bluuebunny/crossref_metadata_2025_split huggingface dataset:
Egg jelly of the newt, Cynops pyrrhogaster contains a factor essential for sperm binding to the vitelline envelope
Authors: Hiyoshi Wataru , Sasaki Takayuki , Takayama‐Watanabe Eriko , Takai Hiroyuki , Watanabe Akihiko , Onitake Kazuo 
Published: March 2007

AbstractThe acrosome reaction of newt sperm is induced at the surface of egg jelly and the acrosome‐reacted sperm acquire the ability to bind to the vitelline envelope. However, because the substance that induces the acrosome reaction has not been identified, the mechanism by which the acrosome‐reacted sperm bind to the vitelline envelope remains unclear. We found here that a Dolichos biforus agglutinin (DBA) specifically mimicked the acrosome reaction immediately upon its addition in the presence of milimolar level Ca2+. Fluorescein isothiocyanate‐labeled DBA bound specifically to the acrosomal cap of the intact sperm in the presence of a Ca2+‐chelating agent, EDTA, suggesting that binding of DBA to the native receptor for the egg jelly substance on the acrosomal region took the place of the egg jelly substance‐induced acrosome reaction. In contrast, the sperm that had been acrosome reacted by DBA treatment did not bind to the vitelline envelope of the egg whose jelly layers were removed. Subsequent addition of jelly extract caused the sperm binding to vitelline envelope, indicating that the egg jelly of the newt contains substances that are involved in not only inducing the acrosome reaction but also binding to the vitelline envelope. This is the first demonstration of the involvement of egg jelly substance in the binding of acrosome‐reacted sperm to the vitelline envelope. J. Exp. Zool. 307A:301–311, 2007. © 2007 Wiley‐Liss, Inc.
Black blood dual phase turbo FLASH MR imaging of the heart
Authors: Sinha Shantanu , Sinha Usha 
Published: March 2007

AbstractAn MR imaging scheme for dark blood cardiac images acquired simultaneously in e∼d diastolic and end systolic phases, in breath‐hold times, is presented. The sequence consists of a magnetization preparation period followed by two segmented k‐space acquisitions. Image quality was investigated with respect to different sequence parameters (optimal values are indicated in brackets): (a) echo time (TE)/repetition time (TR)/flip angle (FA) (3/6.2 msec/20°); (b) number of lines/segments in the acquisition window (11 lines/segment); (c) location of acquisition windows and inversion time; and (d) thickness of slice „reinverted”︁ during preparation (1.53 times the acquisition slice thickness). The image quality of the basal slices at end systole was critically dependent on the last parameter. High quality short axis views of the heart, with good blood signal suppression, were acquired with the optimized sequence on four volunteers from apex to base at two phases in 10 breath‐holds.
Dynamic range extension of cine velocity measurements using motion registered spatiotemporal phase unwrapping
Authors: Yang Guang Z. , Burger Peter , Kilner Philip J. , Karwatowski Stefan P. , Firmin David N. 
Published: March 2007

AbstractA motion‐registered spatiotemporal phase‐unwrapping method for extending the dynamic range of cine magnetic resonance phase velocity measurements is presented. The interframe cardiac movement is estimated from the magnitude image derived from the velocity encoded raw data, which ensures that the phase signal is unwrapped in the temporal direction with reference to pixels belonging to the same anatomic flow region. An extra step of spatial phase correction is then used to further eliminate any residual errors. The combination of spatial and temporal information for phase unwrapping provides a robust way of extending the dynamic range of cine velocity data in the presence of large phase aliasing errors.
The effects of time varying intravascular signal intensity and k‐space acquisition order on three‐dimensional MR angiography image quality
Authors: Maki Jeffrey H. , Prince Martin R. , Londy Frank J. , Chenevert Thomas L. 
Published: March 2007

AbstractThe optimum infusion timing and k‐space ordering for obtaining gadolinium‐enhanced three‐dimensional MR angiograms was determined through computer modeling using temporal contrast characteristics obtained from patient gadolinium infusion data. The effects of bolus timing were evaluated by varying the relationship between peak intravascular gadolinium concentration and the time at which the center of k space was acquired (tck) for sequential and centric acquisition techniques. Flow phantom experiments were performed to validate the theoretical computations.Gadolinium concentration at the time of central k‐space acquisition determines intravascular signal intensity. Artifacts, including vessel broadening and edge ringing, depend on the order in which k space is collected and on how rapidly the gadolinium concentration changes. Artifacts are greatest when the center of k space is acquired before the intravascular gadolinium peak. Application of the optimal infusion timing results in preferential arterial enhancement with a minimum of artifacts in patients undergoing MR angiography.
Viscoelastic property detection by elastic displacement NMR measurements
Authors: Lewa Czeslaw J. , De Certaines Jacques D. 
Published: March 2007

