bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement of skeletal muscle motion in vivo with phase‐contrast MR imaging
Authors: Drace John E. , Pelc Norbert J. 
Published: March 2007

AbstractThe ability to measure skeletal muscle motion with phase‐contrast magnetic resonance (MR) imaging was tested with a motion phantom that simulated muscle activity. Quantitative analytic data on unidimensional, bidirectional skeletal muscle motion measured in vivo was obtained in four healthy volunteers. MR images of the subjectss' forearms were obtained during flexion and extension of the fingers and of the anterior and posterior muscle compartments of the lower leg with various resistances to ankle dorsiflexion and plantar flexion. It was necessary to correct the data for the effects of eddy currents. In vitro evaluation of the technique was done by studying through‐plane sinusoidal motion of solid objects. The largest error was underestimation of the peak excursion of 11.5 mm by 0.09 mm (the root mean square error for the cycle was 0.04 mm) In vivo experiments demonstrated the contraction of muscles in relation to each other. Data acquisition and analysis techniques must be refined, but measuring skeletal muscle motion with phase‐contrast MR imaging should enhance the understanding of bioengineering fundamentals and muscular changes in disease and adaptation.
P‐31 MR spectroscopy of skeletal and cardiac muscle metabolism in patients with systemic sclerosis: A multiple case study
Authors: Doornbos Joost , Luyten Peter R. , Janssen Matthijs , Wasser Martin , De Roos Albert 
Published: March 2007

AbstractThree‐dimensionally localized proton‐decoupled phosphorus‐31 magnetic resonance (MR) spectroscopy of skeletal and cardiac muscle was performed in six patients with systemic sclerosis. Cardiac (n = 9) and skeletal (n = 6) spectra were also obtained in healthy volunteers. Metabolite ratios and intracellular pH were determined from the spectra of skeletal and cardiac muscle. The phosphocreatine‐to‐adenosine triphosphate ratio was normal for both skeletal and cardiac muscle in patients with systemic sclerosis. The pH values of skeletal muscle were similar in patients and control subjects (7.13 ± 0.02 vs 7.12 ± 0.01, respectively). In skeletal muscle, the inorganic phosphate‐to‐phosphocreatine ratio in patients was increased relative to that of control subjects (0.106 ± 0.014 vs 0.086 ± 0.006, respectively; P =.02). P‐31 MR spectroscopy showed no abnormalities in the myocardium of patients with systemic sclerosis. Assessment of the inorganic phosphate‐to‐phosphocreatine ratio in peripheral skeletal muscle may be helpful for assessing disease activity.
Time‐resolved MR imaging by automatic data segmentation
Authors: Fredrickson Jill O. , Pelc Norbert J. 
Published: March 2007

AbstractA method for time‐resolved imaging that provides a flexible trade‐off between imaging time and temporal resolution is presented. It is based on a view order selection technique that automatically segments the acquired raw data into appropriate temporal frames. When used with cardiac monitoring and phase‐contrast imaging, data similar to that obtained with a conventional gated phase‐contrast sequence are acquired rapidly. For many applications, the temporal resolution can be reduced enough to permit imaging within a breath‐hold interval, while still allowing accurate time‐averaged flow quantitation. This is a general technique that can be implemented within a variety of pulse sequences and can resolve other motion cycles, including the respiratory cycle.
Phase I clinical evaluation of a new iron oxide MR contrast agent
Authors: McLachlan Stuart J. , Morris Marie R. , Lucas Maria A. , Fisco Ricardo A. , Eakins Michael N. , Fowler Dennis R. , Scheetz R. Bradley , Olukotun Adeoye Y. 
Published: March 2007

