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Biomedical subjects

H H Schild

Publications and source records attributed to H H Schild.

At least 19 recordsLinked to original sources
PubMed1998

Proton magnetic resonance spectroscopy of the primary motor cortex in patients with motor neuron disease: subgroup analysis and follow-up measurements.

OBJECTIVES: To determine the motor cortex degeneration in patients with amyotrophic lateral sclerosis (ALS) using proton magnetic resonance spectroscopy, and to prove that proton magnetic resonance spectroscopy is suited to monitor the course of disease with follow-up examinations. MATERIALS AND METHODS: We studied 33 patients with ALS whose conditions were diagnosed according to the El Escorial World Federation of Neurology criteria. Nine patients with ALS were followed up for up to 2 years. The control group included 20 healthy volunteers and 4 patients with multifocal motor neuropathy. Proton magnetic resonance spectroscopy determined levels of the brain metabolites N-acetylaspartate (NAA), choline, inositol-containing compounds, glutamate/glutamine, and phosphocreatine. RESULTS: Patients with ALS showed a significant reduction in the NAA-choline (P <.001) and NAA-phosphocreatine (P <.005) metabolite ratios and significantly elevated choline-phosphocreatine (P <.005) ratios compared with controls. Inositol-phosphocreatine ratios were also elevated in case patients, but the increase was less pronounced (P <.05). No differences in glutamate/glutamine-phosphocreatine ratios were detected between case patients and controls. An analysis of subgroups demonstrated less significant differences in NAA-choline metabolite ratios (P<.05), even in patients with pure lower motor neuron syndrome (suspected ALS). No changes in metabolite T1 and T2 relaxation times were observed. Patients with multifocal motor neuropathy showed normal metabolic ratios. Progressive alterations in affected metabolite ratios could be documented in the follow-up examinations. CONCLUSIONS: Spectroscopic changes in the motor cortices of patients with ALS correspond with a reduction in levels of NAA and an elevation in levels of choline and inositol compounds. Since NAA is exclusively expressed in neurons, the observed decrease of NAA reflects neuronal loss or dysfunction. Inositol and choline are associated with plasma membrane metabolism, so the release of these compounds may be related to membrane disorders.

Adult↗
PubMed1998

Indirect MR arthrography: techniques and applications.

Indirect MR arthrography is a relatively new MR technique improving articular and periarticular contrast. It is achieved by injection of paramagnetic MR contrast media intravenously instead of intra-articular injection as in direct MR arthrography. After the injection exercising the joint results in considerable signal intensity increase within the joint cavity. Fat saturated MR sequences then yield arthrographic images. The method is less invasive than direct MR arthrography and first results showed comparable sensitivities and specificities for rotator cuff and glenoid labrum pathology. In this article the technique, established and potential future indications, drawbacks and limitations of the method are reviewed.

Contrast Media↗
PubMed1998

[A rational study of the great abdominal veins using 2D-TOF- and turbo-spin-echo sequences].

PURPOSE: Development of a fast and reliable protocol for the detection and exclusion of abdominal venous thrombosis with an optimised T2-TSE- and 2D-TOF sequence. MATERIAL AND METHOD: Evaluation of the flow-void phenomenon with a flow phantom on a 1.5 and 0.5 Tesla system using different echo times. Examination of 22 patients with suspected abdominal shunt- or abdominal vein-thrombosis with a optimum T2-TSE- and 2D-TOF sequence with a 1.5 or 0.5 Tesla system. Confirmation of thrombosis with contrast-enhanced computed tomography or digital subtraction angiography. RESULTS: The most effective combination of strong flow-void phenomena, signal/noise ratio and scan time was found with the following parameters: TE 120 ms, TR 2000 ms, 5 mm slice gap. In the patient group two complete and two partial thromboses were diagnosed with both sequences. One wrong positive thrombosis occurred in a stenotic anastomosis with the 2D-inflow sequence. CONCLUSION: With optimum parameters the T2-TSE sequence produces a strong "flow-void" phenomenon suitable for "black-blood"-MRA. The use of this sequence alone or in combination with 2D-inflow MRA, if "bright-blood" MRA is recommended, allows a reliable evaluation of thrombosis in abdominal veins without high-tech MRA equipment and contrast media.

