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H Kugel

Publications and source records attributed to H Kugel.

At least 19 recordsLinked to original sources
PubMed2005

Evidence for a neural correlate of a framing effect: bias-specific activity in the ventromedial prefrontal cortex during credibility judgments.

BACKGROUND: Neural processes within the medial prefrontal cortex play a crucial role in assessing and integrating emotional and other implicit information during decision-making. Phylogenetically, it was important for the individual to assess the relevance of all kinds of environmental stimuli in order to adapt behavior in a flexible manner. Consequently, we can in principle not exclude that environmental information covertly influences the evaluation of actually decision relevant facts ("framing effect"). OBJECTIVE: To test the hypothesis that the medial prefrontal cortex is involved into a framing effect we employed functional magnetic resonance imaging (fMRI) during a binary credibility judgment task. METHODS: Twenty-one subjects were asked to judge 30 normalized news magazine headlines by forced answers as "true" or "false". To confound the judgments by formally irrelevant framing information we presented each of the headlines in four different news magazines characterized by varying credibility. For each subject the susceptibility to the judgment confounder (framing information) was assessed by magazine-specific modifications of the answers given. RESULTS: We could show that individual activity changes of the ventromedial prefrontal cortex during the judgments correlate with the degree of an individual's susceptibility to the framing information. CONCLUSION: We found (i) a neural correlate of a framing effect as postulated by behavioral decision theorists that (ii) reflects interindividual differences in the degree of the susceptibility to framing information.

Adult↗
PubMed2005

Dehydration confounds the assessment of brain atrophy.

Computerized brain volumetry has potential value for diagnosis and the follow-up evaluation of degenerative disorders. A potential pitfall of this method is the extent of physiologic variations in brain volume. The authors show that dehydration and rehydration can significantly change brain volume: lack of fluid intake for 16 hours decreased brain volume by 0.55% (SD, +/-0.69), and after rehydration total cerebral volume increased by 0.72% (SD, +/-0.21).

Adult↗
PubMed2005

[Comparison of a T1-weighted inversion-recovery-, gradient-echo- and spin-echo sequence for imaging of the brain at 3.0 Tesla].

PURPOSE: The increased T1 relaxation times at 3.0 Tesla lead to a reduced T1 contrast, requiring adaptation of imaging protocols for high magnetic fields. This prospective study assesses the performance of three techniques for T1-weighted imaging (T1w) at 3.0 T with regard to gray-white differentiation and contrast-to-noise-ratio (CNR). MATERIALS AND METHODS: Thirty-one patients were examined at a 3.0 T system with axial T1 w inversion recovery (IR), spin-echo (SE) and gradient echo (GE) sequences and after contrast enhancement (CE) with CE-SE and CE-GE sequences. For qualitative analysis, the images were ranked with regard to artifacts, gray-white differentiation, image noise and overall diagnostic quality. For quantitative analysis, the CNR was calculated, and cortex and basal ganglia were compared with the white matter. RESULTS: In the qualitative analysis, IR was judged superior to SE and GE for gray-white differentiation, image noise and overall diagnostic quality, but inferior to the GE sequence with regard to artifacts. CE-GE proved superior to CE-SE in all categories. In the quantitative analysis, CNR of the basal ganglia was highest for IR, followed by GE and SE. For the CNR of the cortex, no significant difference was found between IR (16.9) and GE (15.4) but both were superior to the SE (9.4). The CNR of the cortex was significantly higher for CE-GE compared to CE-SE (12.7 vs. 7.6, p < 0.001), but the CNR of the basal ganglia was not significantly different. CONCLUSION: For unenhanced T1 w imaging at 3.0 T, the IR technique is, despite increased artifacts, the method of choice due to its superior gray-white differentiation and best overall image quality. For CE-studies, GE sequences are recommended. For cerebral imaging, SE sequences give unsatisfactory results at 3.0 T.

