bluuebunny/crossref_metadata_2025_split huggingface dataset:
Retrovirus‐mediated gene transfer and expression of EGFP in chicken
Authors: Koo Bon Chul , Kwon Mo Sun , Choi Bok Ruyl , Lee Hoon Taek , Choi Ho Jun , Kim Jin‐Hoi , Kim Nam‐Hyung , Jeon Iksoo , Chang Wonkyong , Kim Teoan 
Published: June 2004

AbstractHere, we successfully demonstrate expression of the EGFP (enhanced green fluorescence protein) gene in chickens using replication‐defective MLV (murine leukemia virus)‐based retrovirus vectors encapsidated with VSV‐G (vesicular stomatitis virus G glycoprotein). The recombinant retrovirus was injected beneath the blastoderm of non‐incubated chicken embryos (stage X). After 12 days incubation, all of the eight living embryos assayed were found to express this vector‐encoded EGFP gene, which was under the control of the RSV (Rous Sarcoma Virus) promoter, in diverse organ tissues, including head, beak, neck, wing, hock, tail, toes, heart, amnion, and yolk sac. Surprisingly, despite the presumed cytotoxicity of EGFP, some embryos hatched and survived and these had prominent green fluorescent spots, both in internal organs and externally. Mol. Reprod. Dev. 68: 429–434, 2004. © 2004 Wiley‐Liss, Inc.
Evaluation of renal parenchymal disease in a rat model with magnetic resonance elastography
Authors: Shah Nihar S. , Kruse Scott A. , Lager Donna J. , Farell‐Baril Gerard , Lieske John C. , King Bernard F. , Ehman Richard L. 
Published: June 2004

AbstractAlterations in the mechanical properties or “hardness” of tissues allow physicians to detect disease by palpation. Recently, attempts have been made to quantitate and image these tissue properties with the use of magnetic resonance elastography (MRE). This technique has been validated in ex vivo specimens, including kidney, breast, and prostate. In this study, in vivo MRE imaging of rat renal cortex is demonstrated and validated with a disease model that will facilitate further studies. Normal rats and rats with nephrocalcinosis induced with either 2 or 4 weeks of ethylene glycol exposure were studied with MRE. Histology in the diseased rats documented the presence of nephrocalcinosis. MRE measurements and images of shear stiffness were highly reproducible in individual rats. The shear stiffness of the renal cortex in normal rats was 3.87 kPa (95% CI 2.84–4.90 kPa). The shear stiffness increased to 5.02 kPa (95% CI 3.34–6.70 kPa) after 2 weeks of exposure, and to 6.49 kPa (95% CI 4.84–8.14 kPa) after 4 weeks of exposure (P = 0.0302, α < 0.05). MRE is capable of detecting alterations in the tissue mechanical properties of kidneys in vivo. It is a promising noninvasive technique that might have pathologic and prognostic significance. Magn Reson Med 52:56–64, 2004. © 2004 Wiley‐Liss, Inc.
High‐resolution multistation peripheral MR angiography using undersampled projection reconstruction imaging
Authors: Du J. , Korosec F.R. , Thornton F.J. , Grist T.M. , Mistretta C.A. 
Published: June 2004

AbstractA novel protocol for three‐station MR angiography (MRA) of the lower extremities is described. A time‐resolved undersampled projection reconstruction (PR) acquisition was used to image the calf station during a first injection, and non‐time‐resolved PR acquisitions were used with the bolus‐chase technique to image the abdomen and thigh stations during a second injection. The streak artifacts resulting from undersampling the PR data were reduced with the use of a spatial Fermi filter based on the sensitivity of each coil element in a peripheral vascular phased‐array coil. This novel technique provided high spatial resolution and a broad range of coverage, and depicted the contrast dynamics in the most distal station of the lower extremities. Magn Reson Med 52:204–208, 2004. © 2004 Wiley‐Liss, Inc.
Fast acquisition‐weighted three‐dimensional proton MR spectroscopic imaging of the human prostate
Authors: Scheenen Tom W.J. , Klomp Dennis W.J. , Röll Stefan A. , Fütterer Jurgen J. , Barentsz Jelle O. , Heerschap Arend 
Published: June 2004

