International Journal of Hyperthermia最新文献

This review was written to be included in the Special Collection 'Therapy Ultrasound: Medicine's Swiss Army Knife?' The purpose of this review is to provide basic presentation and interpretation of the fundamentals of hyperthermia biology, as it pertains to uses of therapeutic ultrasound. The fundamentals are presented but in the setting of a translational interpretation and a view toward the future. Subjects that require future research and development are highlighted. The effects of hyperthermia are time and temperature dependent. Because intra-tumoral temperatures are non-uniform in tumors, one has to account for differential biologic effects in different parts of a tumor that occur simultaneously during and after hyperthermia.

Objective: This study aimed to assess the effectiveness of conventional magnetic resonance imaging (MRI) combined with three-dimensional (3D) ultrasound for the preoperative prediction of nonperfused volume ratio (NPVR) in uterine fibroids after high-intensity focused ultrasound (HIFU) ablation.

Materials and methods: In total, 178 patients who had undergone HIFU ablation therapy for uterine fibroids between July 2021 and August 2023 were enrolled. Baseline clinical, MRI, and 3D ultrasound parameters collected before and after HIFU ablation were analyzed. Multiple linear regression models were constructed for conventional MRI parameters alone and for combined MRI-3D ultrasound parameters to predict NPVR. Paired-sample t-tests and Pearson's correlation were employed to assess relationships between predicted and actual NPVR values. The prediction efficacy of both models was statistically compared.

Results: The combined MRI-3D ultrasound model outperformed the conventional MRI model, with adjusted R² values of 0.597 and 0.553, respectively, both statistically significant (p < 0.05). The combined model revealed that signal intensity on T₂-weighted imaging, degree of enhancement on contrast-enhanced T₁-weighted imaging, maximum distance between the fibroid's dorsal surface and the skin, uterine fibroid vascular network, and fibroid vascularization negatively affected NPVR. The predicted NPVR was significantly correlated with the actual NPVR (p < 0.001).

Conclusions: 3D ultrasound provided essential information for screening fibroids and predicting NPVR before HIFU ablation, serving as a valuable supplement to MRI. The combined MRI-3D ultrasound model shows promise for the preoperative prediction of NPVR in patients with uterine fibroids treated with HIFU and may offer substantial clinical value.

Purpose: The application of histotripsy, an emerging noninvasive, non-ionizing, and non-thermal tumor treatment, is currently limited by the inherent limitations of diagnostic ultrasound as the sole targeting modality. This study evaluates the feasibility and accuracy of cone beam computed tomography (CBCT) guidance for histotripsy treatments in an in vivo porcine model.

Materials and methods: Histotripsy treatments were performed in the liver of seven healthy swine under the guidance of a C-arm CBCT system that was calibrated to the robotic arm of the histotripsy system. For each treatment, pseudotumors (small histotripsy treatments of 15 mm) were created using conventional US guidance to serve as targets for subsequent CBCT guided treatments. A pretreatment CBCT with intravenous contrast was acquired for each swine and the center of the pseudotumor was selected as the target. The robotic arm automatically aligned the transducer to the selected target location. Ultrasound based aberration offset correction was performed when possible, and a 25 mm diameter treatment was performed. A post-treatment CBCT with intravenous contrast was then acquired to evaluate coverage, treatment size, and distance between the pseudotumor target and actual treatment zone center.

Results: Treatments were technically successful and pseudotumors were completely covered in all seven treatments (7/7). The average treatment diameter was 39.3 ± 4.2 mm. The center-to-center distance between pseudotumor and actual treatments was 3.8 ± 1.3 mm.

Conclusion: CBCT provides accurate targeting for histotripsy treatment in vivo. While future work is required to assess safety and efficacy in the presence of obstructions, the proposed approach could supplement ultrasound imaging for targeting.

Background: Chronic neck pain due to cervical facet joint degenerative disease is a leading cause of disability. Denervation of the facet joint capsule with magnetic resonance-guided focused ultrasound (MRgFUS) ablation could provide a noninvasive treatment option. Our study investigates the safety and feasibility of targeting the cervical facet joints with two clinical transducers.

Methods: We simulated MRgFUS treatments in the cervical spine of six individuals using models from MR datasets segmented into eight tissue types. We determined the feasibility of targeting the facet joints in every cervical vertebral level at different trajectories for two 1 MHz clinical transducers. Using acoustic (hybrid angular spectrum method) and thermal (Pennes' bioheat equation) simulations, we determined the feasibility of reaching ablative temperatures at the targets while avoiding thermal damage in off-target locations.

Results: Both simulated transducers produce ablative or near-ablative temperatures at the target while maintaining tissue safety in off-target locations. We quantified the tissue temperature during a 20-second sonication at the target and in important surrounding structures including the spinal nerves, the spinal cord, surrounding CSF, and the major cervical arteries. Temperatures in critical structures demonstrated a less than 3 °C temperature rise, which is well within the level for tissue safety. Ablative thermal doses were achieved at the target (>240 CEM at 43 °C).

