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  • 1
    Electronic Resource
    Electronic Resource
    Cross-sectional Area of Lumbar Vertebrae in Peri- and Postmenopausal Patients With and Without Osteoporosis (2000)
    Springer
    Osteoporosis international 11 (2000), S. 304-309 
    Details
    ISSN: 1433-2965
    Keywords: Key words:Lumbar vertebrae, area – Osteoporosis – Quantitative computed tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract: The purpose of this study was to analyze the midvertebral area of lumbar vertebrae in osteoporotic and nonosteoporotic female patients and to find out whether the midvertebral area may be used as an additional parameter in the diagnosis of osteoporosis. In 195 peri- and postmenopausal patients (average age 51.7 ± 5.2 years) trabecular and cortical bone mineral density (BMD) were determined using quantitative CT (QCT) in L2–4. In addition, midvertebral cross-sectional area was measured in a standardized fashion on the CT sections and the height of the second lumbar vertebra was determined on the lateral digital radiographs. Body height and weight were obtained and vertebral fracture status was determined. According to WHO criteria 29 patients (average age 57.2 years) were considered osteoporotic, 93 osteopenic (average age 52.2 years) and 73 normal (average age 48.6 years). Body weight and size did not show significant differences between the individual groups. Average midvertebral area was 1278 ± 173 mm2 in the osteoporotic patients, 1186 ± 125 mm2 in the osteopenic patients and 1126 ± 127 mm2 in the normals. A correlation of r=−0.39 (p〈0.05) was obtained between BMD and area. Thirty-six of 195 patients showed osteoporotic vertebral fractures. Midvertebral area in these patients was 1266 ± 171 mm2 versus 1159 ± 133 mm2 in the nonfractured females (p〈0.05). We therefore conclude that the lumbar midvertebral area is larger in osteoporotic and osteopenic patients compared with women with normal BMD. In contrast to biomechanical considerations midvertebral area seems not to be suited as an additional measure of bone strength in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001980070118
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  • 2
    Electronic Resource
    Electronic Resource
    Hepatic MR imaging: comparison of RARE derived sequences with conventional sequences for detection and characterization of focal liver lesions (1996)
    Springer
    Abdominal imaging 21 (1996), S. 427-432 
    Details
    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
    URL: http://dx.doi.org/10.1007/s002619900097
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  • 3
    Electronic Resource
    Electronic Resource
    Intracranial vascular stenosis and occlusion: comparison of 3D time-of-flight and 3D phase-contrast MR angiography (1998)
    Springer
    Neuroradiology 40 (1998), S. 567-573 
    Details
    ISSN: 1432-1920
    Keywords: Key words Intracranial blood vessels ; stenosis and occlusion ; Magnetic resonance angiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We compared the value of 3D time-of-flight (TOF) and phase-contrast (PC) MR angiography (MRA) for detection and grading of intracranial vascular steno-occlusive disease. Unenhanced 3D-TOF MRA and 3D-PC MRA (30–60 cm/s velocity encoding) were performed at the level of the circle of Willis in 18 patients, mean age 56 ± 10 years. Postprocessed images using a maximum-intensity projection reconstruction with multiple targetted projections were analysed. A total of 126 vessels was assessed by PC MRA and 143 by TOF MRA, with digital subtraction angiography (DSA) in 15 patients and/or transcranial Doppler sonography (TCD) in 18 as a standard. Two blinded readers reviewed the MRA, DSA and TCD examinations retrospectively. On DSA and/or TCD the two observers found 32 and 28 steno-occlusive lesions. 3D-TOF MRA was more sensitive than 3D-PC MRA (87 % and 86 % vs. 65 % and 60 %) and had a higher negative predictive value (96 % vs. 89 %). Correct grading of stenoses was achieved in 78 % by 3D-TOF and 65 % by 3D-PC MRA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340050645
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  • 4
    Electronic Resource
    Electronic Resource
    Neue MR-Kontrastmittel in der Leberdiagnostik Erste klinische Ergebnisse mit hepatobiliärem Eovist® (Gadolinium-EOB-DTPA) und RES-spezifischem Resovist® (SH U 555 A) (1996)
    Springer
    Der Radiologe 36 (1996), S. 124-133 
    Details
    ISSN: 1432-2102
    Keywords: Schlüsselwörter Leber ; MRT ; Kontrastmittel ; Resovist® ; Eovist® ; Key words Liver ; MRI ; Contrast agents ; Resovist ; Eovist
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The purpose of this work is to describe our initial clinical experience (in 66 patients) with Resovist and Eovist, two new liver-specific MR contrast agents. We focus our report on safety aspects, dose finding, and optimization of technical parameters. Both contrast agents were well tolerated and improved the detectability of focal liver lesions. With Resovist, postcontrast MRI may be started as early as 10 min following injection. The dose of 8 μmol Fe/kg bodyweight was sufficient to achieve diagnostic tumor-liver contrast levels. Since Eovist can also be administered as a bolus, dynamic enhance- ment patterns may be studied for tumor characterization as well. Breath-hold T 1-weighted FLASH images were superior to other T 1-weighted techniques with and without fat saturation.