Brain↗
PubMed2003

Magnetic resonance imaging protocols for examination of the neurocranium at 3 T.

The increasing availability of high-field (3 T) MR scanners requires adapting and optimizing clinical imaging protocols to exploit the theoretically higher signal-to-noise ratio (SNR) of the higher field strength. Our aim was to establish reliable and stable protocols meeting the clinical demands for imaging the neurocranium at 3 T. Two hundred patients with a broad range of indications received an examination of the neurocranium with an appropriate assortment of imaging techniques at 3 T. Several imaging parameters were optimized. Keeping scan times comparable to those at 1.5 T we increased spatial resolution. Contrast-enhanced and non-enhanced T1-weighted imaging was best applying gradient-echo and inversion recovery (rather than spin-echo) techniques, respectively. For fluid-attenuated inversion recovery (FLAIR) imaging a TE of 120 ms yielded optimum contrast-to-noise ratio (CNR). High-resolution isotropic 3D data sets were acquired within reasonable scan times. Some artifacts were pronounced, but generally imaging profited from the higher SNR. We present a set of optimized examination protocols for neuroimaging at 3 T, which proved to be reliable in a clinical routine setting.

Adult↗
PubMed2003

Clinical and diagnostic value of preoperative MR mammography and FDG-PET in suspicious breast lesions.

Dynamic enhanced magnetic resonance (MR) mammography and fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) of the breast were directly compared preoperatively in suspicious breast lesions. Forty-two breast lesions in 40 patients were examined with a three-dimensional dynamic MR imaging series and FDG-PET. The MR and PET examinations were evaluated separately and the results were compared with the histological findings. The sensitivity and specificity of each method were calculated. The diagnostic value of both modalities as single diagnostic tool and in combination was investigated. Nineteen malignant and 23 benign breast lesions were proven histologically. Magnetic resonance mammography and FDG-PET showed a sensitivity of 89 and 63%, respectively. The specificity was 74 and 91%, respectively. The combination of both imaging methods decreased the not-required biopsies from 55 to 17%. Only one false-negative finding-a patient pre-treated with chemotherapy-was observed in both methods. The combination of MR mammography and FDG-PET can help to decrease biopsies of benign breast lesions. Because of their high cost, these modalities should only be used in problematic cases to either rule out or to demonstrate malignancy. The best diagnostic strategy is achieved using MR mammography first. If the diagnosis is still questionable, FDG-PET can be performed.

Breast↗
PubMed2002

MR-guided core biopsies using a closed 1.0 T imager. First clinical results.

OBJECTIVE: High soft-tissue contrast and multiplanar imaging capabilities of MRI may be advantageous in biopsy guidance compared to CT. We report our first results with MR-guided core biopsies using a closed 1.0 T MR imager. METHODS AND PATIENTS: In ten patients, seven liver lesions and one lesion each in the muscle of the back, the gluteal muscle and in the breast were biopsied under MR guidance using MR-compatible needles (Tru-Cut type, 18G and 14G). For control scans T1-weighted turbo-spin-echo (TSE), gradient-echo and T2-weighted TSE sequences were used. RESULTS: In all patients, the suspicious lesions and the biopsy needle were exactly delineated in MR control scans. In nine out of ten patients, the suspicious lesion was clarified histologically. Controls of needle position in a second plane were performed twice. Pushing the inner stylet alone resulted in a distortion of the needle in several cases in its flat area. The small diameter of the MR gantry was inconvenient for a few patients. One complication (intrahepatic bleeding) was observed, which healed up without consequences. CONCLUSION: Using a closed 1.0 T MR imager MR-guided core biopsies can be conducted efficiently. Core biopsies should be taken by pulling and pushing the outer cannula. Advantageous compared to CT are the multiplanar imaging capabilities, while the smaller gantry is disadvantageous.

Adult↗
PubMed2002

A cost-effectiveness evaluation of amlodipine usage in patients with coronary artery disease in Sweden.