Conclusion: This simulation study demonstrates the feasibility and safety of targeting cervical facet joint capsules with clinically available MRgFUS transducers. Integrating these transducers into an MRgFUS device introduces a novel noninvasive modality to treat cervical neck pain.

Objective: The objective of this study was to assess the efficacy of focused ultrasound ablation surgery (FUAS) in treating patients with adenomyosis and coexisting pelvic adhesions.

Materials and methods: A total of 396 patients diagnosed with adenomyosis and who underwent FUAS between January 2014 and December 2022 were enrolled. Pelvic adhesions were evaluated using magnetic resonance imaging (MRI), and the patients were categorized into either adhesive group or non-adhesive group. The aim was to investigate the comparative efficacy between the two groups.

Results: Among the 396 patients, pelvic adhesions were detected in 123 (31.06%) women. Compared to the non-adhesive group, patients in the adhesive group exhibited a higher preoperative dysmenorrhea score (7 vs. 6, p  < 0.001), a lower short-term clinical success rate (74.80% vs. 84.62%, p = 0.025), and a higher long-term cumulative recurrence rate (log-rank p = 0.009). The adhesive group exhibited a high incidence of anal discomfort during the procedure compared to the non-adhesive group (18.70% vs. 7.69%, p = 0.002). Additionally, patients with severe adhesion demonstrated a lower ratio of non-perfused volume ratio (NPVR) (38.81% vs. 46.58%, p = 0.009). Multivariate binary logistic regression analysis revealed that pelvic adhesion independently increased the risk of dysmenorrhea (OR = 4.730, 95%CI: 2.026-11.044, p < 0.001), while severe pelvic adhesion was identified as an independent risk factor for NPVR (OR = 2.226, 95%CI: 1.181-4.196, p = 0.013).

Conclusion: The preoperative assessment of pelvic adhesions plays a crucial role in predicting intraoperative adverse events of FUAS in patients with adenomyosis, as well as determining both short-term and long-term efficacy, thereby providing valuable guidance for the development of comprehensive treatment.

Background: Thyroid nodule rupture (TNR) is a rare and severe complication after thermal ablation (TA), mostly from benign thyroid nodules (BTN).

Objective: To summarize the incidence of TNR after TA and analyze the causes and prevention strategies.

Materials and methods: This retrospective study enrolled 3971 patients who underwent TA for BTN from January 2014 to March 2024. The incidence, causes, and risk factors of TNR were analyzed. Propensity score matching (PSM) controlled for confounding factors. Multivariate regression identified risk factors for TNR. ROC curves determined the optimal cutoff value for the maximum diameter (MD) for TNR.

Results: TNR occurred in 8 cases [0.2% (8/3971)]. The mean time from TA to TNR was 29.6 ± 13.0 days (range, 20-60 days). After PSM, MD was larger in the TNR group than in the non-TNR group [mean 4.1 ± 1.6 cm vs. mean 1.8 ± 1.2 cm; p < 0.001]. The optimal cutoff value of MD for TNR was 2.75 cm. After PSM, the incidence of pressure on the ablation zone was significantly higher in the TNR group than in the non-TNR group [100% (8/8) vs. 0 (0/32); p < 0.001], which has been suspected as a case of TNR. Antibiotic drugs, aspiration, or incision drainage could successfully manage all TNR cases.

Conclusion: TNR could be encountered in case of pressure on the BTN after TA. Protecting the ablation site from pressure might be crucial in preventing TNR, especially within two months. TNR is more likely to occur if the MD of BTN exceeds 2.75 cm under pressure. Observation, antibiotics, and aspiration could successfully manage all TNR cases.

Purpose: In magnetic resonance-guided focused ultrasound (MRgFUS) breast therapies, the focal location must be characterized to guide successful treatment. Focal characterization is difficult because heterogeneous breast tissues introduce phase aberrations that blur and shift the focus and traditional guidance methods do not work in adipose tissues. The purpose of this work is to evaluate numerical simulations of MRgFUS that predict the focal location. Those simulations are compared to clinical magnetic resonance acoustic radiation force imaging (MR-ARFI) data collected during in vivo treatment of breast tumors.

Methods: The focal location was evaluated before MRgFUS treatment with MR-ARFI in five patients. The hybrid angular spectrum method (HAS) was applied to simulate pressure fields which were converted to forces, then convolved with a 3D Green's function (with time-of-arrival weighting) to produce a simulation of the MR-ARFI tissue displacement.

Results: The focal locations found by the simulations and the MR-ARFI measurements were on average separated by 3.7 mm (SD: 0.9 mm). Characterization of the focal zone spatial distributions had a normalized root mean squared difference of 8.1% (SD: 2.5%). The displacement magnitudes of the simulations underestimated the MR-ARFI measurements by 82% (SD: 5.6%).