AbstractAn attempt was undertaken to analyze the phase changes in the transverse magnetization component, M[perp], determined in NMR response by an elastic wave in the presence of two pulses with opposite magnetic field gradient directions. The obtained theoretical results indicate that such changes are significant in biologic tissues. Their measurement by NMR opens up new possibilities for detecting the displacement and some viscoelastic properties such as the adiabatic compressibility coefficient, amplitude wave damping coefficient, frequency and dispersion strength of elastic relaxation processes, etc. The method may be useful in basic applied research and in medical diagnosis of some diseases resulting in the variation of elastic properties of biological tissues, eg, atherosclerosis.
High speed diffusion imaging in the presence of eddy currents
Authors: Sinha Usha , Sinha Shantanu 
Published: March 2007

AbstractThis paper describes two schemes for fast diffusion imaging on a 1.5‐T MRI unit with unshielded gradients and 10‐mT/m gradient system. The prepared longitudinal magnetization is sampled by a turbo fast low‐angle shot (FLASH) sequence. The first scheme involves modifications to a diffusion‐weighted driven‐equilibrium preparation sequence that yields quantitative diffusion imaging. The second scheme consists of four 90° pulses that form the preparatory period with diffusion gradients applied between the first and last two 90° pulses. Sufficient time is allowed between the diffusion gradients and the beginning of the echo readout to allow eddy currents to decay to an acceptable level. Phantom studies show agreement between diffusion coefficients in the literature with those determined using the above schemes. The potential application of these sequences in monitoring temperature is demonstrated in phantoms. Artifact‐free quantitative diffusion‐weighted images of the brain using the second scheme are presented.
MR prediction of benign and malignant vertebral compression fractures
Authors: Moulopoulos Lia A. , Yoshimitsu Kengo , Johnston Dennis A. , Leeds Norman E. , Libshitz Herman I. 
Published: March 2007

AbstractWe reviewed spinal MR images of 58 patients with 98 compressed vertebrae. Benign (47 vertebrae) or malignant (51 vertebrae) etiology was established by biopsy or radiologic follow‐up. Compressed vertebrae were analyzed for presence and characteristics of signal abnormality, altered vertebral contour, Schmorl's nodes, pedicular involvement, and contrast uptake. Statistical analysis was performed. Diffuse and homogeneous decrease in signal intensity on T1‐weighted images, convex vertebral contour, involvement of the pedicles, and a lumbar location were more frequently observed in malignant fractures (P < .01). A thoracic location, lack of signal change, or a band‐like abnormality and absence of pedicular involvement or contour abnormality characterized benign fractures (P < .01). Schmorl's nodes and enhancement did not help establish a diagnosis. When a constellation of MR criteria are applied, the accuracy of the diagnosis of malignant and benign vertebral compression fractures may reach 94%.
Differentiating between T1 and T2* changes caused by gadopentetate dimeglumine in the kidney by using a double‐echo dynamic MR imaging sequence
Authors: Kuperman Vadim Y U. , Karczmar Gregory S. , Blomley Martin J. K. , Lewis Marta Z. , Lubich Leslie M. , Lipton Martin J. 
Published: March 2007

AbstractDynamic MR images of the passage of gadopentetate dimeglumine through the kidneys of normal rats are obtained using a dual gradient‐echo sequence. The amplitudes of gradient echoes are defined by local T1 and T2* values in the tissue. The ratio of these amplitudes, primarily defined by local T2*, can be used to differentiate between T1 and T2* effects. This is particularly important with regard to renal studies because, due to a highly inhomogeneous distribution of gadopentetate dimeglumine in the kidney, T2* shortening can impede MR data analysis. To study changes in the observed signal caused by gadopentetate dimeglumine, curves of MR renal intensity versus time were obtained in the cortex and medulla after administration of the contrast agent. Using T2* compensation, distinct temporal peaks were observed in the cortex and outer medulla, indicating a high concentration of gadopentetate dimeglumine in the vascular phase. The authors conclude that this technique can be a useful tool for studying renal function noninvasively.
Anterior disc displacement without reduction in the temporomandibular joint: MRI and associated clinical findings
Authors: Müller‐Leisse Christoph , Augthun Michael , Bauer Waltraud , Roth Auke , Günther Rolf 
Published: March 2007

