Arrays of multielement ultrasound applicators for interstitial hyperthermia.

Arrays of multielement ultrasound applicators for interstitial hyperthermia have been developed and tested both in vitro and in vivo. The system includes multielement applicators, a 64 channel RF driving unit, a power measuring unit, a 112 channel multisensor temperature measuring unit, and a water cooling unit. Ninety-five arrays of single-element and nine arrays of three-element ultrasound applicators were designed, built, and characterized by measuring transducer efficiency and ultrasound field distribution. Improved uniformity in the azimuthal direction was achieved by using multiple driving frequencies. In addition, production of ultrasound in a desired sector of the transducer was possible by selecting a suitable frequency. Both in vitro and in vivo experiments showed that 92% of monitored temperature points within the target volume of 30 mm x 30 mm x 35 mm achieved a therapeutic temperature rise (above 5 degrees C) when an array of five three-element applicators were used. These results indicated that the arrays of multielement ultrasound applicators have distinct advantages over present interstitial hyperthermia modalities in terms of the capability to control the temperature distribution with a large catheter spacing. As a conclusion, the feasibility of a practical arrays of multielement ultrasound applicators for interstitial hyperthermia was demonstrated.

Computed tomography and magnetic resonance imaging of cavernous sinus enlargement in a dog with unilateral exophthalmos.

Computed tomography (CT), magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) were performed on a dog with a two year history of unilateral exophthalmos occurring two years following head trauma. On CT images, an expansile enhancing mass was present along the right intracranial cavernous sinus and extended through the orbital fissure into the retrobulbar space. With MRI, the structure appeared as a signal void due to the presence of rapidly flowing blood. Gadolinium enhancement of the adjacent brain was not present. A vascular origin of the lesion was confirmed with MRA. Based on the CT and MRI findings, the enlarged cavernous sinus and associated ophthalmic plexus were believed to represent an arterialized aneurysm, most likely the result of traumatic arteriovenous fistulization. Treatment consisted of surgical enucleation. At the time of this report, 29 months later, the dog remains free of clinical signs.

Biological response of nonhuman primates to long-term repeated lung exposure to Ad2/CFTR-2.

We have assessed the safety and efficacy of repeated adenovirus vector administration by exposing the left caudal lung lobe of rhesus monkeys to as many as 17 exposures of Ad2/CFTR-2. After nine doses of either 3 x 10(9) or 3 x 10(10) infectious units, the monkeys were free of adverse effects as assessed by thoracic radiographs, CBCs, clinical chemistries, arterial blood gases, and physical and clinical signs. In some animals elevated protein levels and increased numbers of cells were recovered in bronchoalveolar lavage (BAL), and in all animals there were increased proportions of lymphocytes in the BAL. After 11 doses, two animals were killed. In the lower dose animal (3 x 10(9) IU), there was little histopathology evident. In the higher dose animal (3 x 10(10) IU), histopathology was largely confined to a focal fibrotic lesion that may have been associated with treatment. At the tenth exposure, the dose was increased to 6 x 10(10) or 3 x 10(11) IU. There was evidence of lung injury by thoracic radiographs after two additional exposures and an increase in protein and number of cells in the BAL. The animals were still free of evidence of adverse effects by other parameters, but histopathologic changes were noted upon death. After 15 or 17 doses, three animals were instilled with Ad2/beta gal-2 and killed 3 days later. These animals had greatly reduced levels of transgene expression when compared with controls.

In vivo characterization of cytotoxic intracellular edema by multicomponent analysis of transverse magnetization decay curves.

RATIONALE AND OBJECTIVES: We investigated the multicompartmental nature of T2 decay in a specific white matter edema model. METHODS: Triethyltin (TET) intoxication was produced in six male New Zealand White rabbits. Images were obtained over the 23-day study duration using a 64-echo Carr-Purcell-Meiboom-Gill (CPMG) sequence (repetition time = 3000 msec, echo time = 20 msec). T2 decay curves were extracted from 0.7 x 0.7 x 3.0 mm3 voxels in the corpus callosum and contiguous white matter tracts, cortex, thalamic nuclei, hypothalamic nuclei, and the masseter muscles. The curves were fit with biexponential functions. RESULTS: Increased signal intensity in the corpus callosum was evident 2-3 days after the first TET injection. At this time, a substantial slowly relaxing component appeared in the decay curves of the corpus callosum and, to a lesser extent, in the thalamus and hypothalamus. Changes in the rabbits' body weight, general physical condition, and neurologic state paralleled the growth and regression of the second, slowly relaxing component. CONCLUSION: The appearance and regression of a slowly decaying second component in the T2 decay curve is consistent with the formation and shrink-age of intracellular vesicles in the intramyelin sheaths of central white matter.

Characterization of cerebral infarction by multicomponent analysis of transverse magnetization decay curves.

RATIONALE AND OBJECTIVES: Individual components of the transverse magnetization decay curve (TDC) were assessed for their ability to characterize ischemia in photochemically induced cerebral infarcts. METHODS: Fifty rats were randomly divided into equal-sized experimental and control groups, which were subdivided into groups studied at five different time points, ranging from 6 hours to 22 days. All the rats received transcalvarial irradiation with 560-nm light. Five rats in each time group also received a sensitizing dye before irradiation. In these latter animals, lesions of uniform size and location developed. Lesions were compared with tissue of similar volume and location from the contralateral cortex of the experimental animals and with tissue from both hemispheres of the control animals. TDCs of all the samples were measured and fit with mono- and bi-exponential functions. RESULTS: Unlike the control tissue, infarcted tissue displayed definitive two-component TDC behavior. The time course of the bi-exponential parameters yielded information unavailable from mono-exponential analyses. CONCLUSIONS: Bi-exponential analysis of TDCs may have diagnostic use as a more sensitive indicator of cerebral infarction than mono-exponential analyses.

Nonsurgically managed caudal acetabular fractures in dogs: 15 cases (1979-1984).

Medical records of 15 dogs with nonsurgically managed caudal one-third acetabular fractures were reviewed. In-hospital evaluation of these dogs was possible 6 to 67 months after injury. Thirteen dogs had radiographic evidence of moderate to severe degenerative joint disease in affected hips. Twelve dogs had decreased hip joint range of motion and/or signs of pain on the affected side, and 7 dogs were lame. Because of limited pain-free motion and degenerative joint disease in most affected hips, results of nonsurgical management of caudal one-third acetabular fractures in dogs were considered unsatisfactory.

Intestinal pseudoobstruction in a dog.

A 6-year-old male Yorkshire Terrier had clinical signs including intermittent vomiting and diarrhea associated with abdominal distention. Contrast radiography disclosed dilatation and decreased motility of the small intestine, with dilution of barium. Hemograms, blood chemical profiles, and results of fecal examinations and urinalyses were normal. Obstruction was not found at exploratory laparotomy, but a dilated segment of mid-jejunum was biopsied. There was hypoplasia of the tunica muscularis of the jejunum, without fibrosis, inflammation, or myenteric plexus involvement. The diagnosis was idiopathic intestinal pseudoobstruction. Post-operative care consisted solely of feeding bland foods. Three months after surgery there was progressive deterioration and emaciation due to chronic intestinal malabsorption.