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Biomedical subjects

S Youssefzadeh

Publications and source records attributed to S Youssefzadeh.

At least 19 recordsLinked to original sources
PubMed2001

Clinical application of magnetic resonance imaging in 30 cochlear implant patients.

OBJECTIVE: The goal of this investigation was to provide evidence that magnetic resonance imaging (MRI) can be performed safely and effectively on cochlear implant patients who require diagnosis of additional diseases. STUDY DESIGN: A retrospective study was performed over 5 years. In a total of 300 patients with cochlear implants at the authors' center, MRI was performed whenever it was medically indicated. SETTING: All patients underwent scanning in a Philips Gyroscan T10-NT MRI machine, using commercially available Powertrac 3000 software. PATIENTS: All patients with cochlear implants for whom MRI was indicated (n = 30) were included in this study. They had a wide variety of conditions necessitating MRI, including cervical discus prolapse, hypophyseal adenoma, epipharynx carcinoma, knee degeneration, parotid tumor, and preoperative evaluation for reimplantation and bilateral implantation. RESULTS: No adverse effects from the MRI were reported by any of the patients. The cochlear implants all retained their function. All images were of diagnostic value. Because of the MRI, the patients did not need to undergo additional, more invasive and expensive diagnostic procedures. Examples of MRI images from 5 patients are shown. CONCLUSIONS: MRI on cochlear implant patients, using the Med El Combi 40 and Nucleus mini 22 series at 1 Tesla, can be a safe procedure. Removal of any magnet is not necessary.

Calcinosis↗
PubMed2001

Quantitative US of the calcaneus: cutoff levels for the distinction of healthy and osteoporotic individuals.

PURPOSE: To calculate cutoff levels for quantitative ultrasonography (US) performed to distinguish healthy individuals and those with osteoporosis identified with dual x-ray absorptiometry. MATERIALS AND METHODS: In 1,357 patients (856 females, aged 55.1 years +/- 15.4 [mean +/- SD]; 501 males, aged 50.4 years +/- 15), bone mineral density measurements of the lumbar spine (posteroanterior, L1 through L4) and femoral neck were obtained, and quantitative US was performed to determine the stiffness of the calcaneus. Individuals with a T score less than -2.5 (osteoporotic) at the spine and femur were identified, and upper T-score cutoff values (3 SDs from the mean) in the groups of male and female patients with osteoporosis were identified. RESULTS: Females with dual x-ray absorptiometric values that were indicative of osteoporosis of the spine had an upper T-score cutoff value of -1.0 (males, -0.2). Females who had femoral osteoporosis showed an upper quantitative US T-score cutoff value of -0.6 (males, 0). CONCLUSION: Cutoff values may permit the use of quantitative US to screen for the presence of osteoporosis in the spine and femur. Quantitative US will help to prevent unnecessary dual x-ray absorptiometric and conventional radiographic examinations.

Absorptiometry, Photon↗
PubMed2000

[Clinical utilization of magnetic resonance imaging for patients with cochlear implants].

To date, MR imaging is absolutely contraindicated in cochlear-implanted patients. The aim of this study is to document the potential value of MR imaging in such patients, without injurious or side effects and without technical device failure. After in vitro experimental testing, 25 cochlear implanted patients underwent MRI. Radiological evaluation was also possible. The use of 1-Tesla fast spin echo sequences minimised artifacts. All cochlear implants are still in working order; no changes in fitting data or a reduction in speech understanding were observed. MR helped to avoid other invasive medical procedures.

Austria↗
PubMed2000

[The pharynx. The imaging of its normal anatomy].

BACKGROUND: The pharynx, being part of the digestive as well as the respiratory system, is embedded in the complex spatial anatomy of the neck and, due to its function and location, represents a very sophisticated region. DIAGNOSIS: Cross-sectional imaging with CT and MR imaging plays an indispensable complementary role to clinical work-up, as far as submucosal and deep cervical spaces are concerned. However, as dysphagia is a common symptom in clinical practice, interpretation of double contrast studies and videofluoroscopic investigations are also on frequent demand in the daily routine. CONCLUSION: Close interdisciplinary co-operation and the radiologist's familiarity with the anatomy of the region are required in order to use the diagnostic tools in an optimal fashion.

Cineradiography↗
PubMed2000

[Congenital and benign changes with regard to the pharynx].

DEVELOPMENT: The first part of this article is supposed to present a brief overview on the development of tissues and structures related to the pharynx, as far as they provide a better understanding of the most congenital lesions in this area of the body. BENIGN LESIONS: The second part of this article focuses on benign lesions originating in the pharynx or in neighbouring structures. Functional pharynx abnormalities are beyond the scope of this paper.

Humans↗
PubMed2000

Subchondral bone and cartilage disease: a rediscovered functional unit.