AbstractThe clinical application of 3D proton spectroscopic imaging (3D SI) of the human prostate requires a robust suppression of periprostatic lipid signal contamination, minimal intervoxel signal contamination, and the shortest possible measurement time. In this work, a weighted elliptical sampling of k‐space, combined with k‐space filtering and pulse repetition time (TR) reduction minimized lipid signals, intervoxel contamination, and measurement time. At 1.5 T, the MR‐visible prostate metabolites citrate, creatine, and choline can now be mapped over the entire human prostate with uncontaminated spherical voxels, with a volume down to 0.37 cm3, in measurement times of 7–15 min. Magn Reson Med 52:80–88, 2004. © 2004 Wiley‐Liss, Inc.
Quantification of the curvature and shape of the interventricular septum
Authors: Moses Daniel A. , Axel Leon 
Published: June 2004

AbstractThe interventricular septum (IVS) occupies a unique position within the heart, lying between the left (LV) and right (RV) ventricular cavities. Changes in its normal geometry may signify not only abnormalities of the septal myocardium, but also abnormal pressure differences between the LV and RV. Flattening of the IVS has been noted with cross‐sectional imaging in association with pulmonary hypertension, but the septal curvature and shape have not previously been measured in three dimensions. This paper describes a method to model the RV surface of the IVS from spatially registered cross‐sectional images for measurements of curvature. A smoothing 2D spline surface is constructed through the RV septal surface at regular times during the cardiac cycle, and the principal curvatures, as well as the Gaussian and mean curvatures, shape index, and curvedness, are calculated. Vector and color surface maps and graphs of average curvature and shape indices are constructed. Consistent curvature patterns were observed in four normal subjects. This method of measuring septal geometry can provide potentially useful new information on the effects of RV disease. We examine the problem of describing septal motion, and describe a simple measure of septal curvature that may be of clinical value. Magn Reson Med 52:154–163, 2004. © 2004 Wiley‐Liss, Inc.
MRI measurement of liver regeneration in mice following partial hepatectomy
Authors: Garbow J.R. , Kataoka M. , Flye M.W. 
Published: June 2004

AbstractImprovements in noninvasive imaging modalities are crucial for preoperative in vivo assessments of liver condition and potential for regeneration after liver resection for removal of liver tumors. To that end, an MRI study of liver regeneration in mice following partial hepatectomy is described and validated. Hepatic volumes were accurately measured from contrast‐enhanced, gradient‐echo images of the liver. Regeneration curves were constructed for a series of mice (N = 6) from a longitudinal MR study, with images collected 1, 2, 3, 4, 5, and 9 days following surgery. We validated the MR method by correlating serial MR‐measured volumes with liver wet weight. The success of this method will enable future studies to better elucidate the factors that affect regeneration, and help to optimize the timing and dosing of chemotherapeutics to minimize their deleterious effects on liver regeneration. Magn Reson Med 52:177–180, 2004. © 2004 Wiley‐Liss, Inc.
MR coil design for simultaneous tip tracking and curvature delineation of a catheter
Authors: Zuehlsdorff Sven , Umathum Reiner , Volz Steffen , Hallscheidt Peter , Fink Christian , Semmler Wolfhard , Bock Michael 
Published: June 2004

AbstractIn active catheter tracking, small RF coils are attached to the catheter for localization. For interactive catheter steering at vessel branchings, it is necessary to visualize not only a single point near the catheter tip but also the entire shape and orientation of the catheter's distal end. Therefore, a 35‐mm‐long twisted‐pair RF coil was added to a 5 French intravascular catheter with a single tip‐tracking coil. With the use of small nonmagnetic electronic components at the catheter tip, and a special switching circuitry outside the catheter, the coil assembly could be operated in two different modes. During MRI, the tip‐tracking coil was detuned so that the MR signal was received by the visualization coil only. During tracking, detuning was switched off and the MR signal was predominantly received by the more sensitive tracking coil. The catheter was used in combination with a MR pulse sequence with automatic slice positioning so that the current imaging slice was always placed at the position of the catheter tip. Phantom and animal experiments showed that the catheter tip is better visualized with the combined approach than with a tracking coil alone. Magn Reson Med 52:214–218, 2004. © 2004 Wiley‐Liss, Inc.
Increasing the signal‐to‐noise ratio in DENSE MRI by combining displacement‐encoded echoes
Authors: Kim Daniel , Epstein Frederick H. , Gilson Wesley D. , Axel Leon 
Published: June 2004

