neurologic applications include treatment of benign tumors such as hypothalamic hamartomas with thermal ablation and malignant diffuse intrinsic pontine glioma with low-intensity FUS for blood brain barrier opening and targeted drug delivery. Additionally, low-intensity FUS can be used to treat seizures. Pediatric vascular applications of FUS include treatment of arteriovenous malformations and twin-twin transfusion syndrome using ablation and vascular occlusion. FUS treatment appears safe and efficacious in pediatric populations across many subspecialties. Although there are 7 Food and Drug Administration-approved indications for adult applications of FUS, the first Food and Drug Administration approval for pediatric patients with osteoid osteoma was obtained in 2020. This review summarizes the preclinical and clinical research on focused ultrasound of potential benefit to pediatric populations.

Synthetic CT for the planning of MR-HIFU treatment of bone metastases in pelvic and femoral bones: a feasibility study

Objectives

Visualization of the bone distribution is an important prerequisite for MRI-guided high-intensity focused ultrasound (MRI-HIFU) treatment planning of bone metastases. In this context, we evaluated MRI-based synthetic CT (sCT) imaging for the visualization of cortical bone.

Methods

MR and CT images of nine patients with pelvic and femoral metastases were retrospectively analyzed in this study. The metastatic lesions were osteolytic, osteoblastic or mixed. sCT were generated from pre-treatment or treatment MR images using a UNet-like neural network. sCT was qualitatively and quantitatively compared to CT in the bone (pelvis or femur) containing the metastasis and in a region of interest placed on the metastasis itself, through mean absolute difference (MAD), mean difference (MD), Dice similarity coefficient (DSC), and root mean square surface distance (RMSD).

Results

The dataset consisted of 3 osteolytic, 4 osteoblastic and 2 mixed metastases. For most patients, the general morphology of the bone was well represented in the sCT images and osteolytic, osteoblastic and mixed lesions could be discriminated. Despite an average timespan between MR and CT acquisitions of 61 days, in bone, the average (± standard deviation) MAD was 116 ± 26 HU, MD − 14 ± 66 HU, DSC 0.85 ± 0.05, and RMSD 2.05 ± 0.48 mm and, in the lesion, MAD was 132 ± 62 HU, MD − 31 ± 106 HU, DSC 0.75 ± 0.2, and RMSD 2.73 ± 2.28 mm.

Conclusions

Synthetic CT images adequately depicted the cancellous and cortical bone distribution in the different lesion types, which shows its potential for MRI-HIFU treatment planning.

Key Points

• Synthetic computed tomography was able to depict bone distribution in metastatic lesions.

• Synthetic computed tomography images intrinsically aligned with treatment MR images may have the potential to facilitate MR-HIFU treatment planning of bone metastases, by combining visualization of soft tissues and cancellous and cortical bone.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-022-08568-y.

A Few-Shot Learning Approach Assists in the Prognosis Prediction of Magnetic Resonance-Guided Focused Ultrasound for the Local Control of Bone Metastatic Lesions

Simple Summary

We report a local control prediction model for patients undergoing MRgFUS ablation, and provide promising guidance for clinicians to identify a suitable treatment strategy for bone metastatic lesions. We propose a few-shot learning approach to establish the quick prediction of clinical and radiographic responses. On the basis of demographic data, pre-/post-treatment immune-related cytokine change, and MRI imaging, the most suitable parameters were selected to assess potential treatment outcomes during the acute inflammatory stages within 24 h. Traditional logistic regression and few-shot learning models were compared to identify the best model on an independent test. The best predictive few-shot learning model (accuracy of 85.2%, sensitivity of 88.6%, and AUC of 0.95) was achieved by combining the clinical features with the levels of significant cytokines IL-6, IL-13, IP-10, and eotaxin.

