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  • 11
    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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  • 12
    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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  • 13
    Electronic Resource
    Electronic Resource
    Magnetresonanztomographie einer Leberzirrhose bei einer 17 jährigen Patientin (1996)
    Springer
    Der Radiologe 36 (1996), S. 841-843 
    Details
    ISSN: 1432-2102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001170050147
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  • 14
    Electronic Resource
    Electronic Resource
    Perfusionsuntersuchungen mit paramagnetischen Kontrastmitteln und schnellen Pulssequenzen bei zerebrovaskulären Erkrankungen und Hirntumoren (1996)
    Springer
    Der Radiologe 36 (1996), S. 107-114 
    Details
    ISSN: 1432-2102
    Keywords: Schlüsselwörter Hirnperfusion ; rCBV ; MR-Tomographie ; Zerebrovaskuläre Erkrankungen ; Key words Brain perfusion ; rCBV ; MR tomography ; Cerebrovascular disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The combination of fast MR sequences and rapid i. v. injection of paramagnetic contrast media provides information on cerebral perfusion. MR-perfusion imaging primarily depicts the relative cerebral blood volume. The aim of this study was to test whether MR-perfusion imaging with a clinical MR scanner using a standard 2D-FLASH sequence provides clinically relevant information on patients with cerebrovascular diseases and brain tumors. Brain infarctions, lesions in cerebral microangiopathy and occlusions of the carotid artery with very poor collateralization showed definite differences in perfusion imaging compared with normal controls. However, our results show that acceleration of the imaging sequence and optimization of the contrast bolus and data processing are prerequisites for the clinical use of this method, which in principle may provide information on the absolute cerebral blood volume and even blood flow.
    Notes: Zusammenfassung Die Kombination schneller MR-Sequenzen mit einer i. v. Bolusinjektion paramagnetischen Kontrastmittels liefert Informationen über die zerebrale Durchblutung, wobei mit der MR-Perfusionsuntersuchung primär das relative zerebrale Blutvolumen abgebildet wird. Ziel dieser Untersuchung war es, an einem klinischen MR-Tomographen zu prüfen, welche Informationen mit der MR-Perfusionsuntersuchung mit einer Standard-2D-FLASH-Sequenz bei Patienten mit zerebrovaskulären Erkrankungen und Tumoren zu erhalten sind. Bei Hirninfarkten, mikroangiopathischen Läsionen und sehr schlecht kollateralisierten Gefäßverschlüssen fanden sich Unterschiede zu den Normalpersonen in den MR-Perfusionsbildern. Unsere Ergebnisse zeigen, daß die Beschleunigung der Aufnahmesequenz, die Optimierung des Kontrastmittelbolus und optimierte Auswertung Voraussetzungen dafür sind, daß MR-Perfusionsuntersuchungen, die prinzipiell auch das absolute zerebrale Blutvolumen und den zerebralen Blutfluß bestimmen können, klinisch Einsatz finden werden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001170050047
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  • 15
    Electronic Resource
    Electronic Resource
    Book reviews (1996)
    Springer
    European radiology 6 (1996), S. 357-357 
    Details
    ISSN: 1432-1084
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00180610
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  • 16
    Electronic Resource
    Electronic Resource
    Clinical applications of functional MRI at 1.0 T: motor and language studies in healthy subjects and patients (1999)
    Springer
    European radiology 9 (1999), S. 211-220 
    Details
    ISSN: 1432-1084
    Keywords: Key words: Functional MRI ; 1.0 Tesla ; Motor studies ; Language studies ; Presurgical mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. In this article we describe clinical applications of functional MRI (fMRI) at 1.0 T. All experiments were performed on a commercially available 1.0-T system (Magnetom Impact Expert, Siemens AG, Erlangen, Germany) using a blood oxygen level-dependent (BOLD)-sensitive multi-slice EPI technique (TE 66 ms, 4 mm slice thickness, 210 mm field of view, 64 × 64 acquisition matrix). Different paradigms for localization of the motor cortex and for language lateralization were tested in healthy subjects and patients. Methodological considerations concerning the development of the paradigms are also described. In all healthy subjects, motor activation elicited BOLD signal changes in the sensorimotor cortex, permitting identification of primary motor and sensory cortical areas. Furthermore, focal activation of different cortical areas by a language task was possible in 6 of 10 subjects. Nineteen motor studies were performed in 18 patients with supratentorial lesions, in most cases prior to neurosurgical procedures. In 14 studies, fMRI results demonstrated the localization of the motor hand areas relative to the lesion. The results proved valuable for preoperative planning and contributed to therapeutical decisions. We conclude that functional MRI for clinically relevant applications, such as localization of motor and language function, is feasible even at a field strength of 1.0 T without dedicated equipment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003300050658
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  • 17
    Electronic Resource
    Electronic Resource
    Contrast mechanisms in MR imaging (1999)
    Springer
    European radiology 9 (1999), S. 1032-1046 
    Details
    ISSN: 1432-1084
