bluuebunny/crossref_metadata_2025_split huggingface dataset:
Method choice: Five discussant commentaries
Authors: Greene Jennifer C. , Lipsey Mark W. , Schwandt Thomas A. , Smith Nick L. , Tharp Roland G. 
Published: March 2007

AbstractProductive dialogue is informed best by multiple and diverse voices. Five seasoned evaluators, representing a range of evaluation perspectives, offer their views in two‐ to three‐page discussant contributions. These individuals were asked to reflect and comment on the previous chapters in the spirit of critical review as a key source of evidence about methods choice.
Fabrication of nanostructured hydroxyapatite and analysis of human osteoblastic cellular response
Authors: Guo Xingyuan , Gough Julie E. , Xiao Ping , Liu Jing , Shen Zhijian 
Published: March 2007

AbstractNano‐sized hydroxyapatite (HA) powders were produced by a hydrothermal method and a precipitation method. Spark plasma sintering (SPS) was used to fabricate nanostructured HA (NHA) using nano‐sized HA powders as a precursor. Conventional sintering was employed to produce microstructured HA (MHA). Characteristics of HA powders and HA bulk ceramics after sintering were investigated by XRD, FTIR, SEM, TEM, particle size distribution, and AFM. Dense compacts consisting of equiaxed grains with an average grain size of ∼100 nm were obtained by SPS. Human osteoblasts were cultured on both NHA and MHA and cell attachment, proliferation, and mineralization were evaluated. After 90 min incubation, the cell density on NHA surface was significantly higher than that of MHA and glass control, whereas average cell area of a spread cell was significantly lower on NHA surface compared to MHA and glass control after 4 h incubation. Matrix mineralization was determined after 7 and 14 days incubation by using alizarin red assay combined with cetylpyridinium chloride extraction. NHA shows significant enhancement (p < 0.05) in mineralization compared to MHA. Results from this study suggest that NHA may be a much better candidate for clinical use in terms of bioactivity. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Repair of critical size defects in the rat cranium using ceramic‐reinforced PLA scaffolds obtained by supercritical gas foaming
Authors: Montjovent Marc‐Olivier , Mathieu Laurence , Schmoekel Hugo , Mark Silke , Bourban Pierre‐Etienne , Zambelli Pierre‐Yves , Laurent‐Applegate Lee Ann , Pioletti Dominique P. 
Published: March 2007

AbstractBioresorbable scaffolds made of poly(L‐lactic acid) (PLA) obtained by supercritical gas foaming were recently described as suitable for tissue engineering, portraying biocompatibility with primary osteoblasts in vitro and interesting mechanical properties when reinforced with ceramics. The behavior of such constructs remained to be evaluated in vivo and therefore the present study was undertaken to compare different PLA/ceramic composite scaffolds obtained by supercritical gas foaming in a critical size defect craniotomy model in Sprague–Dawley rats. The host‐tissue reaction to the implants was evaluated semiquantitatively and similar tendencies were noted for all graft substitutes: initially highly reactive but decreasing with time implanted. Complete bone‐bridging was observed 18 weeks after implantation with PLA/ 5 wt % β‐TCP (PLA/TCP) and PLA/5 wt % HA (PLA/HA) scaffolds as assessed by histology and radiography. We show here for the first time that this solvent‐free technique provides a promising approach in tissue engineering demonstrating both the biocompatibility and osteoconductivity of the processed structures in vivo. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Parapancreatic castleman disease: Contrast‐enhanced sonography and CT features
Authors: Mangini Monica , Aiani Luca , Bertolotti Elena , Imperatori Andrea , Rotolo Nicola , Paddeu Antonio , Uccella Silvia , Carrafiello Gianpaolo , Fugazzola Carlo 
Published: March 2007

AbstractCastleman disease is a rare lymphoproliferative disorder that can be classified into 3 types: hyaline‐vascular, plasma cell, and mixed. We report a rare case of localized parapancreatic hyaline‐vascular Castleman disease that was evaluated using contrast‐enhanced sonography and CT. © 2007 Wiley Periodicals, Inc. J Clin Ultrasound, 2007
Sonographic appearance of epididymal microlithiasis
Authors: Vandervelde Clive , Varghese Ajay , Mason Althea , Howlett David 
Published: March 2007

