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Biomedical subjects

G S Weinstein

Publications and source records attributed to G S Weinstein.

At least 55 records · Page 3Linked to original sources
PubMed1996

The role of computed tomography and magnetic resonance imaging in planning for conservation laryngeal surgery.

Refined laryngeal conservation surgeries have been devised to maintain the voice while eradicating even extensive glottic and hypopharyngeal tumors. The role of diagnostic imaging is to adequately define the extent of disease in conjunction with endoscopy. Critical areas to be evaluated are the tongue base, vallecula, pre-epiglottic space, arytenoid cartilages, postcricoid region, hypopharynx, thyroid cartilage, and subglottis.

Humans↗
PubMed1996

Granular cell myoblastoma of the cervical esophagus: MR findings.

Granular cell myoblastomas are uncommon, typically benign tumors. Involvement of the esophagus is rare, and frequently they are asymptomatic. We report a granular cell myoblastoma involving the cervical esophagus in a patient who had paralysis of the true vocal cord and progressive dysphagia. At MR imaging, the circumscribed mass was hypointense on T1-weighted images and mildly hyperintense on T2-weighted images, with homogeneous contrast enhancement.

Adult↗
PubMed1995

Evaluation of osseointegration of endosseous implants in radiated, vascularized fibula flaps to the mandible: a pilot study.

PURPOSE: This study clinically evaluated the osseointegration of implants placed into vascularized fibula flaps used in mandibular reconstruction of cancer patients following radiation treatment and subsequent hyperbaric oxygen (HBO) therapy. MATERIALS AND METHODS: Five head and neck cancer patients had mandibular resection and immediate reconstruction with a vascularized fibula flap. Subsequent therapy included greater than 50 Gy of radiation to the fibula flap over a 6 to 8-week period. Two to 6 weeks following radiation therapy each patient received 20 90-minute daily sessions of HBO at 2.4 atmosphere pressure. Stage 1 implant surgery was performed placing two to six implants (15 mm in length and 3.75 to 4.0 mm in width) into each fibula flap. This was followed by 10 postoperative HBO sessions using the previously mentioned protocol. The stage 2 procedure was performed 6 months after the stage 1 procedure. Osseointegration was assessed clinically using manual force and an electronic device at the time the implants were uncovered and monthly over a 6-month period. RESULTS: All 20 implants placed in the fibula flaps were osseointegrated clinically at the time the implants were uncovered and during the 6-month follow-up. CONCLUSION: In this pilot study, mandibular reconstruction with a vascularized fibula flap and endosseous osseointegrated implants, following radiation of the fibula, was successful. It was concluded that factors such as the graft having its own blood supply and the use of HBO contributed to the successful osseointegration of these implants.

Bone Transplantation↗
PubMed1995

Computed tomography-guided aspirations of parapharyngeal and skull base masses.

Computed tomography (CT)-guided aspirations of 22 parapharyngeal and skull base masses were performed via an oblique approach between the ascending ramus of the mandible and the pterygoid plates. A 22 g spinal needle was inserted through an 18 g introducer needle for sampling. Diagnostic specimens were obtained in 20 cases including six salivary gland neoplasms, five squamous cell carcinomas, five infections, and two cysts. On average, 2.8 passes into the mass were required although fewer were necessary to diagnose neoplasms (2.0 passes). No complications occurred. In this series, 100% of neoplasms were detected cytologically and there were no false-negative results. In two cases (9.1%) there was a discrepancy between the initial aspiration report and the final histologic diagnosis. CT-guided aspirations of skull base masses are a viable alternative to what would otherwise be a difficult surgical approach for biopsy. Diagnostic samples are obtained in 90.9% (20 of 22) with an accuracy of 90% (18 of 20).

Journal Article↗
PubMed1995

Carotid artery invasion by head and neck masses: prediction with MR imaging.

PURPOSE: To determine the value of magnetic resonance (MR) imaging in predicting resectability of head and neck neoplasms around the carotid arteries. MATERIALS AND METHODS: Forty-nine patients (28 male patients and 21 female patients aged 17-79 years; mean, 57.3 years) with head and neck masses and clinical evidence of carotid wall invasion underwent MR imaging. T1-weighted, T2-weighted, and gadolinium-enhanced T1-weighted images were analyzed to determine circumferential involvement of 53 arteries by tumor. RESULTS: More than 270 degrees of circumferential involvement was considered suggestive of unresectability of the malignant neoplasm; 270 degrees or less was considered lack of invasion. The sensitivity of MR imaging for determination of unresectable disease was 100% (12 of 12 cases), specificity was 88% (36 of 41), and accuracy was 91% (48 of 53). Accuracy was 100% for squamous cell carcinoma (n = 29). CONCLUSION: Tumor that encompasses more than 270 degrees of the carotid artery probably cannot be removed from the artery. Tumor that involves 270 degrees or less of the artery can be removed.

