bluuebunny/crossref_metadata_2025_split huggingface dataset:
The application of magnetization transfer to MR angiography with reduced total power
Authors: Parker Dennis L. , Buswell Henry R. , Goodrich K. Craig , Alexander Andrew L. , Keck Nanette , Tsuruda Jay S. 
Published: March 2007

AbstractMagnetization transfer (MT) techniques have been shown to significantly reduce background soft‐tissue signal in time‐of‐flight magnetic resonance angiography. To achieve sufficient suppression, radio frequency (RF) pulses with tip angles on the order of 1000 degrees are typically used, resulting in significant RF power deposition in the patient. Although these power deposition levels do not exceed the FDA guidelines, they are significantly higher than those used in typical imaging techniques. The use of these same magnetization transfer pulses in applications at field strengths higher than 1.5 T will require MT power levels which exceed FDA safety standards. This report demonstrates that the total power deposition required to achieve background tissue suppression can be significantly reduced by the application of the saturation pulses only during the phase‐encoding steps corresponding to the central portion of “k space.” This technique allows equivalent soft tissue suppression with approximately 10% of the energy deposition of conventional magnetization transfer techniques.
High contrast and fast three‐dimensional magnetic resonance imaging at high fields
Authors: Lee Jing‐Huei , Garwood Michael , Menon Ravi , Adriany Gregor , Andersen Peter , Truwit Charles L. , Uǧurbil Kǎmil 
Published: March 2007

AbstractA new three‐dimensional imaging strategy based on magnetization prepared ultrafast gradient recalled echo technique that demonstrates pronounced T1 contrast at high fields is introduced. High‐resolution three‐dimensional image sets of human brain showing high contrast between white and gray matter areas are presented. The ratio of contrast‐to‐noise was examined as a function of the relevant parameters in the imaging sequence; calculations based on high‐field T1 values as well as the experimental data demonstrated that maximal contrast‐to‐noise ratio is attained under the same magnetization preparation conditions both for cortical and subcortical gray matter relative to white matter, leading to approximately equivalent appearance of all gray matter areas in the same image. In addition, the images displayed clear visualization of subtle anatomical structures such as the subthalamic nuclei (ventral tier nuclei, dorsomedial nucleus, and pulvinar) and mammillothalamic tracts.
Myocardial tagging with B1 insensitive adiabatic DANTE inversion sequences
Authors: Tsekos Nikolaos V. , Garwood Michael , Merkle Hellmut , Xu Ya , Wilke Norbert , Uǧurbil Kǎmil 
Published: March 2007

AbstractA new technique, based on adiabatic delays alternating with nutations for tailored excitation (DANTE) inversion sequences, is presented for generating uniform contrast tags across the myocardial wall even in the presence of B1 inhomogeneities. The utility of this pulse was demonstrated using a surface coil for both transmission and signal reception in phantom and animal heart tagging studies. The experimental data demonstrated uniform grid contrast over a sixfold variation of B1 magnitude, sharp tagging profiles, and the ability to follow the cardiac wall motion through the deformation of the fine rectangular tagging grid at different phases throughout the cardiac cycle.
The diminishing variance algorithm for real‐time reduction of motion artifacts in MRI
Authors: Sachs Todd S. , Meyer Craig H. , Irarrazabal Pablo , Hu Bob S. , Nishimura Dwight G. , Macovski Albert 
Published: March 2007

AbstractA technique has been developed whereby motion can be detected in real time during the acquisition of data. This enables the implementation of several algorithms to reduce or eliminate motion effects from an image as it is being acquired. One such algorithm previously described is the acceptance/rejection method. This paper deals with another real‐time algorithm called the diminishing variance algorithm (DVA). With this method, a complete set of preliminary data is acquired along with information about the relative motion position of each frame of data. After all the preliminary data are acquired, the position information is used to determine which data frames are most corrupted by motion. Frames of data are then reacquired, starting with the most corrupted one. The position information is continually updated in an iterative process; therefore, each subsequent reacquisition is always done on the worst frame of data. The algorithm has been implemented on several different types of sequences. Preliminary in vivo studies indicate that motion artifacts are dramatically reduced.
Quite transverse gradiant coils: Lorentz force balanced designs using geometrical similitude
Authors: Bowtell Richard W. , Mansfield Peter 
Published: March 2007

