Biomedical subjects

J Lissner

Publications and source records attributed to J Lissner.

At least 19 recordsLinked to original sources

PubMed1992

[MR angiography in neuropediatric problems: the technic and the clinical results].

31 children aged between 6 months and 14 years with various neurovascular abnormalities were examined by MR angiography in a prospective study. In order to test the sensitivity and specificity of the MR results, these were compared in 8 cases with the findings of digital subtraction angiography or conventional angiography. In 24 patients arterial MR angiography was performed; in 17 these showed anomalies or abnormalities of the intracranial vascular system. In 7 patients venous MR angiography was performed and demonstrated the presence of sinus thrombosis in 6 of these. Comparison between MR angiography and DSA showed agreement in 7 cases; in one patient the degree of a stenosis was exaggerated by MR. The results of this study indicate that arterial and venous MR is of great value as an additional study in paediatric neurovascular problems.

Angiography, Digital Subtraction↗

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

[Pre- and postoperative NMR tomographic studies in avascular femur head necrosis].

46 patients with avascular necrosis of the femoral head were examined by T2- and T1-weighted MR before and after infusion of Gd-DTPA. Both sides were involved in 12 cases. The classification was done according to Ficat. In early stages and in postoperative studies a correlation of signal intensity after infusion of Gd-DTPA and clinical symptoms was found. Hyperintensity of the avascular area or of the implanted material was assumed to be vascularised or vital components in 4 cases of Ficat I and in 15 postoperative studies. Contrariwise, we found in 5 patients with severe postoperative symptoms, low signal intensity areas due to avascular regions.

Contrast Media↗

PubMed1992

[NMR tomography of the liver with the new contrast agent Gd-BOPTA. The results of an in-vivo phase-I test].

A phase 1 study on 8 normals has been carried out to determine the effectiveness and safety during MRI of a new hepatobiliary contrast medium Gd-BOPTA for causing enhancement of the upper abdominal organs. Gradient echo sequences (flash), T1 and T2-weighted spin echo sequences and turbo-flash sequences were used. The contrast medium was given as a single infusion in various concentrations (0.005, 0.05, 0.1, and 0.2 mmol/kg body weight). Optimal contrast of liver parenchyma was obtained with a dose of 0.05-0.1 mmol/kg body weight, resulting in contrast increase of 149.1% during gradient echo sequences and 107.8% during T1 spin echo sequences. In general, the increased contrast lasted for about two hours. Because of the biliary and renal excretion there was an enormous increase in signal intensity of the bile ducts and a significant increase in the kidneys and ureters. The results of the first in-vivo trial of Gd-BOPTA encourages the performance of further clinical studies of this new hepatobiliary contrast medium.

Acetates↗

PubMed1992

[The proton MR spectroscopy of intracranial tumors. The differential diagnostic aspects for gliomas, metastases and meningiomas].

Twenty-two patients with intracranial tumours were examined by MR images and in vivo proton-MR-spectroscopy. The changes of relative concentrations of NAA, PCr/Cr, Cho, and Ins were measured spectroscopically and the amount of these metabolites were related to different tumour groups. Analysis of the results has shown that the spectra from all the tumours differed from normal spectra. All cerebral tumours showed marked reduction of the Pcr/Cho quotient and the NAA/Cho quotient was also reduced. The Ins/Cho quotient for meningiomas and metastases was also lower than in normals; in gliomas of low malignancy the quotient was slightly raised and in gliomas of greater malignancy it was significantly higher than normal. The spectra of cerebral metastases showed unusual high lipid signals of 0.9 ppm and 1.25 ppm. The only common feature for meningiomas was marked reduction of NAA concentration. In summary, localised in vivo proton-MR-spectroscopy can be used clinically to obtain valuable information for the differential diagnosis of gliomas and intracerebral metastases.

Brain Neoplasms↗

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↗

PubMed1992

[Magnetic resonance tomography and magnetic resonance angiography in lymphangiomatosis].