Abstract

Magnetic resonance-guided focused ultrasound surgery (MRgFUS) constitutes a noninvasive treatment strategy to ablate deep-seated bone metastases. However, limited evidence suggests that, although cytokines are influenced by thermal necrosis, there is still no cytokine threshold for clinical responses. A prediction model to approximate the postablation immune status on the basis of circulating cytokine activation is thus needed. IL-6 and IP-10, which are proinflammatory cytokines, decreased significantly during the acute phase. Wound-healing cytokines such as VEGF and PDGF increased after ablation, but the increase was not statistically significant. In this phase, IL-6, IL-13, IP-10, and eotaxin expression levels diminished the ongoing inflammatory progression in the treated sites. These cytokine changes also correlated with the response rate of primary tumor control after acute periods. The few-shot learning algorithm was applied to test the correlation between cytokine levels and local control (p = 0.036). The best-fitted model included IL-6, IL-13, IP-10, and eotaxin as cytokine parameters from the few-shot selection, and had an accuracy of 85.2%, sensitivity of 88.6%, and AUC of 0.95. The acceptable usage of this model may help predict the acute-phase prognosis of a patient with painful bone metastasis who underwent local MRgFUS. The application of machine learning in bone metastasis is equivalent or better than the current logistic regression.

A time-driven activity-based costing approach of magnetic resonance-guided high-intensity focused ultrasound for cancer-induced bone pain

OBJECTIVE

To determine resource consumption and total costs for providing magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) treatment to a patient with cancer-induced bone pain (CIBP).

METHODS

We conducted a time-driven activity-based costing (TD-ABC) of MR-HIFU treatments for CIBP from a hospital perspective. A European care-pathway (including a macro-, meso-, and micro-level) was designed to incorporate the care-delivery value chain. Time estimates were obtained from medical records and from prospective direct observations. To calculate the capacity cost rate, data from the controlling department of a German university hospital were allocated to the modules of the care pathway. Best- and worst-case scenarios were calculated by applying lower and upper bounds of time measurements.

RESULTS

The macro-level care pathway consisted of eight modules (i.e., outpatient consultations, pretreatment imaging, preparation, optimization, sonication, post-treatment, recovery, and anesthesia). The total cost of an MR-HIFU treatment amounted to €5147 per patient. Best- and worst-case scenarios yielded a total cost of €4092 and to €5876. According to cost categories, costs due to equipment accounted for 41% of total costs, followed by costs with personnel (32%), overhead (16%) and materials (11%).

CONCLUSION

MR-HIFU is an emerging noninvasive treatment for alleviating CIBP, with increasing evidence on treatment efficacy. This costing study can support MR-HIFU reimbursement negotiations and facilitate the adoption of MR-HIFU as first-line treatment for CIBP. The present TD-ABC model creates the opportunity of benchmarking the provision of MR-HIFU to bone tumor.Key pointsMagnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) is an emerging noninvasive treatment modality for alleviating cancer-induced bone pain (CIBP).From a hospital perspective, the total cost of MR-HIFU amounted to €5147 per treatment.This time-driven activity-based costing model creates the opportunity of benchmarking the provision of MR-HIFU to bone tumor.

Musculoskeletal Applications of Magnetic Resonance-Guided Focused Ultrasound

Magnetic resonance-guided focused ultrasound (MRgFUS) is a novel noninvasive therapy that uses focused sound energy to thermally ablate focal pathology within the body. In the United States, MRgFUS is approved by the Food and Drug Administration for the treatment of uterine fibroids, palliation of painful bone metastases, and thalamotomy for the treatment of essential tremor. However, it has also demonstrated utility for the treatment of a wide range of additional musculoskeletal (MSK) conditions that currently are treated as off-label indications. Advantages of the technology include the lack of ionizing radiation, the completely noninvasive technique, and the precise targeting that offer unprecedented control of the delivery of the thermal dose, as well as real-time monitoring capability with MR thermometry. In this review, we describe the most common MSK applications of MRgFUS: palliation of bone metastases, treatment of osteoid osteomas, desmoid tumors, facet arthropathy, and other developing indications.