AbstractWe report a case of epididymal microlithiasis that was diagnosed sonographically in a 75‐year‐old man undergoing scrotal sonographic examination to investigate right groin pain associated with an inguinal hernia. The sonographic appearance was that of multiple comet‐shaped foci of microcalcification throughout both epididymides, with associated comet‐tail artifacts. The testes had normal appearance with no evidence of testicular microlithiasis. The patient subsequently remained well after hernia repair. To our knowledge, epididymal microlithiasis has only previously been reported in a cadaveric study; the authors of that study hypothesized that the condition is caused by aging, with ischemia likely implicated in the pathogenesis. There are many other patterns of extratesticular calcification, including sperm granuloma, hematoma, and chronic epididymitis. We discuss how these differ in appearance from epididymal microlithiasis. Epididymal microlithiasis is a completely separate entity from testicular microlithiasis and should be recognized and dismissed by sonographers and radiologists. © 2007 Wiley Periodicals, Inc. J Clin Ultrasound, 2007
Endosonographic diagnosis and follow‐up of phlegmonous gastritis
Authors: Kan‐no Yukiko , Irisawa Atsushi , Takagi Tadayuki , Shibukawa Goro , Wakatsuki Takeru , Suzuki Eiji , Iwadate Haruyo , Sasajima Tomomi , Imamura Hidemichi , Takahashi Yuta , Hikichi Takuto , Ohira Hiromasa 
Published: March 2007

AbstractWe report a case of phlegmonous gastritis in a 36‐year‐old man presenting with anorexia, epigastralgia, and high fever. Endoscopy showed an edematous lesion suggesting a submucosal lesion. Endosonography revealed thickening of the gastric wall, mainly involving the submucosa, with a few anechoic areas. The separation between the submucosa and the muscularis propria was unclear. The patient was treated with antibiotics and endoscopic mucosal resection. Culture of the aspirated pus from the lesion revealed Streptococcus pyogenes. Follow‐up endosonography performed 1 week later showed significant improvement. © 2007 Wiley Periodicals, Inc. J Clin Ultrasound, 2007
Genomic organization, gene structure, and developmental expression of three Clustered otx genes in the sea anemone Nematostella vectensis
Authors: Mazza Maureen E. , Pang Kevin , Martindale Mark Q. , Finnerty John R. 
Published: March 2007

AbstractOtx homeodomain transcription factors have been studied in a variety of eumetazoan animals where they have roles in anterior neural development, endomesoderm formation, and the formation of larval ciliated fields. Here, we describe the gene structure and developmental expression of three Otx loci in the starlet sea anemone, Nematostella vectensis (phylum Cnidaria; class Anthozoa). Nematostella's three Otx genes (OtxA, OtxB, and OtxC) are located in a compact genomic cluster spanning 63.6 kb. The homeodomains of all three Otx genes are highly similar to their bilaterian counterparts, but only OtxB exhibits the conserved WSP motif that is located downstream of the homeodomain in many Otx proteins. The genomic organization, in concert with phylogenetic analyses, indicates that two tandem duplications occurred in the lineage leading to Nematostella some time after the Cnidaria diverged from the Bilateria. In situ hybridization reveals that otx is initially expressed by invaginating mesendodermal cells in the gastrula. Later, each of the three otx paralogs is expressed in three discrete larval body regions: in the endoderm of the foot or physa, in an endodermal ring surrounding the pharynx, and in the ectoderm of the tentacles. These data suggest that a single otx locus had already acquired diverse developmental functions in the cnidarian‐bilaterian ancestor. Furthermore, following two gene duplications in the line leading to Nematostella, there have been only minor alterations in the spatiotemporal expression of the three Otx paralogs. However, the absence of a conserved protein domain in OtxA and OtxC suggests functional evolution of the protein itself. J. Exp. Zool. (Mol. Dev. Evol.) 308B:494–506, 2007. © 2007 Wiley‐Liss, Inc.
Fast “real time” imaging with different k‐space update strategies for interventional procedures
Authors: Busch Martin , Bornstedt Axel , Wendt Michael , Duerk Jeffrey L. , Lewin Jonathan S. , Grönemeyer Dietrich 
Published: March 2007

