Biomedical subjects

Frank Träber

Publications and source records attributed to Frank Träber.

17 recordsLinked to original sources

PubMed2006

Disturbed frontal gyrification within families affected with schizophrenia.

OBJECTIVE: Recently, in a post-mortem and a subsequent structural MR study, a significantly increased gyrification index (GI) was demonstrated in the frontal lobe in individuals with schizophrenia. To examine whether frontal lobe hypergyria is region-specific and whether this might be a suitable endophenotype in the search for the genetic basis of schizophrenia, the frontal as well as parieto-occipital GI were determined in MRI scans of families affected with schizophrenia. METHOD: In the MRI scans of 48 subjects suffering from schizophrenia, in 82 of their first-degree relatives and in 41 control subjects, the GI was determined in three sections anterior to the genu of the corpus callosum and three sections posterior to the splenium, thus allowing for a selective determination of this measure in the frontal as well as the parietal lobe. Outer and inner contours constituting the GI was determined in each section by manual tracing. Statistical analysis was performed using MANOVA with factors diagnostic group and intervening factors from preliminary analyses. RESULTS: The frontal, but not parieto-occipital GI was significantly higher in schizophrenic patients as well as unaffected relatives compared with control subjects (right: 7%, F=13.24, df=3, 155, p<0.0005, left: 6%, F=8.92, df=3, 155, p<0.0005). There was no overall difference between affected and unaffected family members. On the left side however, there was a significant interaction between diagnostic group and genetic loading (F=4.68, df=2, 101, p=0.01): significantly higher GI was found in affected compared with unaffected family members only in uniaffected and not multiaffected families. CONCLUSIONS: These results support our primary finding of hypergyria in the frontal lobe in schizophrenic patients. Compared to the parietal lobe, hypergyria seems to affect the frontal lobe selectively and serves as a suitable neurodevelopmental, possibly even an endophenotypic marker.

Adult↗

PubMed2006

Female pelvis: MR imaging at 3.0 T with sensitivity encoding and flip-angle sweep technique.

This study had institutional review board approval; all 33 patients (mean age, 47 years +/- 16 [standard deviation]) gave informed consent. The aim was to prospectively evaluate the diagnostic image quality yielded by a 3.0-T T2-weighted turbo spin-echo magnetic resonance imaging sequence with a very short imaging time versus that yielded by a standard 3.0-T sequence at imaging of the female pelvis. Signal-to-noise ratio and delineation of gynecologic disorders were approximately equal between the two sequences. The majority of tissue contrasts were comparable, but contrast between fluid and muscle was significantly higher and motion artifacts were reduced (P < .001 for both) with the short imaging time sequence. The fast sequence maintained or improved image quality and thus seems to be advantageous for uncooperative patients.

Adolescent↗

PubMed2006

Proton magnetic resonance spectroscopy in subjects at risk for schizophrenia.

We used proton magnetic resonance spectroscopy (1H MRS) to examine biochemical characteristics of the brain tissue in subjects at risk for schizophrenia. Nineteen participants fulfilling research criteria for an early (n=10) or a late (n=9) at-risk syndrome, 21 patients with full disease according to DSM IV and 31 healthy control subjects were included in the study. Single-voxel 1H MRS was performed in the left frontal lobe, the anterior cingulate gyrus and the left superior temporal lobe. Subjects were followed longitudinally to detect conversion to schizophrenia. We observed a significant reduction of the metabolic ratios NAA/Cr and NAA/Cho in the left frontal lobe and of NAA/Cr in the anterior cingulate gyrus in both at-risk groups and in the schizophrenic patients compared with healthy controls. Those at-risk subjects, who converted to schizophrenia within the observation period, had a higher Cho/Cr and a lower NAA/Cho ratio in the anterior cingulate gyrus compared with non-converters. NAA/Cr did not differ between converters and non-converters. Six at-risk subjects were taking antidepressants, two were taking antipsychotics. There was no difference in any metabolic ratio in any region between at-risk subjects with and without medication. We conclude that the reduction of the neuronal marker NAA in the left prefrontal lobe and the anterior cingulate gyrus may represent a vulnerability indicator for schizophrenia in at-risk subjects, while elevated Cho in the anterior cingulate gyrus may be a predictor for conversion from the prodromal state to the full disease.