Generalised lymphangiomatosis is a rare benign congenital abnormality of the lymphatic vessels with a complex pattern. 3 patients with different types of lymphangiomatosis were studied by MRT and MRA and histopathologically. All patients had multiple organ involvement in the abdomen, the skeleton and the skull. The basis in each case was lymphangiomatosis of capillary-cavernous, cystic or cavernous type. The results of MRT and MRA in diagnosing splenic, vascular and skeletal changes correlated accurately with operative findings and with the histopathological classification. In summary, MRT combined with MRA and using paramagnetic contrast media are the diagnostic methods of choice for the investigation of generalised lymphangiomatosis with multiple organ involvement.

Abdomen↗

PubMed1992

Focal liver lesions: MR imaging with Mn-DPDP--initial clinical results in 40 patients.

Manganese (II) N,N'-dipyridoxylethylenediamine-N,N'-diacetate-5,5'-bis(phosphate) (DPDP) was evaluated as a contrast agent for magnetic resonance (MR) imaging (1.5 T) of focal liver lesions in 40 patients. Doses of 5 and 10 mumol/kg were administered intravenously. Mn-DPDP-enhanced T1-weighted images were compared quantitatively and subjectively with standard T1- and T2-weighted nonenhanced images. Use of Mn-DPDP resulted in a statistically significant increase in signal intensity of liver parenchyma in T1-weighted images at both doses. No enhancement was seen in metastases, cholangiocarcinomas, or lymphomas, while all hepatocellular carcinomas were enhanced. Enhancement was seen in focal nodular hyperplasia and in regenerative nodules. The lesion-to-liver contrast in Mn-DPDP-enhanced gradient-recalled-echo images was superior to that of all precontrast images (P less than .01). The number of nonenhancing malignant liver lesions detected in spin-echo (SE) images was increased (272 in T2-weighted SE images vs 390 in T1-weighted Mn-DPDP-enhanced SE images). Image interpretation (eg, visualization and demarcation of the lesions) was markedly better in Mn-DPDP-enhanced images than in all precontrast images (P less than .001).

Adult↗

PubMed1992

Gadobenate dimeglumine--a new contrast agent for MR imaging: preliminary evaluation in healthy volunteers.

Gadobenate dimeglumine (formerly known as Gd-BOPTA) is a recently developed paramagnetic contrast agent that undergoes biliary as well as renal excretion. It may, therefore, be useful in MR imaging of the liver. Its safety, tolerance, and usefulness in visualizing hepatobiliary structures were studied in eight healthy subjects. Axial abdominal images were obtained with T1-weighted spin-echo and gradient-echo sequences at 1.5 T before and after IV administration of gadobenate dimeglumine in doses of 0.005, 0.05, 0.1, and 0.2 mmol/kg body weight. Two subjects received each dose. Administration of 0.1 mmol/kg resulted in a maximum liver enhancement of 149% on the gradient-echo sequence and of 90% on the T1-weighted spin-echo sequence 60 min after injection. The contrast enhancement of the liver remained virtually constant for 2 hr. The signal-to-noise ratio of the biliary tract increased from 38 to 121 after 2 hr on gradient-echo images. In addition, there was significant contrast enhancement of the kidneys. Optimal visualization of the liver parenchyma was achieved with doses of 0.05 and 0.1 mmol gadobenate dimeglumine/kg. Mild to moderate side effects such as nausea and retching, a sense of warmth at the infusion site, and transient pruritus lasting 1 min were reported by three (38%) of the subjects. The initial results of the first application of gadobenate dimeglumine in humans are encouraging because the contrast agent appears to be reasonably well tolerated at the doses appropriate for hepatobiliary imaging. Further clinical studies of this contrast agent are warranted to assess its effect on liver lesion conspicuity and the frequency with which side effects occur.

Acetates↗

PubMed1992

MR angiography in children with cerebral neurovascular diseases: findings in 31 cases.

