bluuebunny/crossref_metadata_2025 huggingface dataset:
Is TrueFISP a gradient‐echo or a spin‐echo sequence?
Authors: Scheffler Klaus , Hennig Jürgen
Published: January 2003

It is commonly accepted that TrueFISP (balanced FFE, FIESTA) belongs to the class of gradient‐echo (GRE) sequences. GRE sequences are sensitive to dephasing effects of the transverse magnetization between the excitation pulse and echo acquisition, and phase coherence is only established directly after and before excitation pulses. However, an analysis of the phase evolution of transverse magnetization in a TrueFISP experiment shows very close similarities to the echo formation of a spin‐echo (SE) experiment. If dephasing between excitation pulses is below ±π, TrueFISP exhibits a nearly complete refocusing of transverse magnetization at TE = TR/2. Only signals acquired before and after TR/2 show an additional T sensitivity. Magn Reson Med 49:395–397, 2003. © 2003 Wiley‐Liss, Inc.
Theoretical and experimental evaluation of detached endcaps for 3 T birdcage coils
Authors: Alecci Marcello , Collins Christopher M. , Wilson James , Liu Wanzhan , Smith Michael B. , Jezzard Peter
Published: January 2003

The use of detached endcaps for 3 T birdcage coils was investigated both theoretically and experimentally. Finite difference time domain analysis, along with workbench and MRI techniques, were used to map the radiofrequency (RF) B1 distribution along the coil axis with and without an endcap. Without an endcap the measured B1 value at the service end of the birdcage was only 45% of the value at the coil's center. This was improved to 85% with a detached endcap of maximum achievable diameter (375 mm), positioned 4 mm from the RF shield. The B1 field distribution on the patient side of the coil was unaffected by the presence of the endcap. The dependence of the B1 distribution as a function of endcap diameter was also investigated. Surprisingly, simulations and experiments show that there is an optimum ratio of endcap‐to‐birdcage coil diameter (≈1.08) that gives the best B1 homogeneity. In the human head the optimized endcap, positioned 16 mm from the RF shield, improves the MRI signal amplitude from 55% to 85% of maximum toward the service end. This novel endcap design is easy to implement with existing birdcage coils, and could prove useful when flexibility in access to the RF coil is required. Magn Reson Med 49:363–370, 2003. © 2003 Wiley‐Liss, Inc.
Simulations of thermal tissue coagulation and their value for the planning and monitoring of laser‐induced interstitial thermotherapy (LITT)
Authors: Puccini Silvia , Bär Nils‐Karsten , Bublat Martin , Kahn Thomas , Busse Harald
Published: January 2003

MRI information is widely used for the monitoring of thermal therapies, such as laser‐induced interstitial thermotherapy (LITT). However, a detailed knowledge about the relationship between time/temperature exposure and resulting tissue thermal damage is needed to estimate the lesion extent. The aims of this work were to model the thermal response of laser‐irradiated tissue and to assess the value of Monte Carlo simulation (MCS) for tumor therapy planning and monitoring. MCS yielded true 3D distributions of laser‐induced temperature and thermal damage. These results were compared with 2D MR thermometry data from in vitro experiments performed on animal liver tissue over an ordinary range of laser powers (10–25 W) and irradiation times (5–25 min). Clinical reference data were available from MR‐guided liver LITT procedures. MCS correctly predicted the shape of temperature and damage distributions. The quantitative agreement between simulated and measured lesion diameters was within 10% and 15% for the in vitro and in vivo cases, respectively. The simulated 53°C isotherm best estimated the boundary of the final thermal damage (6% variance). This study shows that MCS of interstitial laser coagulation provides unique information that can be of use in the empirical correlation of temperature with thermal damage, and can assist greatly in thermal treatment planning and monitoring. Magn Reson Med 49:351–362, 2003. © 2003 Wiley‐Liss, Inc.
Characterization of aortic root atherosclerosis in ApoE knockout mice: High‐resolution in vivo and ex vivo MRM with histological correlation
Authors: Itskovich V.V. , Choudhury R.P. , Aguinaldo J.G.S. , Fallon J.T. , Omerhodzic S. , Fisher E.A. , Fayad Z.A.
Published: January 2003

In vivo, cardiac‐gated, black‐blood, and ex vivo magnetic resonance microscopy (MRM) images of the aortic root, and histopathology data were obtained from 12 transgenic and wild‐type (WT) mice. MRM was performed using a black‐blood imaging spin‐echo sequence with upstream and downstream in‐flow saturation pulses to obtain aortic root images in three contrast techniques: proton density‐weighted (PDW), T1‐ (T1W), and T2‐weighted (T2W). Aortic wall thickness and area were measured and correlated with histopathology data (R > 0.90). Ex vivo lesion components (lipid core, fibrous tissue, and cell tissue) were identified and characterized by differing image contrast in PDW, T1W, and T2W MRM, and by histopathology. The differences between WT and transgenic mice for maximal wall thickness and area were statistically significant (P < 0.05). This study demonstrates the feasibility of in vivo murine aortic root lesion assessment and ex vivo plaque characterization by MRM. Magn Reson Med 49:381–385, 2003. © 2003 Wiley‐Liss, Inc.
Myocardial tagging with SSFP
Authors: Herzka Daniel A. , Guttman Michael A. , McVeigh Elliot R.
Published: January 2003

