Search PubMed⌕ Search

Biomedical subjects

H Kugel

Publications and source records attributed to H Kugel.

At least 55 records · Page 3Linked to original sources
PubMed1998

Proton MR spectroscopy in infants with cerebral energy deficiency due to hypoxia and metabolic disorders.

PURPOSE: To investigate the similarities and differences of cellular energy deficiencies due to asphyxia and to impaired oxidative phosphorylation caused by enzyme deficiencies using localized 1H-MR spectroscopy of the brain. MATERIAL AND METHODS: In 35 neonates and infants with a postconceptional age of 36.4-153 weeks, 1H-MR spectra were obtained from the basal ganglia. Of the 35 children, 14 served as a control group, 12 suffered from hypoxic-ischemic disease (HIE), and 9 had congenital enzymatic disorders. RESULTS: Eleven of the 12 children with HIE showed low N-acetyl aspartate (NAA) to trimethylamine (TMA) ratios, indicating neuronal damage. Lactate (Lac) to TMA ratios correlated with the HIE grade. Children with congenital disorders of energy metabolism had NAA/TMA ratios ranging from severely decreased to normal, but 7 of the 9 had high Lac signals, even in brains with normal NAA/TMA. CONCLUSION: High Lac/TMA even with normal NAA/TMA in children with enzyme deficiencies, in contrast to Lac/TMA that correlates with clinical grade and low NAA/TMA in asphyxic children, hints at different mechanisms of cell damage in the two disease groups.

Aspartic Acid↗
PubMed1998

[Volume selective 31P NMR spectroscopy for differentiation of graph rejection and acute tubular necrosis after kidney transplantation].

Volume-selective 31P-MR spectra were obtained from 37 patients using a whole-body MR scanner in combination with surface coils and a modified ISIS sequence. The quantitative evaluation took place by line fitting to the signal in the time domain using a non-linear procedure. The following signal intensities were determined: PME, PDE, Pi, gamma-, alpha-, beta-ATP and pH. 1024 excitations were averaged to achieve an adequate signal-to-noise ratio (10.0 +/- 3.3), measurements lasting 34 minutes on average. The mean measured volume was 174 +/- 52.4 ml. Contamination by muscle tissue could be excluded based on the absence of phosphocreatinine signal in the spectra. Contamination by fatty tissue was excluded by visualisation. A reduction in the value of the Pi/alpha-ATP ratio as a function of time was observed due to the regeneration process following reperfusion injury. In transplant rejection (n = 7) a significant rise in Pi/alpha-ATP ratio was seen compared to the control group (n = 20) (0.4 +/- 0.16 vs. 0.22 +/- 0.11, p < 0.01), the calculated difference in pH was significant as well. In cases of acute tubular necrosis a reduced value fore the PME/PDE ratio was observed (0.65 +/- 0.1 vs. 0.96 +/- 0.5, p < 0.04). Acute tubular necrosis could be differentiated from rejection by difference in pH (6.93 +/- 0.1 vs. 7.14 +/- 0.19, p < 0.04).

Adenosine Triphosphate↗
PubMed1997

[31P-MR spectroscopy of the human liver--the spectral indications of lymphoma infiltration].

PURPOSE: To evaluate whether phosphorus magnetic resonance spectroscopy (31P-MRS) enables a non-invasive detection of liver involvement in systemic diseases like Hodgkin's lymphoma. MATERIALS AND METHODS: Using a clinical 1.5 Tesla whole-body MR system image-guided localised phosphorus MR spectra from the anatomically defined volumes of interests were measured. A combination of surface coil, adiabatic excitation pulse and modified image-selected in vivo spectroscopy (ISIS)-sequence was applied. The spectroscopy data were evaluated quantitatively with a time-domain fit programme using non-linear optimisation algorithms to quantify peak areas. After establishment of the examination protocol, 22 healthy volunteers and 13 patients with suspected lymphoma infiltration of the liver were examined. RESULTS: Liver spectra of patients suffering from lymphoma infiltration differed significantly from spectra of persons with normal liver: 1. The peak area ratio of phosphomonoesters (PME) to beta-NTP was elevated in all patients with histologically confirmed liver lymphoma. 2. Patients suffering from Hodgkin's disease with specific or unspecific liver infiltration (n = 7) could be differentiated from patients without liver involvement. In case of infiltrated liver, the peak area ratio PME to beta-NTP was increased, and the pH value was shifted to lower values. Unambiguous differentiation between non-specific (n = 3) and specific (n = 4) infiltration of the liver was not possible. 3. In patients after cytostatic treatment (n = 3), an increase of the peak area ratio of inorganic phosphate to beta-NTP was observed. CONCLUSIONS: Our preliminary results indicate that 31P-MRS can yield pointers to liver involvement in patients with systemic diseases such as Hodgkin's disease, which may be hardly detected by imaging methods.

