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Biomedical subjects

G Grevers

Publications and source records attributed to G Grevers.

At least 109 records · Page 6Linked to original sources
PubMed1994

Glomus tumors of the skull base: combined use of MR angiography and spin-echo imaging.

PURPOSE: To evaluate the use of magnetic resonance (MR) angiography in the diagnosis of glomus tumors of the skull base. MATERIALS AND METHODS: In 40 patients with pulsatile tinnitus, spin-echo (SE) images, single sections, and maximum intensity projections from gradient-echo sequences, including arterial MR angiography and MR venography, were evaluated for tumor detection. Interpretations by two independent observers were correlated with findings from histologic examination, digital subtraction angiography, computed tomography, and clinical follow-up. RESULTS: Glomus tumors were detected near the tympanic plexus (n = 8) and close to the superior (n = 8) and inferior (n = 1) ganglia of the vagus nerve. Sixteen of 18 proved tumors were detected with SE images alone. Although four high-lying jugular bulbs were misinterpreted as tumor due to similar signal intensity, combined evaluation allowed differentiation between tumor and sinusal blood flow in all cases. CONCLUSION: The authors recommend combined SE imaging and MR angiography for ruling out tumor in patients with pulsatile tinnitus.

Adult↗
PubMed1994

Electron-microscopic observations on the muscular coat of swell bodies in human nasal mucosa.

Morphology and function of so-called nasal "swell bodies" or "cavernous tissue" have been studied by many investigators during the past 140 years. However, many details of this interesting and peculiar tissue remained unsolved, even though this vascular system plays an important role in a variety of rhinologic disorders. The present study describes electron-microscopic details of the muscular coat of the different venous structures that form human nasal swell bodies. The specimens were taken from patients requiring removal of conchal mucosa and septoplasty; semithin and ultrathin sections were obtained and examined with the optical and electron microscopes. The histologic evaluation showed differences in the venous wall structure depending on the location of the vessels. The muscular layers were significantly thinner in those parts of the swell bodies located adjacent to the epithelium. Electron-microscopic studies enabled us to determine the cytoplasmic components of smooth muscle cells, i.e., thin filaments, glycogen granules, caveolar plasmalemmal areas, cytoplasmic dense bodies (CDB), and membrane-associated dense bodies (MADB). Another interesting feature was the varying appearance of the basal lamina of smooth muscle cells of the cavernous tissue. Based on the findings of the present study, the morphologic peculiarities of nasal swell bodies are compared and discussed with the appropriate literature. Further immunohistochemical and molecular-biological studies will have to be performed to understand the complex functional mechanism of this unique vascular system.

Endothelium, Vascular↗
PubMed1994

MR diagnosis of head and neck tumors: comparison of contrast enhancement with triple-dose gadodiamide and standard-dose gadopentetate dimeglumine in the same patients.

OBJECTIVE: The purpose of this study was to compare the relative values of MR images obtained with a triple dose of gadodiamide and MR images obtained with the standard dose of gadopentetate dimeglumine for the detection and determination of the extent of tumors of the head and neck. MATERIALS AND METHODS: Forty-two patients with benign and malignant tumors of the head and neck were examined with contrast-enhanced MR imaging in a comparison of a triple dose of gadodiamide (0.3 mmol per kilogram body weight) and a standard dose (0.1 mmol per kilogram body weight) of gadopentetate dimeglumine. All patients underwent MR imaging with both doses of contrast material. Contrast-to-noise ratios and the percentage enhancement of normal and abnormal structures were calculated, and delineation of the lesion and the contrast between tumor and surrounding tissue were evaluated visually. RESULTS: Statistical analysis (Friedman test and Wilcoxon test) of the contrast-to-noise ratios between tumor and white matter, the percentage enhancement, and the visual assessment rating revealed a statistically significant superiority of the triple dose of gadodiamide over the standard dose of gadopentetate dimeglumine. Tumor/muscle contrast-to-noise ratios were not significantly different with the two doses. The detection rate for tumors was no better with the triple dose of gadodiamide than with the standard dose of gadopentetate dimeglumine. CONCLUSION: Use of the triple dose of gadodiamide results in a statistically significant improvement in the visual assessment rating, but it does not increase the number of tumors detected on MR images over the number detected with the standard dose of gadopentetate dimeglumine and does not appear to alter the differential diagnosis.