Conclusions: The agreement between MR-ARFI measurements and simulations demonstrates that HAS can predict the in vivo focal location in heterogeneous tissues, though accurate patient-specific properties are needed to improve predictions of tissue displacement magnitude. Tools developed in this study could be used to streamline MRgFUS treatment planning and optimization, for biomechanical property estimation, and in developing phase aberration correction techniques.

Introduction: Radiofrequency electromagnetic fields applied by capacitive hyperthermia (cRF-HT) might be applicable to improve therapy for glioblastoma patients, but computer simulation data is scarce. We aimed to perform a numerical analysis of cRF-HT treatment in glioblastoma patients.

Methods: The EHY-2030 cRF-HT system (Oncotherm, Budapest, Hungary) was studied using a round 20 cm diameter electrode. Realistic head models and quasi-electrostatic finite element simulations were created (Sim4Life v7.2, ZurichMedTech, Zürich, Switzerland). First, 109 spherical glioblastoma localizations were created within a healthy head model, and three different electrode setups were used to simulate the specific absorption rate (SAR). Then, in 20 real glioblastoma patients, the E-field and SAR in the gross tumor volume (GTV) and its boundary zone were simulated, and transient temperature simulations were performed.

Results: The simulations conducted on 20 patients revealed that the SAR achieved in the GTV and its surrounding boundary zone is highly dependent on the localization of the tumor, with a mean SAR of 24.3 W/kg (ranging from 11.5 to 46.7 W/kg). The mean temperature within the GTV was higher in patients with a resection cavity (mean T₅₀: 40.1 °C) instead of a macroscopic tumor (mean T₅₀: 37.8 °C). The simulation outcome for the 109 artificial tumor localizations indicated enhanced effectiveness when the electrode is setup as close to the GTV as possible.

Conclusion: cRF-HT may induce mild hyperthermia in a subgroup of glioblastoma patients with resection cavities. In macroscopic tumors, temperatures remain below the hyperthermia threshold. Further research is required to assess the clinical benefit of this therapy.

Purpose: This study aimed to investigate the efficacy of triple-freezing cryoablation, the temporal changes of ablation zones, and their association with local tumor progression in patients with lung malignancy.

Methods: This retrospective analysis included patients who underwent triple-freezing cryoablation for lung tumors between 2009 and 2017. The size, shape of the ablation zones, and procedure related complications were evaluated. Fine-Gray regression analysis was utilized to determine the risk factors associated with recurrence while considering mortality as a competing risk.

Results: The study included 41 patients, with 58 ablation sessions for 76 lesions. A tumor size >2 cm was associated with a higher rate of local tumor progression (subdistribution hazard ratio [SHR], 2.623, 95% CI, 1.126-6.107, p = 0.025). An ablation zone-tumor ratio ≥2 emerged as an independent predictor of less local tumor progression (SHR, 0.384, 95% confidence interval [CI]; 0.168-0.877; p = 0.023). There was a 1.7% incidence of adverse events classified as CTCAE (v5.0) grade 3 or higher. Patients without subsequent local tumor progression showed a greater decrease in the ablation zone minor axis at the 6 month-follow up computed tomography (CT) than those with recurrence (25.8% decrease [interquartile range (IQR), 10.3-47.5%] vs 2.4% decrease [IQR, -10.0-7.9%]; p = 0.004).

Conclusion: An ablation zone-tumor ratio of ≥2 was associated with less local tumor progression, and a smaller decrease in the ablation zone at the 6-month follow-up CT indicated a higher rate of subsequent local tumor progression.

Objective: Osteoarthritis of the knee is a common cause of pain, functional disability, and reduced quality of life in the elderly. Despite its prevalence, there are limited currently available noninvasive treatment options. MRI-guided focused ultrasound (MRgFUS) is a noninvasive thermal ablation method which is used in a spectrum of musculoskeletal conditions. It is FDA approved for the treatment of painful bone metastases and osteoid osteoma and has been considered for the treatment of other painful conditions such as osteoarthritis. The purpose of this case report is to describe the use of MRgFUS for the treatment of osteoarthritic knee pain in an active 72-year-old male.

Method: The patient suffered significant limitations due to lateral knee pain with jogging and walking down the stairs. MRgFUS ablation treatment was performed to the lateral knee, targeting the periosteum in the patients' area of pain.

Results: Following treatment, the patient experienced considerable reduction in his activity limiting symptoms with a duration of at least 6 months.

Conclusions: It is important for radiologists to be aware of MRgFUS as an innovative ablation modality. Similar pain reduction was observed in two small series of MRgFUS treatment of knee pain from Japan. MRgFUS appears promising as a safe, noninvasive treatment option for temporary relief of knee pain. This may be particularly valuable for patients who are unwilling or unable to undergo total knee arthroplasty. Future study is needed to assess the efficacy and safety of this treatment in a larger population.