We evaluated a time-of-flight three-dimensional MR angiographic sequence with an ultrashort echo time for its ability to characterize the perfusional state of cerebral aneurysms that had been treated with Guglielmi detachable coils and to depict adjacent cerebral arteries. The results were compared with findings at conventional MR angiography and digital subtraction angiography. Adjacent vessel...

J. Pfeuffer, J. Pauls, M. Augath, T. Steudel, H. Merkle, N. K. Logothetis Max Planck Institute for biological Cybernetics, Tuebingen, D, Germany, LFMI, NIH/NINDS, Bethesda, MD, United States First fMRI results in the awake trained monkey (Macaca mulatta) using a novel vertical 7T/60cm MR system are reported. The setup was custom-designed for MR imaging of monkeys in upright position and simulta...

Introduction: Metabolic imaging with Magnetic Resonance (MR) allows a selective identification of molecules and molecular distribution mapping within various organs. However, both weak nuclear polarization levels and low natural abundance reduce the MR experiment sensitivity. Hyperpolarization methods have been proposed to enhance the polarization of nuclear spins such as C and the feasibility ...

Heavy loading, strong RF loss and the skin effect complicate MR investigations in electric conductive, dielectric media. A set-up was developed for MR studies on swimming marine fish that reduces these limitations. A birdcage resonator adapted to high loadings was used for signal excitation. An insulated inductive coil (2 cm diameter) was fixed onto the fish and placed opposite to a watertight,...

Introduction: After their introduction by Roemer et al [1], phased array coils have become standard in clinical MR imaging. The development of array coils for small animal MRI is of increasing interest. Field strengths of 4.7T and higher are especially suited for small animal work because of the high SNR offered at these field strengths. Isolation preamplifiers are expensive and not ubiquitous ...

PURPOSE To develop a superconducting magnetic resonance (MR) imager that provides direct access to the patient and permits interactive MR-guided interventional procedures. MATERIALS AND METHODS A 0.5-T superconducting magnet that allows a region of vertical access to the patient was designed and constructed. This magnet was integrated with newly designed shielded gradient coils, flexible surf...

Introduction MRI acoustic noise represents a possible hazard to patients and volunteers undergoing scanning and to workers present in the scanner room during imaging. Vibrations in the gradient coils are generated by Lorentz forces, induced by the currents flowing through the gradient coils within the static magnetic field. The vibrations are transmitted to other parts of the scanner and finall...

Rationale and Objectives. A number of recent reports in the MRI literature have established that substantial signal-tonoise ratio (SNR) gains can be achieved with small samples or low resonance frequencies, through the use of high-quality factor high-temperature superconducting (HTS) RF receive coils. We show the application of HTS coils to the imaging of human subjects with improved SNR compar...

Introduction It has recently been demonstrated that substantial SNR enhancements (3.7 times) can be achieved for in vivo MR micro imaging of small animals at 2 T field strength with superconducting RF coils, cooled to 30 K [1]. However, significant SNR gains are expected even with conventional copper coils, cooled with liquid nitrogen (77 K). The latter have several advantages in terms of simpl...

Introduction The magnetic field produced per unit current, B1, and B0 mapping are important criteria when evaluating the performance of micro coils in NMR microscopy [1]. To increase the coil B1 across the sample and achieve high MR image SNR, RF coils should be placed as close as possible to the NMR sample. Bringing coils close to materials with different susceptibility, results in inhomogenei...