AbstractThe principle of active acoustic screening, recently introduced by Mansfield et al. (1) to reduce acoustic noise ingradient coils for MRI, is applied to the design of transverse distributed gradient coils of the fingerprint design. The results indicate that for complete Lorentz force balancing and for exact satisfaction of Kirchoff's law, it is necessary to have a coil system wound on four cylinders if full active magnetic screening of the assembly is required.
MR imaging of regional cardiac function: Low‐pass filtering of wall thickness curves
Authors: Lamb Hildo J. , Singleton Ross R. , Van Geest Rob J. Der , Pohost Gerald M. , Roos Albert De 
Published: March 2007

AbstractWall thickness curves (WTCs) derived from MR images are subject to considerable measurement error. This study determines the effects of low‐pass Fourier filtering of WTCs on functional parameters derived from the curve: peak rate of wall thinning (PRWT) and time to PRWT (TPRWT). The inter‐subject standard deviation (SD) of PRWT changed from 0.35 to 0.18, and the SD of TPRWT from 34.3 to 29.5. Differences between neighboring segments decreased from 0.31 to 0.15% mean thickness/ms for PRWT (P = 0.012), and from 35.0 to 19.0 ms for TPRWT (P = 0.005). It is concluded that filtering of MR imaging‐derived WTCs contributes to a better representation of myocardial wall motion.
Blood oxygenation dependence of t1 and t2 in the isolated, perfused rabbit heart at 4.7t
Authors: Atalay Michael K. , Reeder Scott B. , Zerhouni Elias A. , Forder John R. 
Published: March 2007

AbstractAn MR line scan protocol has been used to measure relaxation parameters (T1 and T2) in isolated, blood perfused rabbit hearts at various blood oxygenations. Hearts were retro‐gradely perfused at 37°C with a cardioplegic solution (modified St. Thomas' solution) containing sheep red blood cells and adenosine (1 mM) to maximally vasodilate the coronary vascular bed. Arresting the hearts eliminated motion complications and minimized arteriovenous oxygenation differences. The authors have found that under conditions of stable flow, there is a strong correlation between T2 in myocardial septa and hemoglobin (Hb) saturation, while tissue T1 is virtually independent of blood oxygenation. These effects are believed to be due to the paramagnetic agent deoxyhemoglobin.
Functional mri of human brain activation combining high spatial and temporal resolution by a cine flash technique
Authors: Merboldt Klaus‐Dietmar , Krüger Gunnar , Hänicke Wolfgang , Kleinschmidt Andreas , Frahm Jens 
Published: March 2007

AbstractFunctional mapping of human brain activation has been accomplished at high spatial and temporal resolution (voxel size 4.9 μl, temporal increment 100 ms). The approach was based on oxygenation‐sensitive long‐echo time FLASH MRI sequences synchronized to multiply repeated cycles of visual stimulation in a CINE acquisition mode. This high temporal resolution revealed that stimulus‐related signal intensity changes in human visual cortex display an initial latency followed by increases extending over several seconds. Furthermore, the temporal characteristics of the complete CINE MRI signal time course depended on the absolute and relative durations of activation and control periods and, for example, caused an apparent absence of a poststimulation “undershoot” phenomenon. Complementing hyperoxygenation due to rapid hemodynamic adjustments, these results suggest signal intensity modulation by enhanced oxygen consumption and concomitant deoxygenation during prolonged and/or repetitive stimulation.
Sequential dynamic susceptibility contrast MR experiments in human brain: Residual contrast agent effect, steady state, and hemodynamic perturbation
Authors: Levin Jonathan M. , Kaufman Marc J. , Ross Marjorie H. , Mendelson Jack H. , Maas Luis C. , Cohen Bruce M. , Renshaw Perry F. 
Published: March 2007