This work presents the first implementation of myocardial tagging with refocused steady‐state free precession (SSFP) and magnetization preparation. The combination of myocardial tagging (a noninvasive method for quantitative measurement of regional and global cardiac function) with the high tissue signal‐to‐noise ratio (SNR) obtained with SSFP is shown to yield improvements in terms of the myocardium–tag contrast‐to‐noise ratio (CNR) and tag persistence when compared to the current standard fast gradient‐echo (FGRE) tagging protocol. Myocardium–tag CNR and tag persistence were studied using numerical simulations as well as phantom and human experiments. Both quantities were found to decrease with increasing imaging flip angle (α) due to an increased tag decay rate and a decrease in myocardial steady‐state signal. However, higher α yielded better blood–myocardium contrast, indicating that optimal α is dependent on the application: higher α for better blood–myocardium boundary visualization, and lower α for better tag persistence. SSFP tagging provided the same myocardium–tag CNR as FGRE tagging when acquired at four times the bandwidth and better tag– and blood–myocardium CNRs than FGRE tagging when acquired at equal or twice the receiver bandwidth (RBW). The increased acquisition efficiency of SSFP allowed decreases in breath‐hold duration, or increases in temporal resolution, as compared to FGRE. Magn Reson Med 49:329–340, 2003. Published 2003 Wiley‐Liss, Inc.
Directional correlation characterization and classification of white matter tracts
Authors: Sun Shu‐Wei , Song Sheng‐Kwei , Hong Chung‐Yi , Chu Woei C. , Chang Chen
Published: January 2003

To study the architectural characteristics of white matter (WM) tracts, the directional correlation (DC), defined as the inner product of the major eigenvector of adjacent pixels, was used as a quantitative index to investigate directional similarity in WM tracts. A region‐growing algorithm was employed to propagate an area from a seed point as a function of the DC threshold (DCt) to critically evaluate the directional properties of WM tracts. As the DCt was increased, more pixels were excluded from the propagated region as their DC fell below the DCt, and neighboring WM tracts could be distinguished as the area decreased. Taking the DC into account, a systematic classification routine for WM tracts was devised and tested on a mouse brain in vivo. The results show that individual WM tracts possess a high degree of directional similarity, and, by careful choice of the DCt value, the proposed classification algorithm can recognize all possible WM tracts in a given data set. Magn Reson Med 49:271–275, 2003. © 2003 Wiley‐Liss, Inc.
Velocity‐driven adiabatic fast passage for arterial spin labeling: Results from a computer model
Authors: Utting Jane F. , Thomas David L. , Gadian David G. , Ordidge Roger J.
Published: January 2003

Velocity‐driven adiabatic fast passage (AFP) is commonly employed for perfusion imaging by continuous arterial spin labeling (CASL). The degree of inversion of protons in blood determines the sensitivity of CASL to perfusion. For this study, a computer model of the modified Bloch equations was developed to establish the optimum conditions for velocity‐driven AFP. Natural variations in blood velocity over the course of the cardiac cycle were found to result in significant variations in the degree of inversion. However, the mean degree of inversion was similar to that for blood moving at a constant velocity, equal to the time‐averaged mean, at peak velocities and heart rates within normal ranges. A train of RF pulses instead of a continuous RF pulse for labeling was found to result in a highly nonlinear dependence of the degree of inversion on RF duty cycle. This may have serious implications for the quantification of perfusion. Magn Reson Med 49:398–401, 2003. © 2003 Wiley‐Liss, Inc.
Characterization of effects of mean arterial blood pressure induced by cocaine and cocaine methiodide on BOLD signals in rat brain
Authors: Luo Feng , Wu Gaohong , Li Zhu , Li Shi‐Jiang
Published: January 2003

A total of 45 male Sprague‐Dawley rats were employed to determine whether cocaine or cocaine methiodide (CM) administration can induce a significant increase in mean arterial blood pressure (MABP) in rats, and whether such an increase in MABP can produce a global increase in blood oxygenation level‐dependent (BOLD) contrast in the rat brain detectable by functional magnetic resonance imaging (fMRI). Cocaine methiodide is a quaternary derivative of cocaine that shares the same cardiovascular effects of cocaine, but does not penetrate the blood‐brain barrier (BBB). Experimental results demonstrated that both CM (with doses of 2.5 and 7.5 mg/kg) and cocaine (with doses of 1.25 and 5.0 mg/kg) can induce a significant MABP change (30–80%). It was found that CM can only produce scattered, weak, and transient BOLD signals in a few voxels of the rat brain, and that these MABP‐induced BOLD signals are not dose‐dependent. In contrast, the administration of cocaine induced dose‐dependent biphasic BOLD signals that were consistent with pharmacologically‐induced cerebral vascular constriction and neuronal activity in the mesolimbic systems of the rat brain. The potential confounding factor of the MABP changes had little effect on the interpretation of drug‐induced BOLD signal changes. These results confirm that the BOLD‐weighted fMRI method can be extended to map drug‐induced neuronal activity. Magn Reson Med 49:264–270, 2003. © 2003 Wiley‐Liss, Inc.
Metabolic profiles of human brain tumors using quantitative in vivo 1H magnetic resonance spectroscopy
Authors: Howe F.A. , Barton S.J. , Cudlip S.A. , Stubbs M. , Saunders D.E. , Murphy M. , Wilkins P. , Opstad K.S. , Doyle V.L. , McLean M.A. , Bell B.A. , Griffiths J.R.
Published: January 2003