Adolescent↗
PubMed1997

[Localization of puncture needles in MRI: experimental studies on precision using spin-echo sequences at 1.0 T].

PURPOSE: To evaluate accuracy of needle localisation using and signal enhancement on a 1.OT MR imager for various needles for MR-guided biopsy. METHODS: The differences between actual and virtual needle position of needles with different orientations were evaluated in a phantom for spin-echo including turbo-spin-echo sequences. RESULTS: Artifacts depended on the orientation of the needle relative to the field B0, frequency-encoding gradients (Gf) and slice orientation. This resulted in different artifact shapes and sizes for left or right and cranial or caudal biopsy access routes. Applying turbo spin echo sequences feasible for biopsy, the signal void of a 18 G needle (Cook) parallel to Gf reached between 0.3 and. 4.6 mm further into the medium than the real needle tip, depending on needle orientation relative to B0. The diameter of the signal void around the needle varied, the needle shaft was right in the centre of the signal void. With Gf orthogonal to the needle the offset of signal void to needle tip ranged from 2.7 to 3.3 mm, while the actual position of the needle shaft was up to 3.3 mm lateral of the signal void center. While nominal echo times did not influence the size of the artifact in turbo-spin-echo sequences, the artifacts increased with smaller matrix and larger water-fat shift. Material and mass of the needle determined the size of the artifacts as well. CONCLUSION: Localisation accuracy of the needle can be optimised by choosing optimal gradient directions depending on whether needle tip or shaft position should be displayed.

Artifacts↗
PubMed1996

A gene for autosomal dominant paroxysmal choreoathetosis/spasticity (CSE) maps to the vicinity of a potassium channel gene cluster on chromosome 1p, probably within 2 cM between D1S443 and D1S197.

Paroxysmal choreoathetosis/episodic ataxia is a heterogeneous neurological syndrome usually inherited in an autosomal dominant manner. Recently, the association of one form of episodic ataxia (defined by the presence of additional myokymia) with point mutations in the potassium channel gene KCNA1 was described. This gene locus on chromosome 12p (HGMW-approved symbol CSE) was excluded in a large pedigree with paroxysmal choreoathetosis and additional spasticity. Linkage to chromosome 1p where a cluster of related potassium channel genes is located, was demonstrated. Genotyping of 18 affected and 11 unaffected family members with 28 microsatellites over a region of 45 cM proved linkage with a lod score of 7.2 at a recombination fraction theta = 0 to D1S451/421/447/GGAT4C11. Crossing-over events in 9 patients and 4 unaffected offspring suggested a probable assignment of the gene to a region of 2 cM between D1S443 and D1S197.

Athetosis↗
PubMed1996

[Comparison of fast turbo-spin-echo and gradient- and spin-echo sequences as well as echo planar imaging with conventional spin-echo sequences in MRI of focal liver lesions at 1.0 tesla].

PURPOSE: To evaluate the value of rapid T2-weighted turbo-spin sequences (TSE), turbo-spin-echo sequences with shortened echo spacing (UTSE), gradient-and-spin-echo sequences (GraSE) and T1-weighted echo-planar imaging (EPI) in comparison with conventional spin-echo sequences (SE) in the diagnosis of focal liver lesions. METHODS: 20 patients with malignant focal liver lesions underwent magnetic resonance imaging at 1.0 tesla. RESULTS: The use of fast T2-sequences (TSE, UTSE, GraSE) reduced the examination time to about 35-50%. Artifacts were reduced compared with the conventional T2-SE sequence. Quantitative analysis demonstrated that UTSE imaging had the highest tumor/liver contrast-to-noise ratio (CNR) followed by TSE, T2-SE and GraSE sequences. CNR with EPI was lower than with the T1-SE sequence (p < 0.05). CONCLUSION: Turbo-spin-echo sequences with shortened echo spacing yield a shorter imaging time and improved image quality without loss of signal intensity in tumor/liver-CNR, compared with conventional T2-pulse sequences in liver imaging at 1.OT.

Adult↗
PubMed1995

Positron emission tomography and magnetic resonance spectroscopy of cerebral glycolysis in children with congenital lactic acidosis.