    Notes: Zusammenfassung In der vorliegenden Arbeit werden erste klinische Ergebnisse (66 Patienten) der für die Leberbildgebung entwickelten Kontrastmittel Resovist® und Eovist® vorgestellt. Es wurden Sicherheitsaspekte, Dosierungsfragen und die optimale Untersuchungstechnik am Beispiel fokaler Leberläsionen untersucht. Beide „leberspezifischen“ Kontrastmittel zeigten bei guter Verträglichkeit eine Verbesserung des Nachweises fokaler Leberläsionen. Die Untersuchung mit Resovist® kann bereits 10 min nach der Kontrastmittelinjektion erfolgen. Mit einer Dosis von 8 μmol Fe/kg Körpergewicht konnte eine ausreichender Tumor-Leber-Kontrast erzielt werden. Da Eovist® zusätzlich im Bolus injiziert werden kann, ergeben sich neben dem Nachweis fokaler Leberläsionen Möglichkeiten der Charakterisierung durch Analyse der Perfusionsmuster. Atemgehaltene T 1-gewichtete FLASH-Sequenzen waren sonstigen T 1-gewichteten Sequenzen ohne und mit Fettgesättigung überlegen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001170050049
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  • 5
    Electronic Resource
    Electronic Resource
    Hochdosierte Anwendung von Gd-DTPA-BMA (Gadodiamid) in der Diagnostik und Therapiebeurteilung maligner Knochentumoren (1996)
    Springer
    Der Radiologe 36 (1996), S. 148-152 
    Details
    ISSN: 1432-2102
    Keywords: Schlüsselwörter Gd-DTPA-BMA ; Magnetresonanztomographie ; Dynamische Studien ; Knochenläsionen ; Präoperative Chemotherapie ; Key words Gd-DTPA-BMA ; Magnetic resonance imaging ; Dynamic studies ; Bone lesions ; Preoperative chemotherapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Purpose: To evaluate the efficacy of high-dose Gd-DTPA-BMA (gadodiamide, Omniscan) as a contrast for magnetic resonance imaging of malignant bone tumors and the use of high-dose dynamic studies for predicting the response to preoperative chemotherapy. Materials and methods: Examinations were performed in 22 patients with suspected malignant bone tumor on a 1.5 T system. In 8 cases a follow-up examination was done after preoperative chemotherapy. Static studies included Pd- and T2-weighted spin-echo sequences as well as T1-weighted spin-echo sequences, obtained pre- and postcontrast. Dynamic studies were performed using a FLASH 2D-gradient-echo sequence (TR 40 ms/TE 10 ms, 90 ° flip angle) every 20 s after intravenous bolus injection of Gd-DTPA-BMA (0.3 mmol/kg body weight). MR images were evaluated qualitatively by visual assessment of conspicuity size, extraosseous delineation and structure of the lesion and quantitatively by measurement of the signal intensities and calculation of the relative increase in signal intensity. Results: Qualitative image analysis showed best demonstration of the lesions on contrast-enhanced T1-weighted images. Comparison of T1-weighted pre- and postcontrast spin-echo sequences revealed significantly better assessment of tumor structure after administration of contrast media. After preoperative chemotherapy, all responders showed a markedly stronger reduction in relative increase in signal intensity in dynamic studies compared to nonresponders. Conclusion: Gd-DTPA-BMA is effective for magnetic resonance imaging of musculoskeletal lesions and improves assessment of the tumor structure. Dynamic studies may help to predict the response to preoperative chemotherapy.
