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J Hennig

Publications and source records attributed to J Hennig.

At least 19 recordsLinked to original sources
PubMed1992

Chemical shift imaging with phase-encoding RF pulses.

An inherent problem of conventional chemical shift imaging is signal contamination into adjacent voxels. This is especially severe in proton spectroscopy of the central nervous system, where the lipid signal from the skull is several orders of magnitude higher than the metabolite resonances from the brain. The reason for the contamination lies in the fact that the distribution of spins does not coincide with the discrete sampling matrix of the discrete Fourier transformation if a continuous phase-encoding scheme using magnetic field gradients is being used. This problem can be overcome if phase encoding is performed by appropriately phase-modulated RF pulses. It is demonstrated that contamination free spectra can be acquired from voxels immediately adjacent to the skull. Using small voxels of 1 x 1 x 2-ml regional variations of N-acetyl aspartate in the cerebellum of patients with oligopontine cerebellar atrophy could be observed.

Atrophy↗
PubMed1992

Conditioning of drug-induced immunomodulation in human volunteers: a European collaborative study.

Although several studies on conditioning of the immune system in animals have been published, no comparable data on human research have been available in the past. The present paper presents results of conditioning studies in volunteers performed in two research centres, namely the University of Trier (Germany) and the University of Utrecht (The Netherlands). After administration of a neutral stimulus (conditioned stimulus: CS), subjects were injected with epinephrine (unconditioned stimulus) for three or four days (depending on study). Subcutaneous injection of epinephrine caused a rapid enhancement of the activity of natural killer cells (NKCA) in venous blood, which was chosen as the unconditioned response. On the test trial, when saline instead of epinephrine was injected, the Trier group found a conditional enhancement of NKCA. No changes in NKCA were found in the control subjects, who received saline injections on all days along with the CS. The Utrecht group tried to replicate these results using a slightly different design. After obtaining non-confirmative results, the Utrecht experimenters tried to parallel the experimental settings of the Trier group as closely as possible. However, once again they failed to replicate the results of the Trier group. Possible reasons for the different results obtained in the two research groups are discussed.

Adult↗
PubMed1991

[Magnetic resonance tomography in the diagnosis of peripheral joints].

Magnetic resonance imaging (MRI) provides an excellent soft tissue contrast with high spatial resolution. Using spin echo and fast gradient echo sequences all relevant joint structures such as the hyaline cartilage, the meniscus, the ligaments, the tendons, the capsulae, and their adjacent muscles and their pathology are visualized. Diagnosis of osteonecrosis, meniscal and cruciate ligament lesions, as well as tumors, represents the major current indication for MRI. Due to its high cost MRI should be employed for the diagnosis of joint disease only to clarify equivocal findings of conventional radiographic, nuclear and tomographic methods. Prior clinical examination and laboratory tests are mandatory. As a component of a stepwise diagnostic approach, MRI often provides reliable differential diagnostic information.

Bone Diseases↗
PubMed1991

Double-volume 1H spectroscopy with interleaved acquisitions using tilted gradients.

A method is presented by which volume selective in vivo 1H spectra of two different voxels can be acquired in an interlaced mode using PRESS or STEAM spectroscopy. Spatially tilted gradients are employed for voxel definition so as to avoid mutual saturation. Independent volume selective shimming of the voxels is possible. Two spectra of volumes as small as (1.5 cm)3 can be acquired from human brain within 14 min even from very disadvantageous locations close to air-borne interfaces.

Adenoma↗
PubMed1991

Coupling effects in volume selective 1H spectroscopy of major brain metabolites.

The effect of PRESS and STEAM sequences on the spectra of coupled substances are discussed using the examples of weakly coupled AX and A2X systems. Maximum differences compared to uncoupled spins occur if the RF pulses are applied to antiphase magnetization. In this case, the spin echo of the PRESS experiment shows a modified dependence on the refocusing flip angle, which may lead to an attenuation of the acquired signal. In STEAM spectroscopy the evolution within the middle interval tm is dominated by zero quantum coherences and longitudinal polarization, whose maximum efficiencies are 25 and 12.5%, respectively. Zero quantum coherences may lead to strong modulations when the tm value is varied. The effects on the spectra of important coupled metabolites of the human brain such as glutamate, GABA, inositol, and particularly lactate, are demonstrated. The observed modulations seem to make the quantification of the spectra rather difficult at echo times above 50 ms.

Aspartic Acid↗
PubMed1991

RARE-MR-urography in the diagnosis of upper urinary tract abnormalities in children.