Congenital lactic acidosis with neurological symptoms may be due to a variety of disorders of energy metabolism. We investigated whether positron emission tomography (PET) and proton magnetic resonance spectroscopy (1H MRS) are capable of demonstrating specific changes to facilitate diagnosis. A corresponding increase of cerebral lactate (with MRS) and rate of glycolysis (with PET) was observed in 2 children with biochemical evidence of defective mitochondrial respiration. No such increase was noted in a child with lactic acidosis due to stress and exercise but normal respiratory chain activity, and in a control case with an epilepsy syndrome without evidence of primary changes of energy metabolism. The results suggest that defects of oxidative phosphorylation may cause a massive increase of glycolysis to cover energy requirements, with corresponding accumulation of lactate in brain tissue. This mechanism can now be demonstrated in vivo and, with further experience, may potentially be used as a diagnostic marker of respiratory chain disorders in brain tissue.

Acidosis, Lactic↗
PubMed1995

MR pulsatility measurements in peripheral arteries: preliminary results.

Phase contrast flow velocity measurements were performed in six healthy volunteers and 30 patients with arteriosclerotic disease. The iliac arteries were investigated in 8 cases and the femoral arteries in 28 cases. In the first 24 patients, 16 evenly distributed data sets were acquired during one cardiac cycle. In the last 12 patients, a trigger pulse followed by the acquisition of 30 evenly distributed data sets was applied every second heart beat. This procedure allowed data to be acquired over a full heart cycle without any acquisition gap. The measured flow velocities were displayed as function of time. Systolic acceleration, postsystolic deceleration and pulsatility of flow velocity were calculated and compared with stenosis grades determined from DSA angiograms. Flattening of the flow velocity patterns was found to correlate with the local severity of arteriosclerotic disease.

Adult↗
PubMed1995

Proton magnetic resonance spectroscopy reflects metabolic decompensation in maple syrup urine disease.

Using localized proton magnetic resonance spectroscopy (1H-MRS), accumulation of branched-chain amino acids (BCAA) and their corresponding 2-oxo acids (BCOA) could be non-invasively demonstrated in the brain of a 9-year-old girl suffering from classical maple syrup urine disease. During acute metabolic decompensation, the compounds caused a signal at a chemical shift of 0.9 ppm which was assigned by in vitro experiments. The brain tissue concentration of the sum of BCAA and BCOA could be estimated as 0.9 mmol/l. Localized 1H-MRS of the brain appears to be suitable for examining patients suffering from maple syrup urine disease in different metabolic states.

Adolescent↗
PubMed1995

Diagnostic performance of digital subtraction angiography (DSA) and magnetic resonance angiography (MRA): preliminary results in vascular occlusive disease of the abdominal and lower-extremity arteries.

Fifty-nine patients with occlusive disease of the aorto-iliac and femoro-popliteal arteries were investigated prospectively by intravenous (IV) or intraarterial (IA) digital subtraction angiography (DSA) and magnetic resonance angiography (MRA). This was accomplished using a two-dimensional (2D) Inflow- (59 patients) and a 2D Phase Contrast- (RSE--rapid sequential excitation) sequence (29 patients). The spectrum of pathology included stenoses < 50%, stenoses 50-89%, stenoses 90-99%, occlusions, aneurysms and status following reconstructive surgery. MRA- and DSA-examinations were evaluated by four radiologists. The diagnoses were made by consent decisions of a radiologist and a vascular surgeon based on clinical and radiological findings. Diagnostic performance of IA-DSA was superior to all other imaging modalities. Vascular delineation of 2D Inflow-MRA was comparable to that of IV-DSA. The image quality of RSE-MRA was not adequate for diagnosis. In conclusion, 2D Inflow-MRA is a promising method for evaluating abdominal and peripheral arteriosclerotic disease. Interpretation of MR-angiograms, however, requires profound knowledge of MRA-techniques, X-ray angiography and hemodynamics.

Adult↗
PubMed1995

[Peripheral occlusive arterial diseases: comparison of diagnostic value of MRA and DSA].