AbstractThe safety and magnetic resonance (MR) imaging potential of BMS 180549, a new superparamagnetic iron oxide contrast agent, were evaluated in a phase I, open‐label, placebo‐controlled study involving 41 healthy subjects. No clinically significant postdose changes in physical examination findings, vital signs, or electrocardiogram results were reported for any of the subjects evaluated. No clinically significant changes in clinical laboratory values were noted by the investigators. Fourteen adverse events considered not serious and considered possibly or definitely related to the drug were reported, three of which required minor treatment. Relaxation time measurements in plasma samples showed a strong, dose‐dependent, and persistent decrease in T1 and T2 values. Significant changes in MR signal intensity of the blood pool and wellperfused organs (liver and spleen) were noted on both T1‐ and T2‐weighted images. Changes in signal intensity of cervical lymph nodes were also observed at the higher doses and late postdose imaging times.
Dynamic gadolinium‐enhanced echo‐planar MR imaging of the liver: Effect of pulse sequence and dose on enhancement
Authors: Reimer Peter , Saini Sanjay , Kwong Ken K. , Cohen Mark S. , Weissleder Ralph , Brady Thomas J. 
Published: March 2007

AbstractTo develop guidelines for clinical magnetic resonance imaging of the liver, the authors undertook an animal study to investigate the effect of dose and pulse sequence on liver signal intensity in gadopentetate dimeglumine—enhanced echo‐planar imaging. Serial imaging of the liver was performed in anesthetized rats after intravenous administration of five different doses (0.01, 0.05, 0.1, 0.2, and 0.5 mmol/kg) of contrast agent, with six different pulse sequences. The results show that gadopentetate dimeglumine—enhanced echo‐planar images obtained during the perfusion phase can yield either positive (due to increased T1 relaxation rates) or negative (due to susceptibility‐induced increased T2 relaxation rates) liver enhancement depending on choice of pulse sequence and dose. At the current clinically recommended dose of 0.1 mmol/kg, maximal liver signal enhancement was seen with a T1‐weighted inversion‐recovery sequence, while maximal liver signal diminution was seen with a T2*‐weighted gradient‐echo sequence. The authors conclude that gadopentetate dimeglumine—enhanced echo‐planar imaging can provide T1, T2, and T2* contrast that may be exploited for both lesion detection and lesion characterization.
Enhanced tumor detection in the presence of fatty liver disease: Cell‐specific contrast agents
Authors: Kreft Burkhard P. , Tanimoto Akihiro , Baba Yuji , Zhao Longhai , Finn J. Paul , Stark David D. 
Published: March 2007

AbstractIt is assumed that hepatobiliary, cell‐specific contrast agents will be adversely affected by the presence of diffuse liver disease. The diagnostic efficacy for tumor detection in the presence of fatty liver disease was experimentally studied at contrast‐enhanced magnetic resonance (MR) imaging with manganese‐DPDP (N,N′‐dipyridoxylethylenediamine‐N,N′‐diacetate 5,5′‐bis[phosphate]) and gadobenate dimeglumine (Gd‐BOPTA/dimeg) and compared with conventional and chemical shift imaging. Carcinosarcoma was implanted into the liver of rats, and fatty liver was induced with L‐ethionine. Without contrast agents, the tumor‐fatty liver contrast‐to‐noise ratio (C/N) was increased on T1‐weighted and decreased on T2‐weighted MR images relative to tumor‐bearing control rats without fatty liver. Chemical shift imaging (phase‐contrast method) increased the tumor—fatty liver C/N from 2.3 ± 1.0 to 6.1 ± 1.7 (P <.001). Mn‐DPDP and Gd‐BOPTA/dimeg increased the tumor—fatty liver C/N from ‐5.4 ± 1.6 to ‐11.0 ± 1.9 and −9.8 ± 3.4, respectively (P <.001). The hepatobiliary, cell‐specific contrast agents were equally effective in both fatty and nonfatty liver and outperformed both chemical shift and conventional MR imaging in detecting liver tumors.
Gadoteridol dose dependence in MR imaging of a liver abscess model
Authors: Runge Val M. , Kirsch John E. , Woolfolk Cecil , Brack Mitchell A. , Garneau Robert A. 
Published: March 2007