AbstractTo determine the value of MRI in temporomandibular joint (TMJ) disorders, the data of MRI‐proven anterior disc dislocation without reduction (ADWOR) were correlated with clinical history and clinical data. MRI demonstrated degenerative bony changes and a reduced sagittal diameter of the condyle, a variable degree of disc deformation, and a thinned bilaminar zone in each of the joints with ADWOR, which clearly differed from patients with anterior disc dislocation with reduction (ADWR) (P = .01) and normal disc position (NDP) (P < .001). Of 59 patients and 83 TMJs that had been investigated in a 2‐year period, as shown by MRI, 22 patients (27 TMJs) had ADWOR (32 %), 16 joints had NDP (19 %), and 40 patients had ADWR (49 %). In patients with ADWOR, the clinical history revealed pain in either of the joints and/or cervical or masticatory muscles in 25 (93%) joints. Clinical investigation revealed various abnormalities in 22 joints; five of those presented without any pathologic clinical finding. Mouth opening was unlimited in nine patients (47%), palpation of the muscles of mastication was painless in 13 patients (52%), and joint noises during mouth opening or closing were noted in 14 patients (56%). According to clinical histories, four patients were suspected to have become symptomatic only after dental treatment. ADWOR is difficult to diagnose with clinical methods alone. The indication for MRI evaluation of the TMJ should be extended for asymptomatic patients with a history of limitation in mouth opening and pathologic x‐ray morphology of the condyle. Because symptoms may arise after dental treatment in these patients, aggravation of internal derangement may be avoided by careful handling.
MR lesion detection in a breast cancer population
Authors: Obdeijn Inge‐Marie A. , Kuijpers Theodore J. A. , van Dijk Pieter , Wiggers Theodore , Oudkerk Matthijs 
Published: March 2007

AbstractImplementation of MR imaging of the breast as an extension of the existing imaging modalities in the diagnosis of breast cancer was evaluated in a university cancer center. MR imaging of the breast was performed in 54 patients, in whom the MR results were compared with the triple test (the combination of clinical examination, mammographic evaluation, and cytology) and the final histological diagnosis. MR imaging of the breast depicted 30 of the 33 malignancies (sensitivity, 91%). In two of the malignancies, the carcinoma was clinically and mammographically occult. For the three patients with a false‐negative MRI diagnosis, the conventional mammography showed suspicious clustered microcalcifications as a sign of in situ carcinoma. For seven patients, MR imaging of the breast incorrectly suggested the presence of a malignant lesion (specificity, 67%). To improve MR specificity, we perform MR‐guided ultrasonographic fine‐needle aspiration biopsy (FNAB). Although MR imaging of the breast is a highly sensitive examination, conventional x‐ray mammography remains the most efficient imaging modality in the diagnosis of breast cancer. In our patient population, MR imaging of the breast had additional value for women with mammographically dense breast tissue and especially for patients with clinical evidence of breast carcinoma that could not be detected with conventional diagnostic methods.
Multislice T1‐weighted hybrid rare in CNS imaging: Assessment of magnetization transfer effects and artifacts
Authors: Melhem Elias R. , Jara Hernan , Yucel E. Kent 
Published: March 2007

AbstractUsing a T1‐weighted hybrid rapid acquisition with relaxation enhancement (RARE) MR sequence that implements an echo‐to‐view mapping scheme termed “low‐high profile order,” we evaluated signal intensity changes in different brain tissues as a function of number of slices, interslice gap, and echo train length (ETL). We also measured phase‐encode and frequency‐encode noise as well as blurring artifacts along the phase‐encode direction as a function of ETL. Off‐resonance magnetization transfer effects were demonstrated to be responsible for signal intensities changes in white matter and gray matter when using multislice techniques. These effects are amplified by increasing the number of slices and ETL. Due to the nature of the implemented echo‐to‐view mapping scheme, no on‐resonance magnetization transfer effects were observed from the intraslice echo train. Selective background (white matter and gray matter) suppression in multislice T1‐weighted hybrid RARE, secondary to off‐resonance magnetization transfer effects, may provide better contrast resolution of enhancing central nervous system (CNS) lesions at much shorter scan time as compared to conventional spin‐echo T1‐weighted sequences. This improvement in contrast resolution as a function of ETL may be limited by worsening phase‐encode noise and blurring artifacts.
Separation of water and fat MR images in a single scan at .35 T using „sandwich”︁ echoes
Authors: Zhang Weiguo , Goldhaber David M. , Kramer David M. 
Published: March 2007