Contrast Media↗
PubMed1994

[Magnetic resonance applied to the diagnosis of Sjogren disease].

In order to characterize typical MRI-findings in patients with Sjögren's syndrome who present recurrent parotid swelling 15 patients with clinical diagnosis of this disease were examined in a prospectives study. Most of the patients showed bilateral enlarged glands with an inhomogeneous, nodular pattern. The signal intensity was very high, especially in the T2 weighted sequences.

Adult↗
PubMed1993

[Magnetic resonance angiography--a new procedure for vascular imaging in the area of the head-neck].

Some six or seven years ago, digital subtraction angiography (DSA) was introduced as a new diagnostic tool in the evaluation of vascular lesions. In the diagnostic management of vascular disorders in the head and neck, DSA could replace conventional angiography almost completely. Now, a new angiographic technique has been developed--magnetic resonance angiography (MRA). In the present study 60 patients with vascular lesions of head and neck were examined with both DSA and MRA in order to compare the diagnostic value of these techniques. Our results indicate that MRA is at least equivalent in the evaluation of vascular disorders in head and neck region. In addition, the advantages of MRA compared to DSA are the following: (1) MRA is a non-invasive technique, thus reducing the angiographic risk. (2) MRA offers the possibility of multiplanar imaging. (3) MRA can be performed simultaneously with MRI if necessary. (4) Compared to other angiographic techniques the patient will not be exposed to radiation.

Angiography, Digital Subtraction↗
PubMed1993

[Reliability of diagnostic procedures in facial paralysis with special reference to magnetic resonance tomography].

Facial nerve palsy is commonly examined using a variety of topodiagnostic and electrophysiological tests. More recently, MRI has also been used to study lesions of the facial nerve. Due to varying time intervals between the onset of symptoms and clinical examination, however, the diagnostic value of these procedures remains limited. In the present study, 30 patients with facial nerve palsy of diverse origin were examined with MRI (1.5 Tesla magnetom) using a special surface coil and 30 degrees parasagittal slices of 3 mm thickness. These special modifications enabled us to visualize the nerve in its entire course through the temporal bone. After the application of Gd-DTPA the enhancement of the contrast medium could be verified in all cases. A moderate enhancement in the geniculate ganglion as well as in the labyrinthine segment correlated with a good prognosis in terms of complete restoration of facial nerve activity, while an increased enhancement correlated with a poor prognosis. Our results indicate that MRI is of superior diagnostic value as compared to clinical and electrodiagnostic tests, at least in the patients we examined in this study. Still, further evaluations are necessary to justify a possible routine clinical use of this procedure.

Blood-Brain Barrier↗
PubMed1993

Skull base tumors: gadodiamide injection--enhanced MR imaging--drop-out effect in the early enhancement pattern of paragangliomas versus different tumors.

A phase III trial was conducted in 40 patients with known or suspected skull base tumors to evaluate the safety and efficacy of high-dose gadodiamide injection for use as a paramagnetic contrast medium in conventional and dynamic magnetic resonance (MR) imaging. Contrast material enhancement was assessed dynamically with use of a gradient-recalled sequence. The time-intensity curve of selected regions of interest showed a reproducible dropout effect in the form of a dip in the curve during the early enhancement of the sigmoid sinus and jugular bulb; the same phenomenon was observed in all glomus tumors of the skull base, regardless of size or location. In contrast, schwannomas, meningiomas, and a variety of other lesions showed a continuous increase in the time-intensity curve. The drop-out sign, which is probably a result of a paramagnetic phenomenon during the early phase of enhancement, seems to be specific for glomus tumors. High-dose gadodiamide injection may show a specific dynamic pattern for glomus tumors, allowing differentiation from other tumors of the middle and posterior skull base.

Drug Combinations↗
PubMed1993

The role of fenestrated vessels for the secretory process in the nasal mucosa: a histological and transmission electron microscopic study in the rabbit.

Both nasal glands and nasal vessels are supposed to be responsible for the humidification of inhaled air. After previous studies on the vasculature of the nasal septal mucosa in the rabbit, we examined vessels of the anterior concha in order to find a morphological equivalent to explain the role of endonasal vasculature in the secretory process of this tissue. The main findings of our study include the detection of fenestrated endothelial walls of both capillaries and venous sinuses located underneath and directly adjacent to the basal cell layers of the epithelium. The same phenomenon-fenestrated vessels underneath the epithelium with the fenestrated parts facing the epithelial cells-has been described in other parts of the body and has been called "polar differentiation." In accordance with the interpretations of other authors, we conclude that these features are responsible for the regulation of endonasal fluid exchange.

