100 research outputs found
Screen-printed flexible MRI receive coils.
Magnetic resonance imaging is an inherently signal-to-noise-starved technique that limits the spatial resolution, diagnostic image quality and results in typically long acquisition times that are prone to motion artefacts. This limitation is exacerbated when receive coils have poor fit due to lack of flexibility or need for padding for patient comfort. Here, we report a new approach that uses printing for fabricating receive coils. Our approach enables highly flexible, extremely lightweight conforming devices. We show that these devices exhibit similar to higher signal-to-noise ratio than conventional ones, in clinical scenarios when coils could be displaced more than 18 mm away from the body. In addition, we provide detailed material properties and components performance analysis. Prototype arrays are incorporated within infant blankets for in vivo studies. This work presents the first fully functional, printed coils for 1.5- and 3-T clinical scanners
Metabolite-specific echo-planar imaging of hyperpolarized [1-- 13 C]pyruvate at 4.7 T
Although hyperpolarization (HP) greatly increases the sensitivity o
A Regional Bolus Tracking and Real-time B Calibration Method for Hyperpolarized C MRI
Purpose: Acquisition timing and B calibration are two key factors that
affect the quality and accuracy of hyperpolarized C MRI. The goal of
this project was to develop a new approach using regional bolus tracking to
trigger Bloch-Siegert B mapping and real-time B calibration based on
regional B measurements, followed by dynamic imaging of hyperpolarized
metabolites in vivo.
Methods: The proposed approach was implemented on a system which allows
real-time data processing and real-time control on the sequence. Real-time
center frequency calibration upon the bolus arrival was also added. The
feasibility of applying the proposed framework for in vivo hyperpolarized
C imaging was tested on healthy rats, tumor-bearing mice and a healthy
volunteer on a clinical 3T scanner following hyperpolarized
[1-C]pyruvate injection. Multichannel receive coils were used in the
human study.
Results: Automatic acquisition timing based on either regional bolus peak or
bolus arrival was achieved with the proposed framework. Reduced blurring
artifacts in real-time reconstructed images were observed with real-time center
frequency calibration. Real-time computed B scaling factors agreed with
real-time acquired B maps. Flip angle correction using B maps results
in a more consistent quantification of metabolic activity (i.e,
pyruvate-to-lactate conversion, k). Experiment recordings are provided
to demonstrate the real-time actions during the experiment.
Conclusion: The proposed method was successfully demonstrated on animals and
a human volunteer, and is anticipated to improve the efficient use of the
hyperpolarized signal as well as the accuracy and robustness of hyperpolarized
C imaging
A Metabolite Specific 3D Stack-of-Spiral bSSFP Sequence for Improved Lactate Imaging in Hyperpolarized [1-C]Pyruvate Studies on a 3T Clinical Scanner
Purpose: The balanced steady-state free precession sequence has been
previously explored to improve the efficient use of non-recoverable
hyperpolarized C magnetization, but suffers from poor spectral
selectivity and long acquisition time. The purpose of this study was to develop
a novel metabolite-specific 3D bSSFP ("MS-3DSSFP") sequence with
stack-of-spiral readouts for improved lactate imaging in hyperpolarized
[1-C]pyruvate studies on a clinical 3T scanner.
Methods: Simulations were performed to evaluate the spectral response of the
MS-3DSSFP sequence. Thermal C phantom experiments were performed to
validate the MS-3DSSFP sequence. In vivo hyperpolarized [1-C]pyruvate
studies were performed to compare the MS-3DSSFP sequence with metabolite
specific gradient echo ("MS-GRE") sequences for lactate imaging.
Results: Simulations, phantom and in vivo studies demonstrate that the
MS-3DSSFP sequence achieved spectrally selective excitation on lactate while
minimally perturbing other metabolites. Compared with MS-GRE sequences, the
MS-3DSSFP sequence showed approximately a 2.5-fold SNR improvement for lactate
imaging in rat kidneys, prostate tumors in a mouse model and human kidneys.