AbstractA new technique was developed to increase the signal‐to‐noise ratio (SNR) in displacement encoding with stimulated echoes (DENSE) MRI. This signal‐averaged DENSE (sav‐DENSE) technique is based on the SNR advantage of extracting a pair of DENSE images with uncorrelated noise from the complex complementary spatial modulation of the magnetization image, and combining them during image reconstruction. Eleven healthy volunteers were imaged at three short‐axis locations with the use of sav‐DENSE, cine DENSE, and myocardial tagging pulse sequences. In this study, sav‐DENSE increased the SNR by 15–34% as compared to cine DENSE. Circumferential strain values measured by sav‐DENSE and myocardial tagging were strongly correlated (slope = 0.95, intercept = –0.02, R = 0.92) and within the 95% limits of agreement. The breath‐hold sav‐DENSE technique yielded relatively accurate and precise quantification of 2D intramyocardial function, with a 40.2‐ms temporal resolution and a 3.5 × 3.5 mm2 spatial resolution. Magn Reson Med 52:188–192, 2004. © 2004 Wiley‐Liss, Inc.
Modified Look‐Locker inversion recovery (MOLLI) for high‐resolution T1 mapping of the heart
Authors: Messroghli Daniel R. , Radjenovic Aleksandra , Kozerke Sebastian , Higgins David M. , Sivananthan Mohan U. , Ridgway John P. 
Published: June 2004

AbstractA novel pulse sequence scheme is presented that allows the measurement and mapping of myocardial T1 in vivo on a 1.5 Tesla MR system within a single breath‐hold. Two major modifications of conventional Look‐Locker (LL) imaging are introduced: 1) selective data acquisition, and 2) merging of data from multiple LL experiments into one data set. Each modified LL inversion recovery (MOLLI) study consisted of three successive LL inversion recovery (IR) experiments with different inversion times. We acquired images in late diastole using a single‐shot steady‐state free‐precession (SSFP) technique, combined with sensitivity encoding to achieve a data acquisition window of <200 ms duration. We calculated T1 using signal intensities from regions of interest and pixel by pixel. T1 accuracy at different heart rates derived from simulated ECG signals was tested in phantoms. T1 estimates showed small systematic error for T1 values from 191 to 1196 ms. In vivo T1 mapping was performed in two healthy volunteers and in one patient with acute myocardial infarction before and after administration of Gd‐DTPA. T1 values for myocardium and noncardiac structures were in good agreement with values available from the literature. The region of infarction was clearly visualized. MOLLI provides high‐resolution T1 maps of human myocardium in native and post‐contrast situations within a single breath‐hold. Magn Reson Med 52:141–146, 2004. © 2004 Wiley‐Liss, Inc.
BOLD response to direct thalamic stimulation reveals a functional connection between the medial thalamus and the anterior cingulate cortex in the rat
Authors: Shyu Bai‐Chung , Lin Chun‐Yu , Sun Jyh‐Jang , Chen Shin‐Lang , Chang Chen 
Published: June 2004

AbstractRecent functional neuroimaging studies in humans and rodents have shown that the anterior cingulate cortex (ACC) is activated by painful stimuli, and plays an important role in the affective aspect of pain sensation. The aim of the present study was to develop a suitable stimulation method for direct activation of the brain in fMRI studies and to investigate the functional connectivity in the thalamo‐cingulate pathway. In the first part of the study, tungsten, stainless steel, or glass‐coated carbon fiber microelectrodes were implanted in the left medial thalamus (MT) of anesthetized rats, and T2*‐weighted gradient‐echo (GE) images were obtained in the sagittal plane on a 4.7 T system (Biospec BMT 47/40). Only the images obtained with the carbon fiber electrode were acceptable without a reduction of the signal‐to‐noise ratio (SNR) and image distortion. In the second part of the study, a series of two‐slice GE images were acquired during electrical stimulation of the MT with the use of a carbon fiber electrode. A cross‐correlation analysis showed that the signal intensities of activated areas in the ipsilateral ACC were significantly increased by about 4.5% during MT stimulation. Functional activation, as assessed by the distribution of c‐Fos immunoreactivity, showed strong c‐Fos expression in neurons in the ipsilateral ACC. The present study shows that glass‐coated carbon fiber electrodes are suitable for fMRI studies and can be used to investigate functional thalamocortical activation. Magn Reson Med 52:47–55, 2004. © 2004 Wiley‐Liss, Inc.
Localized 7Li MR spectroscopy and spin relaxation in rat brain in vivo
Authors: Komoroski Richard A. , Pearce John M. 
Published: June 2004

