Biomedical subjects

F Träber

Publications and source records attributed to F Träber.

At least 19 recordsLinked to original sources

PubMed2007

Double inversion recovery brain imaging at 3T: diagnostic value in the detection of multiple sclerosis lesions.

BACKGROUND AND PURPOSE: To prospectively determine the sensitivity in the detection of multiple sclerosis (MS) lesions by using double inversion recovery (DIR), fluid-attenuated inversion recovery (FLAIR), and T2-weighted turbo spin-echo (T2 TSE) MR imaging at 3T. METHODS: Seventeen patients presenting with a clinically isolated syndrome (CIS) suggestive of MS, 9 patients with definite MS, and 6 healthy control subjects were included. Imaging was performed on a 3T MR system using DIR, FLAIR, and T2 TSE sequences. Lesions were counted and classified according to 5 anatomic regions: infratentorial, periventricular, deep white matter, juxtacortical, and mixed white matter-gray matter. The sensitivity at DIR was compared with the corresponding sensitivity at FLAIR and T2 TSE sequence. The contrast between lesions and normal-appearing gray matter, normal-appearing white matter, and CSF was determined for all sequences. RESULTS: Because of higher lesion-white matter contrast, the DIR showed a higher number of lesions compared with the FLAIR (7% gain, P = 0.04) and the T2 TSE (15% gain, P = 0.01). The higher sensitivity was also significant for the infratentorial region compared with the FLAIR (56% gain, P = 0.02) and the T2 TSE (44% gain, P = 0.02). Compared with the FLAIR, no significant changes of the lesion load measurements were observed in the supratentorial brain: slightly higher numbers of periventricular and mixed gray matter-white matter lesions on the DIR were counterbalanced by a slightly reduced sensitivity regarding juxtacortical lesions. CONCLUSION: DIR brain imaging at 3T provides the highest sensitivity in the detection of MS lesions especially in the infratentorial region.

Adult↗

PubMed2006

[MR techniques for noninvasive diagnosis of prostate cancer].

The diagnosis of prostate cancer is suggested on the basis of an elevated PSA level, abnormal digital exam, and abnormal transrectal ultrasound. US-guided biopsy is used to confirm the diagnosis, but up to 30% of prostate cancer may be missed with this approach. Meanwhile MR imaging and proton MR spectroscopy have emerged as the most sensitive additional tools for the noninvasive evaluation of prostate cancer. This article reviews the clinical indications for MRI of the prostate and summarizes new techniques such as high field strength (3 tesla) and dynamic contrast-enhanced MRI.

Biomarkers, Tumor↗

PubMed2006

[Molecular imaging of apoptosis and necrosis -- basic principles of cell biology and use in oncology].

Soon molecular imaging techniques will play a prominent role in basic scientific research and clinical approaches. In particular, important aspects of medicine such as apoptosis and gene- and stem-cell therapy will play a pivotal role in radiology too. This review presents the basic principles of apoptosis, recent results and future perspectives of apoptosis imaging. Apoptosis or programmed cell death is a precisely regulated, complex cascade of molecular events to eliminate individual cells. Disturbances may lead to diseases like malignancies and neurodegenerative diseases that are of clinical relevance. Several therapeutic strategies in oncology are based on apoptosis induction; conversely, resistance to therapy is indicative of decreased apoptosis induction. Whereas up to now the clinician had to depend exclusively on biopsy specimens to detect apoptosis, the feasibility of non-invasive imaging of this cell-biological phenomenon in vivo opens up new horizons in future. This review focuses on different modifications of this imaging technique, with and without the use of molecular probes (e. g. annexin V, synaptotagmin I), in vitro and in vivo using the various detector systems (like MRI, flow cytometry) currently available. Future perspectives are also addressed.

Animals↗

PubMed2004

[High field MR imaging: magnetic field interactions of aneurysm clips, coronary artery stents and iliac artery stents with a 3.0 Tesla MR system].