Conclusions: Improved lactate imaging using the MS-3DSSFP sequence in
hyperpolarized [1-C]pyruvate studies was demonstrated in animals and
humans. The MS-3DSSFP sequence could be applied for other clinical applications
such as in the brain or adapted for imaging other metabolites such as pyruvate
and bicarbonate
Mineral Composition of Serial Slaughter Holstein Carcasses
Carcasses of 115 Holstein steers were divided into lean, bone, internal cavity, hide, and fat tissues for analysis of P, Ca, K, Mg, and S retention. Every 28 days, five steers from each of two treatments, fed Zilmax for 20 days prior to harvest or not fed Zilmax, were harvested. There were no differences due to treatment or days on feed when mineral retention was expressed as g/100 g of protein gain. Expressing mineral retention relative to protein gain reduced variation due to rate of gain and animal size
Inhibition of Tumor Growth Using Salmonella Expressing Fas Ligand
Intravenous administration of bacteria leads to their accumulation in tumors and to sporadic tumor regression. We therefore explored the hypothesis that Salmonella typhimurium engineered to express the proapoptotic cytokine Fas ligand (FasL) would exhibit enhanced antitumor activity. Immunocompetent mice carrying tumors derived from syngeneic murine D2F2 breast carcinoma or CT-26 colon carcinoma cells were treated intravenously with FasL-expressing S. typhimurium or with phosphate-buffered saline (PBS; control). Treatment with FasL-expressing S. typhimurium inhibited growth of primary tumors by an average of 59% for D2F2 tumors and 82% for CT-26 tumors (eg, at 25 days after initial treatment, mean volume of PBS-treated CT-26 colon carcinomas = 1385 mm3 and of S. typhimurium FasL-treated CT-26 tumors = 243 mm3, difference = 1142 mm3, 95% confidence interval = 800 mm3 to 1484 mm3, P < .001). Pulmonary D2F2 metastases (as measured by lung weight) were reduced by 34% in S. typhimurium FasL-treated mice compared with PBS-treated mice. FasL-expressing S. typhimurium had similar effects on growth of murine B16 melanoma tumors in wild-type mice but not in lpr/lpr mice, which lack Fas, or in mice with disrupted host inflammatory responses. Antitumor activity was achieved without overt toxicity. These preclinical results raise the possibility that using attenuated S. typhimurium to deliver FasL to tumors may be an effective and well-tolerated therapeutic strategy for some cancers
Imaging Renal Urea Handling in Rats at Millimeter Resolution using Hyperpolarized Magnetic Resonance Relaxometry
\textit{In vivo} spin spin relaxation time () heterogeneity of
hyperpolarized \textsuperscript{13}C urea in the rat kidney was investigated.
Selective quenching of the vascular hyperpolarized \textsuperscript{13}C signal
with a macromolecular relaxation agent revealed that a long- component of
the \textsuperscript{13}C urea signal originated from the renal extravascular
space, thus allowing the vascular and renal filtrate contrast agent pools of
the \textsuperscript{13}C urea to be distinguished via multi-exponential
analysis. The response to induced diuresis and antidiuresis was performed
with two imaging agents: hyperpolarized \textsuperscript{13}C urea and a
control agent hyperpolarized
bis-1,1-(hydroxymethyl)-1-\textsuperscript{13}C-cyclopropane-.
Large increases in the inner-medullar and papilla were observed with the
former agent and not the latter during antidiuresis suggesting that
relaxometry may be used to monitor the inner-medullary urea transporter (UT)-A1
and UT-A3 mediated urea concentrating process. Two high resolution imaging
techniques - multiple echo time averaging and ultra-long echo time sub-2 mm
resolution 3D imaging - were developed to exploit the particularly long
relaxation times observed
Imaging of Glucose Metabolism by 13C-MRI Distinguishes Pancreatic Cancer Subtypes in Mice
Metabolic differences among and within tumors can be an important determinant in cancer treatment outcome. However, methods for determining these differences non-invasively in vivo is lacking. Using pancreatic ductal adenocarcinoma as a model, we demonstrate that tumor xenografts with a similar genetic background can be distinguished by their differing rates of the metabolism of 13C labeled glucose tracers, which can be imaged without hyperpolarization by using newly developed techniques for noise suppression. Using this method, cancer subtypes that appeared to have similar metabolic profiles based on steady state metabolic measurement can be distinguished from each other. The metabolic maps from 13C-glucose imaging localized lactate production and overall glucose metabolism to different regions of some tumors. Such tumor heterogeneity would not be not detectable in FDG-PET
South Ridgeline habitat study : Final report
177 pp. Bookmarks supplied by UO. Includes maps and figures. Published August, 2007. Captured January 23, 2008.This report contains documentation of a five-month inventory and assessment of over 2600 acres of
upland habitats on public and private land in the South Ridgeline area of Eugene, Oregon. The
South Ridgeline Habitat Study (SRHS) was undertaken to document the location, quantity, and
quality of upland habitat, and suitability of habitat for uncommon and rare species in the area, and to
do so in a way that meets the inventory standards contained in the administrative rules for Statewide
Planning Goal 5.... This report contains: 1) background information about the study area, including ecological history;
2) methodology for inventory and assessment ratings; and 3) a summary of results. [From the Document
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