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Biomedical subjects

G Grevers

Publications and source records attributed to G Grevers.

At least 145 records · Page 8Linked to original sources
PubMed1990

[3D-MRT-reconstructions of space-occupying lesions in the head and neck regions].

3-D reconstructions in the head and neck were carried out on 21 normals and 11 patients with space-occupying lesions, both before and after the administration of Gd-DTPA. The 3-D reconstructions were obtained by the "ray-tracing" method. For the 3-D reconstructions, portions of the skull surface image were removed to permit views of the deeper tissues. The 3-D reconstructions included an hypoglossus neurinoma, a glomus tumour, two carcinomas of the maxillary antra, three naso-pharyngeal carcinomas, a parotid adenoma, an oro-pharyngeal haemangioma and two lesions in the neck. The 3-D reconstructions provided a better understanding of the morphology than was obtained from the two-dimensional images. 3-D reconstructions of lesions in the head and neck will become a valuable diagnostic method for demonstrating space-occupying lesions, particularly with regard to surgical planning.

Adenoma↗
PubMed1990

[MRT of tumors of the larynx and hypopharynx using Gd-DTPA: clinical value].

Thirty one patients with tumours of the larynx and hypo-pharynx were studied by MRI, both with and without the para-magnetic contrast medium, GD-DTPA. The results were compared with pre-operative laryngoscopy and the final pathological tumour classification. The most accurate results were obtained by comparing T1-weighted sequences before and after the use of GD-DTPA. Because of the relatively rapid mode of examination and the specific enhancement, the method proved ideal for evaluating tumours of the larynx and hypo-pharynx. MRI is a valuable diagnostic technique for staging and treatment planning of patient with tumours of the larynx and hypo-pharynx.

Contrast Media↗
PubMed1990

Parotid gland: plain and gadolinium-enhanced MR imaging.

The purpose of this study was to show the typical appearance of lesions of the parotid gland with plain MR imaging and MR imaging enhanced with gadopentetate dimeglumine. Seventeen patients with inflammatory changes and 43 with benign and malignant tumors were studied. The examinations were carried out with plain T1-weighted sequences with a repetition time (TR) of 500 msec and an echo time (TE) of 25 msec (TR/TE = 500/25), T2-weighted sequences (1,600/90), and gadolinium-enhanced T1-weighted sequences in axial, coronal, and sagittal orientations. For identifying normal anatomic structures such as the facial nerve and the main duct, the administration of gadopentetate dimeglumine was helpful. In inflammatory changes, gadolinium-enhanced images showed no diagnostic advantages. Gadopentetate dimeglumine proved helpful in delineating tumorous lesions and in differentiating benign and malignant lesions. However, an exact differentiation of the different histologic types was not possible. Post-operative fibrosis could be differentiated from recurrent tumors after administration of gadolinium. If a question regarding infiltration or definition of the boundaries of a lesion cannot be answered with non-enhanced MR imaging, gadopentetate dimeglumine administration is advised. However, for routine imaging of the parotid gland, its use is not recommended.

Contrast Media↗
PubMed1990

Tumors of the nasopharynx and adjacent areas: MR imaging with Gd-DTPA.

The purpose of this study was to describe our experience with Gd-DTPA-enhanced MR imaging in the evaluation of the most common nasopharyngeal tumors. Forty-two patients with tumors of the nasopharynx and adjacent spaces had MR imaging before and after IV injection of Gd-DTPA. Images were obtained with a 1.0-T superconducting magnet imaging system in transverse, coronal, and sagittal planes with T1- and T2-weighted sequences. MR images were compared with CT scans and tumor histology. The studies were categorized by using a grading system with grades ranging from unsatisfactory (grade 0) to optimal (grade 3). Contrast-enhanced MR enables better identification of small anatomic details such as both palatini muscles and the pharyngobasilar fascia. MR after Gd-DTPA was superior to CT in all cases except for tumors of the maxillary sinuses. MR with Gd-DTPA is recommended for tumors that are small and difficult to detect on the initial nonenhanced MR examination or that show subtle infiltrations. Because of the increased cost and longer examination time, MR with Gd-DTPA does not need to be done when large tumors are well delineated.

Carcinoma, Adenoid Cystic↗
PubMed1989

[Functional morphology of endonasal blood capillaries].

Harvey (1628) was the first to describe the blood circulatory system. 50 years later, the capillary system was discovered by Marcello Malpighi as a link between arteries and veins. Since then, the microvascular network has been examined abundantly by means of various morphological and physiological techniques. During the last decades the development of the technical equipment enabled us to receive detailed informations on the structural and ultrastructural aspects of the vasculature and--particularly--the capillary endothelium. New electron microscopic investigations on the behaviour of this special cell system. In the present study we combined our own morphological results on the endonasal microcirculatory system--using different morphological techniques--to interpret these anatomical finding under functional aspects.

Capillaries↗
PubMed1989

[The value of high-resolution computerized tomography in abnormalities of the middle ear].