OBJECTIVE: We evaluated the suitability of MR angiography for routine use in children with suspected intracranial vascular disease. SUBJECTS AND METHODS: Thirty-one children, 6 months to 14 years old, with intracranial lesions or clinically suspected vascular malformations were studied prospectively with conventional MR imaging and time-of-flight MR angiography. In nine cases, MR angiographic findings were verified with digital subtraction angiography or conventional angiography. All MR studies were performed on a 1.5-T MR system using a circularly polarized head coil. RESULTS: Arterial MR angiography, performed in 24 cases, revealed congenital abnormalities of the arterial vessels in 20 cases. Vessel stenosis was observed in nine patients, and displacement of intracranial arteries due to tumors could be seen in 10 patients. Seven children had no abnormal findings. Venous MR angiography was performed in seven children, with depiction of sinus thrombosis in six cases. The comparative analysis of MR angiography and digital subtraction angiography showed equivalent results in nine patients; in one patient the degree of stenosis was overestimated with MR angiography. CONCLUSION: MR angiography, when combined with MR imaging, reveals information about soft-tissue and vascular structures in a single setting. At this point, MR angiography can replace invasive conventional angiography or digital subtraction angiography only in selected cases because of software and hardware limitations. Arterial or venous MR angiography can be helpful as an additional scan in MR examinations of children with suspected cerebral neurovascular diseases, and its noninvasive nature makes it well suited for routine use in children.

Adolescent↗

PubMed1992

[Magnetic resonance tomography of the hepatobiliary system: indications, limitations and outlook].

In a prospective study we examined the diagnostic value of MRI and MR cholangiography (MRC) in patients suffering from hepatobiliary disease. By using hepatobiliary contrast media (Mn-DPDP, Gd-BOPTA), sensitivity and specificity of MRI were significantly increased. In 65 patients we comparatively analyzed the diagnostic results of MRI and MRC versus ultrasound, CT and invasive techniques such as ERCP. We conclude that the use of MRI and MRC improves the diagnostic evaluation of patients with hepatobiliary disease.

Biliary Tract Diseases↗

PubMed1992

[Results of photon therapy of malignant tumors of the parotid gland].

Between 1971 and 1982 86 patients have been treated because of a malignant tumor of the parotid gland. 64 patients have been irradiated after complete (n = 49) or incomplete (n = 15) first resection. 12/64 (19%) relapsed locally. The loco-regional tumor control rate five and ten years after postoperative radiotherapy is 72%, 85% after complete resection, and 22% after incomplete resection (p less than 0.01). Tumor size and nodal disease are of prognostic value. Disease-free survival in patients without lymph nodes is 53%, with lymph node metastases 31% after five years (p less than 0.05). Small tumors (T1, 2) have a better local control rate compared to locally advanced tumors (five years: 83% vs. 53%, p less than 0.05). No difference was found neither for the total dose nor the histology of the tumor. Distant metastases became apparent after median eleven months.

Adenocarcinoma↗

PubMed1991

MRI in tracheal stenosis by innominate artery in children.

Pediatric airway obstruction due to anomalies of the course of the innominate artery may produce respiratory distress. MR imaging of the trachea was performed after bronchoscopy on forty-one children with congenital tracheal stenosis. Bronchoscopy only allows the evaluation of the lumen of the trachea, and the degree and location of collapse, and it may be difficult to determine the etiology of the tracheal narrowing. In eighteen out of the forty-one patients MR imaging showed a compression of the trachea by the innominate artery. The MR imaging diagnoses were subsequently compared for accuracy with the diagnoses determined by direct surgical observations. MR imaging of the trachea, the surrounding tissue and vessels allows the evaluation of the cause of tracheal compression and the degree and location of collapse. For evaluation of the cause of airway obstruction. MRI is an ideal method depicting detailed anatomic structure without employing ionizing radiation or intravenous contrast medium.

Brachiocephalic Trunk↗

PubMed1991

[Magnetic resonance tomography of the oropharynx and oral cavity with Gd-DTPA. An optimized study technic and its diagnostic value].

In the evaluation of space-occupying lesions of the oropharynx it is necessary to perform modern imaging methods, such as magnetic resonance imaging additionally to clinical and endoscopical methods. 126 patients were examined using T1-weighted (TR = 500 ms, TE = 25 ms) and T2-weighted (TR = 3000 ms, TE = 25/90 ms) spin-echo-sequences before and after i.v. application of Gd-DTPA. Superficially growing lesions of stage T1 could not be delineated from isointense mucosa. The preoperative staging of T2-T4 lesions can be markedly improved by using T1- and T2-weighted sequences in combination with Gd-DTPA. MR imaging with Gd-DTPA is recommended as the primary diagnostic tool for diagnosing lesions in the region of the oropharynx.

