bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of transmural, endocardial, and epicardial radial strain and strain rate from phase contrast MR velocity data
Authors: Delfino Jana G. , Fornwalt Brandon K. , Eisner Robert L. , Leon Angel R. , Oshinski John N. 
Published: January 2008

AbstractPurposeTo develop a method for computing radial strain (ε) and strain rate (SR) from phase contrast magnetic resonance (PCMR) myocardial tissue velocity data.Materials and MethodsPCMR tissue velocity maps were acquired at basal and mid‐short‐axis slices in the myocardium in 10 healthy volunteers. An algorithm for computing radial strain and SR from PCMR tissue velocity data was developed. PCMR strain values were compared to values computed independently from contours drawn on cine steady‐state free procession (SSFP) images. Peak endocardial and epicardial strain and SR values from PCMR data were compared.ResultsExcellent agreement was observed between peak strain values computed by PCMR and cine SSFP contours (38.1 ± 5.4% vs. 38.1 ± 6.2%; P = not significant [NS]). The presence of an endocardial‐epicardial gradient was demonstrated in both strain and SR: peak endocardial values were larger than peak epicardial values in the basal and mid‐short‐axis slices (P < 0.05).ConclusionThis study presents a method for determining radial strain and SR values from PCMR velocity data. This technique illustrates a difference in strain and SR across the myocardium with peak endocardial values being greater than peak epicardial values. J. Magn. Reson. Imaging 2008. © 2008 Wiley‐Liss, Inc.
Evaluation of quantitative magnetic resonance imaging, biochemical and mechanical properties of trypsin‐treated intervertebral discs under physiological compression loading
Authors: Mwale Fackson , Demers Caroline N. , Michalek Arthur J. , Beaudoin Gilles , Goswami Tapas , Beckman Lorne , Iatridis James C. , Antoniou John 
Published: January 2008

AbstractPurposeTo investigate the influence of targeted trypsin digestion and 16 hours compression loading on MR parameters and the mechanical and biochemical properties of bovine disc segments.Materials and MethodsTwenty‐two 3‐disc bovine coccygeal segments underwent compression loading for 16 hours after the nucleus pulposus (NP) of each disc was injected with a solution of trypsin or buffer. The properties of the NP and annulus fibrosus (AF) tissues of each disc were analyzed by quantitative MRI, biochemical tests, and confined compression tests.ResultsLoading had a significant effect on the MR properties (T1, T2, T1ρ, MTR, ADC) of both the NP and AF tissues. Loading had a greater effect on the MR parameters and biochemical composition of the NP than trypsin. In contrast, trypsin had a larger effect on the mechanical properties. Our data also indicated that localized trypsin injection predominantly affected the NP. T1ρ was sensitive to loading and correlated with the water content of the NP and AF but not with their proteoglycan content.ConclusionOur studies indicate that physiological loading is an important parameter to consider and that T1ρ contributes new information in efforts to develop quantitative MRI as a noninvasive diagnostic tool to detect changes in early disc degeneration. J. Magn. Reson. Imaging 2008. © 2008 Wiley‐Liss, Inc.
New macromolecular polymeric MRI contrast agents for application in the differentiation of cancer from benign soft tissues
Authors: Cyran Clemens C. , Fu Yanjun , Raatschen Hans‐Juergen , Rogut Victor , Chaopathomkul Bundit , Shames David M. , Wendland Michael F. , Yeh Benjamin M. , Brasch Robert C. 
Published: January 2008

AbstractPurposeTo compare three new macromolecular polyethylene glycol (PEG) ‐core dendrimeric gadolinium(Gd)‐based MRI contrast agents for their applicability in quantitative assays of endothelial leakiness and tissue vascular density for the differentiation of cancer from normal soft tissues.Materials and MethodsThirty‐two athymic rats with human breast cancer xenografts (MDA‐MB‐435) were imaged by dynamic MRI following enhancement with one of three new (Gd‐DOTA)‐conjugated PEG‐core dendrimer contrast agents (effective molecular weights 161 to 323 kDa). Results were compared with a prototype macromolecular contrast agent, albumin (Gd‐DTPA). Assays of permeabilities (KPS; μL/min · 100 cm3) and tumor fractional plasma volumes (%) based on a two‐compartment kinetic model were performed for skeletal muscle and tumors.ResultsThe largest PEG‐core contrast agent, PEG20,000‐Gen4‐(Gd‐DOTA), leaked in breast tumors (KPS = 50 ± 23 μL/min · 100 cm3), while exhibiting no measurable transendothelial leak (KPS = 0 μL/min · 100 cm3) in normal soft tissue microvessels allowing successful differentiation (P < 0.05) of cancers from normal muscle. PEG12,000‐Gen4‐(Gd‐DOTA) leaked in tumors and in normal muscle (KPS = 51 ± 26 and KPS = 21 ± 18μL/min · 100 cm3, respectively). The smallest agent, PEG12,000‐Gen3‐(Gd‐DOTA) also showed a measurable leak in both normal and malignant microvessels.ConclusionMRI assays of vascular endothelial leakiness using new PEG‐core, (Gd‐DOTA)‐conjugated macromolecular contrast agents proved applicable for the differentiation of human breast cancer from normal soft tissue. The apparent threshold in effective molecular weight for a clear differentiation of cancer from normal muscle with no measurable leak in the muscle is between 194 and 323 kDa. J. Magn. Reson. Imaging 2008. © 2008 Wiley‐Liss, Inc.
Serial postmortem relaxometry in the normal rat brain and following stroke
Authors: Fagan Andrew J. , Mullin Jim M. , Gallagher Lindsay , Hadley Donald M. , Macrae I. Mhairi , Condon Barrie 
Published: January 2008

