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Biomedical subjects

H Kugel

Publications and source records attributed to H Kugel.

At least 19 recordsLinked to original sources
PubMed1998

Influence of the hepatobiliary contrast agent mangafodipir trisodium (MN-DPDP) on the imaging properties of abdominal organs.

To assess the influence of Mangafodipir Trisodium on the imaging properties of abdominal organs when using T1-weighted gradient-echo (GE) and T2-weighted turbo spin-echo (TSE) sequences, thirty patients with focal lesions in the liver were examined at a field strength of 1.5 T before and after intravenous administration of Mangafodipir Trisodium (dose: 5 micromol/kg of body weight). Administration of Mangafodipir Trisodium led to a significant increase in the signal intensity of the liver tissue (p < 0.001), the spleen (p < 0.01), the pancreas (p < 0.001), and the kidneys (p < 0.001) in the T1-weighted GE sequence, while there was no relevant enhancement in fatty tissue and the musculature. In the T2-weighted turbo spin-echo sequence, there was no relevant change in the signal following administration of a contrast agent. The contrast-to-noise ratio (C/N) between the lesions and the liver tissue increased significantly in the post-contrast T1-weighted GE sequence (p < 0.001), while there was no change in the contrast-to-noise ratio in the post-contrast T2-weighted turbo spin-echo sequence. The contrast-to-noise ratio of the plain T2-weighted TSE sequence was significantly higher than that in the post-contrast T1-weighted GE sequence (p < 0.001). Although Mangafodipir Trisodium was primarily developed as a hepatobiliary contrast agent for demonstration and differentiation of liver lesions, it also affects the signal levels in the pancreas, spleen, and kidneys in the T1-weighted image. Awareness of this effect on the extrahepatic tissue makes it easier to interpret pathological findings in magnetic resonance imaging (MRI) of the abdomen.

Abdomen↗
PubMed1998

[Direct-current treatment of chemically induced mammary carcinoma in an animal model: MR volumetric assessment of the effect of the therapy].

PURPOSE: To investigate the effect of direct current treatment (DCT) on the growth of mammary carcinomas in rats by MR-volumetry. METHODS: Chemically induced mammary adenocarcinomas in a control group (n = 17) were compared with treated tumours (18 C/cm3 in group A: n = 7 or 36 C/cm3 in group B: n = 12). 31 untreated tumours were situated near a treated tumour (group C). Experiments were carried out using one positive electrode in the tumour centre and three negative electrodes in the periphery. The tumour volume was measured by MRI before, and 1, 3, 6, 9 and 12 weeks after treatment. RESULTS: 12 weeks after DCT, the mean tumour volume in group A (164% +/- 158%, p < 0.05) and group B (13% +/- 24%, p < 0.001) was significantly reduced compared to the control group (434% +/- 230, Mann-Whitney U-Test). Complete tumour regression occurred in 42% of tumours in group B and was not achieved in group A, C and control group. Tumour growth in group C was decreased compared to the control group. CONCLUSIONS: The effectiveness of DCT was found to depend on the applied dosage -36 C/cm3 was more effective than 18 C/cm3. The effect of DCT is not limited to the area between the electrodes.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1998

[Correlation of MRI and histopathological findings in inflammatory skin diseases].

PURPOSE: Can spatial and contrast resolution be achieved with currently available MR devices for the successful assessment of inflammatory diseases of the skin? METHOD: High resolution MRI was performed in 20 patients with non-malignant diseases of the dermis and subcutis. The skin biopsies subsequent to the MR examinations were indicated for clinical reasons. The MR examinations were done in the location of later performed skin biopsies using a 1.0 Tesla system (Gyroscan T10 NT, Philips, Best, the Netherlands) and a surface coil of 7.5 cm inner diameter. Conventional spin-echo (SE-Sequenz)- and gradient-echo (GRE)-sequences were optimised to obtain maximum spatial resolution with a sufficient signal-to-noise ratio within a tolerable examination time. MR visualisation of histopathology was assessed by four readers using a questionnaire. RESULTS: In 15 of 20 cases, high resolution MRI allowed a correct classification of the visualised dermal and subcutaneous patterns, in accordance with the histological work-up of the corresponding specimen. Due to the still only suboptimal spatial and contrast resolution the structure of the epidermis could not be assessed adequately. Determination of contrast enhancement or non-enhancement after administration of intravenous contrast agent provided information on the degree of tissue perfusion in 19 patients, which complemented the morphological assessment. CONCLUSION: High resolution MRI allows to identify non-invasively histological main patterns of inflammatory skin diseases. However, final diagnosis often depends on higher microscopic resolution and special staining.