Adenoma↗

PubMed1991

[Diffuse liver parenchymal diseases: the value of MRI compared to sonography and CT].

29 patients with diffuse liver disease were examined by ultrasound, CT and MRI. MRI imaging was performed using T1-and t2-weighted spin-echo-sequences and fast gradient-echo-sequences. The paramagnetic contrast agent Gd-DTPA was applied intravenously (0.1 mmol/kg). In all patients with hepatitis MRI enabled exact liver biopsy by delineation of inflammatory changes in cases of chronic or focal hepatitis. CT and ultrasound were superior to MRI in the detection of focal or diffuse fatty degeneration. However, MRI enabled an exact differentiation of fatty changes from neoplasm. In cases of fibrotic changes the most accurate findings could be shown by MRI. In patients suffering from hemochromatosis MRI supplied additional information compared to CT and ultrasound revealing significant reduction of signal intensity due to reinforced enhancement of iron. Concerning Wilson's disease MRI showed a characteristic pattern of parenchymal changes. The application of Gd-DTPA in cases of diffuse liver disease adds supplementary information about perfusion of liver parenchyma, but its value for diagnostic accuracy is only secondary.

Contrast Media↗

PubMed1991

[NMR tomographic diagnosis with Gd-DTPA in HIV-associated diseases in the head-neck area].

In a prospective study 21 patients suffering from HIV-1 infection underwent MR imaging. The following tumours were found: eight Kaposi's sarcomas, four lymphomas, two squamous-cell carcinomas, and three cases of lymphoid hyperplasia. Furthermore, three cases with lymphoepithelial cysts and one case of inflammatory changes of the parotid glands were studied. Optimal diagnostic results were obtained by using T1- and T2-weighted sequences plain and Gd-DTPA enhanced. Different signal intensities enabled the differentiation of lesions such as inflammation, lymphomas and lymphoid hyperplasia. Besides clinical examination modalities, MR imaging proves to be an important tool in investigating solid, cystic or inflamed processes in HIV-positive patients in the head and neck area.

Carcinoma, Squamous Cell↗

PubMed1991

[The clinical value of Mn-DPDP: a new paramagnetic hepatobiliary contrast medium for magnetic resonance tomography of the liver].

In an open prospective study the tolerance and diagnostic value of the new hepatobiliary contrast agent Mn-DPDP in MR imaging was evaluated in 20 patients suspected of having focal liver lesions. T1- and T2-weighted spin-echo sequences and T1-weighted gradient-echo sequences were obtained before and after intravenous application of Mn-DPDP. In all patients the signal to noise (S/N) values of normal liver tissue increased significantly after application of Mn-DPDP. All focal lesions could be better localized and differentiated due to increased contrast to noise ratios of lesion to liver. Pathological examination revealed in 14 patients malignant and in 5 patients benign liver lesions; one patient had no pathological findings. In metastatic disease of the liver 25-120% more lesions could be detected in MRI after Mn-DPDP-application, compared with the unenhanced images. In 5 patients the lesions showed significant enhancement of Mn-DPDP (2 cirrhotic nodules, 2 hepatocellular carcinomas, 1 focal nodular hyperplasia). Our preliminary results indicate that Mn-DPDP is a well-tolerated contrast agent useful for the detection and differentiation of liver lesions in MR imaging.

Adult↗

PubMed1991

Influence of magnetic resonance imaging on evoked potentials and nerve conduction velocities in humans.

The authors investigated the influence of a 1.0-T magnetic field of a magnetic resonance (MR) imaging device, as well as the possible effects of the changing magnetic field and the RF field, on somatosensory, visual, and auditory evoked potentials and on peripheral nerve conduction velocities. The neural potentials outside and inside the static magnetic field were recorded before and after MR imaging. The measured latencies before and after MR imaging were within the normal range for healthy volunteers. The magnetic field did not significantly alter central or peripheral conduction velocities.

Adult↗