Percutaneous ultrasound-guided radiofrequency electrocautery ablation of prostate tissue in dogs.

RATIONALE AND OBJECTIVES: We investigated the feasibility of percutaneous radiofrequency (RF) electrocautery in ablation of prostate tissue in dogs. METHODS: We used six dogs in whom a specially designed needle was placed percutaneously into the prostate. RF electrocautery was applied to the needle and treatment was monitored with ultrasound. Animals were sacrificed and gross examination of the prostate and surrounding tissues was performed. Histopathologic examinations of the prostate were also performed. RESULTS: The treatment zone appeared as an elliptical echogenic focus on ultrasound that increased in size with the application of current. Gross and histopathologic correlation demonstrated that the treatment area included a central area of char with a surrounding area of coagulation. There were no deleterious effects to surrounding tissues. CONCLUSION: Our results demonstrate the feasibility of percutaneous ultrasound-guided RF electrocautery ablation of canine prostate tissue.

Assessment of catheter placement and patency by color Doppler ultrasonography.

Catheter placement and follow-up, including patency check, usually is required in patients with serious conditions, who often cannot be brought to the Radiology Department for the procedure. In a series of 24 consecutive patients, we show the usefulness of color Doppler ultrasonography with its advantages of portable equipment, lack of ionizing radiation, improved catheter visualization, and ability to determine patency.

Brain gliomas: sonographic characterization.

To determine the ability of ultrasound (US) to help characterize brain lesions and determine the best site for biopsy, intraoperative sonographic examination of nine intracerebral gliomas was performed and correlated with the preoperative computed tomographic (CT), gross intraoperative, and histopathologic findings. Real-time US provided a precise and rapid method for intraoperative localization of intracerebral neoplasms in all cases. While the sonographic appearance of gliomas is nonspecific, US added information on tumor characterization to that provided by CT. All gliomas were sonographically echogenic compared with surrounding brain. US permitted good characterization of the cystic components of tumors; portions of the operation therefore involved surgical drainage rather than resection. Autopsy specimens from five anaplastic cerebral gliomas were examined with US and found to be echogenic. The central portions of all five tumors were echogenic and corresponded to areas of tumor necrosis; thus they were poor sites for biopsy. Alternatively, the best site for biopsy was the inner portion of the echogenic margin of the mass, which usually represented areas of active tumor growth. The information obtained from both preoperative CT and intraoperative US is beneficial in characterizing lesions and predicting the best site for biopsy.

Osteogenesis and leukopoiesis within diffusion-chamber implants of isolated bone marrow subpopulations.

The developmental potential of isolated rabbit bone marrow cell populations was examined following autogeneous implantation into diffusion chambers. After 4 weeks, the implants were harvested and processed for light and electron microscopy. More total tissue was formed in abdominally implanted chambers than in corresponding femoral chambers. Two of the separated marrow cell populations produced significantly greater amounts of fibrous connective tissue, cartilage, and bone than did whole-marrow controls. These two populations, which were defined by density gradients of 1.050-1.055 gm/cm3 and 1.064-1.067 gm/cm3, consistently produced a fibrous connective tissue nodule in which were found dispersed foci of hyaline cartilage and woven bone. The denser population was distinguished further by the presence of leukopoietic foci in several of the implant chambers. Cartilage foci were found predominantly towards the center of the tissue nodules, whereas bone was dominant towards the periphery. Blood vessels, osteoclasts, bone remodeling, and mature lamellar bone were found only in those chambers which had been penetrated by the host's vascular system. The results indicate that 1) normal marrow tissue contains two separate osteoprogenitor cell populations; 2) these two progenitor populations represent separate osteogenic and chondrogenic capabilities; 3) one of these populations possesses a leukopoietic as well as an osteogenic potential; and 4) a competent vascular system is essential for the remodelling of bone into mature bone organs.