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  • 1
    ISSN: 1432-0509
    Keywords: Key words: MRI—Hepatic imaging—RARE—Detection—Characterization.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Background: We compared two T2-weighted turbo spin echo (TSE) sequences with a T2-weighted conventional SE (CSE) sequence to determine whether sequences derived from rapid acquisition with relaxation enhancement such as TSE could replace CSE for the detection and subsequent characterization of focal liver lesions. Methods: A total of 55 consecutive patients with 107 liver lesions underwent magnetic resonance imaging examinations at 1.5 Tesla, with a constant imaging protocol. TSE pulse sequences were acquired with eight echo trains (repetition time [TR], 4718 ms; echo time [TE], 90 ms; acquisition time [TA], 4.03 min; and a symmetric k-space ordering scheme) and 11 echo trains (TR, 4200 ms; TE, 140 ms; TA, 4.40 min; and an asymmetric k-space ordering scheme) and compared with CSE (TR, 2300 ms; TE, 45/90 ms; TA, 9.53 min). Images were analyzed qualitatively by scoring image quality and artifacts and counting focal liver lesions by independent reading with consensus obtained for discrepancies. Quantitative analysis was performed by measuring signal-to-noise (S/N), contrast-to-noise (C/N), and tumor–liver signal intensity (T/L) ratios. Results: T2-weighted TSE sequences provided better subjective image quality and reduced artifacts as compared with the T2-weighted CSE sequence. CSE and TSE sequences exhibited no statistically significant differences in liver S/N, lesion–liver C/N (CSE TE, 90 ms: 18.6 ± 14.0; TSE TE, 90 ms: 16.5 ± 12.9) and the detectability of focal liver lesions. Heavily T2-weighted TSE with a TE of 140 ms allowed correct characterization of focal liver lesions based on a T/L ratio of 3.0 in 84% of patients. Conclusions: T2-weighted TSE sequences are as suited as CSE for the detection (TE, 90 ms), and appear to be superior for the characterization (TE, 140 ms), of focal hepatic lesions. Whether a single sequence, such as a double-echo TSE or a single-echo TSE sequence with a TE between 110 and 120 ms, might perform both functions as well or better than CSE is unknown. However, because of time savings, TSE eventually may be preferred over CSE.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0509
    Keywords: Radiation exposure ; Endoscopic retrograde cholangiopancreatography ; Endoscopic papillotomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Radiation exposure was studied in 327 patients undergoing endoscopic retrograde cholangiopancreatography, or endoscopic papillotomy taking into account fluoroscopy time and incident area exposure. The mean fluoroscopy time was 238±152 seconds and the incident area exposure 3,730±2,790 R×cm2. These results were compared with standard exposures in upper GI series and colon examinations as found in the literature.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1084
    Keywords: Key words: MR imaging ; Turbo inversion recovery ; Brain ; Growth and development ; Myelin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The aim of our work was to determine the efficacy of turbo inversion recovery spin echo (TIRSE) pulse sequences in differentiating patients with normal and abnormal myelination. Twenty neurological normal children (aged 5 months to 12 years) as well as 65 children presenting clinically with neurologic developmental deficits (aged 2 months to 10 years) were examined using TIRSE, T1-weighted SE, and T2-weighted turbo SE pulse sequences. Contrast-to-noise-ratio (CNR) between myelinated white and gray matter was compared for the different pulse sequences. In addition, two readers analyzed all images qualitatively by consensus. The CNR values were significantly higher on TIRSE images as compared with conventional images (p 〈 0.05). Forty-two neurologically abnormal patients displayed a normal myelination on all sequences, whereas 23 showed an abnormal myelination. The TIRSE sequence provided a sensitive and specific depiction of an abnormal myelination in all of these patients. The TIRSE sequence provided additional information to conventional pulse sequences in determining myelination disorders in children, especially in children older than 2 years.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European radiology 8 (1998), S. 834-838 
    ISSN: 1432-1084
    Keywords: Key words: Magnetic resonance imaging ; Brain hemorrhage ; FSE ; GRASE ; Susceptibility artefact
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The aim of this study was to evaluate the sensitivity of gradient-and-spin-echo (GRASE) sequences to susceptibility effects. GRASE sequences with 21 and 33 echoes per echo train were compared with a T2-weighted FSE sequence with an echo train length of 5 by means of MRI in phantoms, volunteers (n = 10), and patients (n = 19) with old hemorrhagic brain lesions. All experiments were performed on a 1.0-T clinical MR system (Impact Expert, Siemens AG, Erlangen, Germany) with constant imaging parameters. Contrast-to-noise ratios (CNRs) of tubes doped with iron oxides at different concentrations, of brain areas with physiological iron deposition (red nucleus, substantia nigra), and of areas of old brain hemorrhage were calculated for FSE and GRASE pulse sequences. Areas of old brain hemorrhage were also qualitatively analyzed for the degree of visible susceptibility effects by blinded reading. The CNR of iron oxide tubes and iron-containing brain areas decreased with increasing echo trains of GRASE sequences. The CNR of GRASE sequences decreased when compared with CNR of their FSE counterparts (GRASE 21 echo trains 23.8 ± 0.8, FSE 5 echo trains 26.7 ± 0.9; p≤ 0.01). Qualitative analysis confirmed these measurements. FSE with an ETL of 5 demonstrated significantly stronger susceptibility effects than their GRASE counterpart with an ETL of 21. The results demonstrate that GRASE sequences do not necessarily compensate for the reduced sensitivity of FSE to susceptibility effects. The complex signal behavior of GRASE makes conventional SE, gradient echo, or FSE sequences containing shorter echo trains preferable when patients with intracranial hemorrhage are clinically evaluated.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1084