Theranostic Nanoplatform with Sequential SDT and ADV Effects in Response to Well-Programmed LIFU Irradiation for Cervical Cancer

Background

Some patients with cervical cancer have the need to preserve fertility; therefore, a minimally invasive treatment option that can effectively inactivate tumors in these patients is necessary.

Methods

In this paper, we designed and prepared nanoparticles (NPs) carrying IR780 and perfluorohexane (PFH) and characterized their properties. We focused on the promotion of programmed low-intensity focused ultrasound (LIFU) irradiation on the penetration and treatment of cervical cancer. First we used penetration-enhancing LIFU irradiation to promote the penetration of the NPs into 3D multicellular tumor spheroids (MCTSs) and tumors in tumor-bearing nude mice. Then we used re-therapeutic LIFU irradiation to achieve antitumor effects in vitro and in vivo. Photoacoustic (PA) and magnetic resonance (MR) imaging were used to monitor and evaluate the targeting and therapeutic effects of these NPs on tumor tissues.

Results

The NPs prepared in this paper exhibited high affinity for HeLa cells, and can selectively achieve mitochondrial localization in the cell due to IR780 assistance. The penetration-enhancing LIFU irradiation have the ability to promote the penetration of the NPs into cervical cancer models in vivo and in vitro. Under LIFU irradiation, the cytotoxic reactive oxygen species (ROS) produced by IR780 during the first half of the re-therapeutic LIFU irradiation and the physical acoustic droplet vaporization (ADV) effect after PFH phase transition during the second half of the re-therapeutic LIFU irradiation can achieve synergistic minimally invasive treatment of tumors, which can be visualized and evaluated by PA and MR imaging in vivo.

Conclusion

Well-programmed LIFU irradiation can promote NP penetration into deep tumor tissue and achieve antitumor effects simultaneously. Linking ROS + ADV effects can induce cell coagulation necrosis and lead to a comprehensive, long-term impact on tumor tissue, providing a conceptual theranostic nanoplatform for cervical cancer.

Interleaved water and fat MR thermometry for monitoring high intensity focused ultrasound ablation of bone lesions

PURPOSE

To demonstrate that interleaved MR thermometry can monitor temperature in water and fat with adequate temporal resolution. This is relevant for high intensity focused uUltrasounds (HIFU) treatment of bone lesions, which are often found near aqueous tissues, as muscle, or embedded in adipose tissues, as subcutaneous fat and bone marrow.

METHODS

Proton resonance frequency shift (PRFS)-based thermometry scans and T1 -based 2D variable flip angle (2D-VFA) thermometry scans were acquired alternatingly over time. Temperature in water was monitored using PRFS thermometry, and in fat by 2D-VFA thermometry with slice profile effect correction. The feasibility of interleaved water/fat temperature monitoring was studied ex vivo in porcine bone during MR-HIFU sonication. Precision and stability of measurements in vivo were evaluated in a healthy volunteer under non-heating conditions.

RESULTS

The method allowed observing temperature change over time in muscle and fat, including bone marrow, during MR-HIFU sonication, with a temporal resolution of 6.1 s. In vivo, the apparent temperature change was stable on the time scale of the experiment: In 7 min the systematic drift was <0.042°C/min in muscle (PRFS after drift correction) and <0.096°C/min in bone marrow (2D-VFA). The SD of the temperature change averaged over time was 0.98°C (PRFS) and 2.7°C (2D-VFA).

CONCLUSIONS

Interleaved MR thermometry allows temperature measurements in water and fat with a temporal resolution high enough for monitoring HIFU ablation. Specifically, combined fat and water thermometry provides uninterrupted information on temperature changes in tissue close to the bone cortex.