RARE-MR-urography (Rapid Acquisition with Relaxation Enhancement) is a fast MR imaging technique (6.4 s/acquisition) that selectively depicts fluid by heavy T2-weighting. From 9/1989 to 11/1990, RARE-MR urograms were prospectively evaluated in the diagnosis of upper urinary tract abnormalities in 55 children. The method is performed in several planes and combined with a coronal, T1-weighted spin-echo sequence. Forty out of 42 kidneys with dilated renal pelvis, and 21 out of 24 dilated ureters were identified, only the mildly dilated ones were missed. Even in non-functioning kidneys the urinary tract was clearly depicted by RARE-MR-urography. However, no differentiation could be made with this technique between vesicoureteral reflux and non-refluxing dilatation of ureter and/or renal pelvis. All 19 pelviureteric obstructions and all eight renal duplications with a dilated segment were identified. RARE-MR-urography is a new tool for diagnosing urinary tract abnormalities in children without having to employ ionizing radiation, contrast media, or general anesthesia. A dilated urinary tract can be shown in one image displaying the entire urinary system, similar to excretory urography. The technique is presently not able to provide the information of voiding cystourethrography or renal scintigraphy, nor is it as easy to perform as ultrasound. However, in certain cases it may replace excretory urography.

Adolescent↗
PubMed1991

[Evaluation of iodine levels in daily dietary intake and urine of persons participating in epidemiological studies in the Krakow macro-region after the disaster in Czernobyl and level of iodine in drinking water of that region].

Following the Czernobyl accident, an epidemiologic study was undertaken in which the daily iodine intake was estimated in 15% of the population studied. Iodine excretion was measured in single morning urine specimens. The iodine content was also assessed in the water form wells and in cow-milk at farms in randomly chosen villages in the region of Krynica and Nowy Sacz. On the basis of a 24-hour diet recall, the mass of each food product consumed daily was estimated for 483 persons in the Kraków voivodship (14.4% of the total population) and for 397 persons in the Nowy Sacz voivodship (15.8% of the total population). Using this data, the nutrient content of the daily diet was calculated for each studied individual. Measurements of iodine content in water and cow-milk show relatively lower iodine levels in the Nowy Sacz voivodship. The estimated value of the iodine content in milk (5.5 micrograms/100 g of milk) was considered in the estimates of the chemical composition of the daily diet of the inhabitants of this region. The mean values of the daily energy as well as the protein and calcium consumption in all subpopulations grouped with respect to domicile, age and sex, fell within the recommended daily allowances for these groups. The iodine content, while widely scattered, concentrated around low values. The median values of the iodine content in children of age 3-10 years, age 10-16 years and in adults, were 66%, 48% and 25-40% of the recommended daily allowances, respectively. No particular differences in the food intakes were observed between inhabitants of Kraków and Nowy Sacz voivodships. Nor were significant differences found in the urine iodine excretion in groups of these regions. The low iodine content in the daily food intake may be an essential factor in the ethiology of the increasing number of thyroid goiter.

Adolescent↗
PubMed1991

[The visualization of heart wall motion using MR-interferography].

MR interferography provides a method for noninvasive measurement of heart wall motion. An interferographic pattern is projected on short axis views of the left ventricle, characterising local motion of the myocardium. In contrast to tagging methods, interferography images the direction and velocity of local wall motion at the moment of acquisition directly. Ten healthy volunteers and 8 patients with myocardial infarction were studied. Contraction, relaxation velocity of the ventricular wall, and rotation (twist) of the left ventricle were recorded. Myocardial scars were identified by abnormal pattern of segmental wall motion. MR interferography represents a promising tool for assessment of the transmural distribution of thickening and of other components of motion within the wall.

Adult↗
PubMed1990

Generalized MR interferography.

Generalized MR interferography allows the measurement of parameters which affect the phase of the MR signal. Interference is generated by the simultaneous generation of two echoes in one excitation cycle. Local variations of the signal phase are transformed into displacement of the stripe pattern generated by interference. A number of possible experiments based on this principle are presented. The resulting interferographic images allow the fast determination of parameters such as field inhomogeneity, susceptibility, flow, and motion.

Fourier Analysis↗
PubMed1990

Measurement of CSF flow using an interferrographic MR technique based on the rare-fast imaging sequence.

