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Biomedical subjects

F Träber

Publications and source records attributed to F Träber.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Pulse triggering for improved diffusion-weighted MR imaging of the abdomen].

PURPOSE: The aim of this work was to reduce the influence of motion on diffusion-weighted MR images of the abdomen by pulse triggering of single-shot sequences. METHODS: Five healthy volunteers were examined both without and with finger pulse-triggering of a diffusion-weighted single-shot echo planar MR imaging sequence at 1.5 T. Series of diffusion-weighted images were acquired at different phases of the cardiac cycle by varying the time delay between finger pulse and sequence acquisition. The measurements were repeated three times. The diffusion weighted images were analysed by measuring the signal intensities and by determining the ADC values within the spleen, kidney and liver. RESULTS: The magnitude of motion artifacts on diffusion weighted images shows a strong dependence on the trigger delay. The optimum trigger delay is found to be between 500 and 600 ms. For these values the abdominal organs appear homogeneous on all diffusion weighted images and the strongest signal intensities are detected. At optimum triggering the accuracy of the apparent diffusion coefficients is up to 10 times better than without triggering. Moreover, the standard deviation of the repeated measurements is smaller than 12% for all volunteers and for all organs. Without triggering the standard deviation is larger by a factor of 4 on average. CONCLUSION: Pulse triggering of single-shot sequences leads to significant reduction of motion related artifacts on diffusion weighted images of the abdomen and provides more accurate and reproducible ADC values.

Abdomen↗
PubMed2000

Middle cerebral artery (MCA) susceptibility sign at susceptibility-based perfusion MR imaging: clinical importance and comparison with hyperdense MCA sign at CT.

PURPOSE: To describe the radiologic findings of susceptibility changes in acute middle cerebral artery (MCA) thromboembolism detected with three-dimensional (3D) susceptibility-based perfusion magnetic resonance (MR) imaging and to compare the detectability and clinical value of this sign with those of the hyperdense MCA sign at computed tomography (CT). MATERIALS AND METHODS: Twenty-three patients (mean age, 55 years) underwent CT and MR imaging within the first 6 hours after the onset of acute MCA stroke. The hyperdense MCA sign at CT and the presence of susceptibility changes in acute thromboembolism as depicted on T2*-weighted 3D perfusion MR images were assessed. The presence of each sign was correlated with clinical presentation. RESULTS: The sensitivity of the hyperdense MCA sign at CT was 54% (negative predictive value, 71%) compared with 82% (negative predictive value, 86%) for the susceptibility changes at MR imaging. There were no false-positive CT or MR readings. The presence of the MCA susceptibility sign correlated positively with the initial clinical presentation (chi(2) = 7.987, P =.009, Spearman rho = 0.589). However, neither of the signs was a predictor for clinical outcome in cases of spontaneous MCA stroke. CONCLUSION: In addition to the information traditionally provided with reconstructed perfusion parameter maps, 3D susceptibility-based perfusion MR images allow the identification of acute MCA thromboembolism with a sensitivity higher than that of CT.

Acute Disease↗
PubMed2000

MR imaging and cardiac pacemakers: in-vitro evaluation and in-vivo studies in 51 patients at 0.5 T.

PURPOSE: To evaluate the safety and feasibility of magnetic resonance (MR) imaging at 0.5 T in patients with implanted cardiac pacemakers. MATERIALS AND METHODS: Twenty-one models of pacemakers and 44 pacemaker electrodes were exposed to in vitro MR imaging with continuous registration of pacemaker output and temperature at the lead tip. Prior to MR imaging examination, pacemakers were programmed to an asynchronous mode (A00, V00, or D00). Pacemakers were examined before and after MR imaging. Forty-four patients with implanted pacemakers underwent 51 MR imaging examinations under cardiologic surveillance, continuous electrocardiography, pulse oximetry, and capnographic monitoring. RESULTS: MR imaging was safely performed in all patients. None of the pacemakers displayed a pacing dysfunction at MR imaging. No changes occurred in the programmed parameters in any device tested in vivo or in vitro. Maximum increases in the temperature at the lead tips were 8.90 degrees C at a specific absorption rate (SAR) of 0.6 W/kg and 23.50 degrees C under a worst-case radio-frequency (RF) heating condition with an SAR of 1.3 W/kg. CONCLUSION: MR imaging at 0.5 T can be safely performed in patients with implanted pacemakers in carefully selected clinical circumstances when appropriate strategies (programming to an asynchronous mode, adequate monitoring techniques, limited RF exposure) are used.

