Image-guided transnasal cryoablation of a recurrent nasal adenocarcinoma in a dog.

An eight-year-old female spayed Airedale terrier with rapid recurrence of a nasal adenocarcinoma following image-guided intensity-modulated radiation therapy was treated with transnasal, image-guided cryotherapy. Ice ball size and location were monitored real-time with computed tomography-fluoroscopy to verify that the entire tumour was enveloped in ice. Serial computed tomography scans demonstrated reduction in and subsequent resolution of the primary tumour volume corresponding visually with the ice ball imaged during the ablation procedure. Re-imaging demonstrated focallysis of the cribriform plate following ablation that spontaneously resolved by 13 months. While mild chronic nasal discharge developed following cryoablation, no other clinical signs of local nasal neoplasia were present. Twenty-one months after nasal tumour cryoablation the dog was euthanased as a result of acute haemoabdomen. Image-guided cryotherapy may warrant further investigation for the management of focal residual or recurrent tumours in dogs, especially in regions where critical structures preclude surgical intervention.

Navigating the thoracic inlet.

The thoracic inlet is often seen on the "edge of the film" at computed tomography (CT); consequently, lesions affecting this structure are easily overlooked. A vascular abnormality that may be overlooked is venous thrombosis. The CT appearance of jugular vein thrombosis varies with the age of the lesion: In the acute phase, there is often loss of soft-tissue planes surrounding an enlarged, peripherally enhancing thrombus. In the chronic phase, the jugular vein appears as a tubular, nonenhancing "mass" without loss of surrounding fat planes. Intrathoracic goiters typically manifest as well-defined, markedly enhanced inhomogeneous lesions that are continuous with the cervical thyroid gland. Thyroid adenomas are typically round or oval low-attenuating lesions that enhance after contrast material administration. Thyroid carcinomas may manifest as single or multiple, irregularly shaped low-attenuating areas with or without calcification. Primary tracheal malignancies may appear as smooth or irregular, sessile or pedunculated intraluminal filling defects. Tracheomalacia manifests as destruction of the tracheal walls with soft-tissue narrowing of the tracheal lumen, whereas esophageal abnormalities manifest as thickening of the esophageal wall, dilatation of the esophageal lumen, or both. Schwannomas manifest as well-circumscribed lesions with soft-tissue attenuation that enhance after contrast material administration. Neurofibromas tend to have lower attenuation than schwannomas. Lymphangiomas typically have a cystic appearance with near water attenuation. Familiarity with the normal anatomy of the thoracic inlet as well as the CT features of related abnormalities is critical for correct diagnosis and prompt treatment.

The rationale and a computer evaluation of a gamma irradiation sterilization dose determination method for medical devices using a substerilization incremental dose sterility test protocol.

The experimental procedure described is designed to allow calculation of the radiation sterilization dose for medical devices to any desired standard of sterility assurance. The procedure makes use of the results of a series of sterility tests on device samples exposed to doses of radiation from 0.2 to 1.8 Mrad in 0.2 Mrad increments. From the sterility test data a 10(-2) sterility level dose is determined. A formula is described that allows a value called DS Mrad to be calculated. This is an estimate of the effective radiation resistance of the heterogeneous microbial population remaining in the tail portion of the inactivation curve at the 10(-2) dose and above. DS Mrad is used as a D10 value and is applied, in conjunction with the 10(-2) sterility level dose, to an extrapolation factor to estimate a sufficient radiation sterilization dose. A computer simulation of the substerilization process has been carried out. This has allowed an extensive evaluation of the procedure, and the sterilization dose obtained from calculation to be compared with the actual dose required. Good agreement was obtained with most microbial populations examined, but examples of both overdosing and underdosing were found with microbial populations containing a proportion of organisms displaying pronounced shoulder inactivation kinetics. The method allows the radiation sterilization dose to be derived from the natural resistance of the microbial population to gamma sterilization.

A biologic comparison of polyglactin 910 and polyglycolic acid synthetic absorbable sutures.

Two synthetic absorbable sutures were implanted in rats for a comparative evaluation of breaking strength, tissue reaction and absorption. Polyglactin 910 suture was stronger than polyglycolic acid suture in both sizes tested and at all time periods from zero to 35 days. Both suture types elicited minimal tissure response. Based upon histologic examination, virtually all remnants of the polyglactin 910 were absorbed by 90 days, while considerable quantities of polyglycolic acid persisted at 120 days. The difference in absorption rates was a highly significant feature of the comparative biologic profiles of the two suture materials.