Abdomen↗
PubMed1998

[31P-mr spectroscopy of peripheral skeletal musculature under load: demonstration of normal energy metabolites compared with metabolic muscle diseases].

PURPOSE: 31P-MR spectroscopy of skeletal muscle under exercise was used to obtain the range of normal variation and comparison was made for different neuromuscular diseases. METHODS: 41 examinations of 24 volunteers and 41 investigations in 35 patients were performed on 1.5 T MR systems (Gyroscan 515 und S15/ACSII, Philips). Localised 31P-MR spectra of the calf muscle were obtained in time series with a resolution of 12 s. RESULTS: Two types of muscle energy metabolism were identified from the pattern of spectroscopic time course in volunteers: While the first group was characterised by a remarkable decline to lower pH values during exercise, the second group showed only small pH shifts (minimum pH: 6.48 +/- 0.13 vs 6.87 +/- 0.07, p < 10(-6)) although comparable workload conditions were maintained. The pH-values correlated well with blood lactate analysis. Patients with metabolic disorders and chronic fatigue syndrome (CFS) showed decreased resting values of PCr/(PCr + Pi) and increased pH levels during exercise. PCr recovery was significantly delayed (0.31 vs 0.65 min-1, p < 0.00005) in metabolic muscle disorders but was normal in CFS patients. CONCLUSION: Findings in volunteers indicate utilisation of different metabolic pathways which seems to be related to the fibre type composition of muscle. Reduced resting levels for PCr/(PCr + Pi), altered pH time courses, and decreased PCr recovery seem to be helpful indicators for diagnosis of metabolic muscle disorders.

Carbohydrate Metabolism, Inborn Errors↗
PubMed1998

[TIPSS: technical and clinical results after 4 years].

PURPOSE: Retrospective analysis of the technical and clinical results after transjugular portosystemic stent shunt (TIPSS) procedure. METHOD: Between 1992 and 1996 we tried to establish a TIPSS in 90 patients. The indications were: recurrent variceal haemorrhage (n = 74), refractory ascites (n = 12), hepatorenal syndrome (HRS) (n = 4). Due to advanced liver cirrhosis 16 patients suffered of severe renal dysfunction (HRS). 57 patients had ascites. RESULTS: TIPSS implantation was technically successful in 96.7% (1992-1994: 5.1%, 1995-1996: 100%) of the patients. Complications occurred in 14.9% (1992-1994: 25.6%, 1995-1996: 6.3%). TIPSS-associated mortality was 2.3% (1992-1994: 5.1%, 1995-1996: 0%). 76.1% of the patients required reinterventions. 85.3% of reinterventions were necessary in the first year after TIPSS placement. The survival rate without reintervention was 28%, 21% and 9% for Child A, B, and C patients, respectively. Recurrent variceal haemorrhage occurred in 12.7%. De novo hepatic encephalopathy developed in 13.8%. Ascites improved in 79.2% and renal function in 75% of the patients. CONCLUSION: TIPSS is an effective method to treat recurrent variceal haemorrhage, refractory ascites and HRS. Complication and mortality rate depend on the investigator's experience and on the technique used.

Adult↗
PubMed1998

[Improved diagnosis of early cerebral infarct by the combined use of diffusion and perfusion].

PURPOSE: To evaluate the feasibility and the diagnostic efficacy of multislice diffusion-weighted and perfusion imaging in addition to FLAIR-TSE, T2w-GraSE and MR-angiography in the diagnosis of acute stroke. METHODS: 18 patients with acute stroke were examined at 1.5 Tesla (Gyroscan ACS-NT, Philips Medical Systems) within 6 (n = 9) and 6-48 (n = 9) hours, respectively, and followed at regular intervals. For diffusion imaging we used a multislice multishot EPI-SE sequence with navigator echo correction and cardiac gating. Perfusion imaging was done by means of a FFE-EPI sequence after bolus injection of Gd-DTPA. RESULTS: The diagnostic value of diffusion-weighted and perfusion imaging was significantly higher compared with FLAIR-TSE (p = 0.0023) and GraSE (p = 0.0012) during the first 6 hours. With FLAIR-TSE and GraSE first pathologic changes were seen after 4 hours. We detected perfusion deficit (rCBV < 10%) and a corresponding drop of the ADC in all infarcts larger than 1 cm in diameter. Within the area of low rCBV the combined analysis of diffusion and perfusion imaging allows to identify an infarct region with characteristics of a penumbra and one with characteristics of the infarct core. TTP was increased in the surrounding tissue. However, parts of this area were rarely included in the infarct. The final extension of the untreated infarct, as revealed by computed tomography, corresponded well to the perfusion deficit. CONCLUSIONS: Early ischaemic cerebral infarcts can be diagnosed with diffusion and perfusion imaging before pathological changes are visualized with other imaging modalities. The combined use may allow to distinguish the infarct core from surrounding, potentially salvageable tissue.

