Biomedical subjects
J L Weissman
Publications and source records attributed to J L Weissman.
Hydroxyapatite cement to repair skull base defects: radiologic appearance.
PURPOSE: To describe the radiologic appearance of hydroxyapatite cement (HAC), which, when mixed with liquid, forms a paste that can be contoured to osseous defects and, over time, becomes "osseointegrated" (native bone grows into the pores of the HAC and forms a strong chemical bond with the substance). METHODS: Between March 1992 and June 1993, 24 adults (16 men, eight women) underwent skull base surgery that included reconstruction or closure with HAC. Fourteen patients had HAC placed in the paranasal sinuses or facial bones, and 10 had HAC placed in the mastoid cavity. RESULTS: HAC is homogeneously radiopaque on CT scans and plain radiographs. Large amounts (ablating a frontal sinus or mastoid air cells) are readily seen; small amounts are inconspicuous. On MR images, HAC is a signal void. Infected HAC in one patient was surrounded be enhancing soft tissue on MR images, separated from native bone by an irregular radiolucent cleft on CT scans. CONCLUSIONS: HAC is a valuable addition to the surgical armamentarium for the repair of skull base defects. More experience will determine the time course for normal osseointegration, as well as the typical appearance of infection.
Head and neck space infections in infants and children.
A retrospective study was performed in 117 children with head and neck space infections treated at the Children's Hospital of Pittsburgh from January 1986 through June 1992. Peritonsillar space infections were the most common (49%), followed by retropharyngeal (22%), submandibular (14%), buccal (11%), parapharyngeal (2%), and canine (2%) space infections. The most common pathogens isolated (N = 78) were the aerobes beta-hemolytic streptococcus (18%) and Staphylococcus aureus (18%), the anaerobes Bacteroides melaninogenicus (17%) and Veillonella (14%), and the gram-negative organism Haemophilus parainfluenzae (14%). beta-Lactamase production by aerobic pathogens was detected in 22% of cultures. Computed tomography scans (N = 16) were reviewed in blinded fashion and compared with operative findings. The sensitivity of computed tomography scan in detecting the presence of an abscess vs. cellulitis was high (91%), whereas the specificity was rather low (60%). Treatment of head and neck space infections in children should consist of accurate physical diagnosis aided by imaging studies, empiric antibiotic therapy that covers gram-negative and beta-lactamase--producing organisms as well as gram-positive organisms and anaerobes, and timely surgical intervention, when indicated.
Imaging of the salivary glands.
CT and MRI have greatly facilitated evaluation of pathology of the three pairs of major salivary glands and the hundreds of minor salivary glands. Imaging can frequently offer a specific histological diagnosis for benign and malignant neoplasms of the parotid, submandibular, and sublingual glands. Obstruction, infection, autoimmune processes, and congenital anomalies also are readily diagnosed. CT and MRI studies assess the anatomic extent of minor salivary gland neoplasms. Sialography continues to provide useful information about intrinsic abnormalities of the parotid and submandibular ducts.
Replacement of a malpositioned tracheoesophageal catheter in the radiology department.
This article describes a safe and easy method to position a tracheoesophageal catheter correctly. The procedure is carried out under fluoroscopic guidance and requires neither general nor local anesthesia. The only modification necessary was removal of the tip of the hollow rubber catheter, to create an opening through which the guide wire could be passed.
Enlarged anterior chamber: CT finding of a ruptured globe.
A deep anterior chamber of the globe is a clinical sign of posterior scleral rupture, an ophthalmologic emergency. On axial CT, the depth of the anterior chambers of ruptured globes was greater than the depth of the anterior chambers of normal globes. The discrepancy between the depth of the two anterior chambers in any patient can also suggest posterior scleral rupture.
Advances in treatment of tumors of the cranial base. Advances in imaging.
Imaging has facilitated aggressive skull base surgery by allowing precise preoperative delineation of the extent of lesions. Continued advances providing even better resolution on imaging studies may in turn facilitate the development of new surgical approaches to the skull base.
Condylar canal vein: unfamiliar normal structure as seen at CT and MR imaging.
PURPOSE: The vein of the posterior condylar canal is often seen (and occasionally misinterpreted) at computed tomography (CT) and magnetic resonance (MR) imaging. The CT appearance of the canal and the vein on a skull specimen was compared with the CT and MR appearance in patients. MATERIALS AND METHODS: One condylar canal of the skull specimen was marked with a wire that also indicated the course of the vein beneath the skull base. Axial and coronal CT images of the specimen were compared with CT or MR images of six patients, studied for various clinical indications, in whom the vein was apparent. RESULTS: In all six patients, the location of the vein beneath the skull base corresponded to the location predicted by the wire on the specimen. The normal vein may be prominent or diminutive. CONCLUSION: Recognition of the normal vein of the posterior condylar canal may prevent misinterpretation of the vein as a neoplasm or an abnormal lymph node at CT or MR imaging.
Thrombosed aneurysm of the cervical carotid artery: avoiding a retrospective diagnosis.
Two patients with neck masses were evaluated, one with computed tomography (CT) and the other with magnetic resonance (MR) imaging. Each mass was correctly identified within the carotid sheath. The correct diagnosis-thrombosed cervical carotid aneurysm--was not considered, necessitating unexpected repair of the aneurysm or artery. Although rare, aneurysm of the cervical carotid artery should be considered in the differential diagnosis of a carotid sheath mass between the jugular vein and carotid artery. Peripheral calcification or enhancement on CT scans and a peripheral signal void on MR images are especially suggestive of the diagnosis.
Imaging of ossicular prostheses.
The prostheses available for reconstruction of the ossicular chain have expanded to include a variety of synthetic materials. Hydroxyapatite contains the inorganic constituents found in human living bone and is currently being incorporated into many new prostheses. This study demonstrates the computed tomography and magnetic resonance image characteristics of eight middle ear prostheses, a block of dense hydroxyapatite, and a human incus. Imaging of ossicular prostheses is more informative with computed tomography.