Adult↗

PubMed2006

Higher sensitivity in the detection of inflammatory brain lesions in patients with clinically isolated syndromes suggestive of multiple sclerosis using high field MRI: an intraindividual comparison of 1.5 T with 3.0 T.

The purpose of this study was to determine the sensitivities in the detection of inflammatory lesions in patients with clinically isolated syndromes suggestive of multiple sclerosis at 3.0 T and 1.5 T. MR imaging of 40 patients at both field strengths was performed in separate sessions including contiguous axial slices of T2 turbo spin-echo (T2 TSE), fluid-attenuated-inversion-recovery (FLAIR) and pre- and postcontrast T1 spin-echo (T1 SE). Inflammatory lesions > 3 mm in size were counted and categorized according to their anatomic location. Lesion conspicuity was assessed on a five-point scale. At 3.0 T, 13% more white matter lesions could be identified on the FLAIR sequence and on the T2 TSE sequence. Compared to 1.5 T 7.5% more contrast-enhancing lesions were detected at 3.0 T. The higher detection rate at 3.0 T was significant for the infratentorial (p = 0.02) and juxtacortical (p < 0.01) region on the FLAIR as well as for the infratentorial (p = 0.03), juxtacortical (p = 0.02) and periventricular (p = 0.03) region on the T2 TSE sequence. The lesion conspicuity was significantly better at 3.0 T for FLAIR and T2 TSE sequences (p<0.01; p=0.01). In conclusion, high-field MRI at 3.0 T provides a significantly higher detection rate of inflammatory brain lesions especially in the infratentorial, juxtacortical and periventricular anatomic region.

Adolescent↗

PubMed2006

Imaging of inflammatory lesions at 3.0 Tesla in patients with clinically isolated syndromes suggestive of multiple sclerosis: a comparison of fluid-attenuated inversion recovery with T2 turbo spin-echo.

The aims of this study were to determine and compare the sensitivity of T2 turbo spin-echo (T2 TSE) and fluid-attenuated inversion recovery (FLAIR) sequences at 3.0 T in the detection of inflammatory lesions in patients with clinically isolated syndromes suggestive of multiple sclerosis. Forty-nine patients were examined with a 3.0 T MRI system using 5 mm axial sections of T2 TSE (2:19 min), FLAIR (4:00 min) and pre- and postcontrast T1 spin-echo sequences (3:37 min). Brain lesions were counted and categorized according to their anatomic location. Patients were classified according to Barkhof MRI criteria for FLAIR and T2 TSE sequences. The FLAIR sequence detected more lesions in every anatomic region except for the infratentorial region. The higher sensitivity was significant for the total number of lesions (p<0.01), the juxtacortical (p<0.01), and the periventricular (p=0.01) region. A 9% increase of infratentorial lesions using the T2 TSE sequence was not significant. The higher sensitivity using the FLAIR sequence resulted in one additional MRI criterion in nine patients, whereas the better detection of infratentorial lesions using the T2 TSE sequence resulted in additional MRI criteria in three patients. In conclusion, FLAIR provides the highest sensitivity when compared with the T2 TSE, although T2 TSE still has a diagnostic relevance in terms of MRI criteria classification.

Adolescent↗

PubMed2006

A multicenter reproducibility study of single-voxel 1H-MRS of the medial temporal lobe.