Adult↗
PubMed1998

[Quantitative evaluation of the suitability of magnetic resonance sequences for the detection of spinal bone marrow metastases of solid tumors].

AIM: To compare MR sequences for the examination of the bone marrow of the spine in the detection of skeletal metastases. METHODS: 20 standardised prospective studies of the cervical, thoracic or lumbar spine in patients with known skeletal metastases were evaluated quantitatively. Studies included T1w SE with and without intravenous contrast medium (CM) administration of Gd-DTPA, T2w TSE with and without frequence selective fat saturation (SPIR), opposed phase gradient echo (opGE) with and without intravenous CM administration of Gd-DTPA and T1w SE CM SPIR sequences. The quantitative parameters signal/noise ratio (SNR), contrast/noise ratio (CNR) and contrast were evaluated. RESULTS: OpGE with contrast showed the best results in SNR, CNR and C. Results were statistically significant. Good SNR and C also was found for T1w SE native. SPIR and T2w sequences were less sensitive. CONCLUSION: OpGE sequences are recommended for the detection of skeletal metastases of the spine.

Bone Marrow Neoplasms↗
PubMed1998

[Diffusion-weighted MR tomography: navigated multi-shot SE-EPI technique for clinical use].

PURPOSE: Evaluation of a navigated multi-shot SE EPI sequence for routine clinical use in MR diffusion imaging. METHODS: We compared a multi-shot SE EPI sequence with the conventional SE sequence as well as with a single-shot SE EPI sequence on a standard 1.5 Tesla MR-scanner (ACS-NT, Philips Medical Systems) with a conventional gradient system (10 mT/m). Image quality and the reproducibility of the apparent diffusion coefficient were analysed with phantoms and with healthy volunteers. The diffusion coefficients of different brain areas were determined in a group of twenty volunteers. RESULTS: The multi-shot SE EPI sequence showed considerably shorter measurement times and smaller motion artifacts than the SE sequence and was less sensitive to susceptibility artifacts than the single-shot version. The reproducibility of the diffusion coefficients was better than 10%. CONCLUSION: The navigated multi-shot SE technique is more practicable and meaningful than the SE and the single-shot SE EPI techniques on a standard 1.5 Tesla MR-scanner with a conventional gradient system. In our opinion it is now the best method for diffusion imaging and should be preferred in clinical use. The determination of diffusion coefficients yields reliable results and characteristic values for different tissue can be obtained.

Adult↗
PubMed1998

[Evaluation of the effects of bioadhesive substances as addition to oral contrast media: an experimental study].

PURPOSE: To evaluate the additional effect of bioadhesives in combination with iotrolan and barium as oral contrast media in an animal model. METHOD: The bioadhesives Noveon, CMC, Tylose and Carbopol 934 were added to iotrolan and barium. The solutions were administered to rabbits by a feeding tube. The animals were investigated by computed tomography (CT) and radiography after 0.5, 4, 12, 24 and in part after 48 hours. Mucosal coating and contrast filling of the bowel were evaluated. RESULTS: Addition of bioadhesives to oral contrast media effected long-term contrast in the small intestine and colon, but no improvement in continuous filling and coating of the gastrointestinal tract was detected. Mucosal coating was seen only in short regions of the caecum and small intestine. In CT the best results for coating were observed with tylose and CMC, in radiography additionally with carbopol and noveon. All contrast medium were well tolerated. CONCLUSION: The evaluated contrast medium solutions with bioadhesives have shown long-term contrast but no improvement in coating in comparison to conventional oral contrast media.

