When a child or young adult presents with a mass in the anterior portion of the neck, diagnostic considerations include a thyroglossal duct cyst and ectopic thyroid tissue. These entities are often suspected clinically, and imaging provides an opportunity to evaluate the extent, confirm the diagnosis, and evaluate for complications. Imaging characteristics of a thyroglossal duct cyst as a simple cyst and of ectopic thyroid tissue as a hyperattenuating soft-tissue mass can help identify these lesions at computed tomography (CT); however, intrinsic magnetic resonance, CT, and ultrasonographic imaging characteristics alone cannot be used to confirm the diagnosis. Rather, knowledge of the typical course of the thyroid primordium during embryologic development is essential to understand the variant locations along this path where thyroid tissue can be found. The migration of thyroid primordium begins at the foramen cecum at the base of the tongue and then loops around the hyoid bone anteriorly and inferiorly and descends anteriorly to the thyrohyoid membrane into the orthotopic location in the infrahyoid portion of the neck. Thyroid ectopia is categorized into one of four typical locations with respect to this embryologic course: (a) the base of the tongue, (b) adjacent to the hyoid bone, (c) the midline infrahyoid portion of the neck, and, rarely, (d) the lateral part of the neck. The differential diagnosis includes metastatic thyroid carcinoma, branchial cleft cyst, lymphatic malformation, abscess, saccular cyst, epidermoid cyst, and squamous cell carcinoma. The relationship of a mass to landmarks such as the foramen cecum, hyoid bone, strap muscles, thyrohyoid membrane, and thyroid cartilage can help differentiate a thyroglossal duct cyst and ectopic thyroid tissue from other anterior neck masses when the embryologic thyroid course is considered.

The aim of this study was to evaluate FDG-PET findings in patients with osteoporosis or preclinical osteoporosis and acute vertebral compression fractures in order to determine whether FDG-PET has a value for distinction of pathological from osteoporotic vertebral fractures. 17 patients with a spontaneous compression fracture of the spine were evaluated by bone scanning with Tc-99m HDP, positron emission tomography with fluorine-18 deoxyglucose (FDG-PET) and magnetic resonance imaging (MRI). Osteoporosis had been established in all cases by X-ray and osteodensitometry. PET and bone scan images were scored independently from 0 (no pathological uptake) to 4 (definitive pathological uptake) by two blinded nuclear medicine physicians. The results of the blinded scoring were compared to MRI findings which served as gold standard. In 13 out of 17 patients, MRI demonstrated a vertebral fracture generating from osteoporosis. In 12 of these 13 cases, PET scans were scored with 0 or 1 and categorized as true negative. Standard uptake values (SUV) ranged between 1.1 and 2.4. In one of the 13 patients, PET was interpreted false positive with an uptake score of 3 (SUV = 2.9). Of the 17 patients, MRI revealed a pathological fracture caused by spondylodiscitis in three patients and by plasmacytoma in one patient. In these patients, all PET scans were highly positive with a score of 3 and 4 and SUV values between 3.8 to 9.8. The bone scans of all 17 patients were positive with scores of 3 or 4 but a differentiation between osteoporotic and pathological fractures was not possible. Our preliminary results indicate that acute vertebral fractures that originated from osteoporosis or preclinical osteoporosis tend to have no pathologically increased FDG uptake. Since a high FDG uptake is characteristic for malignant and inflammatory processes, use of FDG-PET may have potential value for differentiation between osteoporotic and pathological vertebral fractures.

Background and Objectives:Existing tools to diagnose spontaneous intracranial hypotension (SIH), namely spinal opening pressure (OP) and brain MRI, have limited sensitivity. We investigated whether evaluation of brain MRI using the Bern Score, combined with calculated craniospinal elastance, would aid in diagnosing SIH and provide insight into its pathophysiology.Methods:A retrospective chart review was performed of patients who underwent brain MRI and pressure-augmented dynamic CT myelography (dCTM) for suspicion of SIH. Two blinded Neuroradiologists assigned Bern Scores for each brain MRI. OP and incremental pressure changes after intrathecal saline infusion were recorded to calculate craniospinal elastance. The relationship between Bern Score, OP, elastance, and whether a leak was found were analyzed.Results:72 consecutive dCTMs were performed in 53 patients. 12 CSF-venous fistulae, two ruptured meningeal diverticula, two dural defects, and one dural bleb were found (17/53=32%). Among patients with imaging proven CSF leak/fistula, OP was normal in all but one patient, and was not significantly different in those with a leak compared to those without (15.1 vs 13.6 cm H2O, p = 0.24, A=0.40). Average Bern Score in individuals with a leak was significantly higher than in those without (5.35 vs 1.85, p < 0.001, A=0.85), even when excluding pachymeningeal enhancement from the score (3.77 vs 1.57, p = 0.001, A=0.78). Average elastance in those with a leak was higher than in those without, but this difference was not statistically significant (2.05 vs 1.20 mL/cm H2O, p = 0.19, A=0.40). Increased elastance was significantly associated with an increased Bern Score (p < 0.01, 95% CI -0.55, 0.12), and was significantly associated with venous distention, pachymeningeal enhancement, prepontine narrowing, and subdural collections, but not a narrowed mamillopontine or suprasellar distance.Discussion:OP is not an effective predictor for diagnosing CSF leak, and if used in isolation would result in misdiagnosis of 94% of patients in our cohort. The Bern Score was associated with a higher diagnostic yield of dCTM. Elastance was significantly associated with certain components of the Bern Score.

The purpose of this study was to assess the effectiveness of a new generation of high-volume, ceiling-mounted highefficiency particulate air (HEPA)-ultraviolet (UV) air filters (HUVAFs) for their ability to remove or inactivate bacterial aerosol. In an environmentally controlled full-scale laboratory chamber (87 m 3 ), and an indoor therapy pool building, the mitigation ability of air filters was assessed by comparing concentrations of total bacteria, culturable bacteria, and airborne endotoxin with and without the air filters operating under otherwise similar conditions. Controlled chamber tests with pure cultures of aerosolized Mycobacterium parafortuitum cells showed that the HUVAF unit tested provided an equivalent air-exchange rate of 11 hr Ϫ1 . Using this equivalent air-exchange rate as a design basis, three HUVAFs were installed in an indoor therapy pool building for bioaerosol mitigation, and their effectiveness was studied over a 2-year period. The HUVAFs reduced concentrations of culturable bacteria by 69 and 80% during monitoring periods executed in respective years. The HUVAFs reduced concentrations of total bacteria by 12 and 76% during the same monitoring period, respectively. Airborne endotoxin concentrations were not affected by the HUVAF operation.

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