The objective of this analysis was to calculate the cost-effectiveness of amlodipine therapy in patients with coronary artery disease in Sweden. It is hypothesised that treatment with amlodipine will have an impact on overall cardiovascular disease treatment costs, resulting in a positive cost-effectiveness profile. A Markov cohort simulation model was constructed to simulate event-related and procedure-related health economic outcomes of coronary artery disease populations on amlodipine versus those on placebo. Patient level data from the Prospective Evaluation of the Vascular Effects of Norvasc Trial was used to populate the model. The total number of adverse cardiovascular clinical outcomes experienced over a three-year period was lower for patient on amlodipine than for those on placebo. The rate of hospitalisation per patient due to angina, coronary artery bypass graft, percutaneous transluminal coronary angioplasty, congestive heart failure, and myocardial infarction in the placebo cohort was 64.7%, while the rate in the amlodipine cohort was 46.9%. The cost per patient was Swedish kroner (SEK)26,600 for amlodipine patients and SEK27,400 for placebo patients. The use of amlodipine resulted in improved clinical outcomes as well as a slight savings in cost over a three-year period.

Amlodipine↗
PubMed2001

Age related signal decrease in functional magnetic resonance imaging during motor stimulation in humans.

Right handed healthy volunteers underwent functional magnetic resonance imaging (fMRI) examinations on a 1.5 Tesla MRI-scanner (Gyroscan ACS NT; Philips, Best, NL). Blood oxygen level dependent (BOLD) images were obtained using a three dimensional multi-shot echo planar imaging sequence employing a shifted echo technique (Principles of echo shifting with a train of observations). Finger tapping of the right hand was used as a task for motor stimulation. A total of 86 subjects was included into statistical analysis. Absolute and relative signal differences and cluster sizes of activation for the left motor cortex were obtained. In addition, Z-score, pooled Z-score and cross correlation activation maps were calculated and matched with high resolution anatomic images. A significant decrease with age could be detected for absolute and relative signal intensity differences for the whole group and for the male subgroup. Correlation analysis for the female subgroup also bore negative albeit non-significant correlation coefficients. An age-related decline of BOLD-contrast can be assumed to explain signal decrease. This age-related effect should be considered in clinical fMRI applications.

Adult↗
PubMed2001

Age- and sex-specific differences in the 1H-spectrum of vertebral bone marrow.

Correct interpretation of 1H magnetic resonance (MR) studies of the red vertebral bone marrow in patients with disorders of the hematopoietic system requires knowledge of the dependence of the proton spectrum on age and sex. Infiltration of malignant cells causes a decreased red bone marrow fat signal, which is reversed upon successful treatment. The aim of this study was to establish a database of normal water/fat relations from a large group of volunteers. In all, 154 healthy volunteers from 11 to 95 years of age were examined using a 1.5-T MR system (ACS-NT, Philips). A volume of 2-8 ml in the center of a normal vertebral body was selected for spectroscopy using the PRESS sequence without water suppression (TR/TE 2 sec/40 msec). Signal intensities and T2 times of lipid and water resonances were determined. The relative fat signal intensity was calculated corrected for T2 relaxation. The relative proportion of protons in the fat signal increases with age from 24% in the age group 11-20 years to 54% in the group > or = 61 years. The proportion of fat in the vertebral bone marrow in female subjects is less than that in male subjects in the same age group (statistically significant at P < or = 0.01). In the central age group between 31 and 50 years, the difference is largest, at 12%; in the youngest and oldest age group this difference is small. T2 times are neither age nor sex dependent.

Adipose Tissue↗
PubMed2001

Fast sequences with fat suppression in breath-hold mode: new standard in contrast-enhanced T1-weighted MR imaging of renal tumors?