AbstractLocalized 7Li MR point‐resolved spectroscopy (PRESS) was developed as a technique to measure lithium (Li) concentration in rat brain in vivo. Localized 7Li spectra could be obtained at 4.7 T in a 0.7‐ml voxel in rat brain over the entire therapeutic range of serum Li for humans. Localized 7Li spin‐lattice (T1) and spin–spin (T2) relaxation times were measured. Measured intensities were corrected for spin relaxation effects and 7Li MR visibility in vivo. The average T1 was 3.3 ± 0.9 sec, and the average T2 was 82 ± 20 ms. Neither T1 nor T2 correlated with brain concentration. No statistically significant change was found in either T1 or T2 from ∼7–17 days of Li dosing. Magn Reson Med 52:164–168, 2004. © 2004 Wiley‐Liss, Inc.
Functional MRI of the rodent somatosensory pathway using multislice echo planar imaging
Authors: Keilholz Shella D. , Silva Afonso C. , Raman Mira , Merkle Hellmut , Koretsky Alan P. 
Published: June 2004

AbstractA multislice EPI sequence was used to obtain functional MR images of the entire rat brain with BOLD contrast at 11.7 T. Ten to 11 slices covering the rat brain, with an in‐plane resolution of 300 μm, provided enough sensitivity to detect activation in brain regions known to be involved in the somatosensory pathway during stimulation of the forelimbs. These regions were identified by warping a digitized rat brain atlas to each set of images. Data analysis was constrained to four major areas of the somatosensory pathway: primary and secondary somatosensory cortices, thalamus, and cerebellum. Incidence maps were generated. Electrical stimulation at 3 Hz led to significant activation in the primary sensory cortex in all rats. Activation in the secondary sensory cortex and cerebellum was observed in 70% of the studies, while thalamic activation was observed in 40%. The amplitude of activation was measured for each area, and average response time courses were calculated. Finally, the frequency dependence of the response to forepaw stimulation was measured in each of the activated areas. Optimal activation occurred in all areas at 3 Hz. These results demonstrate that whole‐brain fMRI can be performed on rodents at 11.7 T to probe a well‐defined neural network. Magn Reson Med 52:89–99, 2004. Published 2004 Wiley‐Liss, Inc.
Fourier components of inhomogeneously broadened water resonances in breast: A new source of MRI contrast
Authors: Medved Milica , Newstead Gillian M. , Fan Xiaobing , Du Weiliang , Du Yiping P. , MacEneaney Peter M. , Culp Rita M. , Kelcz Frederick , Olopade Olufunmilayo I. , Zamora Marta A. , Karczmar Gregory S. 
Published: June 2004

AbstractHigh spectral and spatial resolution (HiSS) MR data were acquired at 1.5 T using echo‐planar spectroscopic imaging from patients with suspicious breast lesions. The water resonances in small voxels are inhomogenously broadened and often have distinct components. Images were calculated with intensity proportional to the Fourier components of the water resonance in each voxel at different offsets from the peak frequency. The results demonstrate that in breast the off‐peak Fourier component images of water are qualitatively different from those derived from the peak height of the water resonance. These differences most likely reflect underlying anatomy or physiology. In conventional images, the superposition of the various Fourier components of the water signal may cause loss of detail. The synthesis of water Fourier component images from high spectral and spatial resolution data may provide a new form of contrast, and increase sensitivity to subvoxel physiology and anatomy. Magn Reson Med 52:193–196, 2004. © 2004 Wiley‐Liss, Inc.
500‐element ultrasound phased array system for noninvasive focal surgery of the brain: A preliminary rabbit study with ex vivo human skulls
Authors: Hynynen Kullervo , Clement Gregory T. , McDannold Nathan , Vykhodtseva Natalia , King Randy , White P. Jason , Vitek Shuki , Jolesz Ferenc A. 
Published: June 2004

AbstractThe aim of this study was to test a prototype MRI‐compatible focused ultrasound phased array system for trans‐skull brain tissue ablation. Rabbit thigh muscle and brain were sonicated with a prototype, hemispherical 500‐element ultrasound phased array operating at frequencies of 700–800 kHz. An ex vivo human skull sample was placed between the array and the animal tissue. The temperature elevation during 20–30‐sec sonications was monitored using MRI thermometry. The induced focal lesions were observed in T2 and contrast‐enhanced T1‐weighted fast spin echo images. Whole brain histology evaluation was performed after the sonications. The results showed that sharp temperature elevations can be produced both in the thigh muscle and in the brain. High‐power sonications (600–1080 W) produced peak temperatures up to 55°C and focal lesions that were consistent with thermal tissue damage. The lesion size was found to increase with increasing peak temperature. The device was then modified to operate in the orientation that will be used in the clinic and successfully tested in phantom experiments. As a conclusion, this study demonstrates that it is possible to create ultrasound‐induced lesions in vivo through a human skull under MRI guidance with this large‐scale phased array. Magn Reson Med 52:100–107, 2004. © 2004 Wiley‐Liss, Inc.
In vivo cellular imaging of magnetically labeled hybridomas in the spleen with a 1.5‐T clinical MRI system
Authors: Smirnov Pierre , Gazeau Florence , Lewin Maïté , Bacri Jean Claude , Siauve Nathalie , Vayssettes Catherine , Cuénod Charles André , Clément Olivier 
Published: June 2004