Acrylic Resins↗
PubMed1998

Diagnostic value of a superparamagnetic iron oxide in MR imaging of chronic liver disease in an animal model.

OBJECTIVE: The enhancement characteristics and the diagnostic value of a cell-specific superparamagnetic contrast agent (NSR 0430) in different degrees of liver fibrosis and cirrhosis were experimentally studied in an animal model. MATERIALS AND METHODS: Chronic liver damage was induced in rats either by oral administration of carbon tetrachloride (CCl4) for 15 weeks (n = 37) or by oral administration of thioacetamide (TAA) in drinking water for 24-26 weeks (n = 48). Twenty-six animals served as control subjects. T1 and T2 relaxation times for the liver and the spleen were measured in vitro with a spectrometer at 40 MHz. In vivo MR imaging at 1.5 T also was performed using T2-weighted turbo spin-echo sequences before and 1 hr after administration of NSR 0430. All data were correlated with the histologic degree of liver fibrosis and cirrhosis and the amount of connective tissue in the liver, which was measured morphometrically. RESULT: CCl4 produced liver fibrosis in most of the animals, and TAA predominantly caused liver cirrhosis. NSR 0430 caused a T2 relaxation time decrease in the control animals by 49%; in the CCl4 group with light and moderate liver fibrosis, by 25%; in the CCl4 group with severe liver fibrosis or cirrhosis, by 16%; and in the TAA group with cirrhosis, by 30%. On the T2-weighted turbo spin-echo sequences, liver signal-to-noise ratios (SNRs) decreased after contrast agent administration in the control animals by 81% and 79%, depending on the TE parameter. In the CCl4 group, liver SNRs decreased by 96% and 61% in animals with light or moderate fibrosis and by 44% and 55% in animals with severe fibrosis or cirrhosis, depending on the TE parameter. In the TAA group, liver SNR decreased by 61% and 67%, depending on the TE parameter. CONCLUSION: Enhancement of the superparamagnetic contrast agent NSR 0430 is decreased in the presence of liver fibrosis and cirrhosis in an animal model. However, the reduced enhancement is not directly related to the degree of chronic liver damage, which limits the diagnostic value of superparamagnetic contrast agents in the assessment of chronic liver disease.

Animals↗
PubMed1998

[Does angiographic localization of bleeding affect the management and mortality in gastrointestinal hemorrhage of unknown origin?].

PURPOSE: To evaluate the effect of angiography on patient management and mortality in patients with GIB of unknown origin. MATERIAL AND METHODS: 88 angiographies were performed in 74 patients with GIB of unknown origin (18 upper gastrointestinal tract [GIT]), 35 lower GIT. 21 unknown localisation) and were evaluated retrospectively in regard to the influence on patient management and clinical outcome. RESULTS: After unsuccessful endoscopic diagnosis, angiography shows a sensitivity of 60% in the acute phase of GIB. Once the GIB had stopped the sensitivity was 14%. Following angiographic localisation, patients were more commonly treated surgically (71% vs. 44.5%) and subsequently had a lower rate of persistent or recurring bleeding (15% vs. 37.5%) as well as a lower event related mortality (10.5% vs. 25%). Patients with angiographic localisation of the bleeding site had a better outcome than patients with unsuccessful bleeding localisation, with regard to both surgical (85% vs. 62.5%) and conservative (100% vs. 85%) treatment. CONCLUSION: Angiographic localisation should be attempted in all cases of unknown GI-bleeding after endoscopic methods have been unsuccessful or ambiguous, because such a procedure has a positive effect on patient management and outcome. Moreover, angiography also offers therapeutic options.

Adolescent↗
PubMed1997

Effect of cytochrome P450 induction on phosphorus metabolites and proton relaxation times measured by in vivo 31P-magnetic resonance spectroscopy and 1H-magnetic resonance relaxometry in human liver.