Bone Metastases: State of the Art in Minimally Invasive Interventional Oncology

Bone is the third most common site involved by cancer metastases, and skeleton-related events such as intractable pain due to direct osseous tumor involvement, pathologic fracture, and neurologic deficits as a consequence of nerve or spinal cord compression often affect patients' functional independence and quality of life unfavorably. The annual medical-economic burden related to bone metastases is a substantial component of the total direct medical cost estimated by the National Institutes of Health. There have been substantial recent advances in percutaneous image-guided minimally invasive musculoskeletal oncologic interventions for the management of patients with osseous metastatic disease. These advances include thermal ablation, cementation with or without osseous reinforcement with implants, osteosynthesis, thermal and chemical neurolyses, and palliative injections, which are progressively incorporated into the management paradigm for such patients. These interventions are performed in conjunction with or are supplemented by adjuvant radiation therapy, systemic therapy, surgery, or analgesic agents to achieve durable pain palliation, local tumor control, or cure, and they provide a robust armamentarium for interventional radiologists to achieve safe and effective treatment in a multidisciplinary setting. In addition, these procedures are shifting the patient management paradigm in modern-era practice. The authors detail the state of the art in minimally invasive percutaneous image-guided musculoskeletal oncologic interventions and the role of radiologists in managing patients with skeletal metastases. ^©RSNA, 2021.

Current Overview of Treatment for Metastatic Bone Disease

The number of patients with bone metastasis increases as medical management and surgery improve the overall survival of patients with cancer. Bone metastasis can cause skeletal complications, including bone pain, pathological fractures, spinal cord or nerve root compression, and hypercalcemia. Before initiation of treatment for bone metastasis, it is important to exclude primary bone malignancy, which would require a completely different therapeutic approach. It is essential to select surgical methods considering the patient’s prognosis, quality of life, postoperative function, and risk of postoperative complications. Therefore, bone metastasis treatment requires a multidisciplinary team approach, including radiologists, oncologists, and orthopedic surgeons. Recently, many novel palliative treatment options have emerged for bone metastases, such as stereotactic body radiation therapy, radiopharmaceuticals, vertebroplasty, minimally invasive spine stabilization with percutaneous pedicle screws, acetabuloplasty, embolization, thermal ablation techniques, electrochemotherapy, and high-intensity focused ultrasound. These techniques are beneficial for patients who may not benefit from surgery or radiotherapy.

High-Intensity Focused Ultrasound: A Review of Mechanisms and Clinical Applications

High Intensity Focused Ultrasound (HIFU) is an emerging and increasingly useful modality in the treatment of cancer and other diseases. Although traditional use of ultrasound at lower frequencies has primarily been for diagnostic imaging purposes, the development of HIFU has allowed this particular modality to expand into therapeutic use. This non-invasive and acoustic method involves the use of a piezoelectric transducer to deliver high-energy pulses in a spatially coordinated manner, while minimizing damage to tissue outside the target area. This review describes the history of the development of diagnostic and therapeutic ultrasound and explores the biomedical applications utilizing HIFU technology including thermally ablative treatment, therapeutic delivery mechanisms, and neuromodulatory phenomena. The application of HIFU across various tumor types in multiple organ systems is explored in depth, with particular attention to successful models of HIFU in the treatment of various medical conditions. Basic mechanisms, preclinical models, previous clinical use, and ongoing clinical trials are comparatively discussed. Recent advances in HIFU across multiple medical fields reveal the growing importance of this biomedical technology for the care of patients and for the development of possible pathways for the future use of HIFU as a commonplace treatment modality.

