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T Krahe

Publications and source records attributed to T Krahe.

At least 37 records · Page 2Linked to original sources
PubMed1995

[Spectroscopic imaging of the brain. Examination technique and clinical applications].

PURPOSE: MR spectroscopy allows the acquisition of a two-dimensional array of spatially resolved proton spectra of the human brain, known as MR spectroscopic imaging. Here the examination protocol and clinical applications in focal brain lesions are presented. METHOD: An array of data is acquired from a tissue slice positioned in the brain. These data can be presented as a set of spectra, in which each spectrum is allocated to a specific position in the sample, or as a set of images or "metabolite maps". RESULTS: The NAA signal typical for neuronal tissue is decreased in the centre of brain tumours as well as in brain infarcts. The intensity of the choline signal is increased in solid tumour tissue, whereas it is reduced in infarcts. CONCLUSION: Spectroscopic imaging reveals metabolite alterations in and around focal lesions. The spatial resolution of spectroscopic imaging enables matching with other macro-morphological or functional imaging methods like positron emission tomography.

Adult↗
PubMed1994

[Noninvasive quantification of aortic and mitral insufficiency. Comparison of dynamic magnetic resonance imaging and Doppler color echocardiography].

The degree of valvular regurgitation was measured by dynamic magnetic resonance imaging (MRI) and colour-Doppler echocardiography (CDE) in 23 patients (14 men, 9 women; mean age 53 [19-75] years) with aortic (n = 13) or mitral (n = 10) regurgitation. Quantification by MRI was from a section corresponding to the four-chamber view. In aortic regurgitation, maximal regurgitant jet area (JA), ratio of JA to left-ventricular area (JA/LVA) were measured, while in mitral regurgitation, the ratio of JA to left atrial area (JA/LAA) was measured, as well as jet volume (JV) and the ratio of JV to the corresponding volume of the receiving chamber (JV/LVV or JV/LVA). The results were compared with corresponding measurement obtained by CDE in the four-chamber view. The degree of regurgitation was graded as small if JA/LVA or JA/LAA, respectively, was less than 0.2, moderate if 0.2-0.4, and marked if more than 0.4. In the patients with aortic regurgitation the correlation between the two methods was r = 0.91 regarding the jet area, 0.93 regarding JA/LVA and 0.92 regarding JV/LVV and JA/LVA. For mitral regurgitation the r values were 0.93 for JA, 0.89 for JA/LAA, and 0.85 for JV/LAV to JA/LAA. The grading of aortic regurgitation by MRI and CDE agreed in 12 of 13 patients (92%), and in nine of ten (90%) with mitral regurgitation (deviation by one degree of severity in each). These data indicate that quantification of aortic and mitral regurgitation gives similar results with MRI and CDE: thus, MRI is an equal substitute to CDE in patients with inadequate conditions for sonography.

Adult↗
PubMed1994

Beta-blockers in cardiac failure.

The use of beta-blocking agents in patients with heart failure is still controversial. An activated sympatho-adrenal system in heart failure may support blood pressure and cardiac index, on the other hand, it increases cardiac load and myocardial oxygen consumption, reduces myocardial oxygen supply and may contribute to the high incidence of arrhythmias and sudden death. Today there is a certain awareness about the important role of the sympatho-adrenal system in CHF. Short-term studies failed to demonstrate a benefit of beta-blockers while long-term studies have proved major haemodynamic benefit and functional improvement in most patients. The haemodynamic benefit consists of a reduction of heart rate and left ventricular filling pressure and an improvement in exercise capacity. The mechanism of these actions of beta-blockers, with the exception of lowering heart rate, remains unclear. Energy metabolism of the failing heart, which is considered to be deficient, may beneficially be influenced by chronic beta-blocker treatment. Effects of beta-blockers on prognosis in patients with heart failure are also still controversial. Most recent trials (MDC Trial, CIBIS Trial) were inconclusive concerning mortality. Aetiology of heart failure may be important; however, observations on secondary prevention post-myocardial infarction also contradict heart failure studies. Thus, further efforts are urgently needed to define the mechanism of action of beta-blockers in patients with cardiac failure and to identify more clearly patients who benefit from this type of therapy.