Proton spectroscopy can noninvasively provide useful information on brain tumor type and grade. Short‐ (30 ms) and long‐ (136 ms) echo time (TE) 1H spectra were acquired from normal white matter (NWM), meningiomas, grade II astrocytomas, anaplastic astrocytomas, glioblastomas, and metastases. Very low myo‐Inositol ([mI]) and creatine ([Cr]) were characteristic of meningiomas, and high [mI] characteristic of grade II astrocytomas. Tumor choline ([Cho]) was greater than NWM and increased with grade for grade II and anaplastic astrocytomas, but was highly variable for glioblastomas. Higher [Cho] and [Cr] correlated with low lipid and lactate (P < 0.05), indicating a dilution of metabolite concentrations due to necrosis in high‐grade tumors. Metabolite peak area ratios showed no correlation with lipids and mI/Cho (at TE = 30 ms), and Cr/Cho (at TE = 136 ms) best correlated with tumor grade. The quantified lipid, macromolecule, and lactate levels increased with grade of tumor, consistent with progression from hypoxia to necrosis. Quantification of lipids and macromolecules at short TE provided a good marker for tumor grade, and a scatter plot of the sum of alanine, lactate, and δ1.3 lipid signals vs. mI/Cho provided a simple way to separate most tumors by type and grade. Magn Reson Med 49:223–232, 2003. © 2003 Wiley‐Liss, Inc.
Quantitative HRMAS proton total correlation spectroscopy applied to cultured melanoma cells treated by chloroethyl nitrosourea: Demonstration of phospholipid metabolism alterations
Authors: Morvan Daniel , Demidem Aicha , Papon Janine , Madelmont Jean Claude
Published: January 2003

Recent NMR spectroscopy developments, such as high‐resolution magic angle spinning (HRMAS) probes and correlation‐enhanced 2D sequences, now allow improved investigations of phospholipid (Plp) metabolism. Using these modalities we previously demonstrated that a mouse‐bearing melanoma tumor responded to chloroethyl nitrosourea (CENU) treatment in vivo by altering its Plp metabolism. The aims of the present study were to investigate whether HRMAS proton total correlation spectroscopy (TOCSY) could be used as a quantitative technique to probe Plp metabolism, and to determine the Plp metabolism response of cultured B16 melanoma cells to CENU treatment in vitro. The exploited TOCSY signals of Plp derivatives arose from scalar coupling among the protons of neighbor methylene groups within base headgroups (choline and ethanolamine). For strongly expressed Plp derivatives, TOCSY signals were compared to saturation recovery signals and demonstrated a linear relationship. HRMAS proton TOCSY was thus used to provide concentrations of Plp derivatives during long‐term follow‐up of CENU‐treated cell cultures. Strong Plp metabolism alteration was observed in treated cultured cells in vitro involving a down‐regulation of phosphocholine, and a dramatic and irreversible increase of phosphoethanolamine. These findings are discussed in relation to previous in vivo data, and to Plp metabolism enzymatic involvement. Magn Reson Med 49:241–248, 2003. © 2003 Wiley‐Liss, Inc.
Rapid measurement of time‐averaged blood flow using ungated spiral phase‐contrast
Authors: Park Jong B. , Olcott Eric W. , Nishimura Dwight G.
Published: January 2003

A novel ungated spiral phase‐contrast (USPC) imaging method was developed for rapid measurement of time‐averaged blood‐flow rates in the presence of pulsatility. The spatial point‐spread function was analyzed to provide an intuitive understanding of how spiral trajectories, which sample the k‐space origin at every excitation, can mitigate the effects of pulsatility. Pulsatile flow phantom experiments were performed to validate the accuracy and repeatability of the USPC method. The measurement of flow in the renal and femoral arteries of normal volunteers were also performed. The phantom results (error ≤ +9%, SDphantom ≤ 2%, time‐averaged pulsatile‐flow rates = 3–15 ml/s) and in vivo results (SDrenal ≤ 8%, SDfemoral ≤ 14%) demonstrate the potential of the USPC method for rapidly and repeatedly measuring accurate time‐averaged blood flow even in relatively small arteries and in the presence of strong pulsatility. Magn Reson Med 49:322–328, 2003. © 2003 Wiley‐Liss, Inc.
Pulsed arterial spin labeling using TurboFLASH with suppression of intravascular signal
Authors: Pell Gaby S. , Lewis David P. , Branch Craig A.
Published: January 2003

Accurate quantification of perfusion with the ADC techniques requires the suppression of the majority of the intravascular signal. This is normally achieved with the use of diffusion gradients. The TurboFLASH sequence with its ultrashort repetition times is not readily amenable to this scheme. This report demonstrates the implementation of a modified TurboFLASH sequence for FAIR imaging. Intravascular suppression is achieved with a modified preparation period that includes a driven equilibrium Fourier transform (DEFT) combination of 90°–180°–90° hard RF pulses subsequent to the inversion delay. These pulses rotate the perfusion‐prepared magnetization into the transverse plane where it can experience the suitably placed diffusion gradients before being returned to the longitudinal direction by the second 90° pulse. A value of b = 20–30 s/mm2 was thereby found to suppress the majority of the intravascular signal. For single‐slice perfusion imaging, quantification is only slightly modified. The technique can be readily extended to multislice acquisition if the evolving flow signal after the DEFT preparation is considered. An advantage of the modified preparation scheme is evident in the multislice FAIR images by the preservation of the sign of the magnetization difference. Magn Reson Med 49:341–350, 2003. © 2003 Wiley‐Liss, Inc.
High‐resolution 3D proton spectroscopic imaging of the human brain at 3 T: SNR issues and application for anatomy‐matched voxel sizes
Authors: Gruber Stephan , Mlynárik Vladimir , Moser Ewald
Published: January 2003

In a systematic study on the interdependence of linewidth, signal‐to‐noise ratio (SNR), and spatial resolution in 3D proton spectroscopic imaging (1H‐SI) at 3 T, we demonstrate reduced linewidths with increased spatial resolution due to reduced magnetic inhomogeneity within the brain. High‐precision quantitative data (0.75–0.094 cm3) were obtained for all resolutions, enabling the creation of metabolic maps that display details such as the ventricles, sulci, and gyri. High‐resolution 1H‐SI allows differences in metabolic ratios to be estimated for anatomically defined regions in gray (GM) and white matter (WM). Seven distinct regions in a healthy brain were anatomically segmented and their metabolic ratios were compared quantitatively. Data from a tumor patient are also presented to demonstrate potential clinical applications. Because of the high resolution, the metabolite ratios could be determined for distinct pathologic regions within the tumor and its surroundings. The method was additionally applied to a patient with patchy Pelizaeus Merzbacher disease (PMD), and compared to single‐voxel spectroscopy performed in the same session. High‐resolution SI data were demonstrated in our study to allow the direct matching of anatomic and metabolic images. This may enhance the clinical value of 1H‐SI. Magn Reson Med 49:299–306, 2003. © 2003 Wiley‐Liss, Inc.
In vivo 31P magnetic resonance spectroscopy of human brain at 7 T: An initial experience
Authors: Lei Hao , Zhu Xiao‐Hong , Zhang Xiao‐Liang , Ugurbil Kamil , Chen Wei
Published: January 2003