AbstractThe stability and reproducibility of the dynamic susceptibility contrast (DSC) MRI method for sequential relative cerebral blood volume (relCBV) measurements was evaluated to validate the method for use in quantitative studies of cerebral hemodynamics in humans. A spin echo echo planar imaging protocol was used in conjunction with multiple bolus injections of the susceptibility contrast agent gadoteridol (GD). The effects of variation in interbolus interval (10 min to 4 h), the number of injections (two to four), and the effect of the cerebral vasodilating agent acetazolamide (ACZ) were evaluated in 44 experiments performed with 22 normal subjects. Two fundamental observations were made. First, with multiple injections of GD, the change in MR signal over time was not consistent from first to subsequent boluses. A second bolus administered 10 min to 2 h after an initial bolus resulted in signal change of greater amplitude and duration, resulting in artifactually elevated estimates of relCBV, consistent with a residual effect of GD. Second, a relative steady state could be reached with serial injections of GD, such that the profile of subsequent boluses closely paralleled those of previous ones. This facilitates the reliable measurement of relCBV during activation, as demonstrated by use of ACZ.
Orbital navigator echoes for motion measurements in magnetic resonance imaging
Authors: Fu Zhuo Wu , Wang Yi , Grimm Roger C. , Rossman Phillip J. , Felmlee Joel P. , Riederer Stephen J. , Ehman Richard L. 
Published: March 2007

AbstractA single “orbital” navigator echo, that has a circular k‐space trajectory, is used to simultaneously measure in‐plane rotational and multi‐axis translational global motion. Rotation is determined from the shift in the magnitude profile of the echo with respect to a reference echo. Displacements are calculated from the phase difference between the current echo and a reference echo. Phantom studies show that this technique can accurately measure rotation and translations. Preliminary results from adaptive motion correction studies on phantom and human subjects indicate that the orbital navigator echo is an effective method for motion measurement in MRI.
High resolution quantitative relaxation and diffusion mri of three different experimental brain tumors in rat
Authors: Eis Manfred , Els Thomas , Hoehn‐Berlage Mathias 
Published: March 2007

AbstractThe potential of quantitative parameter images of the relaxation times T1 and T2, the proton density p and the apparent diffusion coefficient (ADC) to characterize three different experimental rat brain tumors (F98 glioma, RN6 Schwannoma, and E376 neuroblastoma) was studied. All parameter values, as determined in histologically confirmed regions of interest (ROI), were higher in edema than in tumor, which in turn were elevated with respect to normal brain. ROI values of ADC and T2 delivered statistically significant (P < 0.01) differentiation between tumor and edema. Multidimensional parameter combinations improved differentiation between different tissues. However, the three tumor types could not be differentiated. All parameter maps allowed the identification of the whole tumoredema area. On T2 images, edema could be identified best, whereas the tumor itself was hardly visualized. In many cases, tumor presentation using T1 maps corresponded best with histology, nevertheless suffering from a poor tumoredema differentiation.
Quantification of liver blood volume: comparison of ultra short ti inversion recovery echo planar imaging (ulstir‐epi), with dynamic 3d‐gradient recalled echo imaging
Authors: Schwickert Heidi C. , Roberts Timothy P. L. , Shames David M. , Dijke Cornelis F. Van , Disston Alexander , Mühler Andreas , Mann Jeffry S. , Brasch Robert C. 
Published: March 2007

AbstractAn ultra‐short TI inversion recovery echo‐planar imaging (ULSTIR‐EPI) sequence was designed to reduce the influence of water exchange on fractional tissue blood volume (BV) estimation by measurement of T1‐changes induced by a gadolinium‐based macromolecular contrast medium (MMCM). Fractional liver BV in rats, estimated by ULSTIR‐EPI was compared for accuracy to a fast T1‐weighted three‐dimensional gradient‐echo (3D‐SPGR, 3D‐spoiled gradient recalled acquisition in a steady state) sequence using an in vitro inductively coupled plasma atomic emission spectroscopy (ICP‐AES) assay for BV as a standard. Liver images for fractional BV estimation were acquired in eight rats using both ULSTIR‐EPI and 3D‐SPGR before and after (within 3 to 12 min) intravenous bolus administration of albumin‐Gd‐DTPA30 (0.05 mmol Gd/kg). Whereas both MR techniques may be useful for fractional tissue BV estimation, ULSTIR‐EPI offers certain advantages including greater accuracy, direct T1 maps, and minimization of transendothelial proton exchange effects. 3D‐SPGR imaging offers better spatial resolution, current availability on standard clinical MR systems, and acceptable accuracy.
Detection of bromobenzene‐induced hepatocellular necrosis using magnetic resonance microscopy
Authors: Zhou Xiaohong , Maronpot Robert R. , Hedlund Laurence W. , Cofer Gary P. , Johnson G. Allan 
Published: March 2007