Proton magnetic resonance spectroscopy ((1)H-MRS) has provided evidence for a reduction of N-acetyl-aspartate (NAA) in the medial temporal lobe (MTL) in cerebral disorders such as Alzheimer's Disease. Within the (1)H-MRS study of the German Research Network on Dementia, we determined the multicenter reproducibility of single-voxel (1)H-MRS of the MTL. At five sites with 1.5T MR systems, single-voxel (1)H spectra from the MTL of an identical healthy subject were measured. The same subject was also examined at one of the sites five times to assess intracenter stability. The protocol included water-suppressed spectra with TE 272 ms and TE 30 ms and unsuppressed spectra for absolute quantification of metabolite concentrations. The intracenter reproducibility of absolute NAA concentration, expressed as coefficient of variation (CV), was 1.8%. CV for the concentrations of creatine (Cr), choline (Cho), and myoinositol (MI) and for the ratios NAA/Cr, NAA/Cho, and MI/NAA varied by 11-16%. Intercenter CV was 3.9% for NAA and were below 10% for all other metabolites and metabolic ratios. Our study demonstrates that quantitative assessment of NAA with single-voxel MRS can be performed with high intercenter reproducibility. This is the basis for applying (1)H-MRS in large-scale early recognition and treatment studies in MTL affecting disorders.

Adult↗

PubMed2005

Brain tumors: full- and half-dose contrast-enhanced MR imaging at 3.0 T compared with 1.5 T--Initial Experience.

PURPOSE: To prospectively and intraindividually compare the effect of magnetic resonance (MR) imaging at a higher magnetic field strength (3.0 T) on contrast-to-noise ratio (CNR) at different doses of a T1-shortening contrast agent in patients with contrast-enhancing brain lesions, with 1.5-T MR imaging as a reference standard. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained for all patient and volunteer studies. Twelve patients (six women, six men; mean age, 58 years; range, 29-76 years) with 12 enhancing brain lesions (11 patients with primary brain tumors and one with a solitary cerebral metastasis) underwent contrast material-enhanced MR imaging three times, on three separate days: once at 1.5 T with a full dose of 0.10 mmol/kg gadopentetate dimeglumine, once at 3.0 T with a full dose, and once at 3.0 T with half that dose, 0.05 mmol/kg. The same contrast-enhanced T1-weighted spin-echo images (repetition time msec/echo time msec, 500/12; section thickness, 5 mm; matrix, 256 x 205) were obtained at both 3.0 T and 1.5 T after prior optimization of parameters at 3.0 T. The number and conspicuity of enhancing brain lesions were assessed with blinded clinical image reading. Signal-to-noise ratio and CNR were determined with region of interest analysis of enhancing lesions and normal contralateral white matter. For 3.0 T with half the standard dose and with the full dose, CNR of lesions was intraindividually compared with CNR at 1.5 T with the full dose by using the Wilcoxon matched-pairs signed rank test. RESULTS: At 3.0 T and full dose, CNR was 2.8-fold higher than that at 1.5 T and full dose (P < .001). At the same time, higher lesion conspicuity at clinical image reading was observed. With only half the standard dose, MR imaging at 3.0 T still yielded higher CNR (1.3-fold higher) than that with full dose at 1.5 T (P < .01). CONCLUSION: With the same amount of contrast agent, MR imaging at 3.0 T offered a significantly higher CNR of enhancing cerebral lesions, compared with that at 1.5 T; even with the dose reduced by half, CNR was still higher at 3.0 T.

Adult↗

PubMed2005

MRI of the pelvis at 3 T: very high spatial resolution with sensitivity encoding and flip-angle sweep technique in clinically acceptable scan time.

OBJECTIVE: The higher signal at 3.0-T allows spatial resolution to be increased without loss in image quality. We evaluated a T2-weighted turbo spin-echo sequence with high spatial resolution (3T-HR) to determine whether this provides clinically useful pelvic MRI. MATERIALS AND METHODS: We designed a sequence with high spatial resolution (3T-HR) (0.45x0.46x4 mm) that was combined with parallel imaging and the variable refocusing angle technique (8.06 min). We examined 23 patients with gynecological disorders using 3T-HR and a standard sequence (3T-SP; 4.03 min; equivalent to 1.5 T). Two radiologists analyzed tissue contrast, signal to noise, detail delineation and artifact level. RESULTS: Tissue contrasts and signal to noise were rated equal. Motion artifacts occurred more often with 3T-SP despite the longer scanning time of 3T-HR. The higher spatial resolution provided additional information in four patients. In two patients small myomas were detected, in one patient a lymph node metastasis was apparent, and in one patient 3T-HR excluded tumor invasion. CONCLUSIONS: High spatial resolution pelvic studies with high image quality can be obtained at 3 T in acceptable scan time. The higher spatial resolution that is feasible at 3 T also provides more clinically relevant information.