Capnography↗
PubMed1999

Proton magnetic resonance spectroscopy in Kennedy syndrome.

OBJECTIVE: To seek regional metabolite abnormalities in patients with Kennedy disease (KD) using proton magnetic resonance spectroscopy. DESIGN: Nine patients with KD showing the typical phenotype without clinical signs of upper motor neuron involvement were compared with 17 male, age-matched, healthy control subjects. Relative metabolite concentrations for N-acetyl (NA) groups, choline-containing groups (Cho), phosphocreatine (Cr), and lactate (Lac) were determined in the brainstem and the motor region. RESULTS: Pathologic Lac signals suggesting impaired energy metabolism were absent in patients and controls. In the brainstem area, patients with KD showed a significant reduction in the NA/Cho metabolite ratio (P = .01). In the motor region, NA/Cho (P = .04) and NA/Cr (P = .03) ratios were significantly reduced. The reduction of the NA/Cho ratio in the motor region mainly resulted from decreased metabolite ratios in 3 patients. Changes in metabolite ratios did not correlate with the number of trinucleotide cytosine-adenine-guanine repeats from leukocytes. Because of the relatively small sample size due to the rarity of KD, these results should be considered preliminary. CONCLUSIONS: Spectroscopic data fail to provide further evidence for altered energy metabolism in KD. Metabolite changes in the brainstem indicate a reduction of the neuronal marker NA or elevated Cho. These findings may reflect neuronal loss or gliosis consistent with the known pathologic features. In a subset of patients, altered metabolite ratios best explained by neuronal loss suggest subclinical involvement of the motor region. The extent of metabolite changes does not correlate with the trinucleotide repeat length.

Acetylation↗
PubMed1999

[The quantification of the magnetization transfer contrast (MTC) effect by calculating MT quotients: does it yield additional information for the differentiation of benign and malignant diseases of the locomotor apparatus?].

PURPOSE: To investigate the potential information of the amount of magnetization-transfer effect in musculoskeletal lesions and to compare MT ratios from benign and malignant musculoskeletal lesions. MATERIAL AND METHOD: 49 patients with malignant tumors (3 osteosarcoma, 3 malignant fibrous histiocytoma, 4 chondrosarcoma, 2 Ewing sarcomas) and benign lesions (8 chondroma, 2 fibrous dysplasia, 3 osteoid-osteoma, 6 ganglion cyst, 3 cyst, 3 osteomyelitis, 4 tendinitis, 3 rotator cuff tear, 5 scar tissue) were scanned using routine MRI protocols including T1- and T2-weighted spin echo as well as T2*-weighted gradient echo (FFE) sequences at 1.5 Tesla (ACS II, Philips Medical). Additionally MTC images were generated by combining the FFE sequence and the off-resonance MT technique (-1500 Hz off-resonance frequency, 1770 degrees flip angle and 50 ms pulse duration). MT ratios were calculated as Slo-Slm/Slo. RESULTS: The MT ratio of benign lesions was 26 +/- 15%, that of malignant lesions was 22 +/- 6%. The difference was statistically not significant. As expected muscle showed a high MT ratio of 50 +/- 8%. Scar tissue demonstrated an MT ratio of 39 +/- 16% which was significantly higher than the tumor MT ratios. CONCLUSION: MTC (MT ratios) failed to show significant differences between benign and malignant lesions as was expected due to basic differences in cellularity, rate of mitosis and chromatin content. MTC might however gain more importance in separating scar tissue from recurrent tumor in the future.

Adolescent↗
PubMed1999

[The temporal changes in the diffusion coefficients in stroke].

PURPOSE: Analysis of temporal changes of ADC values at different stages after stroke. MATERIALS AND METHODS: The original images of all scans were evaluated and a region of interest analysis was performed on ADC (apparent diffusion coefficient) maps. 92 patients with symptoms of ischemic stroke were examined at 1.5 Tesla (ACS-NT, Philips Medical Systems). The study protocol included a navigated multishot SE-EPI DWI (b = 0, 189, 750 s/mm-2, TE = 120/140 ms, delta/delta = 49/60 ms), a GraSE (TR/TE = 3500/90 ms) and a FLAIR-TSE (TR/TE/TI = 6000/150/2000 ms) sequence. 8 patients had regular follow-ups. All patients had an additional CT scan. RESULTS: In hyperacute stroke (< 6 h, n = 10) the relative ADC of the infarct core dropped to about 50% and reached a minimum in the acute state (6-48 h, n = 14) during the next few hours. In subacute stroke (< 3 weeks, n = 29) the ADC began to rise significantly (p = 0.001) back to normal values and reached (p < 10(-4)) values similar to cerebrospinal fluid in the chronic state (> 3 weeks, n = 20). The combined use of DWI and conventional MRI improved the diagnostic information in 16% of all MR examination beyond the hyperacute assessment. CONCLUSION: By means of the ADC-values the age of stroke can be determined. Infarcts at different stages can be readily diagnosed with the combined use of DWI, FLAIR-TSE and GraSE. Pitfalls of DWI and conventional imaging can be avoided.