    Keywords: Iotrolan ; Iohexol ; Iopamidol ; Urography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Iotrolan was compared with iohexol and iopamidol for efficacy and general tolerance in excretory urography in three controlled, randomized, inte-individual, double-blind studies. Two hundred and eighty-four patients received fixed doses of 100 ml, 120 ml or 150 ml iotrolan 280 or iohexol 300/iopamidol 300 by rapid or bolus injection. Contrast quality in films taken 3–40 min after injection was rated by experienced radiologists both on an overall basis and with regard to distinct anatomical regions (parenchyma, pelvicalyceal system, ureter, bladder). In all studies, contrast quality was assessed as better in the iotrolan group. In two studies (dosages 100 and 120 ml), significant differences in contrast quality were found in lavour of iotrolan (P 〈 0.05), and in the third study (dosage 150 ml) there was a trend towards better contrast quality in the iotrolan group (P = 0.06). General tolerance of iotrolan was good with only minor side effects (iotrolan 6.3%, iohexol/iopamidol 9.9%), but the difference was not significant. No severe adverse reactions were observed with iotrolan. In comparison with non-ionic monomers, iotrolan shows very good efficacy and general tolerance for excretory urography.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1084
    Keywords: Key words: MRI ; Liver ; Gd-EOB-DTPA ; Characterization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Our objective was to study Gd-EOB-DTPA for the characterization of focal liver lesions by means of dynamic MR imaging. A double-blind and randomized dose-ranging phase-2 clinical trial was performed in 31 patients (liver metastases n = 23, hepatocellular carcinoma n = 4, and hemangioma n = 4) at a field strength of 1.0 Tesla. Gd-EOB-DTPA (Schering AG, Berlin, Germany) was administered as an IV bolus (12.5, 25, or 50 μmol/kg body weight) with dynamic T1-weighted MRI during the distribution and cellular uptake of the contrast agent at multiple time points up to 45 min post contrast. Dynamic changes in tumor signal intensity, tumor–liver contrast, enhancement patterns, side effects, and adverse events were evaluated. Monitoring of vital signs revealed no significant changes during bolus injection of Gd-EOB-DTPA. Liver metastases demonstrated an inhomogeneous uptake of Gd-EOB-DTPA during the distribution phase with a washout effect on delayed images 〉 3 min and highest tumor–liver contrast 20 and 45 min post contrast. Hepatocellular carcinomas showed prolonged enhancement as compared with metastases and hemangiomas. Hemangiomas exhibited an early peripheral–nodular enhancement with subsequent partial or complete filling, persisting enhancement 〈 10 min following injection of Gd-EOB-DTPA, and delayed washout as compared with liver metastases. Initial clinical experience suggests that Gd-EOB-DTPA as a bolus injectable hepatobiliary MR contrast agent may offer useful features for the characterization of focal liver lesions.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1084
    Keywords: Fracture healing ; Magnification radiography ; Roentgen technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of the study was to evaluate the potential of magnification radiography in diagnosing fracture healing and assessing its complications. Seventy-three patients with fractures or who had undergone osteotomy were radiographed with both conventional (non-magnified) and magnification (5-fold) techniques. Since 10 patients were radiographed twice and 1 three times, 83 radiographs using each technique were obtained. All radiographs were analysed and the findings correlated with the patients' follow-up studies. The microfocal X-ray unit used for magnification radiography had a focal spot size of 20–130 μm. As an imaging system, digital luminescence radiography was employed with magnification, while normal film-screen systems were used with conventional radiography. Manification radiography proved superior to conventional radiography in 47% of cases: endosteal and periosteal callus formations were sen earlier and better in 26 cases, and osseous union could be evaluated with greater certainty in 33 cases. In 49% of cases magnification radiography was equal and in 4% inferior to conventional radiography. Additionally an “inter-observer analysis” was carried out. Anatomical and pathological structures were classified into one of four grades. Results were significantly (P 〈 0.01) better using magnification radiography. We conclude that the magnification technique is a good method for monitoring fracture healing in its early stages.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial & engineering chemistry 24 (1932), S. 924-926 
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 42 (1938), S. 229-235 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 33 (1929), S. 873-878 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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