AbstractThe authors used magnetic resonance (MR) microscopy to assess hepatic tissue damage induced by bromobenzene both in living rats and in fixed rat liver tissues. Experiments were conducted at 7 Tesla on three groups of Fisher rats treated with bromobenzene at a single dose of 68, 135, and 269 mg/kg, respectively. Optical microscopy of hematoxylin and eosin stained sections showed liver damage only at the highest dose, whereas with MR microscopy, tissue alterations were detected at all three doses both in vivo and ex vivo. The contrast mechanism of the superior sensitivity of MR microscopy is believed to be related to the changes in local diffusion coefficients that accompany cellular degeneration and death, although other contrast mechanisms may also be involved. The superior sensitivity of MR microscopy, as demonstrated in this study, has many implications for potential use of MR techniques to perform in vivo histology.
Use of epr oximetry with india ink to measure the po2 in the liver in vivo in mice
Authors: Nakashima Toshiaki , Goda Fuminori , Jiang Jinge , Shima Toshihide , Swartz Harold M. 
Published: March 2007

AbstractThe partial pressure of oxygen (pO2) of the liver in vivo in unanesthetized mice was determined using electron paramagnetic resonance (EPR) oximetry with India ink. The EPR spectra were obtained using a low‐frequency (1.2 GHz) EPR spectrometer with a loop gap cavity resonator. The line width of the India ink used in this experiment was reversibly broadened by oxygen and was particularly sensitive to pO2 below 30 torr. After the administration of India ink into the tail vein, the India ink particles were taken up mainly by Kupffer cells in the liver and in part by phagocytes in the spleen. The pO2 measured in the normal liver was about 14 torr and was constant for the 2‐week experimental period. The pO2 decreased when measured at 1, 2, and 6 days after treatment with a hepatotoxin (carbon tetrachloride (CCI4)); within 2 weeks, it returned almost to the initial level. Measurements by EPR at sacrifice of controls and CCI4‐treated mice indicated that more than 90% of the India ink went to the liver; the spleen contained 4.7% of total amount in control mice and 8.8% in CCI4‐treated mice when measured 2 weeks after the treatment. These data indicate the usefulness of India ink for measuring the pO2 of the liver in vivo and that the pO2 in the Kupffer cells is decreased when the liver is damaged by CCI4.
Multiple breath‐hold averaging (mba) method for increased snr in abdominal mri
Authors: Feinberg David A. , Rofsky Neil M. , Johnson Glyn 
Published: March 2007

AbstractBreath‐holding during MR imaging eliminates respiratory motion artifacts but places a major time constraint on data acquisition. This constraint limits image signal‐to‐noise ratio and hence spatial resolution. A new method, multiple breathhold averaging, is presented that overcomes these time limitations. Several images are acquired in sequential breath‐hold periods, separated by periods of normal breathing, and averaged. This averaged image shows the expected increase in SNR with surprisingly little blurring due to misregistration. SNR improvements can be traded for increased spatial resolution. The MBA methodology can also be applied to 3D data acquisitions, dynamic contrast acquisitions, and image subtractions.
Managing components for assemble‐to‐order products with lead‐time‐dependent pricing: The full‐shipment model
Authors: Hsu Vernon Ning , Lee Chung Yee , So Kut C. 
Published: March 2007

AbstractWe study a component inventory planning problem in an assemble‐to‐order environment faced by many contract manufacturers in which both quick delivery and efficient management of component inventory are crucial for the manufacturers to achieve profitability in a highly competitive market. Extending a recent study in a similar problem setting by the same authors, we analyze an optimization model for determining the optimal component stocking decision for a contract manufacturer facing an uncertain future demand, where product price depends on the delivery times. In contrast to our earlier work, this paper considers the situation where the contract manufacturer needs to deliver the full order quantity in one single shipment. This delivery requirement is appropriate for many industries, such as the garment and toy industries, where the economies of scale in transportation is essential. We develop efficient solution procedures for solving this optimization problem. We use our model results to illustrate how the different model parameters affect the optimal solution. We also compare the results under this full‐shipment model with those from our earlier work that allows for multiple partial shipments. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007
Cardiovascular risk factors in confirmed prediabetic individuals. Haffner S M, Stern M P, Hazuda H P, et al. JAMA, 1990; 263: 2893–8
Authors: Shaw K M 
Published: March 2007

