Actinomycosis in the mandible: CT and MR findings

SUMMARY

Mandibular actinomycosis is an uncommon disease. We retrospectively reviewed 6 patients with pathologically proven mandibular actinomycosis who underwent both CT and MR imaging to evaluate the characteristic imaging findings. CT results showed an irregularly marginated lesion with increased bone marrow attenuation, osteolysis, and involvement of the skin in all patients. Periosteal reaction and intralesional gas were seen in 4 patients. MR imaging results revealed low signal on T1-weighted and high signal on T2-weighted images of the mandible, and moderate heterogeneous enhancement was seen in all patients who received intravenous contrast. Cervical lymphadenopathy was not observed. Involvement of the masseter, lateral pterygoid, and medial pterygoid muscles was seen in 4 patients, whereas parotid gland and submandibular gland as well as parapharyngeal space involvement were seen in 3 patients. Familiarity with the imaging findings of mandibular actinomycosis may help to diagnosis this entity.

Relationship between pulmonary resistance and changes in arterial blood gas tension in dogs with nasal obstruction, and partial laryngeal obstruction

Arterial blood gas tension and pulmonary resistance were measured in dogs with surgically created (A) nasal, and (B) laryngeal obstructions. Preobstruction mean values were obtained in all parameters for normal control data. Postobstruction measurements were made, serially, over a period ranging from three days to three months. Changing the dogs from nose to mouth breathers resulted in significant adverse changes in laryngeal resistance, especially marked in the expiratory phase, decreased Po2and retention of Pco2as well as some change in pulmonary resistance. Laryngeal obstruction resulted in significant pre and postobstruction differences in pressure-flow relations in the larynx, k1and k2values and arterial hypoxemia. Results suggest some anatomic and physiologic changes occurring in the lower airway as a result of marked nasal and partial laryngeal obstruction.