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Biomedical subjects

C Krestan

Publications and source records attributed to C Krestan.

At least 19 recordsLinked to original sources
PubMed2006

Modern imaging lymph node staging of the head and neck region.

The aim of this paper is to describe the modern imaging methods, their techniques, ability, and performance in staging head and neck lymph nodes. Also, the imaging morphologies of benign and malignant lymph nodes according to the different imaging techniques will be delineated. The imaging techniques of ultrasound including contrast-enhanced ultrasound, computed tomography and magnetic resonance imaging (MRI) including diffusing weighted imaging and contrast-enhanced iron oxide MRI are explained. Imaging examples of the different modalities of benign and malignant transformed lymph nodes will be demonstrated. Furthermore, the diagnostic sensitivity of each modality will be delineated and further aspects of modern lymph node staging of the head and neck region such as those with special contrast agents will be described. These modern imaging modalities have sensitivity rates of 70-80% depending on the technical equipment and ability and on the experience of the investigator. The technique of near-infrared-imaging will be mentioned in another article in this journal. Also the value of biopsy techniques including recently developed ultrasonography guided needle biopsy with molecular analysis of the cells of about 97-100% accuracy in diagnosing benign from malignant lymph nodes will be mentioned. Overall, the reader will get an overview of the present imaging modalities to potentially stage correctly lymph nodes in the head and neck region to facilitate the therapeutic procedure.

Biopsy, Needle↗
PubMed2006

[Benign and malignant lesions in the region of the inner ear and cerebellopontine angle].

Tumorous lesions in the region of the inner ear and cerebellopontine angle are very rare and can be classified into benign and malignant disease forms. This contribution presents and explains the CT and MRI characteristics of these tumors.High-resolution computed tomography (HRCT) in the axial projection is applied for evaluation in the high-resolution bone window. The coronary slices can be reconstructed from the axial datasets or in individual cases examined in the coronary plane.HRCT excellently demonstrates osseous lesions and in individual cases - e.g., exostoses - it can simply suffice to perform HRCT of the temporal bone, while HRCT is also excellent for detecting osseous lesions to determine whether the tumor is benign or malignant.MRI, on the other hand, excellently shows the extent of tumor spread because of its superb soft tissue contrast. Consequently, HRCT and MRI images of the inner ear and cerebellopontine angle provide meaningful information for visualization and classification of tumorous lesions. The two methods should not be considered as competing but rather as complementary and among other aspects exert considerable influence on the therapeutic approach.

Cerebellar Neoplasms↗
PubMed2005

Matrix-based autologous chondrocyte implantation for cartilage repair with HyalograftC: two-year follow-up by magnetic resonance imaging.

OBJECTIVE: Monitoring of articular cartilage repair after matrix-associated autologous chondrocyte implantation with HyalograftC by a new grading system based on non-invasive high-resolution magnetic resonance imaging. PATIENTS AND METHODS: In 23 patients, postoperative magnetic resonance imaging (MRI) was performed between 76 and 120 weeks. In nine of these patients, five MRI examinations were performed at 4, 12, 24, 52 and 104 weeks after HyalograftC implant. The repair tissue was described with separate variables: degree of defect repair in width and length, signal intensity of the repair tissue and status of the subchondral bone. For these variables a grading system with point scale evaluation was applied. RESULTS CONCLUSION: High-resolution MRI provides a non-invasive tool for monitoring the development of cartilage repair tissue following HyalograftC technology, shows a good correlation with clinical outcome and may help to differentiate abnormal repair tissue from a normal maturation process.

Adult↗
PubMed2005

[Ultrasound contrast agents: substance classes, pharmacokinetics, clinical applications, safety aspects].

Ultrasound contrast agents (UCA) have undergone constant development and improvement in recent years. Greater mechanical stability and improved acoustic properties, combined with new contrast-specific ultrasound sequences, have broadened the potential fields for investigation considerably. Contrast-enhanced ultrasound studies will no longer be complementary investigations, but will be considered as primary techniques. This review article provides a survey of the different drugs used, their chemical properties, and their pharmacokinetic aspects. Summarized are the most important established and published indications for the use of UCA together with an outlook for future applications. Finally this paper discusses the safety profile of these agents, which has become important due to the increasing use of these agents.