PURPOSE: To evaluate magnetic field interactions of commonly used biomedical implants at 3.0 Tesla. MATERIALS AND METHODS: Fourteen aneurysm clips designed for permanent placement in intracranial aneurysms, 19 coronary artery stents and 20 iliac artery stents were evaluated in an actively shielded compact 3.0 T MR system (Intera, Philips Medical Systems, Best, The Netherlands, length of magnet 1.57 m). The magnetic deflection forces (translational movement) were evaluated as follows: The implants were suspended by a fine string and placed in the magnet bore at the location of the maximum magnetic field gradient. The translational forces F (z) were calculated from the measured angle of deflection from the vertical axis. The magnetic field-induced torque (rotational forces) was evaluated as follows: Each implant was placed in the center of the magnetic bore parallel to the static magnetic field B0 (position 0 degrees ). Any possible displacement of the implant was noted on a millimeter scale and any torque qualitatively evaluated using a 5 point grading scale (0: no torque; + 4: very strong torque). The implant was turned in steps of 45 degrees, and the procedure was repeated to encompass a full 360 degrees rotation. RESULTS: In 52 of the 53 devices tested, the deflection force (deflection angle: range 0-21 degrees, translational force: range 0-3.8 mN) was less than the gravitational force (i.e., the implant's weight). These devices (n = 52/53) did not show any alignment to or rotation in the magnetic field at any of the various 45 degrees -increment positions corresponding to a qualitative torque evaluation of grade 0/4. One device (n = 1/53), an iliac artery stent made of stainless steel (Zenith, Cook, Mönchengladbach, BRD), was found to have deflection forces (deflection angle 88 degrees translational force 299 mN) greatly exceeding the gravitational force as well as a pronounced torque (grade 4/4). CONCLUSION: Out of 53 biomedical implants evaluated for magnetic field interactions at 3.0 T, one iliac artery stent made of stainless steel was found to be potentially unsafe based on ASTM criteria. MR imaging at 3.0 Tesla may be performed safely in patients with any of the other 52 different implants evaluated in this study with respect to magnetic field translational attraction and torque.

Alloys↗

PubMed2004

Etiopathogenetic mechanisms in long-term course of schizophrenia.

Schizophrenia is a severe mental disorder with a relapsing long-term course in 80 % of the sufferers. The underlying neurobiological principles of the long-term course are widely unknown. Therefore an attempt is made to evaluate data from structural imaging and neuropsychology to shed some light on these mechanisms. Interestingly there was a significant correlation between length of illness and volume reduction in the prefrontal grey matter in schizophrenia. There was a lack of such a correlation for the whole brain volume, white matter volume or the grey matter volume outside the prefrontal lobe. Furthermore none of the neuropsychological measures correlated with length of illness. Both findings are supported by data from prospective studies up to five years demonstrating a significant loss of frontal grey matter volume, but no change of cognitive dysfunction in the course of time. The attempt is made to connect prefrontal grey matter loss with post-mortem findings of reduced neuropil but preserved cytoarchitecture leading to recently described candidate genes and their function.

Brain↗

PubMed2002

Time-efficient T2 relaxometry of the entire hippocampus is feasible in temporal lobe epilepsy.

OBJECTIVE: To test the clinical usefulness and reliability of a new dual-echo turbo-spin-echo (TSE) sequence for rapid and regional hippocampal T2 relaxometry. METHODS: Hippocampal T2 relaxation time (HRT) was determined by a TSE sequence on three to four consecutive coronal images in 16 control subjects and 12 patients with mesial temporal lobe epilepsy. HRT was related to neuropathology findings in hippocampal specimens including neuronal cell density (ND), results of visual analysis of MR images, clinical outcome after epilepsy surgery, and hippocampal volumetry. RESULTS: Rapid HRT differentiated patients from control subjects; all cases of hippocampal sclerosis (HS; n = 10) were correctly diagnosed. HRT showed a strong correlation with ND in CA1 (p < 0.02) and CA3 (p < 0.05). Diagnoses based on rapid relaxometry concurred fully with results of visual inspection. Mean HRT was prolonged ipsilaterally in all patients with excellent postoperative seizure outcome and bilaterally prolonged or normal in patients with poorer outcome. Rapid HRT was concordant with hippocampal volumetry in 10 of 12 patients. Regional HRT of control subjects revealed significantly higher values in the anterior than posterior hippocampus. In patients with unilateral HS, this gradient was absent. The gradient was also absent contralaterally to HS, although surgical outcome was excellent. CONCLUSIONS: Hippocampal dual-echo TSE-relaxometry can be regarded a reliable technique to detect and quantify HS. With a scan time of 3.31 minutes and immediate off-line analysis lasting a few minutes only, TSE-T2 relaxometry is easy to integrate in the routine diagnostic assessment of hippocampal morphology in large numbers of patients.