Adrenergic beta-Antagonists↗
PubMed1993

[Pulmonary nocardiosis].

The radiological appearances and pulmonary changes during the acute stage and after recovery from pulmonary nocardiosis are described on the basis of 10 confirmed cases. Amongst the 10 patients there were 3 with malignant disease, 1 patient with AIDS, 3 patients following organ transplantation and 3 patients on steroids. In one patient cerebral involvement was demonstrated by MRI.

AIDS-Related Opportunistic Infections↗
PubMed1993

[The computed tomographic differentiation of endobronchial tumors and tumor-caused bronchial compression].

The efficiency of computed tomography in differentiating between a bronchial compression due to tumour formation and an endobronchial tumour was tested in comparison to bronchoscopy results. 624 bronchial segments were evaluated in 65 patients with masses in the pulmonary hilus area. Computed tomographical identification of pathological lesions (n = 71) was achieved with a sensitivity of 83% and a specificity of 96%. Out of 52 bronchial segments with endobronchial tumour, 90% showed pathological lesions and 85% were classified correctly. When the morphology of the bronchial lesions (endoluminal mass, smooth or irregularly demarcated bronchostenosis or bronchial displacement) was assessed with CT, only the CT identification of an endoluminal mass could distinguish endobronchial tumour growth with a probability of 91% from bronchial narrowing due to external causes and normal bronchi.

Adult↗
PubMed1993

[31P-cardio-MR-spectroscopy in myocardial insufficiency].

The relative linear relationships of creatine phosphate/gamma-adenosine triphosphate (PCr/ATP) and of phosphodiester (PDE)/ATP were measured in 38 normals and 27 patients with cardiac insufficiency using cardiac 31P-MR-spectroscopy. There was no significant difference between normals and those with dilated cardiomyopathy (19 cases) and severe aortic valve lesions (8 cases), irrespective of the clinical stage of the cardiac abnormality. Within subgroups of insufficiency there was a correlation between PCr/ATP and the severity of the disease with significant differences between mild and severe cardiac insufficiency. In 6 patients a significant rise in PCr/ATP could be demonstrated following clinical improvement under drug therapy. There was no correlation between the relative linear relationship and the left ventricular ejection fraction.

Adult↗
PubMed1993

[Interobserver variability of dialysis shunt flow measurements using color coated duplex sonography].

A prospective study extending over 4 months was carried out in which 142 shunt volume flow measurements were performed on 43 patients; two up to four operators with varying degrees of experience took part. Flow volumes varied between 51 and 2409 ml/min with an average blood flow volume of 521 ml/min. Comparison of measurements of individual operators showed errors of between 0.5 and 19.8%. Average error was calculated as 11.3%. Shunt flow measurements by colour Doppler sonography provide an easily appreciated and reproducible method for quantifying changes in shunt flow.

Adult↗
PubMed1992

Direct measurement of spin-lattice relaxation times of phosphorus metabolites in human myocardium.

T1 values of phosphorus metabolites visible in human cardiac 31P-MR spectra were determined in 12 volunteers at 1.5 T. Consecutive spectra were acquired with varying pulse repetition time (TR) from 1.6 to 24 s; volume selection was achieved with ISIS. T1's of creatine phosphate (CP), [gamma-P], [alpha-P], and [beta-P]ATP, 2-3 diphosphoglycerate, and phosphodiesters were 6.1 +/- 0.5, 5.4 +/- 0.5, 5.5 +/- 0.5, 5.8 +/- 1.0, 7.6 +/- 1.0, and 5.0 +/- 1.0 s, respectively. CP/ATP ratios showed little change with varying TR; linear regression of CP/ATP vs TR was of borderline significance (r = 0.28, P = 0.06). T1's for CP and ATP were also determined in standard solution (20 mM CP, 10 mM ATP) yielding T1CP of 8.7 +/- 0.2 and T1[gamma-P]-ATP of 9.9 +/- 0.7 s. Thus, T1's for CP and ATP were similar at 1.5 T in both human heart and standard solution. In human cardiac 31P-MR spectra, CP/ATP ratios may need little correction for partial saturation.