In vivo 31P spectra were acquired from the human primary visual cortex at 7 T. The relaxation times of the cerebral metabolites, intracellular pH, rate constant (kf) of the creatine kinase (CK) reaction, and nuclear Overhauser enhancement (NOE) on the detected phosphorus moieties from irradiation of the water spins were measured from normal subjects. With a 5‐cm‐diameter surface coil, 3D 31P chemical shift imaging was performed with a spatial resolution of 7.5 ml and an acquisition resolution of 8 min, resulting in a signal‐to‐noise ratio (SNR) for phosphocreatine (PCr) resonance of 32. The apparent T1 and T2 of PCr measured at 7 T were 3.37 ± 0.29 s and 132.0 ± 12.8 ms, respectively, which were considerably longer than those of adenosine triphosphate (ATP) (T1: 1.02–1.27 s; T2: 25–26 ms). The NOE measured in this study was 24.3% ± 1.6% for PCr, and 10% for ATP. The kf measured in the human primary visual cortex was 0.24 ± 0.03 s−1. The results from this study suggest that ultra‐high‐field strength is advantageous for performing in vivo 31P magnetic resonance spectroscopy (MRS) in the human brain. Magn Reson Med 49:199–205, 2003. © 2003 Wiley‐Liss, Inc.
Quantification of renal perfusion using an intravascular contrast agent (part 1): Results in a canine model
Authors: Aumann Silke , Schoenberg Stefan O. , Just Armin , Briley‐Saebo Karen , Bjørnerud Atle , Bock Michael , Brix Gunnar
Published: January 2003

In this work absolute values of regional renal blood volume (rRBV) and flow (rRBF) are assessed by means of contrast‐enhanced (CE) MRI using an intravascular superparamagnetic contrast agent. In an animal study, eight foxhounds underwent dynamic susceptibility‐weighted MRI upon injection of contrast agent. Using principles of indicator dilution theory and deconvolution analysis, parametric images of rRBV, rRBF, and mean transit time (MTT) were computed. For comparison, whole‐organ blood flow was determined invasively by means of an implanted flow probe, and the weight of the kidneys was evaluated postmortem. A mean rBV value of 28 ml/100 g was found in the renal cortex, with a corresponding mean rBF value of 524 ml/100 g/min and an average MTT of about 3.4 s. Although there was a systematic difference between the absolute blood flow values determined by MRI and the ultrasonic probe, a significant correlation (rs = 0.72, P < 0.05) was established. The influence of the arterial input function (AIF), T1 relaxation effects, and repeated measurements on the precision of the perfusion quantitation is discussed. Magn Reson Med 49:276‐287, 2003. © 2003 Wiley‐Liss, Inc.
Quantification of renal perfusion abnormalities using an intravascular contrast agent (part 2): Results in animals and humans with renal artery stenosis
Authors: Schoenberg Stefan O. , Aumann Silke , Just Armin , Bock Michael , Knopp Michael V. , Johansson Lars O. , Ahlstrom Hakan
Published: January 2003

The interrelation between the morphologic degree of renal artery stenosis and changes in parenchymal perfusion is assessed using an intravascular contrast agent. In seven adult foxhounds, different degrees of renal artery stenosis were created with an inflatable clamp implanted around the renal artery. Dynamic susceptibility‐weighted gradient‐echo imaging was used to measure signal‐time curves in the renal artery and the renal parenchyma during administration of 1.5 mg/kg BW of an intravascular ultrasmall particle iron oxide (USPIO) contrast agent. From the dynamic series, regional renal blood volume (rRBV), regional renal blood flow (rRBF), and mean transit time (MTT) were calculated. The morphologic degree of stenosis was measured in the steady state using a high‐resolution 3D contrast‐enhanced (CE) MR angiography (MRA) sequence (voxel size = 0.7 × 0.7 × 1 mm3). Five patients with renoparenchymal damage due to long‐standing renal artery stenosis were evaluated. In the animal stenosis model, cortical perfusion remained unchanged for degrees of renal artery stenosis up to 80%. With degrees of stenoses > 80%, cortical perfusion dropped to 151 ± 54 ml/100 g of tissue per minute as compared to a baseline of 513 ± 76 ml/100 g/min. In the patients, a substantial difference in the cortical perfusion of more than 200 ± 40 ml/100 g/min between the normal and the ischemic kidneys was found. The results show that quantitative renal perfusion measurements in combination with 3D‐CE‐MRA allow the functional significance of a renal artery stenosis to be determined in a single MR exam. Differentiation between renovascular and renoparenchymal disease thus becomes feasible. Magn Reson Med 49:288–298, 2003. © 2003 Wiley‐Liss, Inc.
The carnosine C‐2 proton's chemical shift reports intracellular pH in oxidative and glycolytic muscle fibers
Authors: Damon Bruce M. , Hsu Alex C. , Stark Heather J. , Dawson M. Joan
Published: January 2003