Contrast Media↗
PubMed2004

Tumors and tumor-like lesions of the neck: from childhood to adult.

In childhood, tumors and tumor-like lesions of the neck are rare and tend to be benign. Very common are congenital cystic lesions (thyroglossal duct cysts, branchial cysts, dermoid cysts, lymphangiomas, cystic hygromas). Common neoplastic lesions are hemangiomas and papillomas. The most common malignant tumors in the head and neck region are lymphomas and rhabdomyosarcomas. Lymph node enlargements, reactive or/and infectious, account also for a significant amount of cervical masses.

Adolescent↗
PubMed2003

[The role of high-resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) in the diagnosis of preoperative and postoperative complications caused by acquired cholesteatomas].

The role of high-resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) in the diagnosis of preoperative and postoperative complications caused by acquired cholesteatomas will be described in this paper. The pre- and postoperative imaging of the temporal bone was performed with HRCT and MRI.HRCT and MRI were performed in the axial and coronal plane. MRI was done with T2 weighted and T1 weighted sequences both before and after the intravenous application of contrast material. All imaging findings were confirmed clinically or surgically. The preoperative cholesteatoma-caused complications depicted by HRCT included bony erosions of the ossicles, scutum, facial canal in the middle ear, tympanic walls including the tegmen tympani, and of the labyrinth. The preoperative cholesteatoma-caused complications depicted by MRI included signs indicative for labyrinthitis, and brain abscess. Postoperative HRCT depicted bony erosions caused by recurrent cholesteatoma,bony defects of the facial nerve and of the labyrinth, and a defect of the tegmen tympani with a soft tissue mass in the middle ear. Postoperative MRI delineated neuritis of the facial nerve, labyrinthitis, and a meningo-encephalocele protruding into the middle ear. HRCT and MRI are excellent imaging tools to depict either bony or soft tissue complications or both if caused by acquired cholesteatomas. According to our findings and to the literature HRCT and MRI are complementary imaging methods to depict pre- or postoperative complications of acquired cholesteatomas if these are suspected by clinical examination.

Brain Abscess↗
PubMed2003

[Flat-screen detector systems in skeletal radiology].

Implementation of flat-panel detectors and digital integration of the technique instead of the use of conventional radiographs leads to a shortening of the work process. With flat-panel technology the image production process is shortened by more than 30%. Major advantages in the implementation of integrated RIS, PACS and flat-panel detector system are increases in quality because most mistakes in picture labeling can be avoided, easier handling without the need for cassettes, and the possibility of image post-processing. The diagnostic quality of the images in the field of musculoskeletal radiology is, in comparison to conventional radiographs, at least adequate and in most cases markedly improved with a marked reduction in radiation exposure of around 30-50%. With respect to the numerous advantages of the digital techniques and especially flat-panel technology there is a very high likelihood that conventional radiographs will be substituted in the coming years, even though the cost of the new technology is currently significantly higher compared to conventional systems.

Artifacts↗
PubMed2003

Spiral CT and radiation dose.

Recent studies in the USA and Europe state that computed tomography (CT) scans compromise only 3-5% of all radiological exams, but they contribute 35-45% of total radiation dose to the patient population. These studies lead to concern by several public authorities. Basis of CT-dose measurements is the computed tomography dose index (CTDI), which was established 1981. Nowadays there are several modifications of the CTDI values, which may lead to confusion. It is suggested to use the standardized CTDI-100 w. value together with the dose length product in all CT-examinations. These values should be printed on all CT-images and allows an evaluation of the individualized patient dose. Nowadays, radiologist's aim must be to work at the lowest maximal diagnostic acceptable signal to noise ratio. To decrease radiation dose radiologist should use low kV and mA, but high pitches. Newly developed CT-dose-reduction soft-wares and filters should be installed in all CT-machines. We should critically compare the average dose used for a specific examination with the reference dose used in this country and/or Europe. Greater differences should caution the radiologist. Finally, we as radiologists must check very carefully all indications and recommend alternative imaging methods. But we have also to teach our customers-patients and medical doctors who are non-radiologists-that a 'good' image is not that which show all possible information, but that which visualize 'only' the diagnostic necessary information.