Adolescent↗

PubMed2002

Perfusion and molecular diffusion-weighted MR imaging of the brain: in vivo assessment of tissue alteration in cerebral ischemia.

The combined use of perfusion imaging (PI) and diffusion-weighted imaging (DWI) is opening a new window into the processes that occur during the first hours of ischemia. DWI detects changes in molecular diffusion associated with cytotoxic edema. PI characterizes the degree of regional hypoperfusion. Regions showing mismatches between DWI and PI, i.e. hypoperfused areas with normal diffusion behavior are considered potentially salvageable. We present results of 11 patients with an occlusion of the middle cerebral artery stem and spontaneous stroke evolution. Whereas the infarct was clearly visible on initial DWI and PI, surrounding tissue at risk of infarction was marked in all patients by an increased blood volume and transit time, but only in a subgroup (n = 3) where alteration were more pronounced this tissue at risk was progressively infarcted. These human DWI and PI data show alterations in the area of tissue at risk which correlates with infarct progression.

Adolescent↗

PubMed2002

In-vivo proton MR-spectroscopy of the human brain: assessment of N-acetylaspartate (NAA) reduction as a marker for neurodegeneration.

Proton magnetic resonance spectroscopy ((1)H-MRS) is a non-invasive method to investigate changes in brain metabolite composition in different cerebral diseases. We performed proton spectroscopy in patients with dementia of the Alzheimer's type (AD) and in patients with motor neuron disease (MND) with the aim to detect the specific metabolic pattern for these neurodegenerative disorders. In the MND group we found a significant reduction of NAA/tCr metabolite ratios in the motor cortex, which correlates with the disease severity and the clinical lateralization of neurological symptoms and further decreases in the time course of the disease. In AD patients a reduction of NAA/tCr was observed in the medial temporal lobe. Since NAA is exclusively expressed in neurons as shown by immunohistochemical studies, reduced NAA levels suggest neuronal loss or dysfunction in the observed regions. The observed regional metabolic alterations reflect the neuronal basis of the characteristic neurological symptoms in AD (dementia) and MND (muscular palsy) and mirrors the disease progress over time.

Aged↗

PubMed2002

[1H-MR Spectroscopy of brain tumors in the course of radiation therapy: Use of fast spectroscopic imaging and single-voxel spectroscopy for diagnosing recurrence].

PURPOSE: To improve differential diagnosis of residual or recurrent tumor vs. tissue necrosis in the course of radiation therapy of neurosurgically-treated brain tumors by application of fast (1)H-MR spectroscopic imaging in combination with single-voxel spectroscopy (SVS). METHODS: 54 patients after with malignant brain tumor (44 cases of glioblastoma, 10 other high-grade gliomas) were examined post-surgically in a total of 140 proton MRS examinations in the course of radiotherapy and in follow-up controls. Fast SI acquisition was performed as single-slice or double-slice TSI sequence with 32 x 32 phase encodings within 11 or 15 minutes, respectively. SVS with TR/TE 2000/272 ms yielded relative metabolite ratios, and in 15 patients the time courses of the absolute concentrations of brain metabolites were also determined. RESULTS: In the group of 44 patients that could be tracked by MRS until therapy completion, TSI localized in 23 patients a persistent or newly arisen distinct choline accumulation indicating residual or recurrent tumor after radiation therapy. In all these cases MRS diagnosis was confirmed histologically or by short-term follow-up. However, in 6 of 15 patients showing a normal choline pattern in the TSI acquisition, tumor recurrence appeared within three months. SVS provided early recognition of recurrent tumor when detecting characteristic alterations of metabolite concentrations oin therapy follow-up. CONCLUSION: TSI and SVS represent complementary MRS techniques and are able to diagnose tumor recurrence early and unambiguously in cases where focal choline accumulation is detected.