MATERIAL AND METHODS: In 59 patients with arterial flow disturbances 2-D inflow sequence of the abdominal and lower leg arteries were prospectively obtained on a 1.5 T MR-imager and were compared with additional DSA examinations. Supplementary Phase Contraste RSE ("Rapid Sequential Excitation") sequences were carried out in 29 patients. MRA and DSA angiograms were evaluated in random order by 4 readers using a questionnaire. The assessment of image quality were evaluated by variance analysis. Diagnostic performance of MRA and DSA was assessed by comparison of the readers' diagnostic assessments with reference diagnoses established by a radiologist and a vascular surgeon with full knowledge of all data concerning a patient. Image quality of inflow MRA was considered inferior to i.a. DSA (p < 0.001) and comparable with i.v. DSA (p = 0.1361). Image quality of RSE-MRA was inadequate (p < 0.001). Correspondingly, i.a. DSA was the superior and RSE-MRA the inferior imaging technique. The accuracy of inflow MRA in determining stenosis grade was 66% and that of RSE-MRA 59%.

Aged↗
PubMed1995

Metabolic changes in acute and subacute cerebral infarctions: findings at proton MR spectroscopic imaging.

PURPOSE: To analyze the advantages of proton magnetic resonance (MR) spectroscopic imaging in the evaluation of acute and subacute cerebral infarcts. MATERIALS AND METHODS: Metabolite maps of choline-containing compounds, total creatine consisting of creatine and phosphocreatine, N-acetyl aspartate (NAA), and lactate were obtained in 23 patients with acute and subacute cerebral infarctions 1-35 days after onset of symptoms. Maps were obtained with a 1.5-T MR system with 32 x 32 phase-encoding steps. RESULTS: Distinct abnormal metabolite distributions could be detected in all lesions larger than 1 cm in diameter. In the center of infarcts with a diameter larger than the section thickness of 2 cm, NAA values decreased to 20% +/- 8 compared with contralateral brain as early as 1 day after onset of symptoms (P < .0001). Choline was reduced to 67% +/- 30 (not significant) and creatine to 51% +/- 22 (P = .0025). Large amounts of lactate were detected in all acute infarcts. Choline, creatine, and lactate values declined during the first 5 weeks after stroke. CONCLUSION: MR spectroscopic imaging allows visualization of metabolic changes in stroke with a reasonable spatial resolution.

Acute Disease↗
PubMed1995

Cine phase contrast angiography of normal and diseased peripheral arteries. Preliminary results.

Cine phase contrast angiography (PCA) is a modified MR phase contrast sequence that acquires up to 22 coronal phase images per mean cardiac cycle. The ability of the sequence to visualise local haemodynamics was investigated in 7 normal volunteers and 9 patients with flow disturbances of the peripheral arteries using a 1.5 T imager. Functional flow information provided by coronal cine PCA was correlated with quantitative data obtained by MR flow measurements and vessel morphology confirmed by conventional angiograms. Due to the yet suboptimal image quality, an aortic dissection and 1 of 4 aneurysms could not be depicted morphologically. The temporal pattern of arterial perfusion in cine PCA corresponded with flow velocity versus time data provided by quantitative MR flow measurements. Accuracy and time resolution of cine PCA was thus sufficient to provide functional information on the severity of occlusive vascular disease.

Adult↗
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↗
PubMed1992

In vivo imaging of glucose consumption and lactate concentration in human gliomas.

Twenty patients with histologically confirmed gliomas were studied with positron emission tomography (PET) and proton magnetic resonance spectroscopy (1H-MRS). PET with 18F-2-fluoro-2-deoxy-D-glucose (FDG) provided tomograms of the metabolic rate of glucose. MRS images were obtained by combining volume-selective excitation with phase-encoded acquisition. With 32 x 32 gradient phase-encoding steps, an in-plane resolution of 7 x 7 mm was achieved. From this set of spectra, lactate maps were created and compared with PET maps of glucose metabolism. Maximum glucose metabolic rates within tumors (relative to metabolic rates of glucose in contralateral regions of the brain) were correlated significantly with maximum lactate concentrations (relative to N-acetyl aspartate peaks in the contralateral part of the brain). In 8 tumors, no lactate was detected, and in 7 of these the maximum glucose metabolic rate was below the median value. The tumor with the highest lactate concentration also had the highest glucose metabolic rate. The topographic relation between glucose metabolic rate and lactate concentration could be analyzed in 9 patients by three-dimensional alignment of the PET and MRS images. In that analysis, maximum lactate concentrations were often not found in the same location as maximum glucose metabolism, but lactate tended to accumulate in tumor cysts, necrotic areas, and the vicinity of the lateral ventricles. The combination of FDG PET and 1H-MRS imaging demonstrates details of the spatial relation between the two poles of nonoxidative glycolysis, glucose uptake and lactate deposition.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