AbstractA necrotic liver abscess model was studied with magnetic resonance (MR) imaging at 1.5 T before and after intravenous administration of gadoteridol at doses of 0.1, 0.25, and 0.5 mmol/kg in 24 rabbits. Enhancement characteristics and lesion delineation were assessed with both breath‐hold and non‐breath‐hold imaging techniques. Lesion delineation, as assessed both by signal intensity measurements and evaluations by two image readers blinded to imaging technique, was greatest on high‐dose (0.5 mmol/kg) breath‐hold images. Lesion rim enhancement was seen consistently only on postcontrast images obtained at a dose of 0.5 mmol/kg and progressed with time after injection of contrast material.
Gd‐EOB‐DTPA enhancement pattern of hepatocellular carcinomas in rats: Comparison with Tc‐99m‐IDA uptake
Authors: van Beers Bernard E. , Grandin Cécile , Pauwels Stanislas , Mottet Isabelle , Goudemant Jean‐François , Delos Monique , Demeure Roger , Pringot Jacques 
Published: March 2007

AbstractThe enhancement pattern of chemically induced hepatocellular carcinomas (HCCs) after intravenous administration of the hepatobiliary magnetic resonance (MR) contrast agent gadolinium‐EOB‐DTPA (ethoxybenzyl‐diethylenetriaminepentaacetic acid) was compared with the uptake pattern of technetium‐99m‐labeled iminodiacetic acid (IDA), a hepatobiliary radioactive tracer. The hepatocyte uptake of both the contrast agent and the scintigraphic agent has been shown to be driven by the organic anion transporter. The tumors enhanced less than the liver after Gd‐EOB‐DTPA administration, whereas the Tc‐99m‐IDA uptake of differentiated HCCs exceeded that of the liver at 30 minutes and 3 hours after administration. The enhancement pattern of a differentiated HCC with Gd‐EOB‐DTPA does not mirror that seen with Tc‐99m‐IDA.
Effect of varying the molecular weight of the MR contrast agent Gd‐DTPA‐polylysine on blood pharmacokinetics and enhancement patterns
Authors: Vexler Vladimir S. , Clément Olivier , Schmitt‐Willich Heribert , Brasch Robert C. 
Published: March 2007

AbstractThe effects of varying the molecular weight of gadolinium‐DTPA (diethylenetriaminepentaacetic acid)—polylysine, a macromolecular magnetic resonance (MR) imaging contrast agent, on blood pharmacokinetics and dynamic tissue MR imaging signal enhancement characteristics were studied in normal rats. Blood elimination half‐life, total blood clearance, volume of the central compartment (Vcc) and the steady‐state distribution volume (Vssd) were calculated for four Gd‐DTPA‐polylysine polymers with average molecular weights of 36, 43.9, 139, and 480 kd and compared with corresponding values for Gd‐DTPA (0.57 kd) and Gd‐DTPA‐albumin (92 kd). Blood elimination half‐life increased sevenfold with an increase in molecular weight from 36 to 480 kd. The Vcc values for all polylysine polymers did not differ significantly from the Vcc value for Gd‐DTPA‐albumin but were significantly smaller than the Vcc value for Gd‐DTPA. The Vssd value for Gd‐DTPA did not differ significantly from the Vssd value for the 36‐ and 43.9‐kd polymers but was significantly larger than the Vssd values for the 139‐and 480‐kd polymers and for Gd‐DTPA‐albumin. On T1‐weighted coronal spin‐echo MR images, dynamic signal enhancement profiles in liver and kidney for the 36‐, 43.9‐, and 480‐kd Gd‐DTPA‐polylysine chelates corresponded to the blood pharma‐cokinetic data. Increasing molecular weight of Gd‐DTPA‐polylysine formulations substantially slows blood clearance and produces a prolonged, almost constant tissue signal enhancement for the 60‐minute observation period.
Gadolinium‐enhanced T1‐weighted versus T2‐weighted imaging of scrotal disorders: Is there an indication for MR imaging?
Authors: Müller‐Leisse Christof , Bohndorf Klaus , Stargardt Achim , Sohn Michael , Neuerburg Jörg , Adam Gerd , Wein Berthold , Urhahn Reinhard , Günther Rolf W. 
Published: March 2007