Adolescent↗
PubMed1998

[Endorectal MRI and ultrasonography in rectal tumors: correlation with histological staging].

PURPOSE: To compare the accuracy of high resolution endorectal magnetic resonance imaging (EMRI) and endorectal ultrasound (EUS) in the preoperative diagnostic of rectal tumours. PATIENTS AND METHODS: Twenty-one patients with known rectal tumours underwent MR imaging with an endorectal surface coil and EUS. Transversal EMR images were obtained using fast T2-weighted sequences and pre- and postcontrast T1-weighted images. EUS was performed using a 7.0 MHz transducer. Results of both methods were compared with specimens from the resected tumours. RESULTS: Rectal wall layers were reliably demonstrated with both methods in all patients. EMRI and EUS determined the depth of rectal wall invasion. EMRI and EUS agreed with pathologic findings in 16/21 cases, respectively. In one case each, both methods understaged one tumour. EMRI overstaged an adenoma as a T2-tumour. In three and four patients, respectively, no staging was possible due to technical problems. CONCLUSION: EMRI and EUS show comparable results in the preoperative T-staging of rectal tumours. Both techniques are not suitable for differentiating benign from malignant lymph nodes accurately. While EMRI is expensive and technically demanding, it allows an objective documentation of pathological findings which is less dependent on the examiner. Two important clinical conclusions can be drawn from the good results of T-staging: Adenomas and T1-tumours can be treated by local excision. In patients with advanced tumours (T3/T4) a neoadjuvant therapy can be initiated.

Adenoma↗
PubMed1998

High-resolution MR imaging of the cutis and subcutis. Histological correlation.

OBJECTIVE: To determine whether the spatial resolution that can be achieved with currently available MR devices is adequate for the evaluation of skin disease. MATERIAL AND METHODS: We correlated high-resolution MR images of the skin with dermatohistopathology in 26 patients. The examinations were carried out on a 1.0 T imager using a commercially available surface coil (ID 7.5 cm) and optimized SE and GE sequences. Image quality was assessed by four readers on a questionnaire. RESULTS: The visualization of the dermis, subcutaneous tissue, and muscle fascia allowed a pattern analysis that gave findings identical to those at dermatohistopathology. It was possible to distinguish septal from lobular panniculitis, and lipatrophia from sclerodermia. Images with contrast media infusion were useful in the differential diagnosis. CONCLUSION: High-resolution MR imaging may narrow down the differential diagnosis of various skin diseases and may help to reduce the number of skin biopsies on certain indications.

Adolescent↗
PubMed1998

Detection of focal hepatic lesions: effects of superparamagnetic iron oxide (AMI-25) on magnetic resonance imaging of the liver using T2-weighted fast spin-echo sequences and gradient-and-spin-echo sequences at 1.0 tesla.

RATIONALE AND OBJECTIVES: The authors evaluate the value of two fast spin-echo sequences (FSE) with different T2-weighting (repetition time [TR]/echo time [TE] = 2000/90 mseconds and TR/TE = 2000/40 mseconds) and combined gradient-and-spin-echo sequences (TR/TE = 2000/90 mseconds) for contrast-enhanced liver imaging with superparamagnetic iron oxide (AMI-25). METHODS: Forty-seven patients with focal liver lesions underwent magnetic resonance imaging at 1.0 tesla. AMI-25 was administered intravenously at a dose of 15 micromol iron/kg. RESULTS: Administration of AMI-25 resulted in a significant increase of lesion/liver contrast-to-noise ratio (C/N) for all T2-weighted sequences (P < 0.001). On the precontrast images, the FSE sequence with a TE of 90 mseconds had the highest C/N (16.0 +/- 4.5) whereas the best postcontrast C/N (27.9 +/- 7.6) was obtained with the mild T2-weighted FSE sequence with a TE of 40 mseconds. CONCLUSIONS: Fast spin-echo sequences are valuable sequences for imaging of the liver at 1.0 tesla. For AMI-25-enhanced magnetic resonance imaging, a mild T2-weighted FSE sequence is recommended.

Adult↗
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↗
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↗