Adult↗

PubMed2001

Proton magnetic resonance spectroscopy and transcranial magnetic stimulation for the detection of upper motor neuron degeneration in ALS patients.

Transcranial magnetic stimulation (TMS) was compared to proton magnetic resonance spectroscopy (1H-MRS) for the detection of upper motor neuron loss or dysfunction in 49 ALS patients classified according to the El Escorial criteria. Abnormal NAA/Cho ratios were detected in 53% of ALS patients. Abnormal TMS results (i.e. cortical inexcitability or prolonged CMCT's) were obtained in 63% of ALS patients. If one or both methods were considered for diagnosis of upper motor neuron degeneration/dysfunction, the percentage of abnormal findings was 77%, whilst in 39% of all patients both methods produced abnormal results. Compared to TMS, 1H-MRS detected more patients with upper motor neuron involvement in the suspected El Escorial subgroup (42% versus 25%), whereas TMS detected more patients with upper motor neuron involvement in the possible (81% versus 50%), probable (71% versus 57%) and definite El Escorial subgroup (71% versus 64%). We conclude that the combined use of 1H-MRS and TMS increases diagnostic accuracy for the detection of upper motor neuron involvement in ALS patients.

Adult↗

PubMed2001

Decrease of N-acetylaspartate in the MTL correlates with cognitive decline of AD patients.

In this (1)H-MRS follow-up study of the medial temporal lobe (MTL) in patients with AD, the authors report a correlation of N-acetylaspartate (NAA)/creatine (Cr) with cognitive decline. Severely progressed patients showed a reduction, whereas stable or mildly progressed subjects showed a slight increase of NAA/Cr. The reduction of NAA/Cr in the MTL represents a correlate of cognitive deterioration in AD, whereas it is of limited use to detect subtle changes over time in clinically stable patients.

Aged↗

PubMed2001

Proton magnetic resonance spectroscopy of the motor cortex in 70 patients with amyotrophic lateral sclerosis.

OBJECTIVE: To evaluate proton magnetic resonance spectroscopy for detection and monitoring of upper motoneuron degeneration in patients with amyotrophic lateral sclerosis. METHODS: Seventy patients with amyotrophic lateral sclerosis according to the El Escorial criteria were compared with 48 healthy control subjects. Single-volume proton magnetic resonance spectroscopy (echo time, 272 milliseconds; repetition time, 2000 milliseconds) was performed in both motor cortices for detection of N-acetylaspartate (NAA), phosphocreatine + creatine ([P]Cr), and choline-containing compounds (Cho) to calculate the metabolite ratios NAA/Cho, NAA/(P)Cr, and Cho/(P)Cr. In addition, absolute metabolite concentrations of NAA, (P)Cr, and Cho were obtained in 30 patients and 15 controls with the unsuppressed water signal used as an internal reference. RESULTS: Absolute concentrations of NAA (P<.001) and (P)Cr (P<.05) were reduced in motor cortices of patients, whereas Cho concentrations remained unchanged. The NAA/Cho and NAA/(P)Cr ratios were reduced in all El Escorial subgroups (P<.001). The Cho/(P)Cr ratio was elevated in patients with definite amyotrophic lateral sclerosis (P<.05). Metabolite ratio changes corresponded to the lateralization of clinical symptoms and were weakly correlated with disease duration and disease severity. In follow-up observations of 16 patients during a mean (+/-SD) of 12.1 +/- 8.7 months, NAA/Cho dropped by 9.1% (P<.01), and Cho/(P)Cr increased by 7.0% (P<.01). Changes of metabolite ratios were significantly correlated with progression of disease severity. CONCLUSIONS: Measurement of NAA concentrations and NAA/Cho ratios appear to be most suitable for detection of motor cortex degeneration by single-volume proton magnetic resonance spectroscopy. Reduced NAA/Cho ratios correspond to aspects of the clinical presentation and reflect disease progression in follow-up measurements.