The appearance of new peaks in the 7.7–8.6 and 6.8–7.4 ppm regions of the postexercise 1H spectrum of frog muscle is reported. These new peaks result from the splitting of single pre‐exercise carnosine C‐2 and C‐4 peaks into two peaks, representing the intracellular pH (pHI) of oxidative and glycolytic fibers. The following data support this conclusion: 1) comparison of means and regression analysis indicates equivalence of the pHI measurements by 1H and 31P NMR; 2) the pre‐ and poststimulation concentrations of carnosine are equal; 3) in ischemic rat hindlimb muscles, the presence of a single, more acidic peak in the plantaris; a single, less acidic peak in the soleus; and two peaks (more and less acidic) in the gastrocnemius correspond to published values for the fiber‐type composition of these muscles; and 4) in muscles treated with iodoacetate prior to and during stimulation, a second peak never appears. These data indicate that it is feasible to measure separately the pHI of oxidative and glycolytic fibers using 1H NMR spectroscopy. Magn Reson Med 49:233–240, 2003. © 2003 Wiley‐Liss, Inc.
Oscillating gradient measurements of water diffusion in normal and globally ischemic rat brain
Authors: Does Mark D. , Parsons Edward C. , Gore John C.
Published: January 2003

Oscillating gradients were used to probe the diffusion‐time/frequency dependence of water diffusion in the gray matter of normal and globally ischemic rat brain. In terms of a conventional definition of diffusion time, the oscillating gradient measurements provided the apparent diffusion coefficient (ADC) of water with diffusion times between 9.75 ms and 375 μs, an order of magnitude shorter than previously studied in vivo. Over this range, ADCs increased as much as 24% in vivo and 50% postmortem, depending on the nature of the oscillating gradient waveform used. Novel waveforms were employed to sample narrow frequency bands of the so‐called diffusion spectrum. This spectral description of ADC includes the effects of restriction and/or flow, and is independent of experimental parameters, such as diffusion time. The results in rat brain were found to be consistent with restricted diffusion and the known micro‐anatomy of gray matter. Differences between normal and postmortem data were consistent with an increase in water restriction and/or a decrease in flow, and tentatively suggest that physical changes following the onset of ischemia occur on a scale of about 2 μm, similar to a typical cellular dimension in gray matter. Magn Reson Med 49:206–215, 2003. © 2003 Wiley‐Liss, Inc.
Undersampled projection reconstruction for active catheter imaging with adaptable temporal resolution and catheter‐only views
Authors: Peters Dana C. , Lederman Robert J. , Dick Alexander J. , Raman Venkatesh K. , Guttman Michael A. , Derbyshire J. Andrew , McVeigh Elliot R.
Published: January 2003

In this study undersampled projection reconstruction (PR) was used for rapid catheter imaging in the heart, employing steady‐state free precession (SSFP) contrast. Active catheters and phased‐array coils were used for combined imaging of anatomy and catheter position in swine. Real‐time imaging of catheter position was performed with relatively high spatial and temporal resolution, providing 2 × 2 × 8 mm spatial resolution and four to eight frames per second. Two interactive features were introduced. The number of projections (Np) was adjusted interactively to trade off imaging speed and artifact reduction, allowing acquisition of high‐quality or high‐frame‐rate images. Thin‐slice imaging was performed, with interactive requests for thick‐slab projection images of the signal received solely from the active catheter. Briefly toggling on catheter‐only projection images was valuable for verifying that the catheter tip was contained within the selected slice, or for locating the catheter when part of it was outside the selected slice. Magn Reson Med 49:216–222, 2003. Published 2003 Wiley‐Liss, Inc.
MRI‐guided coronary catheterization and PTCA: A feasibility study on a dog model
Authors: Serfaty Jean‐Michel , Yang Xiaoming , Foo Thomas K. , Kumar Ananda , Derbyshire Andrew , Atalar Ergin
Published: January 2003

The aim of this work was to demonstrate the feasibility of MRI‐guided coronary artery catheterization and intervention in a dog model. Experiments were performed on 10 healthy dogs. A 9F introducer sheath was placed through a right carotid artery cutdown. A prototype 0.014‐inch coronary MRI guidewire, a prototype 7 French MRI‐guiding catheter, and two flexible surface coils were connected to a GE 1.5 T CV/i scanner for simultaneous visualization of the guidewire, guiding catheter, and chest anatomy. Images were displayed in real time on an in‐room monitor. A nongated, single‐slice fast gradient‐echo sequence was used to obtain real‐time images of the catheters and background anatomy during the intervention. Fifteen selective catheterizations were attempted in the coronary arteries, and all were successful. Selective injection of diluted gadolinium into the MRI‐guiding catheter provided dynamic 2D projection coronary angiography in all cases, confirming successful catheterization. Percutaneous transluminal coronary angioplasty (PTCA) was attempted after two catheterizations, and all attempts were successful. Inflation of the balloon angioplasty catheter was performed successfully in the left anterior and circumflex arteries. Our results indicate that coronary artery catheterization and intracoronary balloon angioplasty are feasible with MRI guidance only. MRI guidance may be used as an alternative to X‐ray guidance in coronary artery interventions in the future. Magn Reson Med 49:258–263, 2003. © 2003 Wiley‐Liss, Inc.
Effects of FK506 on myasthenia gravis patients with high interleukin‐2 productivity in peripheral blood mononuclear cells
Authors: Utsugisawa Kimiaki , Nagane Yuriko , Yonezawa Hisashi , Obara Daiji , Kondoh Ryushi , Tohgi Hideo
Published: January 2003

We compared the early effects of FK506 on clinical severity, interleukin‐2 (IL‐2) production by phytohemagglutinin‐stimulated peripheral blood mononuclear cells (PBMs), and serum levels of acetylcholine receptor antibodies between myasthenia gravis (MG) patients with elevated (>1250 pg/ml, n = 9) or normal (<1250 pg/mL, n = 10) levels of PBM IL‐2 production. Reduction in clinical severity and PBM IL‐2 production were significantly greater in the patients with elevated IL‐2 production than those with normal PBM IL‐2 production in the first month of treatment. Muscle Nerve 27: 245–248, 2003
Preservation stability and in vivo administration of albumin–heme hybrid solution as an entirely synthetic O2‐carrier
Authors: Tsuchida Eishun , Komatsu Teruyuki , Yanagimoto Tetsuya , Sakai Hiromi
Published: January 2003