AbstractThis paper analyses the atherogenic pattern of risk factors in a large number of individuals who when first studied had normal glucose tolerance but who several years later went on to develop diabetes of the non‐insulin‐dependent type. Base line cardiovascular risk factors were studied in 614 non‐diabetic Mexican Amcricans who went on to participate in the San Antonio heart study, an eight year follow‐up. Forty‐three of these went on to develop Type 2 diabetes. These people were therefore considered to have confirmed prediabetes at the initial examination. They were found to have significant elevation of total and low density lipoprotein cholesterol, triglyceride. fasting glucose. and insulin levels, body weight and blood pressure. with low levels of high density lipoprotein cholesterol. People with initial impaired glucosc tolerance at base line were not considered.
Who uses a diabetes “drop‐in” centre
Authors: Dunning P L , Ward G M , Alford F P 
Published: March 2007

AbstractThis study aimed to document patients' reasons for attendance at a “drop‐in” centre serving a general diabetic clinic (n = 756). Over six months the following data were documented: reasons for attendance (self‐initiated or referred and source or referrals); length of consultation; age and sex of clients; whether NIDDM or IDDM; and treatment modes. All 133 minor consultations (<30 min) (95 NIDDM and 38 IDDM) were self‐initiated. Of the 71 major consultations (>30 min) comprising 59 NIDDM (of whom 47 were insulin‐treated) and 12 IDDM, 48 were self‐initiated. The main reasons for major consultations were: 20 presented with persisting hyperglycaemia > 17 mmol/l (17 required insulin adjustment); eight had unfavourable social circumstances affecting diabetes management and required counselling; 10 requested ongoing diabetes education; six presented with foot lesions (two with neuropathic ulcers); and 10 diabetics came with non‐diabetes‐related health problems. Unexpectedly, there were no requests for dietary advice, and few for hypoglycaemia. There were six contacts by relatives, five parents of people with IDDM expressing concern about their child's lifestyle which compromised metabolic control and one husband of a person with NIDDM. We conclude that our clients demonstrate a definite need for diabetes‐related education or advice between clinic visits. In our study the major reasons for seeking advice were for hyperglycaemia needing treatment modification, counselling and to increase diabetes knowledge.
The costs and benefits of introducing a nurse‐run diabetic review service into general practice
Authors: Sullivan F M , Menzies A 
Published: March 2007

AbstractA prospective six‐year study of all diabetic patients in a single practice was conducted to investigate the benefits to patients which resulted from the introduction of a nurse‐run diabetic review service. The opportunity of the audit was also used to determine the capital and running costs of such a service. After initial expenditure of around £200–;300, GPs can expect to devote a total of 10‐15 minutes of their own time and 20‐30 minutes of their nurse's time to providing an annual check to each of their diabetic patients. Using our assumptions, this amounts to a cost to the practice of £4 per nurse review. Further costs beyond this minimum level are calculable for individual practices based on the data presented. Benefits to patients were evident for individual patients whose retinopathy or foot lesions were detected early and in the increasing numbers of examinations performed. It is possible for general practice teams to coordinate a comprehensive review service for their diabetic patients.
Self‐adjustment of insulin: An educational failure?
Authors: Gill G V , Redmond S 
Published: March 2007

AbstractSelf‐adjustment of insulin doses by diabetic patients is widely encouraged but efficacy of technique has not been evaluated or audited.We recently published a series of guidelines for insulin adjustment in the BDA lay journal, “Balance” and a quiz for readers to complete and submit.Six questions gave home blood glucose (BG) profiles on various insulin regimens. Patients were asked what adjustments to dose, if any, were required.Sixty insulin‐treated diabetics responded, 97% were actively adjusting their doses. Only five (8%) answered all six questions correctly; 73% reacted wrongly to a single‐day BG profile; 22% made potentially hazardous changes in response to obviously erratic profiles; 63% changed doses of a once‐daily insulin system despite clear advice to the contrary. When specific insulin changes were indicated, 25% responded with the wrong insulin for a twice‐daily short/intermediate insulin system and 37% for a “Novopen” system.We conclude that even amongst interested and motivated patients knowledge of self‐adjustment principles is poor. These skills need to be specifically taught to selected patients and their response requires auditing. If such a programme cannot be provided, then self‐adjustment should not be encouraged.