AbstractThe feasibility of in vivo cellular imaging using a 1.5 T clinical magnet was studied in the mouse. Hybridoma cells were labeled with anionic γ‐Fe2O3 superparamagnetic iron oxide nanoparticles. These were internalized by the endocytose pathway. Both electron spin resonance and magnetophoresis as a measure of the labeled cells migration velocity under a magnetic field were used to quantify particle uptake. A fast (<2 hr) and substantial (up to 5 pg of iron per cell) internalization of nanoparticles by hybridomas was found, with good agreement between the two methods used. Hybridomas labeled with 2.5 pg iron per cell were injected intraperitoneally to male Swiss nude mice. A decrease in the spleen signal, suggesting a “homing” of labeled hybridomas to this organ, was found 24 hr later by MRI performed at 1.5 T. Furthermore, in labeled cells recovered from the spleen by ex vivo magnetic sorting, a mean of 0.5 pg iron per cell was found, i.e., a value five times lower than that of the injected hybridomas. This finding is consistent with in vivo proliferation of these cells. In addition, the amount of labeled hybridomas present in the spleen was found to correlate with MRI signal intensity. Magn Reson Med 52:73–79, 2004. © 2004 Wiley‐Liss, Inc.
Whole‐brain 3D perfusion MRI at 3.0 T using CASL with a separate labeling coil
Authors: Talagala S. Lalith , Ye Frank Q. , Ledden Patrick J. , Chesnick Scott 
Published: June 2004

AbstractA variety of continuous and pulsed arterial spin labeling (ASL) perfusion MRI techniques have been demonstrated in recent years. One of the reasons these methods are still not routinely used is the limited extent of the imaging region. Of the ASL methods proposed to date, continuous ASL (CASL) with a separate labeling coil is particularly attractive for whole‐brain studies at high fields. This approach can provide an increased signal‐to‐noise ratio (SNR) in perfusion images because there are no magnetization transfer (MT) effects, and lessen concerns regarding RF power deposition at high field because it uses a local labeling coil. In this work, we demonstrate CASL whole‐brain quantitative perfusion imaging at 3.0 T using a combination of strategies: 3D volume acquisition, background tissue signal suppression, and a separate labeling coil. The results show that this approach can be used to acquire perfusion images in all brain regions with good sensitivity. Further, it is shown that the method can be performed safely on humans without exceeding the current RF power deposition limits. The current method can be extended to higher fields, and further improved by the use of multiple receiver coils and parallel imaging techniques to reduce scan time or provide increased resolution. Magn Reson Med 52:131–140, 2004. Published 2004 Wiley‐Liss, Inc.
Contrast‐enhanced dental MRI for visualization of the teeth and jaw
Authors: Olt Silvia , Jakob Peter M. 
Published: June 2004

AbstractA technique for contrast‐enhanced dental MRI is described that enables 3D visualization of the oral cavity, including the jaw and teeth. Since teeth are MR‐invisible, the basic principle of this technique is that the teeth and jaw can be observed indirectly through contrast with a surrounding MR‐visible medium. For this purpose, the oral cavity is filled with a nontoxic substance, such as water or MR contrast media, that gives a high MR signal. A 3D data set covering the entire buccal space is acquired, and the image intensities are inverted. Since isosurface reconstructions of the teeth and jaw, as well as panoramic views analogous to orthopantomography, can be extracted from these data, contrast‐enhanced dental MRI may be useful as a flexible tool for dentistry and orthodontics. Moreover, contrast‐enhanced dental MRI works without radiation exposure, and therefore it is an interesting alternative to X‐ray‐based imaging modalities such as conventional radiography and dental CT. In this article, some preliminary results obtained with contrast‐enhanced dental MRI are shown in order to demonstrate the feasibility and performance of this new approach. Magn Reson Med 52:174–176, 2004. © 2004 Wiley‐Liss, Inc.