    Notes: Zusammenfassung Ziel der Studie: Untersucht wurde, ob die hochdosierte Gabe von Gd-DTPA-BMA (Gadodiamid, Omniscan™) sich für die kontrastmittelunterstützte Magnetresonanztomographie maligner Knochentumoren eignet und ob dynamische Studien bei dieser Dosis eine Beurteilung des Ansprechens auf eine präoperative Chemotherapie ermöglichen. Material und Methode: Die Untersuchungen erfolgten bei 22 Patienten mit Verdacht auf malignen Knochentumor bei einer Feldstärke von 1,5 Tesla. In 8 Fällen wurde eine Verlaufskontrolle nach präoperativer Chemotherapie durchgeführt. Die statischen Untersuchungen umfaßten PD- und T2-gewichtete Spinechosequenzen sowie T1-gewichtete Spinechosequenzen vor und nach Kontrastmittelapplikation. Dynamische Studien wurden mit einer FLASH-2D-Gradientenechosequenz (TR 40 ms/TE 10 ms, Flipwinkel 90 °) im Abstand von je 20 s nach intravenöser Bolusinjektion von Gd-DTPA-BMA (0,3 mmol/kg Körpergewicht) durchgeführt. Die Auswertung der MR-Bilder erfolgte qualitativ durch visuelle Beurteilung der Erkennbarkeit, der Größe, der extraossären Ausdehnung und der Struktur der Läsion und quantitativ mit Messung der Signalintensitäten und Berechnung des relativen Signalanstieges. Ergebnisse: Die qualitative Bildauswertung ergab für die T1-gewichteten Bilder nach Kontrastmittelapplikation die beste Erkennbarkeit der Läsion. Der Vergleich der T1-gewichteten Spinechosequenz vor und nach Kontrastmittelapplikation zeigte eine signifikant verbesserte Beurteilbarkeit der Tumorstruktur nach Kontrastmittelgabe. In den dynamischen Untersuchungen wiesen alle Responder nach präoperativer Chemotherapie einen deutlich stärkeren Abfall des relativen Signalintensitätsanstieges als die Nonresponder auf. Schlußfolgerung: Gd-DTPA-BMA ist ein effektives Kontrastmittel für die Magnetresonanztomographie muskuloskeletaler Läsionen und ermöglicht eine verbesserte Beurteilung der Tumorstruktur. Dynamische Studien können zur Beurteilung des Ansprechens der präoperativen Chemotherapie beitragen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001170050052
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  • 6
    Electronic Resource
    Electronic Resource
    Die Wertigkeit der 3-Phasen-Spiral-CT und der Magnetresonanztomographie in der präoperativen Diagnostik des Pankreaskarzinoms (1996)
    Springer
    Der Radiologe 36 (1996), S. 406-412 
    Details
    ISSN: 1432-2102
    Keywords: Schlüsselwörter Pankreaskarzinom ; Staging ; Gefäßinfiltration ; Spiral-CT ; Magnetresonanztomographie ; Key words Pancreatic carcinoma ; Staging ; Vascular involvement ; Spiral computed tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The purpose of this study was to assess the role of spiral computed tomography (SCT) and magnetic resonance imaging (MRI) in the preoperative work-up of patients with pancreatic carcinoma, regarding local resectability and vascular involvement. Methods and materials: A total of 28 patients (19 men and 9 women; mean age 58 years) with known or highly suspected carcinoma of the pancreas were included in this study. All patients prospectively underwent MRI (± gadolinium-DTPA) and SCT (3-phase examination) as preoperative diagnostic imaging studies, and laparotomy was carried out within 7 days, irrespective of the MRI or SCT findings. SCT and MR studies were reviewed independently by two radiologists, without knowing the results of the surgical exploration. Standardized image analysis was correlated with findings at laparatomy. Results: Laparotomy identified 10 patients to be suitable for surgical resection and 18 pancreatic carcinomas to be unresectable. In 17 of 18 non-resectable carcinomas MRI and SCT were able to obtain correct information about unresectability (sensitivity 94 %), in 7 (MRI), resp. 8 (SCT) carcinomas were correctly considered to be resectable (sensitivity 70 % for MRI and 80 % for SCT). The presence of vascular involvement was depicted by SCT with a sensitivity of 82–100 % and 62–100 % by MRI. The specificity varied between 85–100 % for SCT and 77–100 % for MRI. Conclusion: Both MRI and SCT are good techniques for the preoperative work-up of pancreatic carcinomas in order to obtain a correct assessment of local resectability.