AbstractTo evaluate the use of gadopentetate dimeglumine in magnetic resonance (MR) imaging of scrotal disorders, the clinical, ultrasound, and MR imaging data of 29 patients (age range, 19–75 years) with various intra‐ and extratesticular disorders were retrospectively analyzed. T1‐ and T2‐weighted spin‐echo images (T1‐T2 group) were compared with T1‐weighted spin‐echo images before and after intravenous administration of gadopentetate dimeglumine (T1‐Gd group). A receiver operating characteristic (ROC) analysis of the findings was undertaken. Better contrast between tumor and parenchyma and a clearer demonstration of the tunica albuginea were noted in the T1‐T2 group (although not of diagnostic relevance). ROC analysis revealed no differences between the two imaging groups in the diagnosis of tumor, trauma, hydrocele, or hemorrhage; however, epididymitis was diagnosed more easily with contrast enhancement (0.8834 vs 0.7759, P = .04) and the diagnosis of orchitis was expressed more strongly (0.8221 vs 0.7184, P = .17). Four of the five observers were more confident in making the diagnosis with contrast enhancement. With MR imaging, the diagnosis was correctly suggested in three patients in whom clinical and ultrasound data were inconclusive. Gadolinium‐enhanced MR imaging gives additional information in scrotal disorders and facilitates diagnosis. It may be helpful when findings at physical examination and ultrasound differ and when plain T1‐ and T2‐weighted images are equivocal.
Use of superparamagnetic contrast media to suppress signal from flowing spins: Preliminary experience
Authors: Duerk Jeffrey L. , Hurst Gregory C. 
Published: March 2007

AbstractThe authors describe their preliminary experience with the use of superparamagnetic magnetic resonance (MR) imaging contrast media for suppression of signal from flowing blood. The goal of this work was to determine if a superparamagnetic contrast agent could successfully eliminate blood signal during cardiac‐gated MR imaging, thereby eliminating or reducing flow artifacts associated with the complex and variable hemodynamics within the heart chambers. Imaging and data analysis were performed in 17 dogs subjected to experimental myocardial infarction as part of a parallel project. Six doses (0.2, 1, 2, 3.5, 4, 5, and 10 mg/kg) of AMI‐25, an experimental contrast agent, were used in the study. Spin‐echo imaging was performed immediately before and every 5 minutes (for an average of 25 minutes) after bolus injection of the contrast agent. Variations in the image signal‐to‐noise ratio relative to a baseline (before injection of contrast agent) image were assessed as a function of dose and time. Preliminary results suggest that a considerable reduction in blood flow artifacts and, hence, increases in image signal‐tonoise ratio can be achieved at doses greater than or equal to 3.5 mg/kg, for approximately 20 minutes after injection. Doses equal to or less than 2 mg/kg and images obtained more than 20 minutes after injection (regardless of dose) did not reliably show hemodynamic artifact suppression.
In vivo quantification of the unidirectional influx constant for Gd‐DTPA diffusion across the myocardial capillaries with MR imaging
Authors: Larsson Henrik B. W. , Stubgaard Max , Søndergaard Lars , Henriksen Ole 
Published: March 2007