Adolescent↗

PubMed2005

Relation between cerebrospinal fluid, gray matter and white matter changes in families with schizophrenia.

BACKGROUND: Gray matter reduction and ventricular enlargement belong to the best replicated findings in schizophrenia. Brain morphologic changes were also found in non-schizophrenic family members (FM). The intention of this study was to examine whether non-psychotic first-degree relatives reveal similar morphologic changes as schizophrenic patients and how state of genetic loading contribute to these abnormalities. METHODS: Forty-nine schizophrenic patients, 71 non-schizophrenic FM and 48 control subjects took part in this volumetric MRI study. All subjects were between 18 and 59 years old. Dependent variables were gray matter, white matter and total cerebrospinal fluid (CSF) volume, determined by SPM99 segmentation algorithm. As an important part of CSF lateral ventricle volume was determined manually by removing surrounding CSF areas. RESULTS: In schizophrenic patients compared to controls and non-schizophrenic FM total CSF volumes and lateral ventricles were increased. Gray and, to a lesser degree, white matter volumes were decreased as well. For CSF, gray and white matter there was no significant difference between uni- and multiple affected families. CSF correlated significantly negative with gray matter (r=-0.78) and, less intensive, with white matter (r=-0.40). There were negative correlations between gray and white matter volume as well (r=-0.26). These correlations were not significantly different between the diagnostic groups. CONCLUSION: CSF enlargement and gray matter reductions in schizophrenic patients compared to controls and non-affected FM seem to be interdependent findings. However, this correlation is independent of the factor diagnosis and is therefore not specific for schizophrenia.

Adult↗

PubMed2005

Coronary MR angiography at 3.0 T versus that at 1.5 T: initial results in patients suspected of having coronary artery disease.

PURPOSE: To prospectively evaluate the feasibility, image quality, and accuracy of coronary magnetic resonance (MR) angiography at 3.0 T in patients suspected of having coronary artery disease and to prospectively compare these results with those of coronary MR angiography performed at 1.5 T. MATERIALS AND METHODS: The study was approved by the institutional review board, and informed consent was obtained from all patients. Eighteen patients (11 men, seven women; mean age, 63 years; age range, 45-76 years) suspected of having coronary artery disease who were scheduled to undergo elective conventional coronary angiography (reference standard) were included. For coronary MR angiography at 3.0 and 1.5 T, a vector electrocardiographically gated three-dimensional segmented k-space gradient-echo imaging sequence was combined with real-time respiratory navigator gating and tracking. Signal-to-noise ratios (SNRs), contrast-to-noise ratios (CNRs), scores of image quality and sensitivity and specificity for the detection of coronary artery stenosis on a segment-by-segment basis were assessed at 3.0 and 1.5 T. Data were analyzed for statistical differences by using the Wilcoxon matched-pairs test and the McNemar test. RESULTS: The average increase in SNR at 3.0 T with respect to that at 1.5 T was 29.5% for the left coronary artery (LCA) and 31.2% for the right coronary artery (RCA) (P < .001), and the average increase in CNR was 21.8% for the LCA and 23.5% for the RCA (P < .001). Scores of image quality (P = .77) and diagnostic accuracy for the detection of coronary artery stenoses (sensitivity and specificity: 82% and 89%, respectively, at 3.0 T vs 82% and 88% at 1.5 T; P > .99) were identical or almost identical at both field strengths. CONCLUSION: Coronary MR angiography at 3.0 T is feasible in patients suspected of having coronary artery disease and yields significant increases in SNR and CNR, although current techniques do not result in significantly improved image quality and diagnostic accuracy compared with the quality and accuracy at 1.5 T. (c) RSNA, 2005.

Aged↗

PubMed2005

Three-dimensional dynamic susceptibility-weighted perfusion MR imaging at 3.0 T: feasibility and contrast agent dose.