AbstractA method was developed for separation of water and fat MR images in a single scan with correction of static field inhomogeneity. The imaging sequence uses a single radiofrequency (RF) echo that is „sandwiched”︁ between two gradient echoes. The gradient echoes are used to determine the Bo distribution and to produce out‐of‐phase images after phase correction using the field map. An algorithm was developed to unwrap the phase images for quantitating the Bo inhomogeneity. To account for differences in geometric distortion between the RF echo image and the gradient echo images due to the reversal of the read gradients, methods were developed to correct the images before the calculation of the final water and fat images. The proposed technique was implemented at .35 T. Both phantom and human images were acquired using the method. It is shown that water‐ and fat‐separated images can be obtained in a single scan using the „sandwich”︁ echoes in the presence of a relatively large Bo inhomogeneity.
Analysis and comparison of motion‐correction techniques in diffusion‐weighted imaging
Authors: Trouard Theodore P. , Sabharwal Yashvinder , Altbach Maria I. , Gmitro Arthur F. 
Published: March 2007

AbstractMotion continues to be a significant problem in MRI, producing image artifacts that can severely degrade image quality. In diffusion‐weighted imaging (DWI), the problem is amplified by the presence of large gradient fields used to produce the diffusion weighting. Three correction methods applicable for correction of specific classes of motion are described and compared. The first is based on a generalized projection onto convex sets (GPOCS) postprocessing algorithm. The second technique uses the collection of navigator echoes to track phase errors. The third technique is based on a radial‐scan data acquisition combined with a modified projection‐reconstruction algorithm. Although each technique corrects well for translations, the radial‐scan method proves to be more robust when more complex motions are present. A detailed description of the causes of MR data errors caused by rigid body motion is included as an appendix.
Single‐shot GRASE imaging with short effective TEs
Authors: Johnson Glyn , Feinberg David A. , Venkataraman Viswanathan 
Published: March 2007

AbstractA new phase‐encoding scheme for gradient‐ and spin‐echo (GRASE) imaging giving a short effective TE is described. Unlike previous orders, phase encoding is centric rather than sequential. The sequence is a development of k‐banded GRASE that uses different time segments of the echo train to encode different bands of k space. This phase‐encoding order has been implemented in single‐shot sequences on an imager with high performance gradients. Approximately 144 phase‐encoding lines can be acquired in an echo train time of 390 ms. With centric phase encoding, the effective TE is 8 ms, compared with 75 ms for sequential encoding, and signal‐to‐noise ratios (SNRs) in brain tissue are 50 to 70% higher. The sequence can be employed in, for example, diffusion and velocity imaging.
Development of an MRI‐compatible catheter for pacing the heart: Initial in vitro and in vivo results
Authors: Jerzewski Anastazia , Pattynama Peter M. T. , Steendijk Paul , Doornbos Joost , de Roos Albert , Baan Jan 
Published: March 2007

AbstractAn MRI‐compatible catheter was developed for pacing the heart during MRI imaging. The device was tested in vitro and in vivo in 10 animal experiments, using spin‐echo, gradient‐echo, and echo‐planar MRI sequences. Images were of good quality in all sequences. Pacing was effective without induced arrhythmias. Therefore, pacing the heart during MRI is feasible and seems to be safe when using dedicated hardware.
Ceramic surgical instruments: Ex vivo evaluation of compatibility with MR imaging at 1.5 T
Authors: Shellock Frank G. , Shellock Vincent J. 
Published: March 2007

