0000000000160674
AUTHOR
Oliver K. Mohrs
showing 12 related works from this author
MR-Perfusionsbildgebung des Herzens mit TrueFISP
2001
OBJECTIVE Development and test of a saturation-recovery TrueFISP (SR-Trufi) pulse sequence for myocardial perfusion MR imaging (MRI) using improved gradient hardware. MATERIAL AND METHODS Measurements were performed on a 1.5 T scanner with prototype gradients (50 mT/m, minimum rise time 300 microseconds). T1-weighted first-pass MRI of Gd-DTPA (0.025 mumol/kg) kinetics in the myocardium was performed using an SR-Trufi pulse sequence (TR/TE/alpha = 2.6 ms/1.4 ms/55 degrees) with a saturation preparation of TD = 30 ms before the TrueFISP readout. Measurements were performed in volunteers (n = 4) and in a pig model of chronic ischemia (n = 1). RESULTS In phantoms, the signal intensity was linea…
Erfahrungen mit einer 3D-Navigatorsequenz zur Koronargefäßdarstellung an einem Hochleistungs-MR-System
2002
Purpose: To evaluate MR coronary angiography using a three-dimensional navigator echo sequence on a MR scanner with a high performance gradient system. Material and Methods: Five healthy volunteers were examined with a 1.5 Tesla MR system, using a high performance prototype gradient system (peak amplitude 50 mT/m, rising time 600 μs). For imaging, a navigated gradient-echo pulse sequence with an in-plane resolution between 0.63 × 0.63 and 0.78 × 0.78 mm 2 was used. Per patient two overlapping slabs were acquired. The number of visualised coronary artery segments was estimated (AHA classification). In addition, signal-to-noise measurements were performed in the ascending aorta at the level o…
Kardio-MRT
2004
Since initial reports in the early 1990s cardiac magnetic resonance imaging (CMR) has matured and is likely to become an established method for routine cardiac diagnostics. The development of faster gradient-echo sequences and stronger magnetic fields has led to improved temporal and spatial resolution. Myocardial viability can be examined by morphological and functional analysis. Contrast enhanced MRI (ceMRI), perfusion measurements and regional wall motion analysis are the major diagnostic tools. The ability to image in arbitrary double oblique planes provides comprehensive visualization of the heart. The introduction of the MR navigator technique allowed for free-breathing motion correct…
Ergebnisse der kontrastverstärkten MR-Angiographie der aortoiliakalen Gefäße mit einem 1-molaren Kontrastmittel bei 1,0 T: Vergleich zur i. a. DSA
2004
PURPOSE To evaluate the diagnostic accuracy of contrast-enhanced MR angiography (CE-MRA) using a 1.0 molar contrast agent at 1.0 T for the diagnosis of abdominal aortic aneurysms and stenoses of renal or iliac arteries in comparison to intraarterial digital subtraction angiography (DSA). MATERIALS AND METHODS A total of 19 patients with the suspicion of abdominal aortic aneurysm or stenosis of renal or iliac arteries were examined with CE-MRA at 1.0 T. Intra-arterial DSA served as reference in all cases. After test bolus tracking, 10 or 8 ml of the 1.0 molar contrast agent Gadobutrol corresponding to a dose of 0.1 - 0.15 mmol/kg bw were injected and imaging performed using a FLASH-3D sequen…
Morphologische und funktionelle Evaluation pulmonaler Gefäßanomalien mittels schneller MR-Techniken
2002
Purpose: To evaluate breath-hold MR techniques for morphologic and functional assessment of vascular abnormalities of the pulmonary vasculature. Patients and Methods: 13 patients aged 11 to 60 years with different vascular abnormalities of the pulmonary vasculature (5 patients with 16 arteriovenous malformations, 8 patients with partial anomalous pulmonary venous return) underwent MR imaging at 1.5 T. For morphological assessment, a contrast-enhanced 3D MR angiography (ce-MRA) was performed after a timing run. Segmented cine- and velocity-encoded GRE sequences were used for delineation of associated cardiac septal defects and for determination of systemic left-to-right or intrapulmonary shu…
Bestimmung der myokardialen Perfusionsreserve bei KHK-Patienten mit der kontrastmittelverstärkten MRT: Ein Vergleich zwischen semiquantitativer und q…
2002
OBJECTIVE Comparison between two semiquantitative methods and a quantitative evaluation of myocardial blood flow (MBF) for assessment of myocardial perfusion reserve (MPR) in patients with CAD. MATERIAL AND METHODS 9 patients with coronary stenoses > 50 % were examined with an ECG-gated Saturation Recovery Turbo FLASH sequence by using Gd-DTPA as contrast agent (CA). The entive measurements were performed both during rest and hyperemia induced by adenosine. The up-slopes of the signal-time S(t) curves in the myocardium and left ventricular (LV) cavity were evaluated by a linear fit. MPR was calculated from the original up-slopes of the myocardial S(t) curves and from the up-slopes, which we…