    Notes: Zusammenfassung Das Ziel der vorliegenden Untersuchung an 28 Patienten war die Bestimmung der Wertigkeit der Spiralcomputertomographie (Spiral-CT) und der Magnetresonanztomographie (MRT) im präoperativen Staging des Pankreaskarzinoms. Dazu wurde vergleichend die Infiltration peripankreatischer arterieller und venöser Gefäßstrukturen analysiert. Die Befunde wurden mit dem Ergebnis der Laparotomie korreliert, der alle Patienten unabhängig von den Ergebnissen der Spiral-CT und der MRT unterzogen wurden. Zur präoperativen Bestimmung der lokalen Ausdehnung von Pankreaskarzinomen und damit der Operabilität sind sowohl die 3-Phasen-Spiral-CT und die MRT (± Gadolinium-DTPA) gleichermaßen geeignete Untersuchungsmethoden. Insbesondere können beide Untersuchungsverfahren die Infiltration benachbarter vaskulärer Strukturen präoperativ mit hoher Genauigkeit nachweisen und somit die Planung des operativen Vorgehens beeinflussen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001170050089
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  • 7
    Electronic Resource
    Electronic Resource
    Phase-contrast MR angiography of the lower extremity. Comparison of methods and clinical application (1997)
    Springer
    Der Radiologe 37 (1997), S. 572-578 
    Details
    ISSN: 1432-2102
    Keywords: Key words MR angiography • Time of flight • Phase contrast • Peripheral arteries ; Schlüsselwörter MR-Angiographie • Time-of-Flight • Phasenkontrast • Periphere Gefäße
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Ziel der Studie war die Entwicklung einer praktikablen Untersuchungsstrategie für die MRA der unteren Extremität. Im Probandenteil der Studie wurden 3 MRA-Techniken (2D-TOF mit venöser Sättigung, 3D-Magnitude-Kontrast und 2D-Phasenkontrast mit EKG-Triggerung) intraindividuell prospektiv verglichen. Im Patiententeil der Studie wurden bei n = 45 klinischen MRA-Untersuchungen mittels EKG-getriggerter 2D-PCA 230 Gefäßsegmente intraindividuell mit der arteriellen DSA nach einem fünfstufigen Scoresystem verglichen. EKG-getriggerte PCA-Techniken zeigten die beste Bildqualität in allen Gefäßabschnitten. Dabei betrug der mittlere Rang des Friedman-Testes der PCA-Technik in der Beckenetage 1,2 und an der Oberschenkel- bzw. Knie-/Unterschenkeletage 1,0. Die Patientenuntersuchungen zeigten eine gute Übereinstimmung von DSA und MRA mit einem signifikanten Spearman-Korrelationskoeffizient für die Becken-, Oberschenkel- und Knieetage. MRA-Untersuchungen der unteren Extremität sind unter Einsatz der EKG-getriggerten 2D-PCA-Technik mit vertretbarem Zeitaufwand möglich. Die Abbildungmöglichkeiten der untersuchten Gefäßetagen entsprechen den Bildeinstellungen der DSA und die klinische Auswertung ergab eine gute (Kappa 〉 0,61) bis sehr gute (Kappa 〉 0,81) Übereinstimmung in der Beurteilung pathologischer Gefäßveränderungen.
    Notes: Summary Purpose: To investigate whether phase-contrast MRA is a clinically suited approach to examine arteries of the pelvis and lower extremities. Methods: The study was divided into two parts, a volunteer study and patient study. Three MRA techniques – 2D TOF with venous saturation, 3D magnitude contrast and 2D phase contrast with ECG triggering – were intraindividually compared in 15 volunteers and evaluated by three blinded readers. Subsequently, a total of 230 vessel segments of 45 MRA studies using ECG-triggered phase contrast were compared with intraarterial DSA. All vessel segments were scored by three blinded readers using a five-point scale with DSA serving as the gold standard. Results: ECG-triggered phase contrast provided better image quality than the other MRA techniques as assessed by the Friedman test. Clinical studies demonstrated a significant correlation of DSA and MRA as assessed by the Spearman correlation and kappa statistics for individual readers. Conclusion: MRA of the pelvis and lower extremities may be performed with 2D ECG-triggered phase-contrast MRA within a reasonable time frame ( 〈 30 min). MRA slabs provide orientation similar to that with DSA projections and good to very good correlation of vessel pathology as shown by kappa statistics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001170050255
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  • 8
    Electronic Resource
    Electronic Resource
    Enhancement characteristics of liver metastases, hepatocellular carcinomas, and hemangiomas with Gd-EOB-DTPA: preliminary results with dynamic MR imaging (1997)
    Springer
    European radiology 7 (1997), S. 275-280 
    Details
    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
    URL: http://dx.doi.org/10.1007/s003300050150
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