Adolescent↗
PubMed1995

Reconsidering a paradigm: the spread of supraglottic carcinoma to the glottis.

This study was performed to evaluate the spread of supraglottic carcinoma to the glottic level. Whole organ sections of total laryngectomy specimens from 37 patients with previously untreated supraglottic carcinomas were reviewed retrospectively. Of the 37 specimens, 20 (54%) were noted to have extension of cancer to the glottic level. A significant relationship was noted between glottic extension and abnormal cord motion (P = .0002). A statistically significant trend was noted for the relationship between inferior extension along the supraglottic mucosa and glottic level extension (P < .0001). Contrary to the prevailing model of the spread of supraglottic carcinoma, in which there is a distinct barrier to spread at the ventricle, this analysis of selected supraglottic carcinomas revealed a continuum of spread from the supraglottic to the glottis.

Chi-Square Distribution↗
PubMed1994

Head and neck neoplasms: magnetization transfer analysis.

PURPOSE: Magnetization transfer (MT) imaging enables analysis of the contribution of restricted motion protons in the macromolecular pool to magnetic resonance (MR) signal intensity. The authors undertook this study to determine whether MT ratios (MTRs) could be used to predict pathologic characteristics of head and neck neoplasms. MATERIALS AND METHODS: Fifty-four patients with pathologically proved neoplasms (squamous cell carcinomas, n = 33; non-squamous cell carcinomas, n = 11; benign masses, n = 10) underwent MT imaging. MTRs were correlated with pathologic findings. RESULTS: No statistically significant correlations were noted between MTRs and degree of differentiation, keratinization, cells per high-power field, and rate of mitosis. Statistically significant differences were found between MTRs of malignancies and muscle (P < .01), cerebrospinal fluid (P < .001), fat (P < .001), and benign neoplasms (P < .001). MTRs of muscle were higher than those of benign, squamous cell, and non-squamous cell neoplasms. CONCLUSION: MT imaging shows promise in differentiation of benign from malignant head and neck neoplasms. No statistically significant differences in MTRs were noted among malignancies.

Carcinoma, Squamous Cell↗
PubMed1994

MR of mandibular invasion in patients with oral and oropharyngeal malignant neoplasms.

PURPOSE: To investigate whether MR imaging is an accurate means of assessing mandibular invasion in patients with carcinoma. METHODS: We retrospectively studied the MR scans of 22 patients with pathologic or surgical confirmation of mandibular invasion from oral and oropharyngeal cancers. The MR images were blindly analyzed using primary criteria of: (a) cortical breakdown, (b) replacement of bone marrow fat, or (c) gadopentetate dimeglumine enhancement of a mass at the bone marrow defect. Secondary criteria of: (a) contiguous soft-tissue mass, and (b) mass on both sides of the mandibular cortex were also examined. Mandibular invasion was graded as periosteal/cortical, medullary, or no invasion. RESULTS: Primary positive findings of cortical breakdown and abnormal bone marrow signal were highly sensitive (100%) for periosteal/cortical invasion and medullary involvement, respectively. However, a high rate of false-positive studies hampered the MR accuracy, which fell into the 73% to 77% range. A negative MR study was highly predictive, but a positive study was less valuable. Gadolinium enhancement added little to the MR study's accuracy. False-positive studies mainly occurred in the setting of prior irradiation, osteoradionecrosis, and odontogenic infections. CONCLUSIONS: MR imaging is a sensitive method for detecting mandibular invasion but has a low positive predictive value. A negative study virtually excludes cortical/periosteal or bone marrow invasion.

Adipose Tissue↗
PubMed1994

Magnetization transfer imaging of the head and neck: normative data.

PURPOSE: To determine magnetization transfer ratios for normal head and neck structures so that evaluation of disease will be possible. METHODS: Two-dimensional magnetization transfer imaging was performed in 12 healthy volunteers and 20 patients. We used a repetition time of 500, echo time of 12, 20 degrees flip angle, and a magnetization transfer pulse offset from the resonance frequency of water by 2000 Hz (pulse duration 19 milliseconds, waveform area approximately 10 times greater than that of a 90 degree pulse). Magnetization transfer ratios (1 - [intensity after suppression/intensity before suppression]) were calculated for normal structures. RESULTS: The magnetization transfer ratio of facial muscles (0.54) was equivalent to that of tongue muscles (0.54). These values exceeded those of parotid (0.39) and submandibular glands (0.41). Fat (0.07) and cerebrospinal fluid (0.05) had negligible transfer. CONCLUSION: Magnetization transfer imaging is a simple and effective means of studying the contribution of macromolecular protons to the MR image. Normal neck structures show a wide range of magnetization transfer rates, maximal for muscle and minimal for cerebrospinal fluid and fat.