Animals↗
PubMed1993

Cystic masses in the floor of the mouth: value of MR imaging in planning surgery.

OBJECTIVE: The purpose of this study was to determine the value of preoperative MR imaging for planning the best surgical approach for excising cystic masses in the floor of the mouth. In addition, different sequences and slice orientations were compared in order to develop a standard MR examination technique for this purpose. SUBJECTS AND METHODS: Eleven patients with cystic masses in the floor of the mouth were prospectively examined with MR imaging after palpation and sonography. The imaging protocol included T1- and T2-weighted spin-echo sequences, both unenhanced and contrast enhanced. The exact topographic relationship of these cysts to the surrounding muscles and the value of different MR techniques were analyzed. RESULTS: The mylohyoid muscle, which serves as a key structure in determining the exact position of a cystic mass, was visualized in all cases. T2-weighted images facilitated the primary diagnosis of cystic lesions, whereas T1-weighted images allowed the best visualization of anatomic details. Use of gadopentetate dimeglumine did not provide significant diagnostic information. Coronal and axial slices provided the best visualization of the topographic relationship of cyst and muscles. Sagittal slices were helpful only for midline lesions. In two cases, the choice between the intraoral and the cervical surgical approach was altered by MR imaging findings. CONCLUSION: MR imaging facilitates exact visualization of the location and extent of cystic lesions in the floor of the mouth and is useful for determining their relationship to the surrounding muscles. We conclude that MR imaging is an important adjunct to palpation and sonography in planning the best surgical approach.

Adult↗
PubMed1992

[Provocable tumor of the cheek as a manifestation of so-called "infiltrating lipoma" of the masseter muscle].

We report on a 29-year-old male patient, who presented at our outpatient clinic with a 6-year history of progressive swelling of the right cheek. Contraction of the masseter muscle increased the swelling. MR-Imaging revealed a tumor measuring 2 x 3 cm, which was located within the masseter muscle. The histological diagnosis was infiltrating lipoma, which to our knowledge has not been described in this area before. This particular type of lipoma is extremely rare in the head and neck. The diagnostic and therapeutic management of infiltrating lipoma is discussed, and guidelines for adequate follow-up suggested. In addition, the authors review other sites of this tumor and describe its histological characteristics and differential diagnosis.

Adult↗
PubMed1992

[Magnetic resonance tomography in questionable lesions of the ENT area. Examination technique and results of a prospective study of 1,493 patients].

1493 patients with various lesions in the head and neck region were prospectively evaluated with MR imaging (MRI) and other imaging modalities. The findings of MRI and conventional imaging techniques were correlated with histological findings. All MRI examinations were carried out on a 1.0 and 1.5 Tesla superconducting MR unit employing combined T1 and T2 weighed spin-echo sequences. Dynamic MRI with fast gradient-echo sequences and application of a paramagnetic contrast agent (Gd-DTPA) was additionally performed in 120 patients. 250 patients were examined with non-invasive MR angiography. Appropriate saturation enabled the visualization of either arterial or venous vascular structures. Analysis of metabolic parameters and tumor proliferation was possible through in-vivo spectroscopy in 60 patients. Highest values for specificity and sensitivity of MRI were achieved in the area of the skull base and petrous bone. In comparison to other imaging modalities, the exact differentiation of pathological alterations such as neurinoma, meningioma and glomus tumors succeeded with high accuracy. In the region of the naso- and oropharynx, plain MRI revealed in 77% of the cases adequate diagnostic information, which could be significantly increased with application of the paramagnetic contrast agent Gd-DTPA. Due to multiplanar slice orientation and improved soft tissue differentiation MRI proved to be superior to other imaging techniques in salivary glands and in the region of the neck. As a conclusion, the advantages of MRI are the depiction and visualization of small infiltrations as well as the high sensitivity and specificity of this imaging modality.

Diagnosis, Differential↗
PubMed1992

[The diagnostic value of nuclear magnetic resonance tomography in Sjögen's disease].

