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H Schild

Publications and source records attributed to H Schild.

At least 109 records · Page 6Linked to original sources
PubMed1998

[Magnetization transfer contrast imaging (MTC): its fundamentals, technics and applications].

Using magnetisation transfer (MTC), a new contrast could be achieved on magnetic resonance images (MRI). Two different techniques are available to produce MTC: on- and off-resonance technique. Basic physics of MTC and the two techniques are extensively described in this review article. Potential advantages in using MTC are imaging of cartilage, multiple sclerosis and MR angiography. Particularly the detection of contrast media enhancing brain lesions were improved using MTC. Early cartilage degeneration could be visualised with improved contrast on MTC images. This article gives an overview of potential and accepted applications.

Animals↗
PubMed1998

[Magnetization transfer contrast (MTC)--which is the most MTC-sensitive MRI sequence?].

PURPOSE: This study aimed at evaluating MTC-sensitivity of frequently used MR-sequences. MATERIAL AND METHODS: 7 sequences (T1-, T2-, PD-weighted SE, four gradient-echo sequences) were combined with a 4 element on-resonance MT-Pulse at 0.5 Tesla (T5, Philips medical systems). The measurements were performed at a knee joint and MT-ratios of cartilage, muscle, fat and a copper sulfate phantom were calculated. RESULTS: Proton density weighted gradient and to a lesser degree spin-echo sequences were superior to T1- and T2-weighted sequences in visualising the MT effects. CONCLUSION: It is important to choose an appropriate MR-sequence for MTC experiments. Proton-density gradient echo sequences are recommended for that purpose. T1- and T2-weighted SE sequences should be avoided.

Adipose Tissue↗
PubMed1998

[Radiation exposure of radiation-sensitive risk organs--ocular lens, parotid gland, thyroid gland--in dacryocystography and therapy].

PURPOSE: Evaluation of radiation dose to the radiosensitive head and neck organs and tissues-ocular lens, parotid and thyroid glands--during dacryocystography and fluoroscopy--guided dacryocystoplasty (DCP). METHOD: Radiation dose was determined in an Alderson Rando phantom and in 13 patients. Radiation dose was measured directly using Ca-F2-thermoluminescent dosimetry crystals (TLD) which were placed on each eyelid, parotid gland and thyroid gland. RESULTS: The mean radiation dose to the lens placed next to the path of radiation was 6.58 mGy in the Alderson-Rando phantom and 5.43 mGy in patients during DCP. The mean radiation dose to the contralateral lens was 1.37 mGy and 1.7 mGy to the parotid gland placed next to the x-ray tube. Radiation dose to the thyroid gland was max. 0.4 mGy during DCP. CONCLUSION: Radiation dose to the ocular lens, parotid gland and thyroid gland during fluoroscopy-guided DCP was 25 times higher than during diagnostic dacryocystography. The radiation dose to radiosensitive head and neck organs and tissues during fluoroscopy-guided DCP is much below the threshold dose for ocular lens cataract.

Dacryocystitis↗
PubMed1998

[MRI in patients with cardiac pacemakers: in vitro and in vivo evaluation at 0.5 tesla].

PURPOSE: MRI is currently regarded as absolutely contraindicated in patients with implanted cardiac pacemakers. In this prospective study safety and feasibility of MRI in patients with new generation pacemakers (PM) was evaluated in vitro and in vivo. METHODS: 14 PM models in vitro and 18 patients with implanted new generation PM underwent a MRI exam at 0.5 Tesla with standard spin, turbo spin, and gradient echo (FFE) sequences under continuous ECG-monitoring. PM inquiry was performed before and after the MRI exam, including assessment of stimulation thresholds. RESULTS: In the static magnetic field all PM switched to the asynchronous mode due to activation of the Reed switch, resulting in continuous pacing at a fixed rate. In three PM models in vitro, however, after activation of the Reed switch, there was a software-induced switch back to the demand mode. In these PM inhibition and triggering were observed after starting the MRI scan due to influence of the pulsed magnetic fields. PM program changes, damage of PM components, dislocation/torque of the PM and rapid pacing of the PM were observed neither in vitro nor in vivo. Atrial and ventricular stimulation thresholds remained unchanged. CONCLUSION: MRI at 0.5 Tesla should not be regarded as absolutely contraindicated in patients with implanted new generation PM. However, knowledge of the behaviour of the specific PM model in static and pulsed magnetic fields is required, if necessary also changes of the PM program prior to the MRI exam, continuous ECG monitoring and cardiological stand-by.