The role of subchondral bone in the pathogenesis of cartilage damage has likely been underestimated. Subchondral bone is not only an important shock absorber, but it may also be important for cartilage metabolism. Contrary to many drawings and published reports, the subchondral region is highly vascularized and vulnerable. Its terminal vessels have, in part, direct contact with the deepest hyaline cartilage layer. The perfusion of these vessels accounts for more than 50% of the glucose, oxygen, and water requirements of cartilage. Bony structure, local metabolism, hemodynamics, and vascularization of the subchondral region differ within a single joint and from one joint to another. Owing to these differences, repetitive, chronic overloading or perfusion abnormalities may result in no pathological reaction at all in one joint, while in another joint, these same conditions may lead to osteonecrosis, osteochondritis dissecans, or degenerative changes. According to this common etiological root, similar pathological reactions beginning with marrow edema and necrosis and followed by bone and cartilage fractures, joint deformity, and insufficient healing processes are found in osteonecrosis, osteochondritis dissecans, and degenerative disease as well.

Biomechanical Phenomena↗
PubMed1999

[Malignant tumors of the mouth cavity and oropharynx. Stage classification].

Staging of malignant tumours of the oral cavity and the oropharynx not only requires far more than a basic knowledge of anatomy and the usual pathways of spread, but also a broad understanding of the diagnostic benefits of current imaging modalities. As radiology should never try to replace histology, the main aim should be precise prediction of tumour margins and differentiation of tumour from edema and posttherapeutic changes. Only then will imaging studies have a significant clinical impact.

Carcinoma, Squamous Cell↗
PubMed1999

[Conventional dental radiography and future prospectives].

Until recently, conventional dental radiology was performed by dentists and orofacial surgeons. Due to the rapid development of radiological technique, the demand of radiological advice is increasing. The radiologists see more and more dental patients in their daily routine. The aim of this article is to give an overview on established dental radiology and a glimpse into the future. Conventional dental radiology and digital radiography are presently in use. Intraoral technique comprises dental films, bite-wing views and occlusal radiographs. Panoramic views and cephalometric radiographs are done with extraoral technique. Digital radiography lacks all processes in behalf of film development. It leads to dose reduction and enables image manipulation.

Cephalometry↗
PubMed1999

[Magnetic resonance tomography in dental radiology (dental MRI)].

PURPOSE: To demonstrate the usefulness of Dental-MRT for imaging of anatomic and pathologic conditions of the mandible and maxilla. METHODS: Seven healthy volunteers, 5 patients with pulpitis, 9 patients with dentigerous cysts, 5 patients after tooth transplantation and 12 patients with atrophic mandibles were evaluated. Studies of the jaws using axial T1- and T2-weighted gradient echo and spin echo sequences in 2D and 3D technique have been to performed. The acquired images were reconstructed with a standard dental software package on a workstation as panoramic and cross sectional views of the mandible or maxilla. RESULTS: The entire maxilla and mandibula, teeth, dental pulp and the content of the mandibular canal were well depicted. Patients with inflammatory disease of the pulp chamber demonstrate bone marrow edema in the periapical region. Dentigerous cysts and their relation to the surrounding structures are clearly shown. After contrast media application marked enhancement of the dental pulp can be found. CONCLUSION: Dental-MRT provides a valuable tool for visualization and detection of dental diseases.

Diagnostic Imaging↗
PubMed1999

[Teleradiology in dentistry].

Teleradiology is a means of electronically transmitting radiographic patient images and consultative text. This offers a new way to communicate with other radiologists and transferring clinicians. Different applications of teleradiology, such as on-call services for emergency departments or rural regions, as well as expert consultation (second opinion) already have been realized. Especially in concern of dental radiography, analog (film-based) imaging gets progressively replaced by digital imaging. The combination with ultrafast data transfer offers an increasing efficacy in diagnosis and therapy, acceleration of communication and new means of quality assessment in patient care. Various applications of teleradiology concerning dental medicine are discussed.

Humans↗
PubMed1999

Postoperative imaging of the temporomandibular joint.

Postoperative axiography is compared to preoperative findings and repeated regularly. Postoperative arthroscopy is avoided because of its invasiveness. Plain films comprise panorama views, the axial skull view, the Schüller view in closed and open mouth position, and the Clementschitsch view. They are done in the early postoperative phase (2 days), before and after removal of osteosynthetic material, and after 1 year. Early postoperative computed tomography control is done in patients with intra-articular fractures to look for intra-articular fragments and to check for the position of the affected bones or radiopaque alloplastic materials. Routine magnetic resonance imaging is performed 6 months after disk surgery as a baseline study or whenever symptoms suggest missing recapture of the disk or if there is a discrepancy between clinical and radiological findings. Postoperative internal disk structure may become hyperintense centrally on T1 and T2 due to mucoid degeneration. Postoperative adhesions can be suspected when the disk lacks mobility.

Arthroscopy↗
PubMed1999

Dental vertical root fractures: value of CT in detection.