Sjögren's syndrome is characterised by xerostomia, xerophthalmia and recurrent parotid swelling. There is a high coincidence with rheumatoid diseases. A variety of clinical and laboratory parameters offers important information for diagnosis, but none of them is specific for this disease. 36 patients with clinical diagnosis of Sjögren's syndrome were examined in a prospective study to evaluate the diagnostic significance of this technique. 34 patients showed an inhomogeneous, nodular pattern in the parotid gland. The signal intensity was very high, especially in the T2-weighted sequences. There was a significant correlation of the radiologic changes with the course of the disease. Four patients with the clinical diagnosis of sialadenosis demonstrated bilateral enlarged glands with a homogeneous signal pattern. Patients with acute purulent parotitis demonstrated enlargement of the gland without an alteration in the signal pattern. Patients with chronic recurrent parotitis and patients with radiogenic sialadenitis showed little inhomogeneous increase of signal intensity. Our results indicate that MRI is presently the radiological method of choice in the evaluation of Sjögren's syndrome.

Abscess↗
PubMed1992

[Differential diagnosis of cervical space occupying lesion: the parapharyngeal rhabdomyoma].

A case of a parapharyngeal rhabdomyoma is presented. Only about 30 cases of this benign tumor of striated muscles are reported in the literature. Most tumors were located in the lateral cervical region. Histologically a rhabdomyoma must be distinguished from other mesenchymal tumors, especially from granular cell myoblastoma, hibernoma and reticulohistiocytoma. The value of magnetic resonance imaging in the radiological evaluation of parapharyngeal masses is emphasized. Operative resection is generally regarded as the therapy of choice. Local recurrences have been reported in some cases; malignant degeneration is not known.

Contrast Media↗
PubMed1992

[Chronic recurrent parotitis in childhood].

Juvenile recurrent parotitis (j.r.p.) is distinguished from the adult form by the course of the disease, therapeutic considerations and prognosis. Children suffering from j.r.p. are between 2 and 15 years of age; the male: female ratio is 1.5:1. In the present paper the author describes the different pathogenic theories of j.r.p. in accordance with the relevant literature. Besides malformation of the glandular duct like stenosis and ectasis, functional factors like the character of salivary secretion are suspected as being responsible for the disease. Other authors assume that a viral genesis, allergic factors, a physiological immaturity of the immune response, or family history may be the causes. In the evaluation of children with j.r.p. the patients' history with recurrent swelling episodes of the parotid gland(s) followed by quiescent periods is indicative. Further procedures like ultrasonography, sialography and MRI are discussed according to their diagnostic value. Therapeutic possibilities include antibiotics in the acute stage of the disease as well as parotidectomy in severe cases. Radiotherapy cannot be recommended because of its side effects (facial dysplasia, tumour induction). In most cases, the disease ends at puberty.

Child↗
PubMed1992

[MR angiography for tumor diagnosis in the head-neck region: the study technic and clinical results].

40 normal individuals and 153 patients with lesions in the head and neck were examined by conventional imaging methods and by means of MR angiography (1.5-tesla Magnetom). The problems to be solved concerned the relationship between tumors and vessels and vascular anomalies and abnormalities at the skull base (56 cases), the facial skeleton (62 cases) and the neck (35 cases). Digital subtraction angiography was performed in 54 patients and the findings correlated with MR angiography. Optimal results were obtained by using a FISP 3D sequence; in this way arterial structures could be rendered reproducibly down to a diameter of 2 mm. The venous system in the head and neck was best shown by a FLASH 2D sequence. Correlation with arterial DSA showed high accuracy of MR angiography (91%) concerning displacement of vessels, the topography and the recognition of vascular occlusions. Our results indicate that MR angiography is a rapid and reliable procedure for evaluating the arterial and venous changes due to tumors in the head and neck region.

Angiography, Digital Subtraction↗
PubMed1992

[The clinical value of magnetic resonance tomography in cystic space-occupying lesions of the mouth floor].

11 patients with cystic lesions of the floor of the mouth were examined by MR imaging. Coronal slices provided an optimal visualisation of the lesions, but axial and sagittal slices added important information with regard to the exact topographic relationship between tumour and muscles. In particular, the mylohyoid muscle could be defined as a key structure. T1-weighted sequences enabled best visualisation of anatomic details, whereas T2-weighted sequences facilitated the primary diagnosis of cystic lesions. The contrast agent Gd-DTPA did not add information of significant diagnostic value. Our results indicate that MRI allows an exact visualisation of location and extent of cystic lesions and their relationship to surrounding muscles. We conclude that MRI is of high value in planning the operative strategy.

Cysts↗