The recombinant human serum albumin incorporating a tetraphenylporphyrinatoiron(II) derivative with a covalently linked proximal base (rHSA‐FeP) is an entirely synthetic O2‐carrier as a red blood cell substitute. It shows long‐term preservation stability of both solution properties and O2‐binding ability over a broad temperature range including room temperature. The physicochemical parameters of the rHSA‐Fe(II)P solution ([rHSA]: 5 wt%) stored at 5–40 °C have remained constant over one year. The in vivo safety of this material was also studied by the survival tests and clinical blood chemistry assays. All rats given the 5 wt% rHSA‐Fe(II)P solution have been alive for 14 days after the infusion. During the observation period, no remarkable reaction was seen in the appearance of the animals. Parameters of the clinical blood serum chemistry were all in the normal ranges, and pathological inspections of the major organs showed no significant infarct in their tissues. Copyright © 2003 John Wiley & Sons, Ltd.
A Synopsis of recent attempts toward construction of rechargeable batteries utilizing conducting polymer cathodes and anodes
Authors: Levi M. D. , Gofer Y. , Aurbach D.
Published: January 2003

This paper reports on our recent attempts in the characterization of n‐doping of polythiophene (PTh) and p‐doping of polypyrrole (PPy) for their use as the anode and cathode, respectively, for rechargeable batteries. N‐doping of PTh with large (TEA) cations was studied by combined application of cyclic voltammetry, in situ conductometry and ex situ atomic force microcopy (AFM). The average potential for n‐doping of PTh was close to 1.2 V (versus Li/Li+). Substantial trapping of negatively charged polarons was observed during consecutive n‐doping. Addition of Li‐salt to the background electrolyte, even in a small concentration, resulted in the almost complete deactivation of the film with respect to n‐doping. We suggest that the above drawback can be overcome by using the more robust fluorosubstituted polyphenyl(thiophene), P3FPhTh. On the other hand, when addressing polymer cathodes, specially prepared PPy films showed highly reversible behavior and a large capacity of up to one electron per ring (or 420 mAh per gram of neutral polymer) when cycled up to 4.6–4.7 V (versus Li/Li+). Only above 5 V (versus Li/Li+) did an irreversible over‐oxidation of PPy occur. Electrochemical characteristics of p‐doped PPy cathode are compared with that of lithiated V2O5 film. Two possible alternative ways for changing the dopants in p‐doped PPy, from anions to cations, are discussed. Copyright © 2003 John Wiley & Sons, Ltd.
Flame‐retarded polyolefin systems of controlled interphase
Authors: Marosi Gy. , Anna P. , Márton A. , Bertalan Gy. , Bóta A. , Tóth A. , Mohai M. , Rácz I.
Published: January 2003

The principle of multilayer interphases was proposed earlier for modifying the mechanical properties and UV stability of various multicomponent polymer systems. This paper focuses on the applicability of this principle for improving the performance of intumescent flame‐retardant systems using melamine‐treated ammonium polyphosphate, silicone modified polyol + ammonium polyphosphate, and silicone modified nanoparticles in polypropylene. The structure–property relationship of the formed systems was studied. A melamine layer of 1.45 nm thickness was formed around ammonium polyphosphate in order to improve the hygrothermal stability, but this layer was not shear‐resistant enough. An interphase formed using a special silicone additive is more stable and acts with the intumescent flame‐retardant system synergistically. The advantageous interfacial structure is quite complex in this case: polyphosphate particles are surrounded with a macromolecular layer formed from polyol, silicone, and reactive surfactant in order to ensure good stability, efficiency and compatibility. AFM, XPS and a Cone Calorimeter were used for determining the structure and flame‐retardancy of these systems. Nanocomposites combined with silicone‐containing intumescent system were developed in order to avoid dipping at ignition in the vertical position. SAXS and µ‐TA methods were used for determining the structure of this material. Copyright ­© 2003 John Wiley & Sons, Ltd.
Functionalization of gold electrode surface with heterobifunctional poly(ethylene oxide)s having both mercapto and aldehyde groups
Authors: Kurusu Fumiyo , Ohno Hiroyuki , Kaneko Mitsuhiro , Nagasaki Yukio , Kataoka Kazunori
Published: January 2003

We synthesized heterobifunctional poly(ethylene oxide) (PEO) (α‐formyl‐ω‐mercapto‐PEO; CHO‐PEO400‐SH, average molecular weight of PEO part being 400), which had both an aldehyde group as a binding site with amino group of protein and a mercapto group for gold electrode surface. The CHO‐PEO400‐SH was adsorbed on a gold electrode surface and cytochrome c (cyt.c) was fixed on this modified electrode. The redox response of covalently immobilized cyt.c was observed on the cyclic voltammetry measurement, showing that CHO‐PEO400‐SH can be used as a linker to fix cyt.c on an electrode. Another type of heterobifunctional PEO (α‐formyl‐ω‐(2‐pyridyldithio)‐PEO; CHO‐PEO300‐SS‐Py), which had an aldehyde group and a 2‐pyridinethiol (2‐Py) through disulfide bond, was synthesized to form co‐adsorbed monolayer of PEO chain and 2‐Py on an electrode surface. It was expected, due to the spacer with shorter PEO chain and lower surface density, that better redox response of the fixed cyt.c was obtained. However, the redox response of fixed cyt.c was not detected on the CHO‐PEO300‐SS‐Py modified gold electrode. Instead, this heterobifunctional PEO was found to function as a good promoter for cyt.c dissolved in phosphate buffer solution. Copyright © 2003 John Wiley & Sons, Ltd.
Determination of saponins and alkaloids in Caulophyllum thalictroides (blue cohosh) by high‐performance liquid chromatography and evaporative light scattering detection
Authors: Ganzera M. , Dharmaratne H. R. W. , Nanayakkara N. P. D. , Khan I. A.
Published: January 2003