Contraindications↗
PubMed1998

[Spiral CT and MRT of the operated Stanford-type-A aortic dissection: its course and complications].

PURPOSE: To demonstrate normal postoperative spiral CT and MRI findings and typical complications in patients with aortic repair after Stanford type A aortic dissection. METHODS: 24 patients with aortic repair after Stanford type A aortic dissection were followed up by spiral CT and MRI (0.5 Tesla). Presence of persistent dissection, progressive or new dissection, proximal and distal anastomosis, periprosthetic space, supraaortic vessels, thrombosis and dilatation of the true and false lumen were evaluated. RESULTS: The following postoperative complications were seen: three pseudoaneurysms which developed at the proximal anastomoses of the Dacron prosthesis in two cases and at the insertion site of the reimplanted left coronary artery after implantation of a composite graft (Bentall procedure) in one case; one re-dissection; one perforation of the false lumen; periprosthetic flow in one patient after surgical repair of type A dissection by the graft inclusion technique; progressive dilatation of the false lumen in 4 cases; dilatation of the aortic root in a Marfan patient after replacement of the ascending aorta. CONCLUSION: Precise knowledge of the surgical technique performed is crucial to accurate postoperative imaging evaluation. MRI is the method of choice in the postoperative follow-up of clinically stable patients with aortic dissections.

Aortic Dissection↗
PubMed1998

[MRI, CT and CT arterial portography in the diagnosis of malignant liver tumors in liver cirrhosis].

PURPOSE: To determine the value of magnetic resonance imaging (MRI), computed tomography (CT) and CT arterial portography (CTAP) in detecting malignant liver lesions in cirrhosis patients. MATERIALS AND METHODS: The radiological examinations (CT, MRI and CTAP) of 47 patients suffering from cirrhosis having undergone an orthotopic liver transplantation (OLTX) were analysed retrospectively. The number of detected liver lesions was compared with the results of the histopathological findings after OLTX. RESULTS: 13/21, 11/18 and 7/12 of the malignant lesions were detected by MRI, CT and CTAP respectively. In MRI one false positive case was shown, two in CT and three in CTAP. Almost the same lesions were identified by all three procedures. The examination of the liver with MRI and CT and CTAP did not bring additional information. Most of the lesions that were missed were less than 2 cm in diameter. CONCLUSIONS: The rate of detection of HCC in patients with cirrhosis was about 60%. MRI and CT yielded similar results.

Adult↗
PubMed1998

[Detection of focal lung lesions with magnetic resonance tomography using T2-weighted ultrashort turbo-spin-echo-sequence in comparison with spiral computerized tomography].

PURPOSE: To compare spiral CT and MRT for the detection of focal pulmonary lesions. PATIENTS AND METHODS: 50 patients with focal pulmonary lesions confirmed by spiral CT were examined using a T2-weighted UTSE sequence (TE: 90 ms, TR: 1500-3000 ms, echo interval 9 ms, 8 mm slice thickness, diastolic triggering, expiratory breath gating). Image quality was compared using a 4-stage scale. Lesions with a minimum size of 2 mm were counted and measured in the CT image. The results were compared with the MRT images. RESULTS: The image quality in CT examinations with an average value of 1.22 better than that in MRT (1.78). In total 163 pulmonary lesions with a size of 2-115 mm were found by CT. MRT found 151/163 lesions (92.6%). Of the 12 lesions not detected, 9 were smaller than 4 mm, 1 corresponded to a 12 mm large, completely calcified granuloma. In 2 cases there was a 4 or 5 mm large unspecific scar. Thus, 160/163 (98.1%) of all lesions larger than 3 mm were detected. CONCLUSIONS: MRT with use of a suitable UTSE sequence is an alternative to CT for the detection of focal pulmonary lesions with a size larger than 3 mm.