Our purpose was to analyze detection, diagnostic characterization, and staging of renal solid lesions using different fast T1-weighted sequences with fat suppression in breath-hold mode compared with a gradient-echo sequence after contrast application. Twenty-five patients with focal renal lesions were examined with a T1-weighted ultrafast turbo spin-echo (UTSE) sequence with frequency selective fat suppression (SPIR), two different segmented echo-planar imaging (EPI) sequences - a spin-echo and a gradient-echo echo-planar sequence (SE-, FFE-EPI) combined with SPIR and a gradient-echo (fast field echo, FFE) sequence in a prospective study. The images of all sequences were visually evaluated and in addition to qualitative evaluation the contrast-to-noise ratio (CNR) for cyst and solid lesions was measured. Among the different T1-weighted sequences, the best detection and characterization of renal solid lesions were obtained with the UTSE SPIR and the SE-EPI sequence (sensitivity: 100 and 75%, respectively; specificity: 90 and 75%, respectively). The FFE and FFE-EPI sequences showed lower sensitivity (86%) and the same specificity (75%). The staging of renal tumors was best achieved with the UTSE SPIR and SE-EPI sequence (84 and 73%, respectively). The staging was correct in only 47% and 58 for the FFE and FFE-EPI sequences, respectively. The investigated sequences showed no significant differences in CNR. The combination of fat suppression and breath-hold mode improves detection, characterization, and staging of renal lesions. The UTSE SPIR and SE-EPI sequence in breath-hold mode showed specific image artifacts, but offered high sensitivity and specificity for detection and characterization of renal lesions compared with the FFE sequence. The results of this study suggest, for T1-weighted imaging of renal tumors, use of UTSE or SE-EPI sequences with fat suppression in breath-hold mode for renal imaging.

Adipose Tissue↗
PubMed2001

Functional magnetic resonance imaging of human pontine auditory pathway.

The purpose of this study is to visualize brainstem auditory pathways by functional magnetic resonance imaging (fMRI). Eighteen healthy volunteers (age 28 to 42 years) with normal hearing function underwent fMRI examination on a 1.5 Tesla imaging system (Philips, Best, The Netherlands) with periodic click stimulation. Blood oxygen level dependent images were obtained using a three-dimensional EPI sequence with shifted echo technique (principles of echo shifting with a train of observations). Control scans without click stimulation were obtained in the identical setting. Cross correlation activation maps were calculated using a postprocessing tool (Philips). They were matched with anatomic slices of identical orientation and thickness. Five of 18 subjects were excluded because of motion artifacts. In 4/13 significant activation was observed at the root entry zone of the ipsilateral acoustic nerve corresponding to the cochlear nuclei. In 11/13 subjects, significant activation was found in the same slice contralaterally close to the floor of the 4th ventricle, corresponding to the expected region of the superior olivary nucleus. Activation of the rostral parts of the auditory pathway (inferior colliculus, medial geniculate body) was not found. In the absence of the stimulus no activation occurred in these structures. It was concluded that activation of the brainstem auditory pathways by click stimuli can be visualized by fMRI.

Acoustic Stimulation↗
PubMed2001

[Local therapy of liver metastases of colorectal carcinomas. Laser therapy vs. direct current treatment in the rat model].

PURPOSE: Evaluation of the efficacy of direct current and laser therapy in the treatment of colorectal liver metastases in a rat model. MATERIALS AND METHODS: Liver metastases in 49 rats were induced by subcapsular injection of cells of a colorectal tumor cell line. 3 weeks after inoculation 41 tumors were treated by laser and 56 tumors by direct current therapy. 17 tumors served as a control in the direct current group, 12 in the laser therapy group. The inoculation rate and the tumor size 3 and 5 weeks after therapy were determined by MRI. RESULTS: The MR-tomographically determined inoculation rate was 133 tumors after 151 tumor cell injections (88%). Three and five weeks after laser therapy, tumor growth rates of 15% and 18% were documented (maximum tumor diameter). This represented a significant reduction in growth (p < or = 0.01 and p < or = 0.001) compared to the control group (growth rate 230% and 280%). In the direct current therapy group, growth rates were 40% after 3 and 60% after 5 weeks. Compared to the control group (210% and 290%), this also represented a significant reduction (p < or = 0.001). CONCLUSIONS: This animal study is the first to demonstrate an antitumor effect of direct-current therapy on liver metastases of colorectal cancer in rats. Nevertheless, the laser therapy proved to be more effective.