Adult↗
PubMed1998

Proton magnetic resonance spectroscopy of the primary motor cortex in patients with motor neuron disease: subgroup analysis and follow-up measurements.

OBJECTIVES: To determine the motor cortex degeneration in patients with amyotrophic lateral sclerosis (ALS) using proton magnetic resonance spectroscopy, and to prove that proton magnetic resonance spectroscopy is suited to monitor the course of disease with follow-up examinations. MATERIALS AND METHODS: We studied 33 patients with ALS whose conditions were diagnosed according to the El Escorial World Federation of Neurology criteria. Nine patients with ALS were followed up for up to 2 years. The control group included 20 healthy volunteers and 4 patients with multifocal motor neuropathy. Proton magnetic resonance spectroscopy determined levels of the brain metabolites N-acetylaspartate (NAA), choline, inositol-containing compounds, glutamate/glutamine, and phosphocreatine. RESULTS: Patients with ALS showed a significant reduction in the NAA-choline (P <.001) and NAA-phosphocreatine (P <.005) metabolite ratios and significantly elevated choline-phosphocreatine (P <.005) ratios compared with controls. Inositol-phosphocreatine ratios were also elevated in case patients, but the increase was less pronounced (P <.05). No differences in glutamate/glutamine-phosphocreatine ratios were detected between case patients and controls. An analysis of subgroups demonstrated less significant differences in NAA-choline metabolite ratios (P<.05), even in patients with pure lower motor neuron syndrome (suspected ALS). No changes in metabolite T1 and T2 relaxation times were observed. Patients with multifocal motor neuropathy showed normal metabolic ratios. Progressive alterations in affected metabolite ratios could be documented in the follow-up examinations. CONCLUSIONS: Spectroscopic changes in the motor cortices of patients with ALS correspond with a reduction in levels of NAA and an elevation in levels of choline and inositol compounds. Since NAA is exclusively expressed in neurons, the observed decrease of NAA reflects neuronal loss or dysfunction. Inositol and choline are associated with plasma membrane metabolism, so the release of these compounds may be related to membrane disorders.

Adult↗
PubMed1998

[Magnetization transfer contrast imaging (MTC): its fundamentals, technics and applications].

Using magnetisation transfer (MTC), a new contrast could be achieved on magnetic resonance images (MRI). Two different techniques are available to produce MTC: on- and off-resonance technique. Basic physics of MTC and the two techniques are extensively described in this review article. Potential advantages in using MTC are imaging of cartilage, multiple sclerosis and MR angiography. Particularly the detection of contrast media enhancing brain lesions were improved using MTC. Early cartilage degeneration could be visualised with improved contrast on MTC images. This article gives an overview of potential and accepted applications.

Animals↗
PubMed1998

[Magnetization transfer contrast (MTC)--which is the most MTC-sensitive MRI sequence?].

PURPOSE: This study aimed at evaluating MTC-sensitivity of frequently used MR-sequences. MATERIAL AND METHODS: 7 sequences (T1-, T2-, PD-weighted SE, four gradient-echo sequences) were combined with a 4 element on-resonance MT-Pulse at 0.5 Tesla (T5, Philips medical systems). The measurements were performed at a knee joint and MT-ratios of cartilage, muscle, fat and a copper sulfate phantom were calculated. RESULTS: Proton density weighted gradient and to a lesser degree spin-echo sequences were superior to T1- and T2-weighted sequences in visualising the MT effects. CONCLUSION: It is important to choose an appropriate MR-sequence for MTC experiments. Proton-density gradient echo sequences are recommended for that purpose. T1- and T2-weighted SE sequences should be avoided.

Adipose Tissue↗
PubMed1998

[31P-mr spectroscopy of peripheral skeletal musculature under load: demonstration of normal energy metabolites compared with metabolic muscle diseases].