2,3-Diphosphoglycerate↗
PubMed1992

[Interstitial lung diseases. A comparative study between a film-screen combination and a digital storage phosphor technic].

Chest examinations were carried out in 60 individuals using film-screen and digital storage phosphor techniques and identical radiation doses. 29 of these individuals were patients with interstitial pulmonary disease; 31 were normals. Postprocessing of the digital images was carried out with filtering using an unsharp mask and identical parameters for all patients. An ROC analysis using 10 observers showed no significant difference in the evaluation of the interstitial lung disease. Correlation analysis showed a significant positive correlation (p less than 0.001) for the findings in both techniques. Under the present circumstances, film-screen and digital storage phosphor technique are of equal value in the diagnosis of interstitial pulmonary disease.

Adult↗
PubMed1992

[The value of digital subtraction sialography compared to conventional sialography, salivary gland sonography and surgical findings].

In a prospective study DSA sialography, conventional sialography (100mm technique) and sonography of the salivary glands were performed in 124 patients. The results of imaging could be correlated with those of operation and/or histology in 70 patients. Performing sialography in only one projection DSA sialography is superior to the conventional technique. The results of DSA are equivalent to those of conventional sialography in more than one projection. DSA sialography is the method of choice demonstrating salivary calculi, whereas sonography is superior to DSA sialography in the detection of tumors. In the diagnosis of chronic inflammation of the salivary glands DSA is slightly superior to the other imaging modalities.

Adolescent↗
PubMed1992

[Pharmacokinetics of gadolinium-DTPA in chronic renal insufficiency requiring dialysis].

MRT with gadolinium-DTPA (0.1 mmol/kg body weight) was performed in 10 patients with renal insufficiency requiring dialysis and the clearance of gadolinium-DTPA was studied. After 3 dialysis on 3 successive days more than 97% of the initial concentration of gadolinium-DTPA had been eliminated. Average half-life was 1.87 hours. There were no side effects in any of the patients. Close laboratory observation of liver function showed no significant changes during the period of study. No contra-indication for the use of this contrast medium in patients with renal insufficiency requiring dialysis was found during this study.

Adult↗
PubMed1992

[The determination of myocardial mass by cardiac magnetic resonance tomography. The effect of section alignment and section distance].

The effect of section alignment and distance in volumetric determination of myocardial mass by means of cardiac magnetic resonance imaging (MRI) was studied in 19 isolated pig hearts. Double angulated views taken through the short axis of the heart with a slice thickness of 10 mm and slices at a distance of 0 mm, 1 mm, 3 mm and 5 mm produced accurate left ventricular measurements with cardiac MRI. Measurements in the long axis of the heart resulted in a marked underestimation of myocardial mass; depending on slice intervals, there was an error between 13% and 20%. In vivo measurements in 35 subjects confirmed the effect of section alignment. Measurements in the long axis of the heart produced results of 139.9 +/- 31.7 g, significantly less than measurements in the short axis of the heart of 157.8 +/- 32.3 g.

Adult↗
PubMed1992

[The direct measurement of the spin-grid-relaxation times of phosphorus metabolites in the human myocardium].

The T1 relaxation times of the phosphorus metabolites in human heart muscle measurable by 31P-MR spectra were determined in 12 individuals using a 1.5 Tesla system. Several spectra were recorded consecutively with a pulse repetition time of 1.6 s to 24 s. The T1 times of creatine phosphate (CP), of gamma-, alpha-, beta-adenosintriphosphate (ATP), 2,3-diphosphoglycerate (2,3-DPG) together with anorganic phosphate) and phosphodiester (PDE) showed mean measurements of 6.1 +/- 0.5, 5.4 +/- 0.5, 5.0 +/- 0.5, 5.8 +/- 1.0, 7.6 +/- 1.0, and 5.0 +/- 1.0 s (M +/- SE). The accuracy of the ISIS technique was tested with a special phantom. T1 times were also measured in standard solutions (20 mM CP, 10 mM ATP); CP was 8.7 +/- 0.2 s and gamma-ATP was 9.9 +/- 0.7 s. Corrections for partially saturated 31P-MR spectra--at least for CP/ATP ratios--are relatively small.