Experimental and clinical studies have led to the hypothesis that the phosphodiester signal obtained by 31P magnetic resonance (MR) spectroscopy may be a specific marker for the hepatic induction of oxidative metabolism (P450 induction) by phenobarbitone or ethanol. Systematic studies in humans are lacking. Therefore, we studied 10 volunteers who received rifampin (600 mg/d) for 6 days, resulting in a documented induction of oxidative metabolism as measured by an increase in urinary 6-beta-hydroxycortisol output in all volunteers (P = .0004). 31P-MR spectroscopy and 1H-MR relaxometry were performed before and after hepatic P450 induction. As shown by 31P-MR spectroscopy, the median phosphomonoester concentration (PME) relative to nucleoside triphosphate (NTP) increased by 21% from 0.63 (range, 0.40-0.89) before induction to 0.76 (0.49-1.67) after induction (P = .0451). The median level of phosphodiesters (PDE) relative to NTP increased by 28% from 4.82 (3.41-6.67) before induction to 6.18 (4.63-11.63) after induction (P = .0091). An increase in the level of inorganic phosphates (Pi) relative to NTP was observed, but changes were not significant. As shown by 1H-MR relaxometry, a nonsignificant trend of the liver parenchyma to shorter relaxation times was observed after P-450 induction. In conclusion, both PME/NTP and PDE/NTP ratios (measured by in vivo 31P-MR spectroscopy) increased significantly after hepatic induction with rifampin. Further clinical studies with 31P-MR spectroscopy must take into account the potential effects of P450-inducing agents.

Adult↗
PubMed1997

Diagnostic value of MR imaging in comparison to CT in the detection and differential diagnosis of renal masses: ROC analysis.

The aim of this work was to compare MR imaging and CT in the detection of renal masses and in the differential diagnosis between benign and malignant lesions. In 33 patients with 54 renal lesions CT and MR images were evaluated by four readers with regard to tumor detection and characterization using a receiver-operating-characteristics (ROC) analysis. The MRI protocol consisted of a T1-weighted spin-echo (SE) sequence (TR/TE: 300/10 ms) before and after contrast administration and a heavily T2-weighted turbo-SE (TSE) sequence (TR/TE: 5500/150 ms). Az values for the area under the ROC curves for lesion detection were 0.92 +/- 0.04 for CT and 0.91 +/- 0.05 for MRI, respectively, which was not statistically different. The MRI technique was slightly, but not significantly, better than CT in the overall characterization (accuracy in differentiation between benign and malignant) of renal lesions with an Az value of 0.90 +/- 0.05 compared with 0.88 +/- 0.06 for CT. The MRI technique proved to be statistically superior to CT (p < 0.01) in the correct characterization of benign renal lesions. MRI equals CT in the overall detection and differential diagnosis of renal masses. MRI is very helpful for further differential diagnosis of lesions which are equivocal on CT especially in the differentiation between complicated cysts and cystic or hypovascular renal cell carcinoma.

Adult↗
PubMed1997

Indirect MR arthrography: techniques and applications.

Indirect MR arthrography is a simple noninvasive alternative to direct MR arthrography and can potentially alter the diagnostic work-up of several diseases. Based on current knowledge, these diseases include rotator cuff tears. glenoid labrum tears, recurrent tears of the menisci and classification of osteochondritis dissecans. The technique is recommended for inclusion in the MRI diagnostic array, and may obviate the need for invasive direct MR arthrography. The technique and applications of indirect MR arthrography are summarized in this article, based on our own experiences and that described in the current literature.

Adipose Tissue↗
PubMed1997

[The diagnosis of intra-abdominal hemorrhages with CO2 as the contrast medium].

PURPOSE: Evaluation of carbon dioxide (CO2) as contrast medium for detection of intraabdominal haemorrhage. METHOD: We performed in 5 patients 7 DSA examinations (one with upper and three with lower gastrointestinal bleeding, one traumatic spleen rupture) using an iodinated contrast-medium and CO2 for the localisation of haemorrhage. RESULTS: With iodinated contrast medium it was possible to localise the haemorrhage in three of 5 patients. With CO2 the localisation was possible in all cases. There were no side effects. CONCLUSION: CO2 is useful for detection of intraabdominal bleeding. Even in cases with negative angiographic results with iodinated contrast medium, CO2 may enable localisation of the bleeding vessel. Because of this, we use CO2 and iodinated contrast media in all cases of intraabdominal haemorrhage. Further studies are required.

Angiography, Digital Subtraction↗