PURPOSE: To prospectively investigate if T2*-weighted dynamic susceptibility-weighted first-pass perfusion magnetic resonance (MR) imaging is feasible at 3.0 T and which dose of contrast agent is suitable for high-field-strength imaging. MATERIALS AND METHODS: Informed consent was obtained from all participants; study protocol was approved by the institutional review board. Study included three volunteers (two men, one woman aged 35, 39, and 52 years) and 26 patients (mean age, 49 years +/- 12.8 [standard deviation]; range, 19-76 years). Volunteers underwent 3.0-T perfusion MR imaging with 0.20, 0.10, and 0.05 mmol per kilogram body weight of gadopentetate dimeglumine; patients underwent imaging with 0.10- and 0.05-mmol doses. Perfusion MR imaging was performed with three-dimensional echo-shifted echo-planar imaging (repetition time msec/echo time msec, 14/21; isotropic 4 mm3 voxels; 50 dynamic volumes with 30 sections each, covering entire brain at temporal resolution of 1.5 seconds per MR image). Quality of source echo-planar images and perfusion maps was assessed; perfusion maps obtained at studies with different contrast media doses were compared. Quantitative perfusion values and diagnostic sensitivity of perfusion studies with 0.10-mmol dose were compared with results with 0.05-mmol dose. Image quality scores were compared with marginal homogeneity test for multinomial variables (Mantel-Haenszel statistics for ordered categorized values). Signal-to-noise ratio and baseline signal intensity in perfusion studies were tested (Student t test for paired samples). Mean transit time (MTT), negative integral (NI), and maximum T2* effect from region-of-interest analysis were compared (one-tailed Student t test for paired samples). Quantitative data on number of gamma-fitted pixels were compared (t test for paired samples). Difference with P=.05 (t test for paired samples) was considered significant. RESULTS: Perfusion image quality was satisfactory even in areas close to skull base (47 of 52 images, minor distortions; remaining images, marked distortions). Perfusion imaging with 0.20-mmol dose caused almost complete signal cancellation during first pass, particularly in cortical gray matter, since mean maximum T2* effect of 98%, 99%, and 98% for gray matter was reached such that the accurate calculation of perfusion maps was impossible. With 0.10-mmol dose, the NI and maximum T2* effect were comparable to published data for 1.5-T perfusion imaging with 0.20- and 0.05-mmol doses; perfusion maps of sufficient diagnostic quality were obtained. For gray matter, mean maximum T2* effect was 25.4% +/- 9.8 with 0.10-mmol dose and 17.5% +/- 9.0 with 0.05-mmol dose. For white matter, mean maximum T2* effect was 15.2% +/- 4.5 with 0.10-mmol dose and 7.7% +/- 2.9 with 0.05-mmol dose. Difference in maximum signal intensity decrease was significant (P <.01). For NI, the difference between 0.10- and 0.05-mmol doses was significant: For gray matter, mean NI was 3.1 +/- 1.60 for 0.10-mmol dose and 1.56 +/- 1.16 for 0.05-mmol dose. For white matter, mean NI was 1.35 +/- 0.59 with 0.1-mmol dose and 0.59 +/- 0.30 with 0.05-mmol dose. CONCLUSION: With echo-shifted multishot echo-planar imaging, dynamic susceptibility-weighted perfusion MR imaging at high field strength is feasible without relevant image distortions. Compared with contrast agent dose for 1.5 T imaging, the dose for 3.0 T can be reduced to 0.10 mmol.

Adult↗

PubMed2004

Shape changes in prefrontal, but not parieto-occipital regions: brains of schizophrenic patients come closer to a circle in coronal and sagittal view.