Animals↗
PubMed2001

[MRI with cerebrospinal fluid measurement before and after endoscopic ventriculostomy and aqueductal stenosis].

PURPOSE: Evaluation of MR imaging and CSF flow measurement for planning and follow-up of neuroendoscopic third ventriculostomy in occlusive triventricular hydrocephalus. METHOD: 17 patients with occlusive hydrocephalus due to idiopathic or neoplastic aqueductal stenosis were examined before and after surgery with cardiac-gated T2-weighted and cardiac-gated phase contrast cine sequences. The visibility of anatomic structures and the patency of the ventriculostomy were evaluated. RESULTS: In all 17 patients, the relevant anatomic structures were visible. The cine sequence demonstrated occlusion of the aqueduct and patency of the ventriculostomy in all cases, even in patients with doubtful clinical patterns. CONCLUSIONS: MR imaging with additional cardiac-gated cine sequences allows exact preoperative diagnosis of occlusive hydrocephalus as well as patient selection and planning for endoscopic third ventriculostomy. Non-invasive follow-up, especially in patients with a doubtful clinical pattern, is possible.

Adolescent↗
PubMed2001

[Functional capacity of MRI-compatible biopsy needles in comparison with ferromagnetic biopsy needles. In vitro studies].

PURPOSE: Comparative evaluation of specimens obtained with different MR-compatible biopsy systems and a conventional ferromagnetic system. METHODS: Biopsies of a pig liver were performed post-mortem with three different MR-compatible (Somatex; E-Z-EM; Daum) and one conventional biopsy system (Somatex), five with each device. The specimens were measured and the histopathological quality was graded on a scale from 0 (no tissue) to 9 (best). The tip of the needle was examined with an electron microscope before and after biopsy to demonstrate abrasion. RESULTS: The histopathological score between the first and fifth specimen taken with one biopsy device showed no significant difference. The conventional system yielded significantly better results in nearly all categories (p < 0.05) than the MR-compatible biopsy systems. The areas of the specimens obtained with the MR-compatible biopsy systems (4.27-5.99 mm2) were significantly smaller than those from the conventional system (9.98 mm2). The needle tip abrasion of the different biopsy systems determined by electron microscopy showed no substantial difference. CONCLUSION: Specimens obtained with MR-compatible biopsy systems compared to conventional biopsy systems are of lower histopathological quality. This might be caused by a smaller side notch of the MR-compatible biopsy devices. There was no difference in abrasion of the needle tip due to the softer, non-ferromagnetic alloys.

Animals↗
PubMed2001

[Artifacts in MR Imaging due to ventilation tubes].

UNLABELLED: Artifacts in MR Imaging due to ventilation tubes. PURPOSE: MR examinations may be necessary in patients under artificial ventilation. Possible imaging artifacts originating from ventilation tubing made from silicone are demonstrated. MATERIALS AND METHODS: In silicone carbohydrate residues are bound to silicon atoms. In silicone gels they give strong signals in MR imaging. MR signals from more solid silicone rubber are only possible if the carbohydrate residues in the molecular chain retain a sufficient mobility. To investigate whether silicone tubes give signals in MR images, different tubes for ventilation made from silicone and polyester were examined at 1.5 T (Gyroscan ACS NT, Powertrak 6000 gradients) with MR imaging and spectroscopy (MRS: PRESS, TE = 20 ms; relaxation time measurements: MIXED sequence; imaging: FFE [gradient echo] and TSE sequences). RESULTS: Using short TE (</= 4 ms), tubes and sockets made from silicone could be imaged with FFE and SE sequences. An SE sequence with a short TE = 4 ms provided a sufficient signal intensity to depict the tube clearly besides brain tissue of a volunteer. When foldover occurred, the signal of the tube was projected onto the brain tissue. MR spectra confirmed that the image signal originated from the carbohydrate residues of the silicone molecule chains, not from residual water in the tube wall material. T(2) determinations indicate a multiexponential relaxation including a large component with a short TE (</= 15 ms). Tubes made from a polyester elastomere did not show up in MR images. CONCLUSION: In MR images acquired with very short echo times silicone in ventilation tubes may produce significant artifacts.