A fast MR sequence based on the RARE-myelographic technique allows the determination of cerebrospinal fluid (CSF) flow with a flow sensitivity below 1 mm/sec. The method averages flow over the ECG cycle and consequently measures net flow rather than ECG-dependent flow variations. The noninvasivity of this technique and the very short acquisition time of about 5 sec make this sequence a very useful diagnostic tool for a variety of CSF-flow dependent disorders like the determination of different types of hydrocephalus, the control of shunt operations and the assessment of communication pathways between CSF and cysts.

Arachnoid Cysts↗
PubMed1990

Rheumatoid arthritis lesions of the wrist examined by rapid gradient-echo magnetic resonance imaging.

Alterations of magnetic resonance imaging (MRI) relaxation time and intensity can be helpful in the diagnosis of rheumatoid arthritis (RA) lesions like synovial infiltration, local inflammation and exudation. Fast low angle shot magnetic resonance imaging (FLASH-MRI) is a rapid method showing anatomy and inflammatory pathology of the examined joint comparable to late spin echo T2 images. The following study presents our results of FLASH-MRI wrist examinations of 15 patients suffering from RA according the ARA criteria and 10 healthy volunteers compared to T1 and T2 weighted MR-images and conventional X-rays.

Arthritis, Rheumatoid↗
PubMed1989

The importance of the voxel size in clinical 1H spectroscopy of the human brain.

It is demonstrated that it is possible to acquire two volume selective 1H NMR spectra of human brain in vivo, consisting of voxels of 1.5 X 1.5 X 1.5 cm3, within 14 min with a good S/N ratio. This is mainly achieved by the application of a PRESS sequence generating a spin-echo of the VOI at 135 ms in conjunction with the STABLE technique by which two spectra can be recorded in an interlaced mode. The Bo homogeneity over such small voxels is considerably higher than over larger voxels. With these methodological improvements it is possible to observe morphological heterogeneity of tumors. The results indicate that spectral changes seem to correlate with the metabolic state of the tumor rather than the tumor type. Additionally the spectrum of a patient with multiple sclerosis suggests that even differentiation between tumors and other lesions might not be possible.

Brain↗
PubMed1989

[Study of the degree of discrepancies between analytical and theoretical results of the evaluation of daily food rations].

Thirty-six daily food rations given as the basic diet to children in two paediatric hospitals in the City of Cracow were analysed. Using laboratory methods in these meals the contents were analysed of protein, fat and carbohydrates and the energy value was determined. Parallelly the theoretical values++ of these parameters were calculated using "Tables of Composition and Nutritional Value of Food Products". For the assessment of the differences between analytical and theoretical values the following were used: 1) deviations of the values obtained in analysis from the theoretical ones accepted as 100%, 2) indices of differences. The general characteristics of the results was determined by the arithmetical++ mean, standard deviation, variance coefficient and 95% confidence limits. The results shown in the study demonstrate that the lowest mean deviation from the theoretical values was found in the case of protein (1.1%) and energy value (12.5%) with the largest one for carbohydrates (38.9%).

Child↗
PubMed1988

[Predictive value of magnetic resonance tomography in comparison with sonography and computed tomography in the diagnosis of focal liver lesions].

Ultrasonography and computed tomography are widely used for the diagnosis of focal lesions of the liver. However, the possibilities for tumor characterization and determination of potential malignancy are limited in many cases. Evaluation by magnetic resonance imaging shows a good correlation of relaxation time with the amount of stroma as a proportion of the total cell content of a lesion. This allows differentiation for a number of lesions. Thus, the combination of ultrasonography and magnetic resonance imaging could provide the ideal diagnostic procedure in many cases.

Adult↗
PubMed1987

[MR of the urinary tract in pregnancy].

A report on the application of standard 2D-FT MR combined with RARE-MR-Urography in a pregnant woman with right sided abdominal pain, dilated upper urinary tract and possible stone or inflammatory disease. This technique visualised the complete obstructed ureter in relation to the surrounding organs (uterus, vessels), allows precise diagnosis of the cause of the obstruction and avoids ionising radiation.

Adult↗
PubMed1986

[Pathology of the craniocervical junction as shown by magnetic resonance tomography. 68 cases].

In cases of a suspected lesion at the level of the cranio-cervical junction, MR should be considered as the imaging technique of choice. Tumours, inflammation and degenerative processes can be reliably demonstrated and diagnosed. Administration of contrast media, for example, gadolinium-DTPA, is necessary in selected cases only. Comparing "examination time" of x-ray myelography and high resolution x-ray CT with MR, one can well tolerate the long "acquisition" of MR images.

Arnold-Chiari Malformation↗