AbstractThe authors present an in vivo method for measuring the unidirectional influx constant (Ki) for gadolinium diethylenetriaminepentaacetic acid (DTPA) diffusion across the capillary membrane in the human myocardium with magnetic resonance imaging. Ki, is related to the extraction fraction (E) and the perfusion (F) by the equation Ki = E. F. Ki was obtained by using the longitudinal relaxation rate (R1) as a measure of the myocardial concentration of Gd‐DTPA in the mathematical model for transcapillary transport across capillary membranes. Myocardial enhancement after Gd‐DTPA injection was followed by using inversion‐recovery Turbo‐FLASH (fast low‐angle shot) images obtained in real time. The results were comparable to those obtained from studies with positron emission tomography in humans and invasive studies in animals. A method for obtaining the input function nonin‐vasively is also presented. Comparison with direct arterial blood sampling showed that the noninvasive input function may be even more accurate with regard to timing and curve shape than the invasive input function. The procedure may therefore prove useful in clinical studies.
Selective enhancement of experimental rat brain tumors with Gd‐TPPS
Authors: Bockhorst Kurt , Els Thomas , Hoehn‐Berlage Mathias 
Published: March 2007

AbstractThe synthetic metalloporphyrin gadolinium (III)‐tetraphenylporphine sulfonate (TPPS) was successfully used as a contrast agent for in vivo magnetic resonance (MR) imaging of rat brain glioma. After injection of Gd‐TPPS, the signal intensity of experimental rat brain glioma distinctly increased on T1‐weighted MR images, an effect similar to that produced by the clinically applied MR imaging contrast agent gadolinium diethylenetriaminepentaacetic acid (DTPA). In contrast to other contrast agents studied (Gd‐DTPA, manganese [III]‐TPPS), Gd‐TPPS produced hypointensity in glioma on T2‐weighted images. The tumor‐selective accumulation of paramagnetic Gd‐TPPS in glioma shortened T1 by 53%, from 1,315 msec ± 199 to 628 msec ± 106, and T2 by 34%, from 86 msec ± 4 to 57 msec ± 5 (2 days after injection of 0.25 mmol/kg Gd‐TPPS). The relaxation times of normal cortex, striaturn, corpus callosum, and temporal muscle were not significantly affected. As a result, gliomas appeared hyperintense on T1‐weighted images and hypointense on T2‐weighted images. Owing to the strong effect of Gd‐TPPS on the T2 of glioma, normal brain tissue, tumor, and peritumorous edema could be distinguished on T2‐weighted images alone.
Repeat cerebral blood volume assessment with first‐pass MR imaging
Authors: Runge Val M. , Kirsch John E. , Wells John W. , Dunworth John N. , Hilaire Luna , Woolfolk Cecil E. 
Published: March 2007

AbstractThe feasibility of performing multiple first‐pass studies with dynamic, contrast material‐enhanced magnetic resonance (MR) imaging was evaluated in a cat model of acute middle cerebral artery (MCA) ischemia. Two dynamic series of SSFP (steady‐state free precession) images were acquired in each animal (n = 5) with a conventional 1.5‐T imager. The initial first‐pass study was acquired at 60 minutes after MCA occlusion, and the second study at 70 minutes, with each performed during an intravenous bolus injection of a 0.5 mmol/kg dose of gadoteridol. In both first‐pass studies, differentiation of normal and ischemic gray and white matter was highly statistically significant. At a threshold of P<.01, no statistically significant difference in the peak signal intensity between the first and second studies was noted. A difference between the two studies in the recovery to baseline was seen, presumably due to T1 effects. First‐pass MR studies can be repeated within the time frame of a single clinical examination, expanding their utility.
Early identification of sites of embryo implantation in rats by means of gadolinium‐enhanced MR imaging
Authors: Hamilton G. Scot , Kennedy Thomas G. , Karlik Stephen J. 
Published: March 2007

