Learn More
A novel method for amplitude of radiofrequency field (B1+) mapping based on the Bloch-Siegert shift is presented. Unlike conventionally applied double-angle or other signal magnitude-based methods, it encodes the B(1) information into signal phase, resulting in important advantages in terms of acquisition speed, accuracy, and robustness. The Bloch-Siegert(More)
The Shinnar-Le Roux (SLR) radiofrequency (RF) pulse design algorithm is widely used for designing slice-selective RF pulses due to its intuitiveness, optimality, and speed. SLR is limited, however, in that it is only capable of designing one-dimensional pulses played along constant gradients. We present a nonuniform SLR RF pulse design framework that(More)
PURPOSE To use electromagnetic (EM) simulations to study the effects of body type, landmark position, and radiofrequency (RF) body coil type on peak local specific absorption rate (SAR) in 3T magnetic resonance imaging (MRI). MATERIALS AND METHODS Numerically computed peak local SAR for four human body models (HBMs) in three landmark positions (head,(More)
Current spokes pulse design methods can be grouped into methods based either on sparse approximation or on iterative local (gradient descent-based) optimization of the transverse-plane spatial frequency locations visited by the spokes. These two classes of methods have complementary strengths and weaknesses: sparse approximation-based methods perform an(More)
In a recent work, we presented a novel method for B 1+ field mapping based on the Bloch-Siegert shift. Here, we apply this method to automated fast radiofrequency transmit gain calibration. Two off-resonance radiofrequency pulses were added to a slice-selective spin echo sequence. The off-resonance pulses induce a Bloch-Siegert phase shift in the acquired(More)
PURPOSE Acoustic noise during magnetic resonance imaging (MRI) is the main source for patient discomfort and leads to verbal communication problems, difficulties in sedation, and hearing impairment. Silent Scan technology uses less changes in gradient excitation levels, which is directly related to noise levels. Here, we report our preliminary experience(More)
PURPOSE To compare an external sensor-based k-space calibration technique with a routine precalibration method for quantification of method accuracy and reduction of spiral imaging artifacts to obtain improved image quality. MATERIALS AND METHODS Recently, magnetic field monitoring (MFM) has been introduced as a new calibration technique of gradient(More)
PURPOSE to evaluate the influence of bone-conduction in the MR environment compared to a standardized acoustic environment. MATERIALS AND METHODS Acoustic noise is an unwanted side effect of MRI that is commonly tackled with passive hearing protection. In an MR scanner, however, with the patient completely surrounded by the MR sounds and in close contact(More)