Experimental assessment of clinical MRI-induced global SAR distributions in head phantoms.

OBJECTIVE: Accurate estimation of SAR is critical to safeguarding vulnerable patients who require an MRI procedure. The increased static field strength and RF duty cycle capabilities in modern MRI scanners mean that systems can easily exceed safe SAR levels for patients. Advisory protocols routinely used to establish quality assurance protocols are not required to advise on the testing of MRI SAR levels and is not routinely measured in annual medical physics quality assurance checks. This study aims to develop a head phantom and protocol that can independently verify global SAR for MRI clinical scanners. METHODS: A four-channel birdcage head coil was used for RF transmission and signal reception. Proton resonance shift thermometry was used to estimate SAR. The SAR estimates were verified by comparing results against two other independent measures, then applied to a further four scanners at field strengths of 1.5 T and 3 T. RESULTS: Scanner output SAR values ranged from 0.42 to 1.52 W/kg. Percentage SAR differences between independently estimated values and those calculated by the scanners differed by 0-2.3%. CONCLUSION: We have developed a quality assurance protocol to independently verify the SAR output of MRI scanners.

Location of the narrowest area of the pharynx regarding body mass index and obstructive sleep apnoea severity.

BACKGROUND: Among authors studying morphological determinants of the obstructive sleep apnoea (OSA) controversies exist on the location of the narrowest area within the pharynx, critical for development of obstruction. Those disagreements primarily revolve around differences between obese and nonobese OSA patients. Determination whether the location and size of the narrowest area within the pharynx differentiates the obese and nonobese OSA patients. MATERIALS AND METHODS: A population of 55 subjects was investigated after being diagnosed with OSA in the Polysomnography Laboratory of the Department and Clinic of Otolaryngology in the Medical University of Warsaw, Poland. Additionally a head computed tomography (CT) was performed in all the subjects. The CT images were used to do several crucial measurements which described the geometry of the facial skeleton as well as soft tissues of the head. The obtained results were correlated with apnoea-hypopnoea index (AHI) and body mass index (BMI) values. The data were statistically analysed. RESULTS: The distance between the hard palate and posterior pharyngeal wall parallel to the horizontal plane as well as the shortest distance between the soft palate and posterior pharyngeal wall significantly differentiated patients in the subgroups by AHI but not by BMI. CONCLUSIONS: Pharyngeal obstruction at the level of the hard and soft palate differentiates patients with severe OSA from patients with mild and moderate OSA regardless of BMI.

Morphological predictors of sleep apnoea severity.

BACKGROUND: Obstructive sleep apnoea (OSA) does not always depend on obesity but on a certain morphological configuration. The study objective was to verify a hypothesis about a relation between anthropometric features and OSA occurrence and severity. MATERIALS AND METHODS: The study involved 138 patients, who had reported in Department and Clinic of Otolaryngology, Warsaw Medical University, due to suspected OSA. Each patient underwent morphological evaluation according to visual analogue scales. The assessment involved nasal septum morphology evaluation according to a 4-grade scale, palate morphology evaluation according to the 4-grade Friedman scale, whereas the facial profile, oropharyngeal isthmus, and the shape of the nasopharynx were assessed according to our own 3-grade scale. RESULTS: Statistical analysis confirmed the high concordance of the basic polysomnographic parameters with the Friedman scale and the shape of the oropharyngeal isthmus. CONCLUSIONS: 1. The modified Mallampati score as well as evaluation of the shape of the oropharyngeal isthmus demonstrated high concordance with the basic polysomnographic parameters. 2. The neck circumference is a significant predictor of the apnoea-hypopnoea index value in males suffering from the OSA syndrome.

Clinical use of allogeneic bone granulates to reconstruct maxillary and mandibular alveolar processes.

INTRODUCTION: Lack of adequate mass of a patient's own bone is still a clinical problem in dental implantology; it precludes dental embedment. Surgical widening of an atrophied alveolar process with the use of an allogeneic bone granulate to fill the bone defect constitutes a first-line method to prepare for implant-prosthetic treatment. Transplantation of allogeneic material allows reconstruction of optimal height, thickness, and width of the alveolar process facilitating a procedure with a good long-term outcome. The study assessed outcomes following augmentation of atrophied alveolar processes before intraosseous implantation. MATERIALS AND METHODS: Filling bone defects in the maxilla and mandible as an introductory measure for implant-prosthetic treatment was performed in 59 patients (24 females and 35 males of age range 22-65 years). Bone granulate was used for maxillary sinus floor elevation (n=29), augmentation of the postextraction alveoli (n=12), and filling of defects in the outer table of the compact bone formed following inflammatory conditions (n=18). The bone grafts were covered with plasma-rich fibrin (PRF) obtained from the patient's blood to accelerate the formation of synostoses and prevent epithelial penetration between the patients' own bone and the bone graft. RESULTS: In all of the patients normal union was observed, as confirmed by radiological images as well as intraprocedural assessment. Sufficient height and width as well as thickness of the alveolar process was obtained, which allowed embedment. CONCLUSIONS: Allogeneic bone granulate constitutes a good material to reconstruct maxillary and mandibular alveolar processes in out-patient care.

Micromethod for detection of oligoclonal IgG in unconcentrated CSF by polyacrylamide gel electrophoresis.

A micromethod to detect oligoclonal IgG from 50 microL of unconcentrated CSF was developed by using polyacrylamide gel electrophoresis in sodium dodecyl sulfate (SDS-PAGE). Of 17 patients with multiple sclerosis, oligoclonal bands were demonstrated in 16 instances (94%) by micro-SDS-PAGE and in 13 (76%) by agarose gel electrophoresis. The corresponding figures among 30 patients with optic neuritis were 16 (54%) and five (17%), respectively, and among ten patients with other neurological disease the figures were two (20%) and none, respectively. Thus, micro-SDS-PAGE is more sensitive than agarose gel electrophoresis for detection of oligoclonal IgG. The small volume of unconcentrated CSF that is required enhances the usefulness of this test.