Prä- und postoperative Evaluation von linksventrikulären Herzspitzenaneurysmen mittels Cine-MRT
2001
Purpose: To demonstrate the usefulness of cine-MRI for the evaluation of apical left ventricular aneurysms (ALVA) and for prediction of the surgical outcome. Materials and Methods: We investigated 28 patients with ALVA, 13 of them additionally after aneurysmectomy at 1.5 T; 15 healthy volunteers served as normal controls. For cine-MRI k-space segmented FI-2D-GE sequences were used. Analysis comprised the calculation of cardiac volume indices, cardiac function, and percentual myocardial thickening (PMT). For prediction of surgical results we divided left ventricle into an aneurysmatic and a non-aneurysmatic part. The non-aneurysmatic part was assumed as the left ventricle after surgical remo…
The Adverse Events and Hemodynamic Effects of Adenosine-Based Cardiac MRI
2011
OBJECTIVE We wanted to prospectively assess the adverse events and hemodynamic effects associated with an intravenous adenosine infusion in patients with suspected or known coronary artery disease and who were undergoing cardiac MRI. MATERIALS AND METHODS One hundred and sixty-eight patients (64 ± 9 years) received adenosine (140 µg/kg/min) during cardiac MRI. Before and during the administration, the heart rate, systemic blood pressure, and oxygen saturation were monitored using a MRI-compatible system. We documented any signs and symptoms of potential adverse events. RESULTS In total, 47 out of 168 patients (28%) experienced adverse effects, which were mostly mild or moderate. In 13 patie…
MRT des Herzens bei Verdacht auf Myokarditis
2002
Purpose To evaluate the potential of ECG-gated breath-hold MRI in diagnosing acute myocarditis. Material and methods Cardiac MRI was performed on 21 consecutive patients with suspected myocarditis. ECG-gated breath-hold T2-weighted images with fat suppression were acquired in 3 standard views. T1-weighted imaging (FLASH) was performed 10 min after IV administration of Gd-DTPA. Laboratory data included creatine kinase, troponin T and serological tests, ECG findings and echocardiography. Imaging findings were retrospectively compared to the discharge diagnoses. Signal alterations were semiquantitatively classified. Results Acute myocarditis was diagnosed in 9 patients and cardiac sarcoidosis …
Noonan-Syndrom mit der ungew�hnlichen Kombination von hypertropher Kardiomyopathie, konnatal bikuspider Aortenklappe und Aortenisthmusstenose mit hyp…
2004
Das Noonan-Syndrom ist gekennzeichnet durch kraniofaziale Dysmorphien wie Ptosis der Augenlider, Pterygium colli und durch einen tiefen nuchalen Haaransatz, durch Skelettveranderungen wie Kleinwuchs, Klinodaktylie, Kiel- und Trichterbrust und durch Organfehlbildungen, hauptsachlich Herzfehler, seltener einer Retentio testis und Nierenfehlbildungen. Das Noonan-Syndrom weist ein ahnliches Erscheinungsbild auf wie das Ullrich-Turner-Syndrom. Im Gegensatz zu dieser Chromosomenaberration sind aber Patienten beiderlei Geschlechts betroffen, sie weisen einen unauffalligen Chromosomensatz (46, XX bzw. 46, XY) auf und sind zeugungsfahig. Bei etwa der Halfte der Patienten mit Noonan-Syndrom bestehen …
Influence of contrast agent dose and image acquisition timing on the quantitative determination of nonviable myocardial tissue using delayed contrast…
2004
BACKGROUND: Delayed contrast-enhanced magnetic resonance imaging (ceMRI) has been shown to identify areas of irreversible myocardial injury due to infarction (MI) with high spatial resolution, allowing precise quantification of nonviable (hyperenhanced) myocardium. The aim of our study was to investigate the size of nonviable myocardium quantitatively as a function of time post-contrast when inversion time is held constant in patients post-myocardial infarction using two contrast agent (CA) doses. METHODS: Nine patients with chronic MI underwent two MR scans on a 1.5 Tesla system. Contrast-enhanced MRI data in two short-axis (SA) slices were continuously acquired until 40 minutes after CA i…
Dynamic contrast-enhanced myocardial perfusion imaging using saturation-prepared TrueFISP.
2002
Purpose To develop and test a saturation-recovery TrueFISP (SR-TrueFISP) pulse sequence for first-pass myocardial perfusion imaging. Materials and Methods First-pass magnetic resonance imaging (MRI) of Gd-DTPA (2 mL) kinetics in the heart was performed using an SR-TrueFISP pulse sequence (TR/TE/α = 2.6 msec/1.4 msec/55°) with saturation preparation TD = 30 msec before the TrueFISP readout. Measurements were also performed with a conventional saturation-recovery TurboFLASH (SRTF) pulse sequence for comparison. Results SR-TrueFISP images were of excellent quality and demonstrated contrast agent wash-in more clearly than SRTF images. The signal increase in myocardium was higher in SR-TrueFISP …