AbstractInterventional procedures under MR guidance require the images to be acquired with a fast acquisition strategy, a rapid reconstruction algorithm for “real‐time” imaging (ie, high temporal resolution), acquisition of at least three adjacent slices to track a tool reliably, and high tissue contrast to ensure safe positioning of interventional devices. Often times, the field strength for interventional MR‐imaging units is limited by the open magnet design. This complicates the trade‐off between scan time and image quality, particularly when applied during low field interventional MRI procedures. To minimize the impact of some of these tradeoffs, a combination of keyhole techniques or modified k‐space trajectories, in conjunction with a fluoroscopic (ie, continuous acquisition) mode and a real time reconstruction, permits rapid imaging in a low field system using standard (speed optimized) reconstruction hardware and standard gradient electronics. The purpose of this study was to design and describe different keyhole strategies that can be used in a real time mode to increase the image frame rate by a factor of up to 16. By updating the entire raw data space with our strategies, even small changes of the object could be recognized. Our results using these new strategies on two commercially available open magnet MR‐imaging units (Siemens Magnetom Open 0.2T resistive magnet, Toshiba Access 0.064T permanent magnet) and a 1.5T superconductive solenoidal magnet design imager (Siemens SP) are presented to show the potential of these acquisition strategies in interventional MRI. Furthermore, these strategies may also be helpful for several other medical applications requiring high temporal resolution like contrast‐enhanced breast imaging or functional brain imaging.
MR‐guided biopsy using a T2‐weighted single‐shot Zoom Imaging sequence (Local Look technique)
Authors: Buecker Arno , Adam Gerhard , Neuerburg Joerg M. , Glowinski Arndt , van Vaals Joop J. , Guenther Rolf W. 
Published: March 2007

AbstractThe purpose of this study was to demonstrate the utility of a T2‐weighted single shot turbo spin‐echo technique — the so‐called “Local Look” (LoLo) and more recently renamed “Zoom Imaging” technique — for MR‐guided percutaneous interventions. We performed 28 procedures on 22 patients using a 1.5‐T system for MR guidance. All procedures were controlled with the LoLo technique, which acquires T2‐weighted images in 600 msec. This is achieved by using a small field of view (250 × 125 mm) along with a maximum echo train length, the so‐called “single shot method.” To prevent backfolding artifacts, the 90° and 180° pulses were oriented orthogonally to each other. Because signal is created only in the region in which the pulses overlap, no backfolding can occur from outside this area. Half of the biopsies were additionally monitored using a fast gradient‐echo sequence, which was compared with the LoLo technique. All of the procedures were technically successful, and there were no procedural complications. The LoLo technique produced images that had good contrast between the lesion and the needle artifact, and the artifact size was smaller than that produced by the gradient‐echo technique. Subjective judgment of the ability to accurately delineate the needle tip indicated that the LoLo technique was either superior to (73%) or equal to (27%) the gradient‐echo sequence in all cases. The LoLo technique is an accurate and effective method for MR guidance of percutaneous procedures, because it shows good lesion contrast and small needle artifacts. The additional use of a gradient‐echo sequence during the procedure planning stage is advisable in more difficult cases, particularly when adjacent blood vessels are a concern. Monitoring of the needle tip is best performed with the LoLo technique.
Gradient echo MRI for measurement of the pulmonary autograft diameter after transplantation to the aortic root: Validation and comparison with ultrasound
Authors: Hokken Raymond B. , de Bruin Hein G. , Taams Meindert A. , Bogers Ad J. J. C. , van Herwerden Lex A. , Roelandt Jos R. T. C. , Bos Egbert , Oudkerk Matthijs 
Published: March 2007

AbstractThe purpose of this study was to s the value of MRI for measurement of pulmonary autograft diameters after transplantation to the aortic root in adults. Thirty‐eight adults underwent this operation. MRI and trans‐esophageal echocardiography (TEE) were performed in 30 and 27 patients, respectively, after a mean follow‐up period of 2.8 years. For internal validation of MRI, measurements at the diastolic short and long axes of the sinus level were used. Pulmonary autograft diameters were measured and compared with MRI and TEE at five different levels: the subannular region (1), an‐nulus (2), sinus (3), sinotubular junction (4), and the distal part of the autograft (5). The correlation coefficient (r2) between long‐ and short‐axis measurements for corresponding sinuses was .97. Diameters obtained with MRI were 1 to 3 mm larger than those obtained with TEE (P < .05), except for the annulus at systole (P > .3). Cine gradient echo MRI is an appropriate technique to evaluate pulmonary autograft diameters during follow‐up. Concordance with TEE was good, apart from a systematic difference of ≈︁ 2 mm.
Optimized outer volume suppression for single‐shot fast spin‐echo cardiac imaging
Authors: Le Roux Patrick , Gilles Raymond J. , McKinnon Graeme C. , Carlier Pierre G. 
Published: March 2007

