Gabriele Marianne Beck

Changes in myocardial oxygenation and perfusion under pharmacological stress with dipyridamole : Assessment using T*2 and T1 measurements

The aim of this pilot‐study was to evaluate changes in myocardial oxygenation and perfusion under pharmacological stress with dipyridamole (DIP) by means of MRI. Twenty healthy volunteers were examined using a multi‐echo gradient‐echo sequence. The differential myocardial signal response due to the blood oxygen level dependent (BOLD) effect was studied under variable conditions of myocardial oxygen supply caused by the vasodilator DIP. Unlike contrast agents (CA) methods, which require at least two injections of CA and DIP, the presented methods require only a single infusion of DIP. To assess changes in myocardial perfusion, a saturation recovery TurboFLASH (SRTFL) sequence with centric reordering for T1 measurements was used with global and slice‐selective spin‐preparation (five volunteers). The signal response was measured at baseline conditions and when myocardial blood flow was increased during pharmacological stress with DIP. Administration of DIP induced a 17 ± 9% increase in T*2. Enhanced perfusion resulted in a 15 ± 5% decrease of T1 after slice‐selective spin preparation and a calculated increase in absolute perfusion of about 5.1 ml/(g × min), which reflects coronary reserve.

Contrast-enhanced timing robust acquisition order with a preparation of the longitudinal signal component (CENTRA plus) for 3D contrast-enhanced abdominal imaging

To investigate a new image acquisition method that enables an accurate hepatic arterial phase definition and the visualization of contrast agent uptake processes in abdominal organs like liver, spleen, and pancreas.

Reducing oblique flow effects in interleaved EPI with a centric reordering technique.

Segmented interleaved echo planar imaging offers a fast and efficient approach to magnetic resonance angiography. Unfortunately, this technique is particularly sensitive to oblique flow in the imaging plane. In this work, a mathematical analysis of oblique flow effects for several types of k‐space coverage is presented. The conventional linear acquisition scheme, an alternating centric and a nonalternating centric encoding scheme are compared with respect to their flow properties. It is shown both by simulations and imaging experiments that artifacts from oblique in‐plane flow are effectively reduced by both centric reordered phase‐encoding schemes. The nonalternating centric acquisition scheme is preferred to the alternating centric scheme due to the smoother phase error transition in k‐space in the presence of obliquely‐angled flow. Magn Reson Med 45:623–629, 2001.

Non-contrast enhanced 4D intracranial MR angiography based on pseudo-continuous arterial spin labeling with the keyhole and view-sharing technique

4D dynamic MR angiography (4D‐MRA) using pseudo‐continuous arterial spin labeling (pCASL), combined with Keyhole and View‐sharing (4D‐PACK) for scan acceleration, is introduced. Its validity for arterial inflow dynamics visualization was investigated through comparison with 4D‐pCASL and contrast inherent inflow enhanced multiphase angiography (CINEMA).