Percutaneous management of bone metastases: State of the art

Interventional radiology is playing an increasingly important role in the local treatment of bone metastases; this treatment is usually done with palliative intent, although in selected patients it can be done with curative intent. Two main groups of techniques are available. The first group, centered on bone consolidation, includes osteoplasty/vertebroplasty, in which polymethyl methacrylate (PMMA) is injected to reinforce the bone and relieve pain, and percutaneous osteosynthesis, in which fractures with nondisplaced or minimally bone fragments are fixed in place with screws. The second group centers on tumor ablation. tumor ablation refers to the destruction of tumor tissue by the instillation of alcohol or by other means. Thermoablation is the preferred technique in musculoskeletal tumors because it allows for greater control of ablation. Thermoablation can be done with radiofrequency, in which the application of a high frequency (450 Hz-600 Hz) alternating wave to the tumor-bone interface achieves high temperatures, resulting in coagulative necrosis. Another thermoablation technique uses microwaves, applying electromagnetic waves in an approximate range of 900 MHz-2450 MHz through an antenna that is placed directly in the core of the tumor, stimulating the movement of molecules to generate heat and thus resulting in coagulative necrosis. Cryoablation destroys tumor tissue by applying extreme cold. A more recent, noninvasive technique, magnetic resonance-guided focused ultrasound surgery (MRgFUS), focuses an ultrasound beam from a transducer placed on the patient's skin on the target lesion, where the waves' mechanical energy is converted into thermal energy (65 °C-85 °C). Treatment should be planned by a multidisciplinary team. Treatment can be done with curative or palliative intent. Once the patient is selected, a preprocedural workup should be done to determine the most appropriate technique based on a series of factors. During the procedure, protective measures must be taken and the patient must be closely monitored. After the procedure, patients must be followed up.

Imaging of vascular malformations with a high-intensity focused ultrasound probe for treatment planning

OBJECTIVE

We aimed to investigate whether a current commercially available high-intensity focused ultrasound (HIFU) probe can adequately image targeted vascular malformations (VMs) in anticipation of HIFU treatment planning and delivery.

METHODS

We enrolled 10 consecutive patients who were scheduled to undergo treatment of symptomatic peripheral VMs confirmed by routine preoperative contrast-enhanced magnetic resonance imaging and soft tissue duplex ultrasound. The lesions were situated no more than 6 cm from the skin. After induction of general anesthesia and before surgical intervention, we prepared and positioned the Sonablate HIFU probe (SonaCare Medical, LLC, Charlotte, NC) to obtain multiple B-mode images of the targeted VM in the transverse and longitudinal dimensions. We then rated the quality of the images and the feasibility of the imaging process itself using a previously devised questionnaire aimed at evaluating the adequacy of the images for potential HIFU treatment planning and delivery. The patients subsequently underwent surgical intervention and clinical follow-up for their VM per the standard protocol.

RESULTS

The study included 10 participants aged 21 to 67 years (mean ± standard deviation, 36.5 ± 16.5 years). Six patients (60%) identified as female. The VMs imaged consisted of eight venous (80%), one lymphatic (10%), and one combined lymphovenous (10%) malformation. The lesions were in the extremities only (50%), trunk only (20%), trunk and extremities (20%), or neck and extremities (10%). Pain related to the VM was present in all 10 patients (100%). In all 10 patients, the boundary and location of the VM could be visualized via the HIFU probe despite the diminished B-mode imaging resolution. The absence of Doppler functionality in the HIFU probe did not prevent the identification of the VMs in any patient up to a depth of 6 cm. The results from the postimaging survey showed that difficulty in preparing the study device for imaging was 1.1 ± 0.3 and difficulty in use was 1.1 ± 0.1, with a score of 1 equal to easy and 5 to difficult. The stability of the acoustic coupling to the patient was 1.3 ± 0.2, with a score of 1 representing very stable.

CONCLUSIONS

We were able to ultrasonically identify and outline all targeted peripheral VMs using a commercially available HIFU probe in anticipation of treatment planning and delivery. Baseline magnetic resonance imaging and soft tissue duplex ultrasound remain essential tools for guiding probe placement and HIFU imaging.