AbstractTo determine if magnetic resonance (MR) imaging techniques can be used to examine sites of embryo implantation in intact rats, pregnant animals were imaged with gadopentetate dimeglumine‐enhanced MR imaging approximately 10 hours after initiation of implantation on day 5 of pregnancy. T1‐weighted, three‐dimensional SPGR (spoiled gradient‐recalled acquisition in the steady state) sequences were used to image the volume of abdomen containing the uterine horns before and after injection of gadopentetate dimeglumine into a femoral venous catheter. While unenhanced images provided little detail in uterine tissue, analysis of the gadolinium‐enhanced abdominal images with interactive vascular imaging allowed easy identification of sites of embryo implantation along both uterine horns in four of four pregnant rats. These punctate patterns of enhancement match those of macroscopic bluing after injection of Evans blue dye. Similar gadolinium‐enhanced MR imaging of nonpregnant rats produced only a slight, generalized enhancement of entire uterine horns. The authors conclude that local increases in extracellular fluid volume, vascular permeability, and blood flow in the uterus may all contribute to the gadolinium enhancement of the implantation sites. They propose that this approach can be used in experimental settings to provide information regarding embryo implantation unaccessible with traditional approaches. In clinical settings, gadolinium‐enhanced MR imaging may be used to examine potential causes of infertility, including luteal phase defects.
MR imaging of crohn disease: Use of perflubron as a gastrointestinal contrast agent
Authors: Anderson Clinton M. , Brown Jeffrey J. , Balfe Dennis M. , Heiken Jay P. , Borrello Joseph A. , Clouse Ray E. , Pilgram Thomas K. 
Published: March 2007

AbstractThis study was undertaken to evaluate the use of perflubron (perfluorooctylbromide) as an oral contrast agent for magnetic resonance (MR) imaging of patients with Crohn disease. MR examinations were performed before and after perflubron administration in 12 patients with documented Crohn disease. Glucagon was administered intramuscularly before the post‐perflubron examinations. Each patient also underwent abdominal computed tomography within 48 hours of MR imaging. The imaging studies were analyzed for effectiveness of bowel marking with oral contrast agent, clarity of bowel wall visualization, and presence of bowel wall thickening and extraluminal manifestations of Crohn disease such as abscess or fistula formation. Analysis of the imaging studies showed effective marking of the bowel with perflubron and improved bowel wall visualization on postcontrast MR images. Detection of bowel wall thickening and extraluminal complications of Crohn disease was not significantly improved on postcontrast MR images. The authors conclude that perflubron administration effectively marked the bowel and increased the clarity of bowel wall visualization but did not significantly increase the detection of abnormalities related to Crohn disease in the study population.
Dynamic contrast‐enhanced MR imaging of the pituitary gland with fast spin‐echo technique
Authors: Davis Wayne L. , Lee James N. , King Brian D. , Harnsberger H. Ric 
Published: March 2007

AbstractPreliminary work has demonstrated that dynamic contrast material—enhanced magnetic resonance imaging improves the detection sensitivity for pituitary microadenomas. The authors present a new method of obtaining dynamic contrastenhanced pituitary images with a short TR/TE fast spin‐echo technique. This approach allows acquisition of contrast‐enhanced spin‐echo images with high temporal and spatial resolution. The new technique is applied in a small group of patients and control subjects.
Carotid plaque formation and its evaluation with angiography, ultrasound, and MR angiography
Authors: Wasserman Bruce A. , Haacke E. Mark , Li Debiao 
Published: March 2007

AbstractThe accurate assessment of carotid artery disease is an important challenge for magnetic resonance (MR) angiography. Studies indicate that the detection and grading of stenosis and the evaluation of plaque morphology are all important steps in the clinical assessment of atherosclerosis. The prevalence of significant carotid artery stenosis in the elderly population and even in patients with symptoms of carotid artery disease is low; clinical risk seems to correlate more closely with plaque morphology and surface characterization than with the degree of stenosis. This highlights the importance of MR angiography and ultrasound, which can help characterize plaque morphology in addition to showing the degree of stenosis. The authors review the present understanding of plaque formation, comparisons of plaque imaging with conventional angiography, ultrasound, and MR angiography, and recent progress in MR angiography techniques. Several studies, including the North American Symptomatic Carotid Endarterectomy Trial and the European Carotid Surgery Trial, are discussed regarding the current objectives of carotid artery imaging. The sensitivity and specificity of plaque detection and morphologic evaluation continue to improve.