Europe↗
PubMed2002

Pathophysiology and imaging in inflammatory and blastomatous synovial diseases.

Variable pathologies are subsumed under the term "synovial disease", including common pathologies such as rheumatoid arthritis. While formerly radiologists had to rely on conventional radiographs and bone scintigraphy with their inherent problems in visualizing soft tissue, noninvasive imaging of the synovium has recently improved substantially with the technical development of MRI and (Doppler) ultrasound. These imaging modalities allow differentiation of characteristic pathologic features based on a profound knowledge of normal anatomy and pathophysiology.

Arthritis, Infectious↗
PubMed2002

MRI of the cartilage.

With the introduction of fat-suppressed gradient-echo and fast spin-echo (FSE) sequences in clinical routine MR visualization of the hyaline articular cartilage is routinely possible in the larger joints. While 3D gradient-echo with fat suppression allows exact depiction of the thickness and surface of cartilage, FSE outlines the normal and abnormal internal structures of the hyaline cartilage; therefore, both sequences seem to be necessary in a standard MRI protocol for cartilage visualization. In diagnostically ambiguous cases, in which important therapeutic decisions are required, direct MR arthrography is the established imaging standard as an add-on procedure. Despite the social impact and prevalence, until recent years there was a paucity of knowledge about the pathogenesis of cartilage damage. With the introduction of high-resolution MRI with powerful surface coils and fat-suppression techniques, visualization of the articular cartilage is now routinely possible in many joints. After a short summary of the anatomy and physiology of the hyaline cartilage, the different MR imaging methods are discussed and recommended standards are suggested.

Cartilage, Articular↗
PubMed2002

[Change in process management by implementing RIS, PACS and flat-panel detectors].

Implementation of radiological information systems (RIS) and picture archiving and communicating systems (PACS) results in significant changes of workflow in a radiological department. Additional connection with flat-panel detectors leads to a shortening of the work process. RIS and PACS implementation alone reduces the complete workflow by 21-80%. With flatpanel technology the image production process is further shortened by 25-30%. The workflow-steps are changed from original 17-12 with the implementation of RIS and PACS and to 5 with the integrated use of flatpanels. This clearly recognizable advantages in the workflow need an according financial investment. Several studies could show that the capitalisation-factor calculated over eight years is positive, with a gain range between 5-25%. Whether the additional implementation of flatpanel detectors results also in a positive capitalisation over the years, cannot be estimated exactly, at the moment, because the experiences are too short. Particularly critical are the interfaces, which needs a constant quality control. Our flatpanel detector-system is fixed, special images--as we have them in about 3-5% of all cases--need still conventional filmscreen or phosphorplate-systems. Full-spine and long-leg examinations cannot be performed with sufficient exactness. Without any questions implementation of integrated RIS, PACS and flatpanel detector-system needs excellent training of the employees, because of the changes in workflow etc. The main profits of such an integrated implementation are an increase in quality in image and report datas, easier handling--there are almost no more cassettes necessary--and excessive shortening of workflow.

Austria↗
PubMed2002

[Coxarthrosis].