AbstractAmong the ultrafast MRI techniques, the single‐shot fast spin‐echo sequence offers a robust alternative to echo planar imaging, essentially because of a much reduced sensitivity to B0 inhomogeneity. This property is particularly appealing in situations in which B0 in‐homogeneities can be severe and difficult to correct, such as in cardiac imaging. With single‐shot cardiac imaging, however, achieving high resolution over the necessarily large field of views without introducing back‐folding artifacts is problematic. One option is to use multishot sequences. However, then issues related to cardiac gating arise. Another solution is to use, optimized presaturation slabs with quadratic phase pulses generated by the Shinnar‐LeRoux algorithm. These can be set to reduce the field of view in the phase‐encoding direction, resulting in a reduction in the number of phase‐encoding steps. For instance, for a 1 × 2‐mm spatial resolution, over a rectangular, 250 × 125‐mm field of view, and using a half Fourier acquisition, an echo‐train length of only 40 is required. With a 4.5‐msec echo spacing, the total imaging time is ≈︁ 180 msec. The efficacy of this solution on phantoms and volunteers is demonstrated. Multislice short‐axis examinations of the whole heart, realized within a single short breath‐hold of ∼ 10 seconds, are shown. The possibility of investigating not only cardiac anatomy but also both contractility and myocardial perfusion is discussed.
Three‐dimensional high‐resolution dynamic contrast‐enhanced MR angiography of the pelvis and lower extremities with use of a phased array coil and subtraction: Diagnostic accuracy
Authors: Yamashita Yasuyuki , Mitsuzaki Katsuhiko , Ogata Ichiro , Takahashi Mutsumasa , Hiai Yasuhiro 
Published: March 2007

AbstractIn this study, our purpose was to compare the high‐resolution contrast‐material‐enhanced three‐dimensional subtraction MR angiography with conventional angiography for occlusive disease in the pelvic and lower extremity arteries. A three‐dimensional fast‐imaging with steady precession (FISP) sequence with a 256 × 512 matrix was obtained on 1.5T MR unit using a phased array coil. Twenty patients with arteriosclerotic obstructive disease underwent subtraction dynamic contrast‐enhanced MR angiography. In 15 patients, three regions (pelvis, upper knee, and lower knee) were sequentially obtained after repeated injection of gadolinium‐diethylenetriamine pentaacetic acid (Gd‐DTPA). In the other five patients, one region was imaged (total of 50 examinations); a maximum‐intensity projection (MIP) algorithm was used for subtracted images. All patients also underwent conventional angiography. Angiographic images were divided into several anatomical segments. Three blinded radiologists independently graded a total of 50 anatomic segments with stenotic or obstructive diseases and 90 segments without disease. Subtracted images allowed resolution of small branch vessels in all examinations, although misregistration was seen in eight examinations of five patients. All arteries larger than 1 mm in diameter were visualized on subtracted images. For detection of significant stenosis (>50%), MR angiography had 96% sensitivity and 83% specificity. The correlation coefficient of degree of agreement between MR angiography and conventional angiography was .92. Stenotic vessels tended to be overestimated. We conclude that high‐resolution dynamic contrast‐enhanced three‐dimensional MR angiography is capable of depicting small vessel anatomy of the pelvis and lower extremities. Sequential MR angiography of different regions was feasible by repeated injection of Gd‐DTPA and subtraction. This technique is highly sensitive in detecting lesions, but stenosis tended to be overestimated.
A new method for imaging perfusion and contrast extraction fraction: Input functions derived from reference tissues
Authors: Kovar David A. , Lewis Marta , Karczmar Gregory S. 
Published: March 2007