PURPOSE: To determine the value of computed tomography (CT) in the diagnosis of dental vertical root fractures relative to the value of conventional dental radiography. MATERIALS AND METHODS: Thirty-seven patients with 42 teeth in which vertical root fracture was clinically suspected underwent dental radiography and axial CT. Two radiologists evaluated the images independently and by consensus for a fracture line. The results were compared with intraoperative findings. RESULTS: Twenty-eight of the 42 teeth were proved intraoperatively to be fractured. The sensitivity and specificity averaged for the two reviewers in the assessment of vertical fractures were 23% and 70%, respectively, with dental radiography and 100% and 100%, respectively, with CT. Consensus reading showed sensitivities of 25% for dental radiography and 75% for CT. Eight (reviewer A) or nine (reviewer B) false-negative CT findings were encountered in cases in which metallic artifacts obscured parts of the root and in cases in which the root was very small in diameter. Interobserver agreement was 95% for dental radiography and 93% for CT. CONCLUSION: CT is superior to dental radiography in the detection of dental vertical root fractures.

Adult↗
PubMed1998

Treatment of a local recurrence of a carcinoid tumor of the middle ear by extended subtotal petrosectomy.

A recurrence of a primary carcinoid tumor of the middle ear 15 years after radical tympanomastoidectomy is reported. An extended subtotal petrosectomy using a craniocervical approach with temporary infracondylar mandibulotomy was performed, since imaging studies demonstrated an extensive tumor with a close relationship to the tegmen tympani, facial nerve, and ascending and horizontal portions of the carotid canal. The tumor was metabolically inactive. Histopathological examination showed a solid, trabecular tumor that was positive for pancytokeratin Lu5, neuron-specific enolase, pancreatic intestinal polypeptide and glucagon. Neuroendocrine-granules were demonstrable under electron microscopy. This case is reported to show that primary middle-ear carcinoid tumors can recur years after radical tympanomastoidectomy.

Biomarkers, Tumor↗
PubMed1998

Venous contrast fluid level in computed tomography.

OBJECTIVE: To evaluate the clinical significance of a venous contrast fluid level during computed tomography (CT). METHODS: An incidentally found contrast fluid level in the left internal jugular vein during CT in an otherwise healthy patient was the reason for investigation of this phenomenon. We collected data over a 4-year period at our institution and reviewed the case notes of seven patients exhibiting this CT finding. We also performed conventional radiography, CT, venography and colour-coded Doppler sonography to rule out an underlying pathology in those patients. Additional in-vitro CT studies were performed to define conditions of flow leading to a contrast fluid level. Flow dynamics in the internal jugular veins were studied in vivo by using colour-coded Doppler sonography in 20 normal volunteers. RESULTS: In addition to our first patient, we found seven patients with a venous contrast fluid level among a total of 58400 contrast-enhanced CT examinations performed in our institutions. The investigations were performed on various CT-units, with different scan protocols, injection rate, dose and manufacturer of non-ionic contrast agent. The contrast fluid level was encountered unilaterally in the left internal jugular vein in seven patients and in the inferior vena cava in one patient. All patients were free of symptoms and the outcome of all other examinations was unremarkable. In-vitro and in-vivo studies showed that pure contrast agent entering a vessel (in case of the internal jugular vein due to physiological flow and/or stasis) can produce a contrast fluid level. CONCLUSION: The occurrence of a venous contrast fluid level during contrast enhanced CT is an incidental finding of no pathological significance and need not initiate costly further examinations.

Adult↗
PubMed1998

[The value of sonography in the intensive care unit for the diagnosis of diaphragmatic paralysis].

PURPOSE: To assess the value of bedside sonography in the detection of diaphragmatic paralysis in patients in the intensive care unit. METHODS: In this study, 100 patients who were admitted to the intensive care unit after thoracic operations were evaluated. Sonography of each hemidiaphragm was performed with coronal scans at the mid-axillary line on both sides with the patient supine. Absent and paradoxical diaphragmatic movement was considered to be indicative of diaphragmatic paralysis. All patients underwent additional fluoroscopy within 5 days. RESULTS: In 13 patients (13%) sonography revealed diaphragmatic paralysis. All these results were confirmed with fluoroscopy resulting in a sensitivity and specificity for sonography of 100%. CONCLUSION: Bedside sonography of the diaphragm at the intensive care unit is a reliable tool for diagnosing diaphragmatic paralysis.

Adult↗
PubMed1997

[Pre- and postoperative roentgen diagnosis for cochlear implant patients].

Radiologic means aid in assessment of the most suitable side for operation and allow the surgeon to be prepared for special situations in order to perform the operation without difficulties [22]. The most suitable modalities are CT and MRI preoperatively. In uncomplicated cases, conventional imaging suffices for the postoperative needs. CT should only be performed if the patient complains of symptoms.

Cochlear Implants↗