Adolescent↗
PubMed1998

[1H MR spectroscopy of the lumbar spine in diffuse osteopenia due to plasmacytoma or osteoporosis].

PURPOSE: To evaluate the role of in vivo 1H MR spectroscopic determination of relaxation times and of fat and water content to differentiate between infiltration of multiple myeloma or osteoporosis in patients with roentgenologic unclear demineralization of the lumbar spine. PATIENTS, MATERIALS AND METHODS: Ten patients each with osteoporotic reduction of bone mineral density (BMD), histologically proven multiple myeloma who showed only diffuse tumor manifestations without tumor compression fractures in the spine, and volunteers were investigated. Osteoporosis was confirmed by dual-energy X-ray absorptiometry (DXA) (Hologic QDR 2000 device, Siemens Medical Systems). The MR investigations were performed with a 1.5 T whole body system (Gyroscan S15/ACS II, Philips Medical Systems). Localized MR spectra from a cubic volume of about 8 cm3 were acquired by the PRESS technique. Chemical shift selective T1 relaxation times were obtained from an IR series, T2 was measured by variation of the interval between the first and the second echo in the volume selection scheme. Statistical analysis was done using the Kruskal-Wallis test and the Mann-Whitney test with the software SPSS. RESULTS: There were highly significant differences in T2 values and fat content between patients with osteoporosis and multiple myeloma. T2 values were decreased in osteoporosis (37 ms and 59 ms vs. 44 ms and 70 ms in plasmocytoma) and fat content was decreased in multiple myeloma (20% vs 31% and 34% in volunteers and osteoporosis). Between volunteers and patients with osteoporosis the differences in the T2 of the fat component was significantly different. CONCLUSIONS: In our preliminary experience MRS is helpful in the differential diagnosis of bony demineralization. It enables a differentiation between osteoporosis and diffuse multiple myeloma. T2 value measurements may be helpful in the diagnostic trial of osteoporosis.

Adult↗
PubMed1998

[MRI diagnosis of right ventricular dysplasia].

PURPOSE: Right ventricular dysplasia (RVD) represents an important cause of sudden death and ventricular arrhythmias in young patients. The aim of this study was to describe diagnostic diagnostic criteria and the MR-tomographie aspects of the disease. METHODS: 34 patients with clinically suspected RVD were examined by 0.5-T MRI (cardiac-gated T1-weighted spin echo sequences and cine gradient echo sequences). RVD was confirmed in 16 patients and ruled out in 18 patients. MR images were evaluated for presence of: 1. right myocardial fatty infiltration, 2. dilatation of the right ventricle, 3. dilatation of the right ventricular outflow tract, and 4. localised right ventricular aneurysm. RESULTS: Right myocardial fatty infiltration was detected by MRI in 11 of 16 patients (69%) with RVD. Dilatation of the right ventricle was seen in 5 patients, dilatation of the right outflow tract in one patient, and localised right ventricular aneurysm in two patients with RVD. CONCLUSIONS: MRI is able to demonstrate fatty replacement of right ventricular myocardium in most cases and plays an important role in the diagnosis of RVD.

Adipose Tissue↗
PubMed1998

Cell lines transfected with the TAP inhibitor ICP47 allow testing peptide binding to a variety of HLA class I molecules.