Adult↗

PubMed2001

Phenotype assignment in symptomatic female carriers of X-linked adrenoleukodystrophy.

However, only very few studies have systematically investigated the extent and distribution of nervous and endocrine system involvement in female carriers of X-ALD. To define the phenotype in symptomatic female carriers of X-ALD we performed a prospective study including eight symptomatic women who were followed for a mean period of 3.4+/-1.8 years (range 1-6) using standardized clinical examination protocols, magnetic resonance imaging and spectroscopy, evoked potential studies including visual, brainstem auditory, somatosensory and magnetic evoked potentials, neurographic recordings and endocrine studies. Spastic paraparesis and decreased vibration sense in the lower extremities were the most frequent clinical findings. Slightly hyperintense symmetric parieto-occipital white matter lesions on magnetic resonance imaging were detectable in two of seven cases, and the N-acetylaspartate/choline ratios on magnetic resonance spectroscopy were decreased in three of seven patients. P40 latencies were abnormal in all patients, and central motor conduction times to the lower extremities in seven of eight patients. Prolonged latencies of brainstem auditory evoked potential waves III-V or interpeak latencies of waves I-III, I-V and III-V were detectable in all patients. The degree of walking impairment was positively correlated with the duration of clinical disease (r=0.58, P < 0.05) and inversely correlated with the N-acetylaspartate/choline ratios (r=0.85; P < 0.05). Neurographic recordings revealed only subtle abnormalities, suggesting that nervous system involvement in symptomatic female carriers of X-ALD is confined mainly to the central nervous system. No evidence of adrenal insufficiency was detected in any of the patients.

Adrenal Insufficiency↗

PubMed2000

Proton MR spectroscopy detects a relative decrease of N-acetylaspartate in the medial temporal lobe of patients with AD.

BACKGROUND: The reduction of N-acetylaspartate (NAA) detected by proton MR spectroscopy (1H-MRS) represents a robust but unspecific marker for neuronal loss or dysfunction. OBJECTIVE: To apply 1H-MRS in two brain regions that reflect the characteristic spatial distribution of neuronal loss in AD. These regions are the medial temporal lobe (MTL), which is affected early in AD, and the primary motor and sensory cortex (central region), which is affected late in the disease and might serve as an intraindividual control region in mild to moderate disease stages. METHODS: Twenty patients and 18 volunteers underwent 1H-MRS in both brain areas. The metabolic ratios of NAA/creatine and choline/creatine were determined. Additionally, the metabolic ratios of the MTL were divided by the ratios of the central region to assess the relative change in the MTL in individual subjects. All ratios were correlated with psychometric test scores. RESULTS: A significant reduction of NAA/creatine and choline/creatine ratios was detected in the MTL of patients with AD. In the central region, no significant difference between the groups was found. NAA/creatine (MTL/central region) was reduced in patients with AD and showed a correlation with the Mini-Mental State Examination and the cognitive part of the Alzheimer Disease Assessment Scale scores. Choline/creatine (MTL/central region) did not show a significant difference between groups. CONCLUSION: Assessing the distribution of NAA/creatine reduction guided by the expected neuropathologic change can improve the role of 1H-MRS in the assessment of AD. The disease severity can be monitored by relative reduction of NAA/creatine in the MTL in comparison with an intraindividual unaffected control region.

Aged↗

PubMed2000

Decreased frontal lobe ratio of N-acetyl aspartate to choline in familial schizophrenia: a proton magnetic resonance spectroscopy study.