The roots of Caulophyllum thalictroides, traditionally used for the treatment of menstrual difficulties and as an aid in childbirth, contain saponins, which are considered to be responsible for the uterine stimulant effects, together with teratogenic alkaloids. An HPLC method has been developed which permits the determination of the triterpene saponins in the plant and also the separation of four alkaloids. The best results were obtained with a C‐12 stationary phase using ammonium acetate buffer (pH 8.0) and acetonitrile as mobile phase. Owing to their low UV absorbance, the saponins were detected by evaporative light scattering, whereas the alkaloids were monitored by UV at 310 nm. The identities of the compounds were confirmed in an LC‐MS experiment. Different plant samples and commercial products have been analysed using the described method, and remarkable qualitative and quantitative variations were revealed. Comparing the daily uptake of total saponins, a difference of greater than 100‐fold was observed within the various products; the alkaloid content on the other hand was more uniform. Copyright © 2003 John Wiley & Sons, Ltd.
Fungitoxic phenols from carnation (Dianthus caryophyllus) effective against Fusarium oxysporum f. sp. dianthi
Authors: Curir Paolo , Dolci Marcello , Dolci Paola , Lanzotti Virginia , Cooman Luc De
Published: January 2003

The phenol compositions of two cultivars of carnation (Dianthus caryophyllus) namely “Gloriana” and “Roland”, which are partially and highly resistant, respectively, to Fusarium oxysporum f. sp. dianthi have been investigated with the aim of determining if endogenous phenols could have an anti‐fungal effect against the pathogen. Analyses were performed on healthy and F. oxysporum‐inoculated in vitro tissues, and on in vivo plants. Two benzoic acid derivatives, protocatechuic acid (3,4‐dihydroxybenzoic acid) and vanillic acid (4‐hydroxy‐3‐methoxybenzoic acid), were found within healthy and inoculated tissues of both cultivars, together with the flavonol glycoside peltatoside (3‐[6‐O‐(α‐L‐arabinopyranosyl)‐β‐D‐glucopyranosyl] quercetin). These molecules proved to be only slightly inhibitory towards the pathogen. 2,6‐Dimethoxybenzoic acid was detected in small amounts only in the inoculated cultivar “Gloriana”, while the highly resistant cultivar “Roland” showed the presence of the flavone datiscetin (3,5,7,2′‐tetrahydroxyflavone). The latter compound exhibited an appreciable fungitoxic activity towards F. oxysporum f. sp. dianthi. Copyright © 2003 John Wiley & Sons, Ltd.
HPLC isolation of the anti‐plasmodially active bisbenzylisoquinone alkaloids present in roots of Cissampelos mucronata
Authors: Tshibangu Jeannette Ndaya , Wright Anthony D. , König Gabriele M.
Published: January 2003

The methanolic extract of dried, powdered Cissampelos mucronata roots possesses significant in vitro activity against Plasmodium falciparum. In order to enable further pharmacological testing, the substances responsible for the observed activity were purified, mainly by HPLC, using various stationary and mobile phases. The active principles were determined to be a series of bisbenzylisoquinoline alkaloids, a group of natural products for which one of the first routine preparative HPLC separation methods is described. Copyright © 2003 John Wiley & Sons, Ltd.
Analysis of volatile fractions of Schisandra chinensis (Turcz.) Baill. using GC‐MS and chemometric resolution
Authors: Li Xiao‐Ning , Cui Hui , Song You‐Qun , Liang Yi‐Zeng , Chau Foo‐Tim
Published: January 2003

The two‐dimensional data obtained from GC‐MS has been used qualitatively and quantitatively to determine the components of the volatile fractions of Schisandra chinensis obtained by six different extraction methods. Sub‐window factor analysis (SFA) was employed to confirm the identities of components determined in different samples. With the help of SFA, and other chemometric techniques, peak purity in the chromatograms was determined, and overlapping peaks were resolved to yield a pure chromatographic profile and mass spectrum for each component. It is demonstrated that the accuracy of qualitative and quantitative analysis may be greatly enhanced using chemometric resolution methods, such methods being particularly valuable with respect to the analysis of complex samples such as traditional Chinese medicines. It is further demonstrated that different extraction methods give rise to volatile fractions of S. chinensis which differ qualitatively and quantitatively in their composition. Copyright © 2003 John Wiley & Sons, Ltd.
Determination of the absolute configuration of 6‐alkylated α‐pyrones from Ravensara crassifolia by LC‐NMR
Authors: Queiroz E. F. , Wolfender J.‐L. , Raoelison G. , Hostettmann K.
Published: January 2003

The absolute configuration of asymmetric centres of two α‐pyrones isolated from Ravensara crassifolia was determined using the Mosher method. The conventional analysis of the purified ester derivatives by 1H‐NMR was replaced by a rapid and sensitive method in which the α‐pyrones were analysed under isocratic reversed‐phase LC‐NMR conditions prior to and after derivatisation reactions. Comparison of the LC‐1H‐NMR spectra of the actual α‐pyrones with those of the corresponding Mosher's esters recorded in the acetonitrile:deuterated water solvent system exhibited shifts comparable with those obtained using conventional deuterated solvents. Based on the shifts recorded, determination of the absolute configuration was possible by application of Mosher rules. The use of LC‐NMR has permitted a direct analysis of crude reaction mixtures containing less than 50 µg of the starting material. Completion of the reaction was checked by LC‐MS and the crude reaction mixture was analysed by stop‐flow LC‐NMR. This methodology seems very promising for the determination at the micro‐scale level of the absolute configuration of natural products which are available only in very small amounts. Copyright © 2003 John Wiley & Sons, Ltd.
Identification and characterisation of the Chinese herb Langdu by LC‐MS/MS analysis
Authors: Su Xiao‐Li , Lin Rui‐Chao , Wong Siu‐Kay , Tsui Shu‐Ki , Kwan Sik‐Yiu
Published: January 2003