AbstractThis study describes a new method for analysis of dynamic MR contrast data that greatly increases the time available for data acquisition. The capillary input function, CB(t), is estimated from the rate of contrast agent uptake in a reference tissue such as muscle, based on literature values for perfusion rate, extraction fraction, and extracellular volume. The rate constant for contrast uptake (the product of perfusion rate, F, and extraction fraction, E; F‐E) is then determined in each image pixel using CB(t), extracellular volume (relative to the reference tissue) measured from MR and the tissue concentration of contrast media as a function of time calculated from the MR data. The “reference tissue method” was tested using rats with mammary (n = 10) or prostate (n = 15) tumors implanted in the hindlimb. Dynamic MR images at 4.7 T were acquired before and after Gd‐DTPA intravenous bolus injections to determine F·EGd‐DTPA. Acquisition parameters were optimized for detection of the first pass of the contrast agent bolus, so that “first‐pass analysis” could be used as the “gold standard” for determination of F·E. The accuracy of values of F·E determined using the reference tissue method was determined based on comparison with first‐pass analysis. In some cases, deuterated water (D2O) was injected IV immediately after Gd‐DTPA measurements, and the reference tissue method was used to calculate F, based on the rate of uptake of D2O. Comparison of rate constants for Gd‐DTPA uptake and D2O uptake allowed calculation of EGd‐DTPA. Values for F·EGd‐DTPA, F, and EGd.DTPA were determined for selected regions and on a pixel‐by‐pixel basis. Values for F·E and EGd.DTPA measured using the reference tissue method correlated well (P = .90 with a standard error of ±.016, n = 15) with values determined based on first‐pass contrast media uptake. The reference tissue method has important advantages: (a) A large volume of reference tissue can be used to determine the contrast agent input function with high precision. (b) Data obtained for 20 minutes after injection are used to calculate F or F·E. The greatly increased acquisition time can be used to increase the spatial resolution, field of view or SNR of measurements. The reference tissue method is most useful when the volume of tissue that must be imaged and/or the spatial resolution required precludes use of traditional first‐pass methods.
Limits to the accuracy of vessel diameter measurement in MR angiography
Authors: Hoogeveen Romhild M. , Bakker Chris J. G. , Viergever Max A. 
Published: March 2007

AbstractThis work addresses the fundamental limits imposed by the MRI process on the accuracy with which vessel diameters and cross‐sectional areas can be derived from time‐of‐flight (TOF) and phase‐contrast (PC) MR source images. By means of simulations and in vitro experiments, it is demonstrated that, even in the absence of flow‐related artifacts, severe inaccuracies in the determination of diameters or cross‐sectional areas may occur solely because of the physical process of the MR image acquisition. Resolution and intraluminal saturation have strong effects on the vessel appearance and thus on the diameter estimation error. It is shown that low resolution leads to diameter overestimation or even underestimation and that intraluminal saturation causes severe underestimation, even for relatively low flip angles. Velocity and velocity encoding do not have a major influence on lumen appearance in PC images. Accurate diameter estimations can be attained only if lumen diameters constitute at least three pixels for both TOF and PC acquisitions, provided that intraluminal saturation is suppressed or avoided. Additionally, since the constitution of TOF and PC images is dissimilar, lumina should be analyzed differently to obtain accurate diameters and cross‐sectional areas.
In Vivo quantitative mapping of cardiac perfusion in rats using a noninvasive MR spin‐labeling method
Authors: Belle Valérie , Kahler Elke , Waller Christiane , Rommel Eberhard , Voll Sabine , Hiller Karl‐Heinz , Bauer Wolfgang R. , Haase Axel 
Published: March 2007

AbstractMeasurement of myocardial perfusion is important for the functional assessment of heart in vivo. Our approach is based on the modification of the longitudinal relaxation time T1 induced by magnetic spin labeling of endogenous water protons. Labeling is performed by selectively inverting the magnetization within the detection slice, and longitudinal relaxation is measured using a fast gradient echo MRI technique. As a result of blood flow, nonexcited spins enter the detection slice, which leads to an acceleration of the relaxation rate. Incorporating this phenomenon in a mathematical model that describes tissue as two compartments yields a simple expression that allows the quantification of perfusion from a slice‐selective and a global inversion recovery experiment. This model takes into account the difference between T1 in blood and T1 in tissue. Our purpose was to evaluate the feasibility and reproducibility of this technique to map quantitatively myocardial perfusion in vivo in rats. Quantitative maps of myocardial blood flow were obtained from nine rats, and the reproducibility of the technique was evaluated by repeating the whole perfusion experiment four times. Evaluation of regions of interest within the myocardium yielded a mean perfusion value of 3.6 ± .5 ml min−1 g‐1 over all animals, which is in good agreement with previously reported literature values.