Cost-Effective, Integrated In Vitro Phantoms for Cardiac MRI.

To provide lab scale in vitro phantom solutions for cardiac MR (CMR) studies that can be used for imaging structure and function as well as calorimetric measurements. The phantoms were purposed to accept user inputs such as beats per minute (BPM) and flow rate. We developed two generations of phantoms. The first phantom was developed using poly vinyl alcohol driven by a mechanical setup. The second was a 3D-printed phantom controlled through a user interface (UI) and a peristaltic pump. These phantoms were scanned for the characteristics mentioned above, which were qualitatively and quantitatively assessed through postprocessing of CMR images and compared with in vivo data.

12-channel receive array with a volume transmit coil for hand/wrist imaging at 7 T.

PURPOSE: To develop a coil configuration for high-resolution imaging of different regions of the hand and wrist at 7 T. MATERIALS AND METHODS: A quadrature bandpass birdcage and a 12-channel high density receive array were developed for imaging metacarpus and wrist. Workbench and magnetic resonance imaging (MRI) measurements were done to characterize the coil and obtain in vivo images. Electromagnetic simulations were performed to assess the uniformity of transmit profile and calculate the specific absorption rate (SAR). RESULTS: The results obtained show that the constructed transmit coil can be used in combination with receive arrays, without the need to retune the same. The developed wrist array was used to produce images of ultrahigh resolution (0.19 × 0.19 × 0.5 mm(3) ), revealing fine anatomical details. Simulations show that a near-uniform transmit profile is possible throughout the hand. No inhomogeneities were observed in the transmit profile, unlike a human head or abdomen at 7 T, due to the small volume of the hand and its low conductive regions. CONCLUSION: While transceive arrays are usually preferred at 7 T due to issues related to decrease in wavelength, it is shown in this study that with regard to hand-imaging optimized high-density receive arrays are a good solution to obtain images of extremely fine resolution of different regions.

Dynamic MR imaging of a minipig's knee using a high-density multi-channel receive array and a movement device.

OBJECT: To construct an optimised, high-density receive array and a movement device to achieve dynamic imaging of the knee in orthopedic large animal models (e.g., minipigs) at 1.5 T. MATERIALS AND METHODS: A 13-channel RF receive array was constructed, and the crucial choice of the array element size (based on considerations like region of interest, geometry of the minipig's knee, achievable signal-to-noise ratio, applicability of parallel imaging, etc.) was determined using the Q factors of loops with different sizes. A special movement device was constructed to guide and produce a reproducible motion of the minipig's knee during acquisition. RESULTS: The constructed array was electrically characterised and the reproducibility of the cyclic motion was validated. Snapshots of dynamic in vivo images taken at a temporal resolution (308 ms) are presented. Some of the fine internal structures within the minipig's knee, like cruciate ligaments, are traced in the snapshots. CONCLUSION: This study is a step towards making dynamic imaging which can give additional information about joint injuries when static MRI is not able to give sufficient information, a routine clinical application. There, the combination of a high-density receive array and a movement device will be highly helpful in the diagnosis and therapy monitoring of knee injuries in the future.