There is some evidence for prefrontal (PF) lobe changes in schizophrenia while the parieto-occipital (PO) region seems to be unaffected. This magnetic resonance imaging (MRI) study was performed to examine shape differences as part of the spectrum of structural abnormalities in schizophrenia. The measurements were done on families affected with schizophrenia to identify the influence of genetic and environmental factors on these changes. The sample under study consisted of 164 subjects including 45 family members (FM) suffering from schizophrenia, 27 FM with other psychiatric disorders and 51 FM without psychiatric disorders based on ICD-10 criteria. In addition, 41 nonpsychiatric control subjects were included in the study. On defined planes at the corpus callosum boundary of the PF and the PO, brain width, height and length were measured on coronal slices. Ratios of these linear measurements were also calculated based on the idea that a plane can be approximated by a circle if the concerning ratio comes close to 1. It was hypothesized that these relative brain shape parameters, especially the PF ratio width/height, would show differences between schizophrenic patients and control subjects. For all members from families with schizophrenia compared with control subjects, there were significant differences in the PF, but not in the PO region. PF height was increased. PF ratios of width/height and height/(2 x length) were closer to 1 in affected families than in control subjects. The results can be interpreted as an indication for PF brain shape changes in subjects with a disposition for schizophrenia. On coronal and sagittal planes situated at the corpus callosum, their PF could be approximated by a circle better than in control subjects. As the frontal lobe takes shape late in brain development, underlying genetic mechanisms may be dysregulated in schizophrenic patients and subjects at risk to develop the disorder.

Adult↗

PubMed2004

1H metabolite relaxation times at 3.0 tesla: Measurements of T1 and T2 values in normal brain and determination of regional differences in transverse relaxation.

PURPOSE: To measure 1H relaxation times of cerebral metabolites at 3 T and to investigate regional variations within the brain. MATERIALS AND METHODS: Investigations were performed on a 3.0-T clinical whole-body magnetic resonance (MR) system. T2 relaxation times of N-acetyl aspartate (NAA), total creatine (tCr), and choline compounds (Cho) were measured in six brain regions of 42 healthy subjects. T1 relaxation times of these metabolites and of myo-inositol (Ins) were determined in occipital white matter (WM), the frontal lobe, and the motor cortex of 10 subjects. RESULTS: T2 values of all metabolites were markedly reduced with respect to 1.5 T in all investigated regions. T2 of NAA was significantly (P < 0.001) shorter in the motor cortex (247 +/- 13 msec) than in occipital WM (301 +/- 18 msec). T2 of the tCr methyl resonance showed a corresponding yet less pronounced decrease (162 +/- 16 msec vs. 178 +/- 9 msec, P = 0.021). Even lower T2 values for all metabolites were measured in the basal ganglia. Metabolite T1 relaxation times at 3.0 T were not significantly different from the values at 1.5 T. CONCLUSION: Transverse relaxation times of the investigated cerebral metabolites exhibit an inverse proportionality to magnetic field strength, and especially T2 of NAA shows distinct regional variations at 3 T. These can be attributed to differences in relative WM/gray matter (GM) contents and to local paramagnetism.

Adult↗

PubMed2003

Influence of genetic loading, obstetric complications and premorbid adjustment on brain morphology in schizophrenia: a MRI study.

Cerebrospinal fluid (CSF) space enlargement in schizophrenia is a prominent finding. This study was initiated to examine the influence of genetic loading, obstetric complications and premorbid adjustment on the extent of this enlargement. The sample of this MRI study consisted of 40 schizophrenic patients, 24 psychiatric and 40 healthy family members from 10 uniaffected and 19 multiple affected families with schizophrenia, such as 27 control subjects from non-affected families. The ventricle-to-brain-ratio (VBR), and the areas of the third ventricle, sylvian fissure, temporal horn and interhemispheric fissure at the slice where these structures reached their maximum were examined relatively to the corresponding total brain areas. The sum of CSF areas was calculated as a parameter for global atrophy. From MANCOVA adjusted for intervening variables the right VBR and the sum of CSF areas revealed significant differences between diagnostic groups. For these areas schizophrenic patients showed an increase compared to control subjects and family members with psychiatric disorder. Genetic loading influenced the interhemispheric fissure, enlarged in multiple affected compared to uniaffected families, and the temporal horn asymmetry, which was right sided (right > left) in control subjects and multiple affected families, but inverted in uniaffected families. Neonatal obstetric complications influenced only the size of the VBR, while premorbid adjustment predicted various CSF areas. In conclusion, schizophrenic subjects from multiple and uniaffected families showed a global atrophy, which was most pronounced in the VBR. Genetic loading seems to have an impact on frontal regions as the interhemispheric fissure and on the temporal horn.