Middle ear malformations are common congenital disorders of the head and neck area. Recent advances in plastic and middle ear surgery have improved the prognosis of patients suffering from congenital hearing disorders. However, sophisticated preoperative procedures are mandatory. The development of HR-CT has improved the radiologic possibilities to evaluate middle ear disorders significantly. In the present study we examined by means of HR-CT twenty patients with congenital middle ear malformation. Our findings include different sizes of the middle ear as well as dysplastic alterations of the malleus and incus. The inner ear was normal in almost all cases. Our results indicate that preoperative HR-CT is a reliable diagnostic method to demonstrate middle ear disorders.

Ear Ossicles↗
PubMed1989

[Multiplanar imaging of the temporal bone. Initial results].

In the head and neck area CT imaging (particularly the HR-technique) is a well-established diagnostic procedure. Besides other locations it has been successfully used in the preoperative evaluation of the temporal bone. Nevertheless, the sophisticated anatomy of this special area is hard to interpret in certain cases. In the present study we report on our preliminary results in producing a multiplanar reconstruction of the area mentioned above. Temporal bones were used that had been excised during autopsy. The specimen were examined under a CT imager of the 3rd generation with a high-resolution mode. Sections of 1 mm thickness were obtained. For the evaluation a surface model was used; the segmentation was carried out mainly automatically. The surface was calculated using a triangulation algorithm. The obtained data enabled us to receive three-dimensional aspects of the temporal bone; these reconstructions could be examined from any desired perspective. Our results indicate that the multiplanar reconstruction might be of great importance for the diagnostic evaluation of temporal bone diseases in the future. In the meantime several technical problems have to be solved to guarantee a sufficient quality of the reconstructed specimen.

Computer Simulation↗
PubMed1989

[Radiologic diagnosis of the middle ear. Possibilities and perspectives].

During the past few years the importance of imaging methods for the diagnosis of head and neck diseases has increased significantly. Due to the rapid development of new techniques like "high-resolution" CT (HR-CT) and magnetic resonance imaging, radiology has become an important factor in the preoperative evaluation of many diseases in our discipline. The middle ear region in particular is known to be a complicated area and was often hard to interpret by radiological methods used so far. In the present paper the diagnostic value of HR-CT is demonstrated. Over the past two years we examined 130 patients suffering from middle ear diseases like malformations (MEM), otosclerosis, cholesteatoma and temporal bone fractures (TBF) with HR-CT. From our point of view the indications for this special examinations should be limited to MEM and TBF. The results and side effects of HR-CT and conventional tomography are compared and discussed. Finally, future perspectives of middle ear imaging are presented. Different reconstructive techniques have been developed during the past years, which might supply additional information for further questions arising in middle ear pathology in the future. At the present time none of these methods are ready for routine clinical use.

Ear Diseases↗
PubMed1989

[Modern radiologic diagnosis of the nasopharynx].

The nasopharynx is one of the most delicate areas of the head and neck for diagnosis and treatment. Biopsies can be taken easily under local anaesthesia; however, since many tumours in this particular region grow in the submucosa, biopsies taken from the superficial tissue layers might not show any signs of malignancy. Thus, diagnostic imaging has become important in evaluating the nasopharyngeal region. Until the early seventies, when computed tomography (CT) was introduced, conventional tomography was commonly used. Since the development of CT and --particularly--the "high-resolution" technique, tumour infiltration of the skull base and parapharyngeal space as well as intracranial extension can be evaluated sufficiently and the different compartments of the soft tissue can be clearly distinguished due to their varying density. Magnetic resonance imaging (MRI)--a new technique introduced a few years ago--yields a much better soft tissue contrast than CT. Contrast enhancement after application of Gd-DTPA provides further information on tumour outlines and architecture. Benign lesions can be distinguished from malignant tumours, as well as recurrent tumours from postoperative fibrosis. MRI can also show large bony defects while minor infiltrations of the skull base are detected by HR-CT. Both MRI and CT are well-established methods in diagnosing diseases of the nasopharynx and its surroundings. For evaluations of the vascular supply prior to operation digital subtraction angiography (DSA) might be necessary in some cases.

Contrast Media↗
PubMed1989

[MRI of the nasopharynx with Gd-DTPA: its value and differential diagnostic criteria].

81 patients with masses in the nasopharynx were examined by MRI and CT. In cases of primary lesions of the nasopharynx (such as carcinomas and fibromas), MRI with Gd-DTPA was superior to CT. Secondary tumors involving the nasopharynx were visualized equally well with MRI with Gd-DTPA and CT. The results show that MRI should be the primary method of examination in lesions of the nasopharynx. CT is a secondary procedure useful for showing small areas of bone erosion. MRI with the paramagnetic contrast medium Gd-DTPA permits differentiation between inflammatory, cystic and neoplastic masses.

Angiography↗
PubMed1989

Paragangliomas of the jugular bulb and carotid body: MR imaging with short sequences and Gd-DTPA enhancement.

Twenty-six patients with glomus jugulare (16), glomus tympanicum (three), or carotid glomus (seven) tumors were examined with contrast-enhanced CT scans and MR scans without and with Gd-DTPA. MR and CT scans had similar sensitivities, but the enhanced MR scans were diagnostically more specific than either CT or nonenhanced MR. Dynamic MR scanning permitted measurement of the degree of Gd-DTPA enhancement over time. We recommend contrast-enhanced MR with short sequences and a dynamic approach in patients with suspected carotid, tympanic, and jugular paragangliomas.