Neuropathological and neuroimaging studies suggest neuronal dysfunction in schizophrenia. N-acetyl aspartate (NAA) is a useful marker of neuronal dysfunction that can be measured with magnetic resonance spectroscopy (MRS). In the present study NAA, choline (Cho), phospho-creatine ((P)Cr), inositol containing compounds and glutamine/glutamate (Glx) were assessed in the left frontal lobe and basal ganglia of subjects with familial schizophrenia, family members with mixed psychiatric diagnoses, unaffected family members, and community controls. Concentrations of metabolites were analyzed and expressed as ratios. NAA/Cho, NAA/(P)Cr and Glx containing compounds showed a negative correlation with age in the frontal lobe. After covarying for age, subjects with schizophrenia had a significant reduction in the left frontal lobe NAA/Cho ratio compared with unaffected family members (P=0.018) as well as with community non-familial (P=0.037) controls. These MRS observations support the hypothesis of a disease-related neuronal deficit in the frontal lobe of schizophrenic patients, and relatively normal basal ganglia.

Adult↗

PubMed2000

Ultra-fast three-dimensional MR perfusion imaging of the entire brain in acute stroke assessment.

We sought to evaluate a three-dimensional (3D) whole-brain perfusion technique based on echo-shifting (PRESTO) for its performance in evaluation of acute stroke. Twenty-six patients were scanned within 6 hours after onset of hemispheric symptoms, and the results were compared with results of diffusion-weighted imaging (DWI) and digital subtraction angiography (DSA). The signal-to-noise ratio of the images was 61 +/- 3 pre-contrast and 47 +/- 3 at the bolus peak. Brain coverage on perfusion parameter maps was 95% +/- 2% compared with that displayed on T2-weighted images, with only minor artifacts related to susceptibility at the skull base. Measured regional cerebral blood volume (rCBV) reduction closely correlated to lesion size on initial DWI and to final clinical outcome (P = 0.006), consistent with results previously reported for 2D perfusion methods. Mismatches between DWI and perfusion imaging characterized the total extent of tissue at risk, and the contrast timing correlated with the amount of collateral circulation as shown on DSA. In conclusion, 3D imaging using the PRESTO technique permits high-quality perfusion imaging of the entire brain.

Adolescent↗

PubMed2000

[The diagnostic problems in magnetic resonance tomography of the bone marrow in patients with malignomas under G-CSF therapy].

AIM: To study the effect of G-CSF therapy directly by MRI and 1H MRS in the lumbar and femoral bone marrow and differentiate between malignant bone marrow infiltration (MBMI) and reconversion of red marrow. METHODS: Thirteen patients could be examined twice, before and during G-CSF medication and another six only during treatment. T1 weighted spin-echo and opposed-phase gradient-echo images as well as the spectroscopic data (T2 values, water content) were analysed. RESULTS: After G-CSF a pathologic bone marrow signal intensity was seen in 8/13 (lumbar) and 11/13 (femoral) patients respectively. The majority of the signal alterations were diffuse (6 and 8), the minority focal (2 and 3). If a patient was successfully stimulated, a significant increase in water content occurred (21% lumbar, 34% femoral). T2 values did not change significantly, nor did they correlate with the stimulation success. CONCLUSIONS: MR tomography and -spectroscopy are suitable to detect lumbar and femoral bone marrow stimulation by G-CSF quantitatively and qualitatively. The changes may simulate MBMI. The adequate judgement of G-CSF treated bone marrow without pretherapeutic images is not possible.

Adult↗

PubMed2000

Primary central nervous system immunocytoma: MRI and spectroscopy.

We report on a young woman with a primary cerebral immunocytoma. Most primary cerebral nervous system lymphomas (PCNSL) are highly malignant undifferentiated B-cell tumours, there are few data on the clinical course, MRI and spectroscopy findings of this rare PCNSL subtype. MRI revealed a radially enhancing tumour with mild perifocal oedema. MR spectroscopy indicated low cell turnover. Slow clinical progression, no significant changes with treatment, and imaging findings were consistent with a low-grade malignant tumour.

Adult↗