Adolescent↗

PubMed2002

Regional N-acetylaspartate reduction in the hippocampus detected with fast proton magnetic resonance spectroscopic imaging in patients with Alzheimer disease.

OBJECTIVE: To detect regional metabolic changes that resemble the expected spatial pattern of neuronal loss in patients with Alzheimer disease (AD). METHODS: Thirty-four patients with AD and 22 healthy control subjects were included in the study. Single-slice fast proton spectroscopic imaging was performed in parallel angulation to the temporal lobes. Proton spectra were selected from the hippocampus, the lateral temporal lobe, and the occipital lobe of both hemispheres to determine metabolite concentration of N-acetylaspartate (NAA), total creatine (tCr), including phosphocreatine and creatine, and choline-containing compounds (Cho). The metabolic ratios of NAA/tCr and Cho/tCr were calculated and compared between patients with AD and healthy volunteers. RESULTS: The NAA/tCr ratios were significantly reduced in the left (F(1,1) = 4.34, P =.04) and right hippocampus (F(1,1) = 9.96, P =.003) in patients with AD. The Cho/tCr ratios remained unchanged in both hippocampi. There was no significant change of either NAA/tCr or Cho/tCr in the lateral temporal and occipital lobes of patients with AD. CONCLUSION: This study provides evidence that fast proton spectroscopic imaging may detect the regional pattern of disturbed neuronal integrity in patients with AD with high spatial resolution in a short acquisition time.

Aged↗

PubMed2002

Evaluation of a new ultrasmall superparamagnetic iron oxide contrast agent Clariscan, (NC100150) for MRI of renal perfusion: experimental study in an animal model.

PURPOSE: To determine the diagnostic value of a new ultrasmall superparamagnetic iron oxide Clariscan, (NC100150) for the evaluation of renal perfusion in an animal model using a 3D-FFE-EPI sequence. MATERIALS AND METHODS: Four groups of four rabbits each were imaged after bolus injection of NC100150, using a 1.5 T MR system (Gyroscan ACS-NT). T2*w MR images in the coronal plane were acquired over 60 seconds with an echo-shifted 3D-FFE-EPI sequence (TR/TE/alpha = 18/25 msec/8 degrees ). Data were transferred to a workstation and converted into concentration curves. Based on the fitted concentration time curves, parameter maps were calculated pixelwise: bolus arrival time (T0), time-to-peak (TTP), mean transit time (MTT), and relative bolus volume (rBV). Maximum signal decrease was determined with respect to the baseline value. RESULTS: Mean MTT increased from 4.2 seconds at a dose of 0.25 mg to 5.9 seconds at 1.0 mg (P < .0001). The maximum signal decrease was observed at 0.75 mg, corresponding to 85% of the baseline value. Transit times of the contrast bolus were accurately calculated for the cortex and the outer medulla, but at the level of the inner medulla no arterial flow profile was identified. No significant difference between the cortex and the outer medulla was found for either T0 or rBV, but medullar TTP and MTT were prolonged with regard to cortical TTP and MTT (6.3 seconds vs. 5.7 seconds, P < .001; 5.7 seconds vs. 4.2 seconds, P < .0001). CONCLUSION: The employed intravascular contrast agent is well suited to assess renal perfusion. By the use of a T2*w3D perfusion sequence, cortical and medullar transit times can be quantified and physiologic information on regional perfusion differences can be obtained.

Animals↗

PubMed2002

Abdomen: diffusion-weighted MR imaging with pulse-triggered single-shot sequences.

Magnetic resonance (MR) diffusion measurements of the abdomen were performed in 12 healthy volunteers by using a diffusion-weighted single-shot sequence both without and with pulse triggering for different trigger delays. Pulse triggering to the diastolic heart phase led to reduced motion artifacts on the diffusion-weighted MR images and to significantly improved accuracy and reproducibility of measurements of the apparent diffusion coefficients, or ADCs, of abdominal organs.

Abdomen↗