    Keywords: Key words: MR imaging ; Contrast mechanisms ; Proton density ; T1 ; T2 ; Spin echo ; Gradient echo ; Turbo spin echo ; Echo-planar imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. This paper is a brief introduction to tissue-specific parameters and the utilization of various MR imaging sequences to display these parameters in order to differentiate normal from pathologic tissue and function. The three dominant tissue-specific parameters discussed are proton density, longitudinal relaxation time T1, and transverse relaxation time T2. For the utilization of gradient-echo sequences, transverse relaxation time T2* is introduced, more dependent on the environment or tissue interfaces than on the tissue itself. Another tissue-specific parameter is the concentration of macromolecules and their hydration layers as targeted with magnetization transfer imaging. Still another tissue-specific parameter is the chemical environment. Functional parameters that influence the contrast are diffusion, perfusion, flow, or motion. The sequence-related utilization of these tissue-specific parameters start with magnetization preparation as in spectral suppression of fat signal, relaxation-dependent elimination of fat or cerebrospinal fluid (CSF) signal, simple inversion pulse, magnetization transfer saturation, or diffusion weighting. Possible contrast mechanisms for the tissue-specific parameters are discussed for each of the commonly used sequences, whether of spin-echo type or of gradient-echo type, with or without magnetization preparation, conventional single-echo acquisition, or contemporary multiecho acquisition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003300050789
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  • 18
    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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  • 19
    Electronic Resource
    Electronic Resource
    Hepatic MRI with SPIO: detection and characterization of focal liver lesions (1998)
    Springer
    European radiology 8 (1998), S. 1198-1204 
    Details
    ISSN: 1432-1084
    Keywords: Key words: Iron oxides ; Liver ; SPIO ; USPIO
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. A variety of parenterally administered iron oxides have been developed for contrast-enhanced MRI of the liver. Two different classes of iron oxides are currently clinically approved or in phase 3 trials: superparamagnetic iron oxides (SPIO) with a high R2/R1 relaxivity ratio and short blood half-life (AMI-25 and SH U 555 A), and ultrasmall paramagnetic iron oxides (USPIO) with a lower R2/R1 relaxivity ratio and longer blood half-life (AMI-227). All iron oxides significantly increase tumor-to-liver contrast and allow detection of more lesions than unenhanced MRI on T2-weighted images at a field strength of 0.2–1.5 T. Malignant lesions without phagocytic cells exhibit constant signal on T2-weighted accumulation phase images with all three iron oxides. All iron oxides cause a signal decrease of benign lesions with either phagocytic cells or a significant blood pool on T2-weighted accumulation phase images. The signal decrease of benign lesions is proportional to the Kupffer cell activity or tumor vascularity and is useful for lesion characterization. Another enhancement feature for the differentiation of benign from malignant lesions is ring enhancement of malignant lesions (metastases) on T1-weighted enhanced images either during the perfusion phase with SH U 555 A or during the accumulation phase with AMI-227, which is attributed to the blood pool effects of the compounds. Differentiation of lesions and vessels is easier on enhanced images with angiographic effects than on unenhanced images. Iron oxides improve the quality of two-dimensional MR angiography techniques of the portal venous system by decreasing background signal (liver tissue with all iron oxides) and increasing intravascular signal (AMI-227). The use of iron oxides for hepatic MRI provides an alternative to the existing multistep diagnosis with CT, CT portography, MRI and biopsy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003300050535
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  • 20
    Electronic Resource
    Electronic Resource
    Phase-contrast MR angiography of peripheral arteries: technique and clinical application (1999)
    Springer
    European radiology 9 (1999), S. 122-127 
    Details
    ISSN: 1432-1084
    Keywords: Key words: MR-Angiography (MRA) ; Phase-Contrast-MRA (PC-MRA) ; Peripheral Arterial Occlusive Disease (PAOD) ; Stenoses ; Occlusions ; Aneurysms ; Postsurgical follow-up
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. This articles describes Phase-Contrast-MRA (PC-MRA) techniques and their current clinical applications for peripheral arteries based on more than 250 clinical MRA studies performed at two institutions. PC-MRA depends on phase shifts caused by blood flow and thus this technique permits the use of coronal or sagittal slice orientations with large FOV's along the direction of the vessel of interest. Clinical applications focus on patients with peripheral arterial occlusive disease (PAOD) describing the role and limitations of PC-MRA for the work-up of stenoses, occlusions, aneurysms, and postsurgical follow-up. Recommendations for clinical routine are provided. A combined MR angiographic approach with various MRA techniques depending on the vessel segment to be imaged, PC-flow velocity measurements, and high-resolution scans of the vessel wall may turn out to be diagnostically effective and provide a comprehensive test for PAOD within the near future.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003300050642
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