Adult↗
PubMed2001

In vitro evaluation of intravascular stent artifacts in three-dimensional MR angiography.

RATIONALE AND OBJECTIVES: To evaluate the intraluminal signal characteristics of various stents and stent-grafts in contrast-enhanced three-dimensional MR angiography (3D MRA) in vitro. METHODS: Fourteen stents made of different materials (steel, nitinol, tantalum, cobalt-based alloy, polyethylene) and six stent-grafts were implanted in plastic tubes simulating the common iliac artery. The tubes were filled with gadopentetate dimeglumine in water at a concentration of 25 mmol/L and positioned in a plastic container filled with water. For imaging, the container was placed in the center of the magnet, parallel, orthogonal, and diagonal to the z axis. A 3D gradient-echo sequence (T1-FFE) was acquired with the following parameters: repetition time 5.3 ms, echo time 1.6 ms, flip angle 50 degrees, slice thickness 1.5 mm, and acquisition matrix 256 with zero filling to 512. To evaluate the influence of the frequency-encoding gradient on the appearance of the artifacts, stents were examined with their axes oriented in all three directions both with the frequency-encoding gradient in the feet-head and right-left directions. The size and pattern of stent-related artifacts were evaluated semiquantitatively for each measurement. RESULTS: Five different components of artifacts could be distinguished: homogeneous signal reduction inside the stent, narrowing of the stent lumen, structures of various shapes inside the stents, signal reduction or signal increase at the ends of the stents, and shift of the intraluminal signal orthogonal to the longitudinal axis of the vessel. The size of the artifacts depended heavily on the material of the stent. The polyethylene stent showed no artifacts, the tantalum stent only minor artifacts. Nitinol stents were characterized by artifacts at both ends and signal reduction intraluminally. Stents made of steel demonstrated the strongest artifacts, characterized by almost complete signal loss intraluminally. The characteristics of the artifacts of all stents depended on the direction of the stent relative to the frequency-encoding gradient. CONCLUSIONS: Three-dimensional MRA follow-up after stent placement may be applicable for stent patency evaluation in all instances. However, grading of stenoses seems to be unrealistic in steel stents and in most nitinol stents.

Arteries↗
PubMed2001

Relation between 1H MR spectroscopic imaging and regional cerebral glucose metabolism in Alzheimer's disease.

1 H Magnetic resonance spectroscopic imaging (MRSI) and positron emission tomography (PET) of (18) F-2-fluoro-2-deoxy-D-glucose (FDG) were performed in 18 patients with probable Alzheimer's disease (AD) and 3 normal controls. We measured the distribution and relative signal intensities of N-acetyl aspartate (NAA; a presumed neuronal marker), choline residues (Cho) representing cellular membrane compounds and of creatine-containing metabolites (Cr), and correlated these to regional cerebral glucose metabolism (rCMRGI) after coregistration of both imaging-techniques. The pattern of choline was significantly different between AD and normals (p < 0.01). RCMRGI was significantly related to Cho/Cr (r=-0.21, p<.05) and NAA/Cho quotients (r=0.35, p<.001). Our results suggest that in AD reduced neuronal energy performance and membrane abnormalities contribute to metabolic deterioration.

Adult↗