AbstractThe purpose of this study was to evaluate the MR compatibility of ceramic instruments. Nine different ceramic instruments were tested with respect to ferromagnetism, heating, and artifacts using previously described techniques. There was no magnetic field attraction, temperature increases were ≤.1°C, and artifacts involved a signal void similar to the size and shape of each instrument. The ceramic instruments were demonstrated to be compatible with MR imaging and acceptable for use during intraprocedural MR imaging.
A simulation study to assess SVD encoding for interventional MRI: Effect of object rotation and needle insertion
Authors: Duerk Jeffrey L. , Wu Dee H. , Chung Y. C. , Liang Zhi‐Pei , Lewin Jonathan S. 
Published: March 2007

AbstractSingular value decomposition (SVD) encoding offers great promise to provide high spatial and temporal resolution required for interventional MRI (I‐MRI) (1). This study investigates its efficacy when (a) objects are rotated and (b) a small device (ie, a needle) is moved within anatomic structures. It was found that SVD‐encoded MRI is biased toward the reference from which encoding vectors are derived, thus providing a potential limitation under conditions in which the object has undergone significant global change. Reference images with partial device insertion may be needed to accurately resolve the device or track the object motion. Theoretically, the differences between the reference and the object being imaged suggest that SVD encoding is suboptimal (in a minimum mean squared error sense). Other encoding/reconstruction algorithms may come closer to achieving the desired advantages in spatial and temporal fidelity.
MR imaging of the female pelvic floor in the supine and upright positions
Authors: Fielding Julia R. , Versi E. , Mulkern R. V. , Lerner M. H. , Griffiths D. J. , Jolesz F. A. 
Published: March 2007

AbstractThe goal of this study was to determine whether a .5‐T open configuration magnet system could be used to evaluate the female pelvic floor support structures and their functional changes in the upright and supine positions. We evaluated five normal volunteers with full bladders in the supine and sitting positions. Multiple measurements were obtained, including distance between symphysis and urethra, bladder neck to fixed pubococcygeal line, and posterior urethrovesical angle. The pelvic floor was evaluated for integrity of the urethra, vagina, and supporting ligaments. High quality, interpretable images were obtained for all five patients in both positions. Most of the pelvic floor structures were stable, with the exception of the posterior urethrovesical angle, which increased in the sitting position. We conclude that the vertically open configuration magnet system shows promise for evaluation of the female pelvic floor, including urinary stress incontinence and prolapse.
Artifact in SE phase images can mimic aortic dissection
Authors: Boer Jacques A. Den , Rozeboom Alfred R. 
Published: March 2007

AbstractPhase images of cardiac‐triggered thoracic spin‐echo scans can present an artifactual border‐like feature across the aorta. This may be misinterpreted as a dissection. The artifact results from helical flow in the aorta; cause and appearance of the artifact are discussed.
Principles of contrast enhancement in the evaluation of brain diseases: An overview
Authors: Runge Val M. , Muroff Lawrence R. , Wells John W. 
Published: March 2007

AbstractIntravenous contrast media are widely used in MR imaging of the brain. Clinical utility is high in both neoplastic and non‐neoplastic disease. The agents approved to date are all gadolinium chelates, with extracellular distribution and renal excretion. The agents differ in regard to the maximum dose that can be administered and the theoretical safety margin. When administered at the same dose, the efficacy of the different available agents is comparable. Described in the following review article are the diagnostic use of contrast media and the patterns of enhancement encountered in neoplastic disease, infection, vascular disorders, and diseases of white matter. Only in congenital brain disease, when acute abnormalities are not suspected clinically and neoplastic disease is not a question, is contrast enhancement not indicated.The gadolinium chelates play a major role in the evaluation of patients by MR with known or suspected brain disease. These agents improve both the sensitivity and specificity of the examination. In many cases, lesions cannot be identified before contrast administration. Lesion delineation, assessment of lesion activity, and differential diagnosis are all improved, in general, with the addition of postcontrast scans. The scope of applications continues to expand as the modality and clinical experience matures.
Effects of contrast dose, delayed imaging, and magnetization transfer saturation on gadolinium‐enhanced MR imaging of brain lesions
Authors: Mathews Vincent P. , Caldemeyer Karen S. , Ulmer John L. , Nguyen Hoang , Yuh William T. C. 
Published: March 2007

AbstractThis paper discusses the types of paramagnetic agents available for clinical brain imaging and reviews investigations that have sought to optimize the use of these agents by varying the administered dose, delaying the imaging time after contrast administration, and altering image contrast by using magnetization transfer saturation pulses.