Carotid Body Tumor↗
PubMed1989

[Magnetic resonance tomography of the parotid gland: plain diagnosis and Gd-DTPA].

Pathological lesions of the parotid gland were examined comparatively with different examination sequences both plain and with the contrast medium Gd-DTPA. There were 36 benign lesions (parotitis, Sjögren's syndrome, adenoma, etc.) and 24 malignant tumours (squamous cell carcinoma, adenocarcinoma, adenoid cystic carcinoma etc.) Examinations were carried out at 1.0 T with long and short spin echo sequences in transverse and frontal layer orientation before and after application of Gd-DTPA as contrast medium. In the patients suffering from parotitis the best results were obtained with plain T1 and T2 sequences; the contrast medium Gd-DTPA remained without superior diagnostic relevance. However, in Sjögren's syndrome (myoepithelial sialadenitis) administration of the contrast medium always yielded a characteristic honeycomblike pattern. In benign and malignant space-occupying growths MRI supplied additional diagnostic information with Gd-DTPA in respect of defining the tumour borderlines and paths of infiltration. MRI is now a significant diagnostic tool in inflammatory and tumorous lesions of the parotid gland.

Adenocarcinoma↗
PubMed1988

Scanning electron microscopic studies of the nasal blood vessels.

Current histological and transmission electron microscopic techniques are insufficient for studying all different aspects of vascular morphology. As a result, we have used scanning electron microscopy (SEM) to examine nasal blood vessels. In our present studies the nasal septa of 15 rabbits were fixed by vascular perfusion, dried by the critical point method and coated with gold for SEM studies. Lower magnifications of specimens using this method show the tissue arrangement in the nasal septum. In higher magnifications the different vessels can be distinguished by their morphological features. The course of the vascular structures can be observed as well as the junctions between the different vessels. Our results indicate that different morphological techniques must be combined to understand the endonasal vasculature.

Animals↗
PubMed1988

[Arterial and venous digital subtraction angiography. A current study technic for otorhinolaryngology].

Digital subtraction angiography (DSA) is a rather new radiographic technique for imaging different vascular alterations, particularly in the head and neck area, and can replace angiography in most cases. Nevertheless, routine application of DSA - intravenously or intraarterially - seems to present a problem to many clinicists. In the present paper, therefore, we try to introduce these important techniques by means of several examples from patients who have undergone these procedures to demonstrate the actual indications of DSA for oto-rhino-laryngological diseases.

Carotid Artery Diseases↗
PubMed1988

[Laryngeal cancer in immunosuppressive therapy with cyclosporin A].

As a serious side effect of immunosuppressive therapy following organ transplantation, the incidence of malignancies shows a significant threefold increase compared with the age-matched general population. Under treatment with conventional immunosuppressive drugs (azathioprine, steroids and antilymphocyte globulin) patients are supposed to be susceptible to skin and lip cancers (40%) whereas the recently introduced new immunosuppressive drug cyclosporine A shows a comparable incidence of non-Hodgkin lymphomas (41%) and the patients seem to develop more potentially life threatening tumours of internal organs. In the present paper we report on a case of laryngeal carcinoma following immunosuppressive treatment with cyclosporine A 10 months after heart transplantation.

Adult↗
PubMed1988

[The variability of the surface morphology of olfactory sensory receptors].

The olfactory epithelium of the adult hamster (mesocricetus auratus) was examined by light- and scanning electron microscopy. Tissues were perfusion-fixed in buffered glutaraldehyde solution. Of particular interest were the regionally varying, thickly structured olfactory boarder and the polymorphic olfactory receptors. The forms varied from simple, smooth olfactory vesicles to highly differentiated receptors with up to 20 cilia of varying length per vesicle. The cilia were tapered at such a rate that the distal segments had an average diameter 1/2 to 1/3 of the proximal segment. The distal segments were arranged in a parallel fashion occasionally over more than 100 microns in length between the surface of the epithelium and the loose meshlike plexus of the olfactory border. A second receptor type was also frequently observed in which the surface area was increased through microvilli. These variations in the structure of the receptors are discussed with regard to new immunohistochemical results. Further experiments should determine the relationship of local morphological differences.

Animals↗
PubMed1988

[Meningioma of the sphenoid bone with involvement of the tympanic cavity].

Meningiomas are the most common benign neoplasms of the central nervous system, while meningiomas involving temporal bone are quite rare. If these tumours originate from the sphenoid they usually infiltrate the middle cranial fossa, the orbit, the cavernous sinus and the internal carotid artery. Only a small number of sphenoidal meningiomas infiltrating the middle ear have been reported so far. In these cases, differentiation from other middle ear diseases, particularly glomus tumour and chronical otitis media, is difficult. In this study the case of a sphenoidal meningioma involving the temporal bone and the middle ear is presented. The importance of computerized tomography and particularly MR tomography in evaluating intracranial and intratympanic meningiomas is discussed.

Biopsy↗