In-Tsang Lin

Time-Evolution contrast of target MRI using high-stability antibody functionalized magnetic nanoparticles: an animal model

In this work, high-quality antibody functionalized Fe3O4 magnetic nanoparticles are synthesized. Such physical characterizations as particle morphology, particle size, stability, and relaxivity of magnetic particles are investigated. The immunoreactivity of biofunctionalized magnetic nanoparticles is examined by utilizing immunomagnetic reduction. The results show that the mean diameter of antibody functionalized magnetic nanoparticles is around 50 nm, and the relaxivity of the magnetic particles is 145 (mMċs)-1. In addition to characterizing the magnetic nanoparticles, the feasibility of using the antibody functionalized magnetic nanoparticles for the contrast medium of target magnetic resonance imaging is investigated. These antibody functionalized magnetic nanoparticles are injected into mice bearing with tumor. The tumor magnetic-resonance image becomes darker after the injection and then recovers 50 hours after the injection. The tumor magnetic-resonance image becomes the darkest at around 20 hours after the injection. Thus, the observing time window for the specific labeling of tumors with antibody functionalized magnetic nanoparticles was found to be 20 hours after injecting biofunctionalized magnetic nanoparticles into mice. The biopsy of tumor is stained after the injection to prove that the long-term darkness of tumor magnetic-resonance image is due to the specific anchoring of antibody functionalized magnetic nanoparticles at tumor.

High-T/sub c/ Superconducting receiving coils for nuclear magnetic resonance imaging

Nuclear magnetic resonance (NMR) microscopy poses high demands on the sensitivity of the receiver coils. We have developed high-T/sub c/ superconducting (HTS) tape receiving coils for nuclear magnetic resonance imaging. The surface receiver coil is constructed from high-T/sub c/ Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub y/ tape coil and cooled in liquid nitrogen temperature. The desired receiver surface coil is numerically simulated and optimized to have high value of the unloaded quality factor. With this HTS receiver coil we have obtained significant improvement in the unloaded Q-value, loaded Q-value and substantial gain in signal-to-noise ratio (SNR). The SNR improvement of 2.4 was achieved in the kiwi imaging and improvement of 2.7 in the braining imaging of rat at 300 K. The MRI microscopy is tested and compared the results with copper receiver.

Anti-CEA-functionalized superparamagnetic iron oxide nanoparticles for examining colorectal tumors in vivo

Although the biomarker carcinoembryonic antigen (CEA) is expressed in colorectal tumors, the utility of an anti-CEA-functionalized image medium is powerful for in vivo positioning of colorectal tumors. With a risk of superparamagnetic iron oxide nanoparticles (SPIONPs) that is lower for animals than other material carriers, anti-CEA-functionalized SPIONPs were synthesized in this study for labeling colorectal tumors by conducting different preoperatively and intraoperatively in vivo examinations. In magnetic resonance imaging (MRI), the image variation of colorectal tumors reached the maximum at approximately 24 h. However, because MRI requires a nonmetal environment, it was limited to preoperative imaging. With the potentiality of in vivo screening and intraoperative positioning during surgery, the scanning superconducting-quantum-interference-device biosusceptometry (SSB) was adopted, showing the favorable agreement of time-varied intensity with MRI. Furthermore, biological methodologies of different tissue staining methods and inductively coupled plasma (ICP) yielded consistent results, proving that the obtained in vivo results occurred because of targeted anti-CEA SPIONPs. This indicates that developed anti-CEA SPIONPs owe the utilities as an image medium of these in vivo methodologies.

Human hand imaging using a 20 cm high-temperature superconducting coil in a 3T magnetic resonance imaging system

A high-temperature superconducting (HTS) radio-frequency (rf) coil has been proposed as a promising tool in the investigation of tissue microscopy with high resolution due to its low-resistant characteristic for magnetic resonance (MR) probe design. In this work, a 200 mm in diameter Bi2Sr2Ca2Cu3Ox (Bi-2223) tape HTS rf coil was built; and a signal-to-noise ratio (SNR) with the HTS tape coil having 2.22 folds higher than that of a home-made copper coil for a phantom MR study was demonstrated. Testing results were in agreement with predicted ones, and the difference between the predicted SNR gains and measured SNR gains is 0.9%. Using in vivo imaging, a SNR with the HTS tape coil having 1.95 folds higher than that of a home-made copper coil for a human hand MR study was presented. The HTS coil is expected to generate a higher SNR gain after optimization. Further applications of a functional magnetic resonance imaging system are under investigation to test the applicability of this HTS coil system in a 3T s...

Diffusion tensor imaging using a high-temperature superconducting resonator in a 3 T magnetic resonance imaging for a spontaneous rat brain tumor

This study investigates the peri-tumor signal abnormalities of a spontaneous brain tumor in a rat by using a 4 cm high-temperature superconducting (HTS) surface resonator. Fractional anisotropy (FA) values derived from diffusion tensor imaging reflect the interstitial characteristic of the peri-lesional tissues of brain tumors. Low FA indicates interstitial tumor infiltration and tissue injury, while high FA indicates better tissue integrity. Better delineation of tissue contents obtained by the HTS surface resonator at 77 K may facilitate therapeutic strategy and improve clinical outcomes.

