Radio-frequency (RF) hepatic ablation, offers an alternative method for the treatment of malignancies. We employed finite-element (FEM) analysis to determine tissue temperature distribution during RF ablation. constructed three-dimensional (3-D) thermal-electrical FEM models consisting a four-tine probe, tissue, and large blood vessel (10-mm diameter) located at different locations. simulated our analyses under temperature-controlled (90/spl deg/C) 8-min also present preliminary result from...

Knowledge of electrical tissue conductivity is necessary to determine deposition electromagnetic energy and can further be used diagnostically differentiate between normal neoplastic tissue. We measured 17 rats with a total 24 tumours the K12/TRb rat colon cancer cell line. In each animal we in vivo hepatic tumour at seven frequencies from 10 Hz 1 MHz, different stages 6 12 weeks after induction. Conductivity liver was 1.26 ± 0.15 mS cm−1 Hz, 4.61 0.42 MHz. 2.69 0.91 5.23 0.82 significantly...

To develop and validate a computational model that simulates (1) tissue heating with high intensity focused ultrasound (HIFU), (2) resulting hyperthermia-mediated drug delivery from temperature-sensitive liposomes (TSL).HIFU in was simulated using heat transfer based on the bioheat equation, including heat-induced cessation of perfusion. A spatio-temporal multi-compartment pharmacokinetic intravascular release doxorubicin TSL, its transport into interstitium, cell uptake. Two schedules were...

Purpose: Mild hyperthermia (40–45°C) is a proven adjuvant for radiotherapy and chemotherapy. Magnetic resonance guided high intensity focused ultrasound (MR-HIFU) can non-invasively heat solid tumours under image guidance. Low temperature-sensitive liposomes (LTSLs) release their drug cargo in response to (>40°C) may improve delivery when combined with mild hyperthermia. The objective of this study was develop implement clinically relevant MR-HIFU heating algorithm combination...

Radiofrequency (RF) ablation is a minimally invasive method for treatment of primary and metastatic liver tumors. One the currently commercially available devices employs an internally cooled 17-gauge needle probe. Within probe, cool water circulated during ablation, which cools tissue close to probe resulting in larger lesions. We evaluated effect different cooling temperatures on lesion size. created finite-element model, simulated 12 min impedance-controlled determined temperature...

Purpose: Finite element method (FEM) models are commonly used to simulate radio frequency (RF) tumor ablation. Prior FEM of RF ablation have either ignored the temperature dependent effect microvascular perfusion, or implemented using simplified algorithms reduce computational complexity. In this modeling study, authors compared different perfusion on zone dimensions with two commercial electrodes in hepatic tissue. They also examine tissue type and inter-patient variation dimensions....

We measured the ex vivo electrical conductivity of eight human metastatic liver tumours and six normal tissue samples from patients using four electrode method over frequency range 10 Hz to 1 MHz. In addition, in a single patient we before after thermal ablation tumour tissue. The average was significantly higher than entire (from 4.11 versus 0.75 mS cm−1 at Hz, 5.33 2.88 MHz). found no significant correlation between size conductivity. While had considerably tissue, two similar throughout...

Purpose: Studies have demonstrated a synergistic effect between hyperthermia and chemotherapy, clinical trials in image-guided drug delivery combine high-temperature thermal therapy (ablation) with chemotherapy agents released the heating zone via low temperature sensitive liposomes (LTSL). The complex interplay heat-based cancer treatments such as ablation may require computational models to identify relationship heat exposure pharmacokinetics order optimise delivery.Materials methods:...

Various liposomal drug carriers have been developed to overcome short plasma half-life and toxicity related side effects of chemotherapeutic agents. We a mathematical model compare different liposome formulations doxorubicin (DOX): conventional chemotherapy (Free-DOX), Stealth liposomes (Stealth-DOX), temperature sensitive (TSL) with intra-vascular triggered release (TSL-i), TSL extra-vascular (TSL-e). All were administered as bolus at dose 9 mg/kg. For TSL, we assumed locally due...

There is a lack of studies that examine dynamics heat-induced shrinkage organ tissues.Clinical procedures such as radiofrequency ablation, microwave ablation or high-intensity focused ultrasound, use heat to treat diseases cancer and cardiac arrhythmia.When applied tissues, occurs due protein denaturation, dehydration, contraction collagen at temperatures greater 50ºC.This particularly relevant for image-guided tumor where pre-and post-treatment images are compared any changes in dimensions...

Introduction Radiofrequency ablation (RFA) is used for the local treatment of liver cancer. RFA effective small (<3cm) tumors, but tumors > 3 cm, there a tendency to leave viable tumor cells in margins or clefts overlapping zones. This increases possibility incomplete recurrence. Lyso-Thermosensitive Liposomal Doxorubicin (LTLD), thermally sensitive liposomal doxorubicin formulation intravenous administration, that rapidly releases its drug content when exposed temperatures >40°C. When with...

Radio-frequency (RF) ablation has become an important means of treatment nonresectable primary and metastatic liver tumors. Major limitations are small lesion size, which make multiple applications necessary, incomplete killing tumor cells, resulting in high recurrence rates. We examined a new bipolar RF method incorporating two probes with hooked electrodes (RITA model 30). performed monopolar vivo experiments on three pigs. The were 2.5 cm apart rotated 45 degrees relative to each other....

Radio-frequency (RF) ablation is an important means of treatment nonresectable primary and metastatic liver tumors. RF ablation, unlike cryoablation (a method tumor destruction that utilizes cold rather than heat), must be performed with a single probe placed serially. The any but the smallest requires use multiple overlapping zones. We evaluated performance configuration incorporating two hooked probes (RITA model 30). were lined up along same axis in parallel 20 mm apart. Three different...

Radiofrequency (RF) ablation is a treatment modality that kills unwanted tissue by heat. Starting with cardiac arrhythmia in the 1980s, RF has found clinical application number of diseases, and now choice for certain types cancers. During ablation, an electrode inserted into or steered intravascularly to target region under medical imaging guidance. Then, volume surrounding destroyed heating via electric current. This paper reviews biophysics during ablation. Effects electrical conductivity...

Most drugs cannot penetrate the blood-brain barrier (BBB), greatly limiting use of anti-cancer agents for brain cancer therapy. Temperature sensitive liposomes (TSL) are nanoparticles that rapidly release contained drug in response to hyperthermia (>40 °C). Since also transiently opens BBB, we hypothesized localized can achieve delivery across BBB when combined with TSL. TSL-encapsulated doxorubicin (TSL-Dox) was infused intravenously over 30 min at a dose 0.94 mg/kg anesthetized beagles...

Introduction: For computational models of microwave ablation (MWA), knowledge the antenna design is necessary, but proprietary clinical applicators often unknown. We characterised specific absorption rate (SAR) during MWA experimentally and compared to a multi-physics simulation.Methods: An infrared (IR) camera was used measure SAR within split ex vivo liver model. Perseon Medical's short-tip (ST) or long-tip (LT) were placed on top tissue sample (n = 6), power (15 W) applied for 6 min,...

Effective drug delivery in brain tumors remains a major challenge oncology. Although local hyperthermia and stimuli-responsive systems, such as thermosensitive liposomes, represent promising strategies to locally enhance solid improve outcomes, their application intracranial malignancies unexplored. We hypothesized that the combined abilities of closed-loop trans-skull Magnetic Resonance Imaging guided Focused Ultrasound (MRgFUS) with those drugs can alleviate challenges survival gliomas....