PURPOSE: 31P-MR spectroscopy of skeletal muscle under exercise was used to obtain the range of normal variation and comparison was made for different neuromuscular diseases. METHODS: 41 examinations of 24 volunteers and 41 investigations in 35 patients were performed on 1.5 T MR systems (Gyroscan 515 und S15/ACSII, Philips). Localised 31P-MR spectra of the calf muscle were obtained in time series with a resolution of 12 s. RESULTS: Two types of muscle energy metabolism were identified from the pattern of spectroscopic time course in volunteers: While the first group was characterised by a remarkable decline to lower pH values during exercise, the second group showed only small pH shifts (minimum pH: 6.48 +/- 0.13 vs 6.87 +/- 0.07, p < 10(-6)) although comparable workload conditions were maintained. The pH-values correlated well with blood lactate analysis. Patients with metabolic disorders and chronic fatigue syndrome (CFS) showed decreased resting values of PCr/(PCr + Pi) and increased pH levels during exercise. PCr recovery was significantly delayed (0.31 vs 0.65 min-1, p < 0.00005) in metabolic muscle disorders but was normal in CFS patients. CONCLUSION: Findings in volunteers indicate utilisation of different metabolic pathways which seems to be related to the fibre type composition of muscle. Reduced resting levels for PCr/(PCr + Pi), altered pH time courses, and decreased PCr recovery seem to be helpful indicators for diagnosis of metabolic muscle disorders.

Carbohydrate Metabolism, Inborn Errors↗
PubMed1998

[Improved diagnosis of early cerebral infarct by the combined use of diffusion and perfusion].

PURPOSE: To evaluate the feasibility and the diagnostic efficacy of multislice diffusion-weighted and perfusion imaging in addition to FLAIR-TSE, T2w-GraSE and MR-angiography in the diagnosis of acute stroke. METHODS: 18 patients with acute stroke were examined at 1.5 Tesla (Gyroscan ACS-NT, Philips Medical Systems) within 6 (n = 9) and 6-48 (n = 9) hours, respectively, and followed at regular intervals. For diffusion imaging we used a multislice multishot EPI-SE sequence with navigator echo correction and cardiac gating. Perfusion imaging was done by means of a FFE-EPI sequence after bolus injection of Gd-DTPA. RESULTS: The diagnostic value of diffusion-weighted and perfusion imaging was significantly higher compared with FLAIR-TSE (p = 0.0023) and GraSE (p = 0.0012) during the first 6 hours. With FLAIR-TSE and GraSE first pathologic changes were seen after 4 hours. We detected perfusion deficit (rCBV < 10%) and a corresponding drop of the ADC in all infarcts larger than 1 cm in diameter. Within the area of low rCBV the combined analysis of diffusion and perfusion imaging allows to identify an infarct region with characteristics of a penumbra and one with characteristics of the infarct core. TTP was increased in the surrounding tissue. However, parts of this area were rarely included in the infarct. The final extension of the untreated infarct, as revealed by computed tomography, corresponded well to the perfusion deficit. CONCLUSIONS: Early ischaemic cerebral infarcts can be diagnosed with diffusion and perfusion imaging before pathological changes are visualized with other imaging modalities. The combined use may allow to distinguish the infarct core from surrounding, potentially salvageable tissue.

Adult↗
PubMed1998

[Diffusion-weighted MR tomography: navigated multi-shot SE-EPI technique for clinical use].

PURPOSE: Evaluation of a navigated multi-shot SE EPI sequence for routine clinical use in MR diffusion imaging. METHODS: We compared a multi-shot SE EPI sequence with the conventional SE sequence as well as with a single-shot SE EPI sequence on a standard 1.5 Tesla MR-scanner (ACS-NT, Philips Medical Systems) with a conventional gradient system (10 mT/m). Image quality and the reproducibility of the apparent diffusion coefficient were analysed with phantoms and with healthy volunteers. The diffusion coefficients of different brain areas were determined in a group of twenty volunteers. RESULTS: The multi-shot SE EPI sequence showed considerably shorter measurement times and smaller motion artifacts than the SE sequence and was less sensitive to susceptibility artifacts than the single-shot version. The reproducibility of the diffusion coefficients was better than 10%. CONCLUSION: The navigated multi-shot SE technique is more practicable and meaningful than the SE and the single-shot SE EPI techniques on a standard 1.5 Tesla MR-scanner with a conventional gradient system. In our opinion it is now the best method for diffusion imaging and should be preferred in clinical use. The determination of diffusion coefficients yields reliable results and characteristic values for different tissue can be obtained.