An LC‐MS/MS method has been developed for the identification of three species of herb used as the traditional Chinese medicine Langdu, namely Stellera chamaejasme L., Euphorbia ebracteolata Hayata and E. fischeriana Steud. As these herbs contain different mixtures of marker compounds, they could be unambiguously differentiated from each other by comparing their respective characteristic segmental multiple reaction monitoring profiles. The profiles indicated that S. chamaejasme contained daphnetin, skimmetine, stellerin, chamaechromone and neochamaejasmin, E. fischeriana contained ebracteolata compound B, ingenol, jolkinolide B and fischeriana A, whilst E. ebracteolata contained ebracteolata compounds B and C along with ingenol. These results were confirmed from the respective MS/MS spectra. The method has been successfully applied to differentiate these herbs from the related species Alocasia macrorrhiza (L.) Schott and E. kansui Liou. Copyright © 2003 John Wiley & Sons, Ltd.
Guaiacylglycerol‐7′‐O‐methyl 8′‐vanillic acid ether and related compounds from Boreava orientalis
Authors: Sakushima Akiyo , Ohno Kosei , Maoka Takashi , Coskun Maksut , Guvenc Aysegul , Erdurak Ceyda Sibel , Ozkan Ayse Mine , Seki Koh‐ichi , Ohkura Kazue
Published: January 2003

The threo and erythro forms of guaiacylglycerol‐7′‐O‐methyl 8′‐vanillic acid ethers, threo and erythro guaiacylglycerol 8′‐vanillin ethers, and threo guaiacylglycerol 8′‐(4‐hydroxymethyl‐2‐methoxyphenyl) ether have been isolated from fruits of Boreava orientalis. Structural determinations were made on the basis of UV, MS, 1H‐ and 13C‐NMR spectral data, including two‐dimensional shift correlation. The relative configurations were assigned on the basis of 1H‐NMR chemical shifts. Copyright © 2003 John Wiley & Sons, Ltd.
HPLC‐NMR/HPLC‐MS analysis of the bark extract of Stauranthus perforatus
Authors: Setzer William N. , Vogler Bernhard , Bates Robert B. , Schmidt Jennifer M. , Dicus Christopher W. , Nakkiew Pichaya , Haber William A.
Published: January 2003

A combination of HPLC‐MS and HPLC‐NMR techniques has been used to analyse the cytotoxic fractions of the dichloromethane extract of bark of Stauranthus perforatus. Six furanocoumarins (byakangelicol, heraclenin, heraclenol, imperatorin, isopimpinellin and xanthotoxin) and nine quinoline alkaloids (two known compounds, veprisine and 5‐hydroxy‐1‐methyl‐2‐phenyl‐4‐quinolone, along with seven novel compounds, stauranthine, 3′,4′‐dihydroxy‐3′,4′‐dihydroveprisine, 3′,4′‐dihydroxy‐3′,4′‐dihydrostauranthine, 3′,6′‐dihydroxy‐3′,6′‐dihydroveprisine, 3′,6′‐dihydroxy‐3′,6′‐dihydrostauranthine, 6′‐hydroxy‐3′‐ketoveprisine and 6′‐hydroxy‐3′‐ketostauranthine) have been identified in the fractions. Copyright © 2003 John Wiley & Sons, Ltd.
Phase behaviour of methylcellulose–poly(acrylic acid) blends and preparation of related hydrophilic films
Authors: Khutoryanskiy Vitaliy V , Cascone Maria Grazia , Lazzeri Luigi , Nurkeeva Zauresh S , Mun Grigoriy A , Mangazbaeva Rauash A
Published: January 2003

The phase behavior of methylcellulose‐poly(acrylic acid) mixtures was studied in aqueous solution. It was shown that the complexation between the two polymers decreases considerably the cloud‐point of methylcellulose. The addition of inorganic salts shifts the critical pH values toward a higher pH region. Films were prepared based on methylcellulose‐poly(acrylic acid) blends and were analyzed by dynamic mechanical thermal analysis, scanning electron microscopy and thermal gravimetric analysis. The miscibility between the two polymers in the films was shown. It was found that the thermal treatment of the films leads to their cross‐linking with the formation of materials swellable both in water and ethanol.

© 2003 Society of Chemical Industry
Grafting polythiophene on polyethylene surfaces
Authors: Chanunpanich N , Ulman A , Strzhemechny Y M , Schwarz S A , Dormicik J , Janke A , Braun H G , Kratzmüller T
Published: January 2003

Polythiophene (PT) was grafted on PE film using three reaction steps. First, PE films were brominated in the gas phase, yielding PE–Br; second, a substitution reaction of PE–Br with 2‐thiophene thiolate anion gave the thiophene‐functionalized PE; finally PT was grafted on the PE surface using chemical oxidative polymerization to give PE–PT. The polymerization was carried out in a suspension solution of anhydrous FeCl3 in CHCl3, yielding a reddish PE–PT film after dedoping with ethanol. ATR‐FTIR shows that the PT was grafted on PE in the 2,5‐position. SEM imaging revealed islands of PT on the PE film. AFM analysis found the thickness of islands to be in the range of 120–145 nm. The conductivity of these thin films was in the range of 10−6 S cm−1, a significant increase from the value of ∼10−14 S cm−1 measured for PE film.

© 2003 Society of Chemical Industry