Percutaneous management of bone metastases: state of the art

Interventional radiology is playing an increasingly important role in the local treatment of bone metastases; this treatment is usually done with palliative intent, although in selected patients it can be done with curative intent. Two main groups of techniques are available. The first group, centered on bone consolidation, includes osteoplasty / vertebroplasty, in which polymethyl methacrylate (PMMA) is injected to reinforce the bone and relieve pain, and percutaneous osteosynthesis, in which fractures with nondisplaced or minimally bone fragments are fixed in place with screws. The second group centers on tumor ablation. Tumor ablation refers to the destruction of tumor tissue by the instillation of alcohol or by other means. Thermoablation is the preferred technique in musculoskeletal tumors because it allows for greater control of ablation. Thermoablation can be done with radiofrequency, in which the application of a high frequency (450 Hz-600Hz) alternating wave to the tumor-bone interface achieves high temperatures, resulting in coagulative necrosis. Another thermoablation technique uses microwaves, applying electromagnetic waves in an approximate range of 900MHz to 2450MHz through an antenna that is placed directly in the core of the tumor, stimulating the movement of molecules to generate heat and thus resulting in coagulative necrosis. Cryoablation destroys tumor tissue by applying extreme cold. A more recent, noninvasive technique, magnetic resonance-guided focused ultrasound surgery (MRgFUS), focuses an ultrasound beam from a transducer placed on the patient's skin on the target lesion, where the waves' mechanical energy is converted into thermal energy (65°C-85°C). Treatment should be planned by a multidisciplinary team. Treatment can be done with curative or palliative intent. Once the patient is selected, a preprocedural workup should be done to determine the most appropriate technique based on a series of factors. During the procedure, protective measures must be taken and the patient must be closely monitored. After the procedure, patients must be followed up.

MRI-Guided Focused Ultrasound of Osseous Metastases: Treatment Parameters Associated With Successful Pain Reduction

BACKGROUND

A phase 3 multicenter trial demonstrated that magnetic resonance imaging (MRI)-guided focused ultrasound (US) is a safe, noninvasive treatment that alleviated pain from bone metastases. However, outcomes varied among institutions (from 0%-100% treatment success).

PURPOSE

The aim of this study was to identify patient selection, technical treatment, and imaging parameters that predict successful pain relief of osseous metastases after MRI-guided focused US.

MATERIALS AND METHODS

This was a secondary analysis of a phase 3 clinical study that included participants who received MRI-guided focused US treatment for painful osseous metastases. Noncontrast CT was obtained before treatment. T2-weighted and T1-weighted postcontrast MRIs at 1.5 T or 3 T were obtained before, at the time of, and at 3 months after treatment. Numerical Rating Scale pain scores and morphine equivalent daily dose data were obtained over a 3-month follow-up period. At the 3-month endpoint, participants were categorized as pain relief responders or nonresponders based on Numerical Rating Scale and morphine equivalent daily dose data. Demographics, technical parameters, and imaging features associated with pain relief were determined using stepwise univariable and multivariable models. Responder rates between the subgroup of participants with all predictive parameters and that with none of the parameters were compared using Fisher exact test.

RESULTS

The analysis included 99 participants (mean age, 59 ± 14 years; 56 women). The 3 variables that predicted successful pain relief were energy density on the bone surface (EDBS) (P = 0.001), the presence of postprocedural periosteal devascularization (black band, BB+) (P = 0.005), and female sex (P = 0.02). The subgroup of participants with BB+ and EDBS greater than 5 J/mm2 had a larger decrease in mean pain score (5.2; 95% confidence interval, 4.6-5.8) compared with those without (BB-, EDBS ≤ 5 J/mm2) (1.1; 95% confidence interval, 0.8-3.0; P < 0.001). Participants with all 3 predictive variables had a pain relief responder rate of 93% compared with 0% in participants having none of the predictive variables (P < 0.001).