The immediate early protein ICP47 of the Herpes simplex virus is known to block the human transporter associated with antigen processing (TAP), thereby creating a TAP-deficient phenotype in any human cell transfected with the corresponding cDNA. Exploiting this inhibitory activity, we constructed a selection of human cell lines each co-expressing one of the cDNAs of human leukocyte antigen (HLA) class I alleles HLA-A*1101, A24, A*3101, A*6601, B8 and B*1516, and the cDNA encoding the ICP47 molecule. The cell lines generated showed diminished HLA class I surface expression and the inhibition of the TAP function was confirmed in peptide translocation assays. The addition of specific exogenous peptide ligands restored the expression of the corresponding HLA class I molecules. Thus, the ICP47 transfectants provide us with a tool to closely examine peptide-HLA class I interactions, to confirm HLA class I ligand motifs and to test peptides predicted to bind.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1998

[Aortic rupture and retroperitoneal bleeding im Behcet disease].

Although retroperitoneal hemorrhage is a rather seldom complication of Behçet's syndrome it is in no way unusual. Younger patients in particular those from the eastern Mediterranean or east Asian regions in whom a retroperitoneal hemorrhage or an aneurysm in the aorto-iliaco-femoral flow region has be diagnosed must be considered for the differential diagnosis of Behçet's syndrome. The consequences for the surgeon are resection deep into healthy tissue and in general an appropriately close follow-up with strict avoidance of arterial angiography.

Aorta, Abdominal↗
PubMed1998

[MRI in typical and atypical aortic dissection].

PURPOSE: To determine the value of MRI in typical and atypical aortic dissections. METHODS: MRI investigations on 16 patients with aortic dissections were analysed retrospectively; for 8 patients CT investigations carried out at almost the same time were available for comparison. RESULTS: In all cases the diagnosis of aortic dissection was possible from MRI and CT. If a dissection membrane and a double lumen were present these were detected in all patients by both methods. In three patients with atypical dissections, only an asymmetrical abnormal wall thickening as sole sign for the presence of an aortic dissection was seen. A differentiation between true and false lumen was possible in 16 of 17 MRI investigations and in 5 of 8 CT investigations on the basis of differing blood flow velocities or, respectively, the detection of a thrombus in the false lumen. The relationship of the dissection membrane to the large aortic branches as well as the determination of the branch vessel origin with regard to true or false lumen could be evaluated better with MRI than with CT. CONCLUSIONS: Thus MRI has a significant role in the diagnosis and follow-up of aortic dissections. The advantage in comparison to the alternative spiral CT technique is, in addition to the absence of radiation exposure, the better analysis of the extent of the dissection as a result of the multi-planar slice orientation (especially in the region of the aortic arch and the arch vessel origins) without the necessity to administer iodine-containing contrast media.

Adult↗
PubMed1998

[Diagnosis and therapy of Budd-Chiari syndrome].

PURPOSE: Budd-Chiari syndrome is a fairly uncommon disease in Europe. This often leads to its late diagnosis. The syndrome is characterised by portal hypertension and splanchnic congestion due to obstruction of hepatic venous outflow. This paper describes the treatment of three patients with Budd-Chiari syndrome by interventional therapeutic techniques and discusses alternative treatment modalities. PATIENTS AND METHODS: The first patient presented with veno-occlusive disease and was treated by the placement of a transjugular intrahepatic portosystemic stent-shunt. The second patient showed an occlusion of the major hepatic veins. After percutaneous recanalisation, a stent was placed in the right hepatic vein which remained patient. The third patient had a membranous obstruction of the right hepatic vein which was treated by percutaneous balloon dilatation. RESULTS: In all patients the clinical symptoms resolved completely after treatment and no complications were encountered. CONCLUSIONS: The authors conclude that interventional therapeutic techniques offer a wide variety of possibilities for the treatment of patients with Budd-Chiari syndrome and are safe, effective and relatively inexpensive. However, further studies are required to assess the long-term results and survival rates of these patients.

Adult↗