Adult↗
PubMed1993

Calvarial bone graft harvest. Techniques, considerations, and morbidity.

The importance of calvarial bone grafting in craniomaxillofacial trauma and facial reconstructive surgery is now widely recognized. Numerous harvesting techniques have evolved to optimize the desired thickness, size, shape, and curvature for a particular reconstructive need. At the same time, donor site selection and morbidity must be considered. This report includes a discussion of several currently utilized calvarial bone graft harvesting techniques, with emphasis on minimizing complications and morbidity. Choice of optimal harvesting technique and donor site for specific reconstructive situations will likewise be discussed. Finally, the specific morbidity in our multi-institutional calvarial bone graft harvest series of 121 patients and over 350 grafts will be reviewed.

Bone Transplantation↗
PubMed1991

Isocratic high-performance liquid chromatography-photodiode-array detection method for determination of lysine- and arginine-vasopressins and oxytocin in biological samples.

A simple, isocratic, sensitive (1 ng), and specific high-performance liquid chromatographic (HPLC) method based on photodiode-array detection (PAD) is described for simultaneous quantitation of the bioactive peptides, lysine vasopressin (LVP), arginine vasopressin (AVP) and oxytocin (OXY). Acidified pig plasma and left ventricular (LV) tissue samples were first extracted with Sep-Pak C18 columns, and the bioactive peptides were eluted with methanol, then dried at 37 degrees C and reconstituted with HPLC mobile phase. The bioactive peptides were separated by HPLC on a Dynamax 3009-A C8 column with a mobile phase of 0.1% trichloroacetic acid-50 mM heptanesulfonic acid-30mM triethylamine-20% acetonitrile in water, pH 2.5 and identified with a Waters 990-PAD system (spectrum index plots in the range 200-400 nm). Standards of LVP, AVP and OXY and their mixtures showed a linear increase in the range 5 to 100 ng and were eluted at 6.1, 6.9 and 4.6 min, respectively. Spectrum analysis showed a distinct absorption peak at 280 nm, corresponding to peptide bonds. The reproducibility of the method coefficient of variation for standards is 6.9, 5.8 and 4.7% for LVP, AVP and OXY, respectively. In plasma and tissue it is much higher: 12.9% (LV tissue) and 18.6% (plasma) for LVP. Pig plasma contains negligible amounts of AVP and OXY; LVP is much higher (0.28 +/- 0.19 ng/ml). In pig tissue, LVP predominates (6.95 ng/g wet weight) compared to AVP (1.45) and OXY (1.50). Spectral analysis is necessary to identify the bioactive peptide peaks among interfering substances and to increase the sensitivity four-fold. The method described here is useful for the simultaneous determination of LVP, AVP and OXY in the nanogram range and can be extended to picogram levels by employing PAD spectral analysis techniques.

Animals↗
PubMed1991

Protection of ischemic heart from reperfusion injury by myo-inositol hexaphosphate, a natural antioxidant.

Myo-inositol hexaphosphate (phytic acid), a highly charged antioxidant, has been found to chelate metal ions such as iron and calcium and to scavenge hydroxyl radicals, .OH. This study examined the efficacy of this antioxidant and redox agent in attenuating myocardial reperfusion injury. Sprague-Dawley rats were injected intravenously with three different doses of phytic acid (group 1, saline solution only, control; group 2, 1.5 mg/100 g; group 3, 7.5 mg/100 g; group 4, 15 mg/100 g) 30 minutes before excision of hearts. Isolated hearts were prepared by the Langendorff technique. Global ischemia was induced for 30 minutes, followed by 30 minutes of reperfusion. As expected, in group 1, reperfusion was associated with enhanced creatine kinase release, reduced coronary flow, poor recovery of ventricular function as evidenced by reduced left ventricular developed pressure and the first derivative of left ventricular pressure, and increased lipid peroxidation. Groups 3 and 4, but not group 2, demonstrated myocardial protection as evidenced by reduced creatine kinase release, improved left ventricular function and coronary flow, and decreased lipid peroxidation compared with the control group. These results suggest that potential use of this antioxidant in salvaging the heart from ischemic and reperfusion injury.

Animals↗