Joseph E. Piel

128-channel body MRI with a flexible high-density receiver-coil array.

To determine whether the promise of high‐density many‐coil MRI receiver arrays for enabling highly accelerated parallel imaging can be realized in practice.

Accelerated spectroscopic imaging of hyperpolarized C-13 pyruvate using SENSE parallel imaging.

The ability to accelerate the spatial encoding process during a chemical shift imaging (CSI) scan of hyperpolarized compounds is demonstrated through parallel imaging. A hardware setup designed to simultaneously acquire 13C data from multiple receivers is presented here. A system consisting of four preamplifiers, four gain stages, a transmit coil, and a four receive channel rat coil was built for single channel excitation and simultaneous multi‐channel detection of 13C signals. The hardware setup was integrated with commercial scanner electronics, allowing the system to function similar to a conventional proton multi‐channel setup, except at a different frequency. The ability to perform parallel imaging is demonstrated in vivo. CSI data from the accelerated scans are reconstructed using a self‐calibrated multi‐spectral parallel imaging algorithm, by using lower resolution coil sensitivity maps obtained from the central region of k‐space. The advantages and disadvantages of parallel imaging in the context of imaging hyperpolarized compounds are discussed. Copyright

Micromultiplane transesophageal echocardiographic probe for intraoperative study of congenital heart disease repair in neonates, infants, children, and adults

This study reports the development of a micromultiplane 8.2-mm transesophageal echocardiographic probe. The probe is applicable to newborn infants and can deliver diagnostic images in adults.

Peripheral nerve stimulation characteristics of an asymmetric head-only gradient coil compatible with a high-channel-count receiver array

To characterize peripheral nerve stimulation (PNS) of an asymmetric head‐only gradient coil that is compatible with a commercial high–channel‐count receive‐only array.

High slew-rate head-only gradient for improving distortion in echo planar imaging: Preliminary experience.

To investigate the effects on echo planar imaging (EPI) distortion of using high gradient slew rates (SR) of up to 700 T/m/s for in vivo human brain imaging, with a dedicated, head‐only gradient coil.

High slew-rate head-only gradient for improving distortion in echo planar imaging

To investigate the effects on echo planar imaging (EPI) distortion of using high gradient slew rates (SR) of up to 700 T/m/s for in vivo human brain imaging, with a dedicated, head‐only gradient coil.

Three-frequency RF coil designed for optimized imaging of hyperpolarized, 13C-labeled compounds

Imaging exams involving hyperpolarized, 13C‐labeled compounds require novel RF coils for efficient signal utilization. While 13C coils are required for mapping the spatial distribution of the hyperpolarized compounds, imaging/pulsing at different frequencies is also needed for scan setup steps prior to the image acquisition. Imaging/pulsing at the 1H frequency is typically used for anatomical localization and shimming. Flip angle (FA) calibration, which is difficult or impossible to achieve at the 13C frequency, can be accurately performed at the 23Na frequency using the natural abundance signal that exists in any living tissue. We demonstrate here a single RF resonant structure that is capable of operating linearly at the 1H and 23Na frequencies for scan setup steps, and in quadrature at the 13C frequency for imaging. Images at the three resonant frequencies of this coil are presented from an exam involving hyperpolarized 13C compounds in vivo. Magn Reson Med 60:928–933, 2008.

Lightweight, compact, and high-performance 3T MR system for imaging the brain and extremities: FOO et al.

To build and evaluate a small‐footprint, lightweight, high‐performance 3T MRI scanner for advanced brain imaging with image quality that is equal to or better than conventional whole‐body clinical 3T MRI scanners, while achieving substantial reductions in installation costs.

7.5-MHz pediatric phased array transesophageal endoscope

This work extends the clinical benefits of phased array transesophageal echocardiography with high detail and contrast resolution to include neonatal patients. We have built several prototype, 64‐element, 7.5‐MHz phased array transducers housed in 6.2‐mm endoscope shafts for use with commercially available imaging systems. The acoustic design is standard, but the miniaturized packaging of the electrical connections was quite challenging. The endoscopes demonstrate very good structural resolution and excellent sensitivity for color flow imaging and continuous‐wave Doppler. They have been used on patients as small as 1.9 kg, frequently as an anatomical guide during catheter‐based interventions and during congenital heart surgery. Array test data and representative clinical studies are shown.