CONCLUSIONS

High EDBS during treatment, postprocedural periosteal devascularization around the tumor site (BB+), and female sex increased the likelihood of pain relief after MRI-guided focused US of osseous metastasis.

Combining radiotherapy and focused ultrasound for pain palliation of cancer induced bone pain; a stage I/IIa study according to the IDEAL framework

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Combined treatment of EBRT and MR-HIFU is feasible and well tolerated by patients.

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Clinical outcomes of combined treatment of EBRT and MR-HIFU are promising.

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Superiority of combined treatment over standard EBRT needs to be evaluated in a comparative study.

Background

Cancer induced bone pain (CIBP) strongly interferes with patient’s quality of life. Currently, the standard of care includes external beam radiotherapy (EBRT), resulting in pain relief in approximately 60% of patients. Magnetic Resonance guided High Intensity Focused Ultrasound (MR-HIFU) is a promising treatment modality for CIBP.

Methods

A single arm, R-IDEAL stage I/IIa study was conducted. Patients presenting at the department of radiation oncology with symptomatic bone metastases in the appendicular skeleton, as well as in the sacrum and sternum were eligible for inclusion. All participants underwent EBRT, followed by MR-HIFU within 4 days. Safety and feasibility were assessed, and pain scores were monitored for 4 weeks after completing the combined treatment.

Results

Six patients were enrolled. Median age was 67 years, median lesion diameter was 56,5 mm. In all patients it was logistically possible to plan and perform the MR-HIFU treatment within 4 days after EBRT. All patients tolerated the combined procedure well. Pain response was reported by 5 out of 6 patients at 7 days after completion of the combined treatment, and stabilized on 60% at 4 weeks follow up. No treatment related serious adverse events occurred.

Conclusion

This is the first study to combine EBRT with MR-HIFU. Our results show that combined EBRT and MR-HIFU in first-line treatment of CIBP is safe and feasible, and is well tolerated by patients. Superiority over standard EBRT, in terms of (time to) pain relief and quality of life need to be evaluated in comparative (randomized) study.

Interventional Techniques for Bone and Musculoskeletal Soft Tissue Tumors: Current Practices and Future Directions - Part I. Ablation

Musculoskeletal (MSK) image-guided oncologic intervention is an established field within radiology. Numerous studies have described its clinical benefits, safety, cost effectiveness, patient satisfaction, and improved quality of life, thereby establishing image-guided oncologic intervention as a preferred pathway in treating patients presenting with specific benign MSK tumors. But there is a paradigm shift on the horizon because these techniques may also support established pillars (surgery, systemic treatment, radiotherapy) in the treatment of malignant MSK tumors. Unlike benign tumors, where they are used as primary therapy lines with curative intent, such interventions can be selected for malignant tumors as adjuvant treatment in painful or unstable bone or soft tissue lesions or as more palliative therapy strategies. Using examples from our clinical practices, we elaborate on the benefits of applying a multidisciplinary approach (traditionally involving MSK radiologists, oncologists, orthopaedic surgeons, microbiologists, pathologists, physiotherapists, and pain management experts), ideally within a sarcoma treatment center to deliver a patient-specific therapy plan and illustrate methods to assess the benefits of this model of care.In this article, we review the current repertoire of ablation techniques, demonstrate why such procedures offer value-based alternatives to conventional treatments of specific tumors, and reflect on future directions. Additionally, we review the advantages and limitations of each technique and offer guidance to improve outcomes.

Musculoskeletal interventional oncology: current and future practices

Management of musculoskeletal (MSK) tumours has traditionally been delivered by surgeons and medical oncologists. However, in recent years, image-guided interventional oncology (IO) has significantly impacted the clinical management of MSK tumours. With the rapid evolution of relevant technologies and the expanding range of clinical indications, it is likely that the impact of IO will significantly grow and further evolve in the near future.

In this narrative review, we describe well-established and new interventional technologies that are currently integrating into the IO armamentarium available to radiologists to treat MSK tumours and illustrate new emerging IO indications for treatment.