Adult↗
PubMed1998

[1H MR spectroscopy of the lumbar spine in diffuse osteopenia due to plasmacytoma or osteoporosis].

PURPOSE: To evaluate the role of in vivo 1H MR spectroscopic determination of relaxation times and of fat and water content to differentiate between infiltration of multiple myeloma or osteoporosis in patients with roentgenologic unclear demineralization of the lumbar spine. PATIENTS, MATERIALS AND METHODS: Ten patients each with osteoporotic reduction of bone mineral density (BMD), histologically proven multiple myeloma who showed only diffuse tumor manifestations without tumor compression fractures in the spine, and volunteers were investigated. Osteoporosis was confirmed by dual-energy X-ray absorptiometry (DXA) (Hologic QDR 2000 device, Siemens Medical Systems). The MR investigations were performed with a 1.5 T whole body system (Gyroscan S15/ACS II, Philips Medical Systems). Localized MR spectra from a cubic volume of about 8 cm3 were acquired by the PRESS technique. Chemical shift selective T1 relaxation times were obtained from an IR series, T2 was measured by variation of the interval between the first and the second echo in the volume selection scheme. Statistical analysis was done using the Kruskal-Wallis test and the Mann-Whitney test with the software SPSS. RESULTS: There were highly significant differences in T2 values and fat content between patients with osteoporosis and multiple myeloma. T2 values were decreased in osteoporosis (37 ms and 59 ms vs. 44 ms and 70 ms in plasmocytoma) and fat content was decreased in multiple myeloma (20% vs 31% and 34% in volunteers and osteoporosis). Between volunteers and patients with osteoporosis the differences in the T2 of the fat component was significantly different. CONCLUSIONS: In our preliminary experience MRS is helpful in the differential diagnosis of bony demineralization. It enables a differentiation between osteoporosis and diffuse multiple myeloma. T2 value measurements may be helpful in the diagnostic trial of osteoporosis.

Adult↗
PubMed1998

Diagnostic value of a superparamagnetic iron oxide in MR imaging of chronic liver disease in an animal model.

OBJECTIVE: The enhancement characteristics and the diagnostic value of a cell-specific superparamagnetic contrast agent (NSR 0430) in different degrees of liver fibrosis and cirrhosis were experimentally studied in an animal model. MATERIALS AND METHODS: Chronic liver damage was induced in rats either by oral administration of carbon tetrachloride (CCl4) for 15 weeks (n = 37) or by oral administration of thioacetamide (TAA) in drinking water for 24-26 weeks (n = 48). Twenty-six animals served as control subjects. T1 and T2 relaxation times for the liver and the spleen were measured in vitro with a spectrometer at 40 MHz. In vivo MR imaging at 1.5 T also was performed using T2-weighted turbo spin-echo sequences before and 1 hr after administration of NSR 0430. All data were correlated with the histologic degree of liver fibrosis and cirrhosis and the amount of connective tissue in the liver, which was measured morphometrically. RESULT: CCl4 produced liver fibrosis in most of the animals, and TAA predominantly caused liver cirrhosis. NSR 0430 caused a T2 relaxation time decrease in the control animals by 49%; in the CCl4 group with light and moderate liver fibrosis, by 25%; in the CCl4 group with severe liver fibrosis or cirrhosis, by 16%; and in the TAA group with cirrhosis, by 30%. On the T2-weighted turbo spin-echo sequences, liver signal-to-noise ratios (SNRs) decreased after contrast agent administration in the control animals by 81% and 79%, depending on the TE parameter. In the CCl4 group, liver SNRs decreased by 96% and 61% in animals with light or moderate fibrosis and by 44% and 55% in animals with severe fibrosis or cirrhosis, depending on the TE parameter. In the TAA group, liver SNR decreased by 61% and 67%, depending on the TE parameter. CONCLUSION: Enhancement of the superparamagnetic contrast agent NSR 0430 is decreased in the presence of liver fibrosis and cirrhosis in an animal model. However, the reduced enhancement is not directly related to the degree of chronic liver damage, which limits the diagnostic value of superparamagnetic contrast agents in the assessment of chronic liver disease.

Animals↗
PubMed1997

Effect of cytochrome P450 induction on phosphorus metabolites and proton relaxation times measured by in vivo 31P-magnetic resonance spectroscopy and 1H-magnetic resonance relaxometry in human liver.