Using high-Tc superconducting resonator for enhancement of diffusion tensor imaging

Here, a report on diffusion tensor imaging (DTI) using a 125.3 MHz high-temperature superconducting (HTS) surface resonator for magnetic resonance imaging (MRI) is presented. A 40 mm in diameter Bi2Sr2Ca2Cu3Ox (Bi-2223) tape surface resonator was built. Using a HTS surface resonator at 77 K than a similar copper surface resonator at 300 K, the capacity to save the accuracy of DTI in a reduced scan time (11 min) was demonstrated. The standard deviation of deviation angles of DTI fiber tracking was also improved by 2.5 gains. The use of HTS surface resonator may improve the reliability of fiber tracking experiments.

A temperature-stable cryo-system for high-temperature superconducting MR in-vivo imaging.

To perform a rat experiment using a high-temperature superconducting (HTS) surface resonator, a cryostat is essential to maintain the rats temperature. In this work, a compact temperature-stable HTS cryo-system, keeping animal rectal temperature at 37.4°C for more than 3 hours, was successfully developed. With this HTS cryo-system, a 40-mm-diameter Bi2Sr2Ca2Cu3Ox (Bi-2223) surface resonator at 77 K was demonstrated in a 3-Tesla MRI system. The proton resonant frequency (PRF) method was employed to monitor the rats temperature. Moreover, the capacity of MR thermometry in the HTS experiments was evaluated by correlating with data from independent fiber-optic sensor temperature measurements. The PRF thermal coefficient was derived as 0.03 rad/°C and the temperature-monitoring architecture can be implemented to upgrade the quality and safety in HTS experiments. The signal-to-noise ratio (SNR) of the HTS surface resonator at 77 K was higher than that of a professionally made copper surface resonator at 300 K, which has the same geometry, by a 3.79-fold SNR gain. Furthermore, the temperature-stable HTS cryo-system we developed can obtain stable SNR gain in every scan. A temperature-stable HTS cryo-system with an external air-blowing circulation system is demonstrated.

Enlargement of the field of view and maintenance of a high signal-to-noise ratio using a two-element high-Tc superconducting array in a 3T MRI.

Abstract This study examines the enlargement of the field of view (FOV) and the maintenance of a high signal-to-noise ratio (SNR) through the use of two high-temperature superconducting (HTS) resonators in a 3T MRI. Two Bi2Sr2Ca2Cu3Ox (Bi-2223) surface resonators, each of 4-cm diameter, were used in a 3T MRI. Professionally made copper resonators operate at 300 K, but each Bi-2223 resonator, operated at 77 K and demonstrated a 3.75 fold increase in SNR gain. For the same scanning time, the SNR of the images of a rat’s brain and back, obtained using two small Bi-2223 surface resonators, was higher than that obtained using a single 8-cm surface resonator.

A 40-mm High-Temperature Superconducting Surface Resonator in a 3-T MRI System: Simulations and Measurements

In this paper, the Ansoft high-frequency structure simulation (HFSS) was adapted to investigate the unloaded quality-factor value of the radio-frequency (RF) receiving resonator. This paper focused on the materials aspects, and a comparison between electromagnetic stimulations and measurement was conducted. A 40 mm in diameter Bi2Sr2Ca2Cu3Ox (Bi-2223) tape high-Tc superconducting RF resonator in 3 T was stimulated and built. The simulation models were established according to the experimental dimension of the Bi-2223 surface resonator. Measurements show that the Bi-2223 surface resonator at 77 K provides a gain of 3.84-fold signal-to-noise ratio on phantom images over that of the homemade copper resonator at 300 K. Measuring results were in accordance with predicted ones, and the difference between the predicted SNR gains and measured SNR gains is 1%. This paper suggests that using a Bi-2223 surface resonator at 77 K could be more useful for magnetic resonance imaging coils than a copper surface resonator at 300 K.

Non-invasive Fiber Tracking on Diffusion Tensor MRI Using High-Temperature Superconducting Tape RF coil

High-temperature superconducting (HTS) coil is the reactance created by the inductive loop. A trimmer one of the best ways to increase the signal-to-noise ratio (SNR). Bi2Sr2Ca2Cu3Ox (Bi-2223) tapes were suitable to use because of the easier fabrications and lower cost. In this study, we built HTS Bi-2223 tape coils and demonstrated that the SNR of using the HTS tape coil was 3 or 4 folds higher than that of the traditional copper coil for a rat brain MR study. Acquisition time of MR diffusion tensor imaging (DTI) can be reduced by factor of 9 for the same signal-to-noise. Accuracy of fiber tracking using DTI is also significantly improved by a factor of 2.5 or so using HTS coil. In summary, with this HTSC system, a 3T MR system could reach the high signal-to-noise of 12 T MR system with the advantage of less T2 shortening effects at high field. Currents researches are focused on brain connectivity and fMRI studies