High-intensity focused ultrasound for prostate cancer

High-intensity focused ultrasound (HIFU) is a noninvasive procedure that has shown promising results in a wide range of malignant and nonmalignant conditions, including localized prostate cancer (PCa). This review aims to describe the application of HIFU in the management of patients with PCa, explaining its basic therapeutic principles, going through the main phases during aHIFU session, and providing an overview of the main available pieces of evidence from literature. HIFU treatment for prostate cancer is increasingly performed with high success and safety. MR guidance (MR-guided HIFU) has the advantage of real-time intraprocedural thermometric feedback that ensures that the whole region of interest has been covered by critical thermal damage (and that all surrounding healthy tissues have been spared). The absence of comparative long-term trials prevents HIFU from being considered as afirst choice for the treatment of patients with PCa.

Ultrasound for the treatment of acute kidney injury and other inflammatory conditions: a promising path toward noninvasive neuroimmune regulation

Acute kidney injury (AKI) is an important clinical disorder with high prevalence, serious consequences, and limited therapeutic options. Modulation of neuroimmune interaction by nonpharmacological methods is emerging as a novel strategy for treating inflammatory diseases, including AKI. Recently, pulsed ultrasound (US) treatment was shown to protect from AKI by stimulating the cholinergic anti-inflammatory pathway. Because of the relatively simple, portable, and noninvasive nature of US procedures, US stimulation may be a valuable therapeutic option for treating inflammatory conditions. This review discusses potential impacts of US bioeffects on the nervous system and how this may generate feedback onto the immune system. We also discuss recent evidence supporting the use of US as a means to treat AKI and other inflammatory diseases.

Improved Treatment Response Following Magnetic Resonance Imaging-Guided Focused Ultrasound for Lumbar Facet Joint Pain

Magnetic resonance imaging–guided focused ultrasound (MRgFUS) is a noninvasive modality that allows for precise tissue ablation with sparing of surrounding structures. Early reports of the use of MRgFUS for the treatment of facet joint osteoarthritis are promising. We present a case of facet joint pain treated successfully by MRgFUS at our institution. Magnetic resonance imaging–guided focused ultrasonography may be a useful modality for patients with facet joint–mediated low back pain, particularly in the setting of limited or refractory response to conventional treatments.

The safety and the efficacy of computed tomography guided percutaneous radiofrequency ablation of osteoid osteoma

Objective

The aim of this study was to investigate the efficacy and safety of Computed Tomography (CT) guided percutaneous Radiofrequency Ablation (RFA) in the treatment of osteoid osteoma (OO).

Methods

A total of 116 patients (82 male and 34 female patients; mean age of 17.7 years; age range 13-months-42 years) who had 118 CT guided RFA treatment between June 2015 and November 2018 (42 moths) with the diagnosis of OO were included in this study. All the patients had pre-procedural CT examinations. The clinical and technical success and the safety of the treatment were evaluated by assessing the clinical pain symptoms, complication rates and recovery of posture and gait.

Results

All the patients had a favorable immediate relief of the known pain caused by osteoid osteoma in 24 h after the procedure. Only in two patients (15-years-old boy with OO in right femoral neck and a 12 years old boy with OO in femur diaphysis) pain relapse was occurred in 3 months and 12 months after RFA and a second RFA was performed. During follow-up they had no pain. The technical success and efficacy-rates of the procedure were recorded as 100% and 98% respectively in this study. No significant complication was observed during treatment or recovery period. Seven minor complications were noted which were successfully treated.

Conclusion

The rapid relief of pain symptoms, low relapse rate and low complication rates demonstrate the efficacy and safety of RFA therapy. RFA is an out-patient procedure that patients can be mobilized immediately after the procedure. RFA can be safely used as a first choice of treatment method in OO therapy.

Level of evidence

Level IV, therapeutic study.