Experimental and clinical studies have led to the hypothesis that the phosphodiester signal obtained by 31P magnetic resonance (MR) spectroscopy may be a specific marker for the hepatic induction of oxidative metabolism (P450 induction) by phenobarbitone or ethanol. Systematic studies in humans are lacking. Therefore, we studied 10 volunteers who received rifampin (600 mg/d) for 6 days, resulting in a documented induction of oxidative metabolism as measured by an increase in urinary 6-beta-hydroxycortisol output in all volunteers (P = .0004). 31P-MR spectroscopy and 1H-MR relaxometry were performed before and after hepatic P450 induction. As shown by 31P-MR spectroscopy, the median phosphomonoester concentration (PME) relative to nucleoside triphosphate (NTP) increased by 21% from 0.63 (range, 0.40-0.89) before induction to 0.76 (0.49-1.67) after induction (P = .0451). The median level of phosphodiesters (PDE) relative to NTP increased by 28% from 4.82 (3.41-6.67) before induction to 6.18 (4.63-11.63) after induction (P = .0091). An increase in the level of inorganic phosphates (Pi) relative to NTP was observed, but changes were not significant. As shown by 1H-MR relaxometry, a nonsignificant trend of the liver parenchyma to shorter relaxation times was observed after P-450 induction. In conclusion, both PME/NTP and PDE/NTP ratios (measured by in vivo 31P-MR spectroscopy) increased significantly after hepatic induction with rifampin. Further clinical studies with 31P-MR spectroscopy must take into account the potential effects of P450-inducing agents.

Adult↗
PubMed1997

[Shortening of the measurement time by 1H-MR turbo spectroscopic imaging of the brain].

PURPOSE: Development of a new technique for reduction of measurement time in 1H-MR spectroscopic imaging of the brain. Optimisation of the sequence parameters in volunteer and in patient examinations and comparison to the results obtained with conventional 2 D-SI. METHODS: Examination of 20 healthy volunteers and 5 patients in a 1.5 T whole-body MR system. In "turbo-spectroscopic imaging" (TSI) sequences, a train of spin-echo signals with different phase encoding is acquired after each 90 degrees excitation. 32 x 32 matrix elements covered a field of view of 20 cm, and additional volume selection was performed by double spin echo excitation. Measurement duration 9 min with acquisition of four phase encoding steps per TR interval, whereas the corresponding 2 D-SI sequence (TR/TE 2000/272 ms) took 30 min. RESULTS: The TSI data sets yielded maps of the regional distribution of metabolite concentrations with a quality comparable to the 2 D-SI results. Signal homogeneity and delineation of brain lesions, however, were superior in conventional spectroscopic imaging. The T2 relaxation of the metabolites required a reduced sampling interval for each phase-encoded echo, and hence the frequency resolution of the corresponding TSI spectra was not always sufficient for separating choline and creatine signals. CONCLUSION: With measurement durations < 10 min the TSI technique allows in clinical studies a combination with single-voxel MRS for accurate quantification and with a diagnostic MRI within a total examination time of less than one hour.

Adult↗
PubMed1997

[MR relaxation time measurements with and without selective fat suppression (SPIR) in endocrine orbitopathy].

PURPOSE: To determine the value and utility of relaxation time measurements with magnetic resonance (MR) imaging in patients with Graves' ophthalmopathy (G.O.). MATERIALS AND METHODS: 20 orbits were studied in control subjects and 58 orbits in patients with G.O. T2 relaxation times of extraocular muscles and retrobulbar fat tissue were calculated. The thickness of the eye muscles was correlated with the calculated T2 times. 18 orbits were measured before and after retro-orbital radiation therapy. RESULTS: Upper limits of determined normal T2 values were 60 ms in extraocular eye muscles and 40 ms in retrobulbar fat tissue. 89% (17/19) of the patients with G.O. had prolonged T2 times in extraocular eye muscles. The retrobulbar fat tissue in 5 of 38 orbits revealed minimal edema with the use of fat saturated sequences. T2 relaxation times decreased significantly (p < 10(-4)) after 10 Gy radiation therapy. No correlation was found between enlargement and T2 relaxation times in extraocular eye muscles (r = 0.44 in patients before radiation therapy). CONCLUSION: In patients with G.O. the determination of the enlargement of extraocular eye muscles in computed tomography is not a sufficient parameter for an antiinflammatory therapy, since CT cannot visualise eye muscle edema. T2 relaxation time measurements with MR imaging allow differentiation between edematous and fibrotic changes. This is the diagnostic method of choice in patients with Graves' ophthalmopathy.

Adipose Tissue↗