2,3-Diphosphoglycerate↗
PubMed1992

[MR tomographic volumetry of the subarachnoid space in HIV-associated brain atrophy].

The CSF volume of 45 patients with HIV infection was measured at various clinical stages and the results compared with 24 normals. 60% of all patients showed increased CSF spaces as an indication of cerebral atrophy. Serial measurements were particularly valuable during the early stages of atrophy since there is marked variation in the normal CSF volume. Conventional measurements, with the exception of the width of the third ventricle, were much less sensitive than these quantitative measurements. Classification of HIV infection according to the clinical stage was useful since CSF volume and volume increase correlated with the stage of HIV infection.

AIDS Dementia Complex↗
PubMed1992

31P magnetic resonance spectroscopy in dilated cardiomyopathy and coronary artery disease. Altered cardiac high-energy phosphate metabolism in heart failure.

BACKGROUND: The purpose of this work was to further define the value of cardiac 31P magnetic resonance (MR) spectroscopy for patients with coronary artery disease and dilated cardiomyopathy. METHODS AND RESULTS: Blood-corrected and T1-corrected 31P MR spectra of anteroseptal myocardium were obtained at rest using image-selected in vivo spectroscopy localization, a selected volume of 85 +/- 12 cm3, and a field strength of 1.5 T. Nineteen volunteers had a creatine phosphate (CP)/ATP ratio of 1.95 +/- 0.45 (mean +/- SD) and a PDE/ATP ratio of 1.06 +/- 0.53; in four patients with left anterior descending coronary artery (LAD) stenosis, six patients with chronic anterior wall infarction, and four patients with chronic posterior wall infarction, CP/ATP and phosphodiester (PDE)/ATP ratios did not differ from those in volunteers. Twenty-five measurements of 19 patients with dilated cardiomyopathy yielded a CP/ATP of 1.78 +/- 0.51 and a PDE/ATP of 0.98 +/- 0.56 (p = NS versus volunteers). When these patients were grouped according to the severity of heart failure, however, CP/ATP was 1.94 +/- 0.43 in mild (p = NS versus volunteers) and 1.44 +/- 0.52 in severe DCM (p < 0.05), respectively. No correlation was found between CP/ATP and left ventricular ejection fraction or fractional shortening, but correlation of CP/ATP with the New York Heart Association (NYHA) class was significant (r = 0.60, p < 0.005). Six patients with dilated cardiomyopathy were studied repeatedly before and after 12 +/- 6 weeks of drug treatment leading to clinical recompensation with improvement of the NYHA status by 0.8 +/- 0.3 classes. Concomitantly, CP/ATP increased from 1.51 +/- 0.32 to 2.15 +/- 0.27 (p < 0.01), whereas PDE/ATP did not change significantly. CONCLUSIONS: Cardiac high-energy phosphate metabolism at rest is normal in LAD stenosis and chronic myocardial infarction in the absence of heart failure. The CP/ATP ratio has low specificity for the diagnosis of dilated cardiomyopathy. However, CP/ATP correlated with the clinical severity of heart failure and may improve during clinical recompensation.

Adult↗
PubMed1991

[In vivo 31P-cardiac magnetic resonance spectroscopy: methods and the first clinical results].

31P-magnetic resonance (MR) spectra of the heart can be obtained from well-defined myocardial regions by combined MR imaging and variable selected volumes for spectroscopy. 31P-spectra of 33 volunteers and of 43 patients with dilated and hypertrophic cardiomyopathy and with coronary artery disease were quantified using a curve-fitting routine. To optimize our technique, we recorded unsaturated and partially saturated spectra in several volunteers. Relative peak areas and signal-to-noise ratios showed significant changes with varying pulse repetition times. Saturation factors were applied to correct spectra from volunteers and patients for the effects of partial saturation. Under resting conditions, peak areas of volunteers and patients from the various groups were statistically indistinct.

Adult↗