Osteoarthritis of the hip joint is a very common disease. There is a minor prevalence of males. By etiology one can distinguish primary (idiopathic) from secondary osteoarthritis. Secondary are due to well-known etiologies as overweight, repetitive traumata, malposture, muscle- and tendon-imbalance etc. Osteoarthritis includes not only cartilage abnormalities, but also such of the subchondral-region, synovialis, synovial fluid and periarticular muscles. The cartilage shows in osteoarthritis typically edema and swelling, defects with tears, fibrillation, and "baldness" and (or) cartilagenous repair-islands and joint space narrowing as well, while subchondrally micro-edema, necrosis, ev. microfractures, "cysts", demineralisation followed by sclerosis, osteophyte-formation and deformity is seen. With conventional radiographs and CT joint space narrowing, subchondral cysts, sclerosis and osteophytes and deformities are well delineated, MRI however allows visualization of subtle bone marrow and cartilage abnormalities. Clinically, the diagnosis of pre-osteoarthritis becomes more and more important. This includes e.g. deformities and malpostures, labrum-pathologies and structural imbalances. There are three prognostic different types of hip-osteoarthritis depending on the migration of the head of the hip joint: the most common are the latero-cranial and the medio-caudal ones, while the central one is found very rarely. Basic imaging method are conventional radiographs, and CT, followed by MRI. The diagnosis of an "activated osteoarthritis" is made by bone-scintigraphy or MRI with i.v. application of contrast-media. The labrum- and cartilage diagnosis should be done with MRI or MR-arthrography. Functional computer-animated analysis will be of great diagnostic value in the near future. MRI indications are differences between clinical results and imaging, missing clinical improvement of an "activated" osteoarthritis under standard therapy, unclear joint-pain and before any arthroscopy.

Aged↗
PubMed2002

[Diagnostic imaging in hip prostheses].

Hip arthroplasty has become a common and still increasing procedure for the treatment of osteoarthritis, advanced head necrosis, post-inflammatory arthritis or rheumatoid arthritis. Radiography is the most important imaging modality for monitoring the normal, asymptomatic hip arthroplasty. Radiographs are obtained at the end of a surgical treatment, to exclude complications like fracture or component misplacement. In the follow-up radiographs are used for the diagnosis of loosening and infection of the hip arthroplasty as well as soft tissue ossification. Together with the history and clinical information, the analysis of morphological findings allows to find the grade of loosening. MRI has been advocated in the diagnosis of infection, in particular in the localisation of soft tissue involvement. Imaging, especially by radiographs, is used for the evaluation of the normal and complicated follow-up of hip arthroplasty.

Aged↗
PubMed2001

[Internal derangement of the temporomandibular joint].

Internal Derangement is one of the most common disorders of the Temporomandibular joint. It is defined as an abnormal anatomical relationship between the discus articularis and the other structures of the temporomandibular joint. More than 2/3 of patients with clinical symptoms of the temporomandibular joint have an internal derangement. The most frequent finding in internal derangement is an anterior dislocation of the disc with reduction after mouth opening. In more severe cases a complete anterior dislocation is found without reduction of the disc. Internal derangement is a risk factor for developing osteoarthritis with remodeling of the condylus and the fossa mandibularis. The most important modalities of radiologic diagnosis are arthrography, CT and MRI. The diagnosis of craniofacial dysfunction has been improved dramatically by modern imaging techniques, which have become essential tools for primary diagnostic and evaluation after conservative or surgical therapy. MRI has become the gold standard.

Humans↗
PubMed2001

[Non-neoplastic arthropathies of the temporomandibular joint].

The pathologic conditions that involve the TMJ are similar to those conditions that involve other joints in the body. Therefore, many of the radiologic characteristics are also similar. Nevertheless, because of the complex structure and function of this small joint, it is essential to know the variety of diseases that can involve the temporomandibular joint. It is also important to understand that functionally both TMJ's act as a single unit and that any alteration in function caused by a pathologic process on one side may lead to dysfunction on the contralateral side. It is essential that the radiologist is familiar with the principles of TMJ function as well as TMJ pathology.

Diagnosis, Differential↗
PubMed2001

[Traumatic temporomandibular joint injuries].

Injuries of the temporomandibular joint are mostly due to injuries or fractures of the mandibular condyle. Fractures of the skull base involving the temporomandibular joint are rare. Classification of fractures refers to their anatomical positions and the presence or absence of a luxation. Further, it is important whether the fracture is intra- or extra-capsular. The primary imaging method should be orthopantomography. As for therapy planning, especially surgery, also evaluation of soft tissue is necessary, computed tomography is the imaging method of choice. For diagnosis of complications or internal derangement of the temporomandibular joint, magnetic resonance imaging is to be recommended.

Humans↗
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↗