Ferromagnetic Self-Regulating Reheatable Thermal Rod Implants forin SituTissue Ablation
| Autor: | Jaime Landman, Chandru P. Sundaram, Jamil Rehman, Robert D. Tucker, David Bostwick, Ralph V. Clayman |
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| Rok vydání: | 2002 |
| Předmět: |
In situ
Electromagnetic field medicine.medical_specialty Hot Temperature Swine Urology medicine.medical_treatment Physics::Medical Physics Biocompatible Materials Calorimetry Kidney Ferric Compounds Necrosis Electromagnetic Fields Electrical current Neoplasms Materials Testing Thermal medicine Animals Pancreas Tissue ablation business.industry Uterus Hyperthermia Induced Prostheses and Implants Radiofrequency Therapy equipment and supplies Ablation Surgery Magnetic field Liver Ferromagnetism Female Condensed Matter::Strongly Correlated Electrons business human activities Biomedical engineering |
| Zdroj: | Journal of Endourology. 16:523-531 |
| ISSN: | 1557-900X 0892-7790 |
| DOI: | 10.1089/089277902760367502 |
| Popis: | Ferromagnetic compounds, when placed in a radiofrequency magnetic field, develop an electrical current. When placed in tissue, resistance to the transmission of the electrical current leads to heating of the tissues next to the ferromagnetic compound. The Curie temperature is a transition point at which the development of a particular temperature within the material results in loss of its magnetic properties; as such, when this temperature is reached, there is cessation of current, and thus heat production stops. Our goal was to examine the ablative impact of permanently implanted palladium and cobalt self-regulating temperature rods on solid abdominal and pelvic organs. These rods were designed to develop a maximum temperature of 70 degrees C.In 16 pigs, renal, hepatic, uterine, and pancreatic ferromagnetic rods were placed using a template. The rods were delivered in 1-cm parallel rows of two rods each in order to ablate 7 g of tissue. The animals were subsequently treated in an extracorporeal magnetic field of 50 gauss rms at a frequency of 50 kHz. The position of the rods was confirmed by fluoroscopy before the animal was put in the magnetic field. The animals received one or two treatment sessions. Intralesional and extralesional temperatures were measured continuously. Serum chemistry was analyzed before surgery, after each treatment, and at the time of harvest. Two weeks following therapy, the treated tissues were harvested and examined histopathologically.In all tissues with properly aligned rods, the temperature of the tissue surrounding the rods exceeded 50 degrees C. Histologic review showed confluent tissue necrosis in 7 of 9 kidneys (78%), 6 of 9 livers (67%), 1 of 3 pancreases (33%), and 1 of 3 uterine specimens (33%). Necrosis extended for 2 mm beyond the periphery of the rods. All failures were secondary to technical misalignment of the rods, which occurred because of our attempt to treat more than one organ in each animal.Ferromagnetic rods, when properly aligned in a magnetic field, create well-defined areas of necrosis. There are no skip areas of viable tissue within the treated area, and there is a precipitous fall-off of injury just outside the area of treatment. Also, because the rods can be reactivated at any time, recurrent lesions within the same site can be treated. This form of minimally invasive in situ ablative therapy appears promising. Clinical trials in the kidney and in other abdominal and pelvic organs are pending. |
| Databáze: | OpenAIRE |
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