AbstractPurposeTo investigate MRI for noninvasive autopsy by means of measurements of serial changes in relaxation parameters of the rat brain during the postmortem interval.Materials and MethodsPostmortem relaxometry measurements were performed before and hourly after death for 24 h on five control rats and five rats that underwent middle cerebral artery occlusion. Analyses were performed on representative regions of gray, white, and mixed gray/white matter structures.ResultsSignificant decreases in both T1 and T2 values were measured in all areas in the control group within 24 h of death. In the stroke animals, T2 differences between normal and ischemic striatal tissue decreased by 11 ± 4% (P < 0.01), with a complete convergence of T2 values observed between ischemic striatal tissue and nonischemic cortical tissue.ConclusionLesion conspicuity and the ability to differentiate between different tissue compartments are significantly affected by postmortem interval, and alterations to pulse timing parameters will be necessary if the sensitivity of MRI to detect central nervous system diseases in postmortem tissue is to be maintained. Indeed in the case of stroke at least, convergence of T2 values with normal tissue post mortem indicates that T1‐weighted images may be more sensitive to the presence of such lesions. J. Magn. Reson. Imaging 2008. © 2008 Wiley‐Liss, Inc.
Navigation concepts for MR image‐guided interventions
Authors: Moche Michael , Trampel Robert , Kahn Thomas , Busse Harald 
Published: January 2008

AbstractThe ongoing development of powerful magnetic resonance imaging techniques also allows for advanced possibilities to guide and control minimally invasive interventions. Various navigation concepts have been described for practically all regions of the body. The specific advantages and limitations of these concepts largely depend on the magnet design of the MR scanner and the interventional environment. Open MR scanners involve minimal patient transfer, which improves the interventional workflow and reduces the need for coregistration, ie, the mapping of spatial coordinates between imaging and intervention position. Most diagnostic scanners, in contrast, do not allow the physician to guide his instrument inside the magnet and, consequently, the patient needs to be moved out of the bore. Although adequate coregistration and navigation concepts for closed‐bore scanners are technically more challenging, many developments are driven by the well‐known capabilities of high‐field systems and their better economic value. Advanced concepts such as multimodal overlays, augmented reality displays, and robotic assistance devices are still in their infancy but might propel the use of intraoperative navigation. The goal of this work is to give an update on MRI‐based navigation and related techniques and to briefly discuss the clinical experience and limitations of some selected systems. J. Magn. Reson. Imaging 2008;27:276–291. © 2008 Wiley‐Liss, Inc.
Stem cell therapy: MRI guidance and monitoring
Authors: Kraitchman Dara L. , Gilson Wesley D. , Lorenz Christine H. 
Published: January 2008

AbstractWith the recent advances in magnetic resonance (MR) labeling of cellular therapeutics, it is natural that interventional MRI techniques for targeting would be developed. This review provides an overview of the current methods of stem cell labeling and the challenges that are created with respect to interventional MRI administration. In particular, stem cell therapies will require specialized, MR‐compatible devices as well as integration of graphical user interfaces with pulse sequences designed for interactive, real‐time delivery in many organs. Specific applications that are being developed will be reviewed as well as strategies for future translation to the clinical realm. J. Magn. Reson. Imaging 2008;27:299–310. © 2008 Wiley‐Liss, Inc.
Magnetic resonance guidance for radiofrequency ablation of liver tumors
Authors: Clasen Stephan , Pereira Philippe L. 
Published: January 2008

AbstractImage‐guided thermal ablation of liver tumors is a minimally invasive treatment option. Techniques used for thermal ablation are radiofrequency (RF) ablation, laser interstitial thermotherapy (LITT), microwave (MW) ablation, high‐intensity focused ultrasound (HIFU), and cryoablation. Among these techniques RF ablation attained widespread consideration. Image guidance should ensure a precise ablation therapy leading to a complete coagulation of tumor tissue without injury to critical structures. Therefore, the modality of image guidance has an important impact on the safety and efficacy of percutaneous RF ablation. The current literature regarding percutaneous RF ablation mainly describes the use of computed tomography (CT) and ultrasonography (US) guidance. In addition, interventional MR systems offer the possibility to utilize the advantages of MR imaging such as excellent soft‐tissue contrast, multiplanar and interactive capabilities, and sensitivity to thermal effects during the entire RF ablation procedure. Monitoring of thermally induced coagulation by MR imaging is supportive to control the ablation procedure. MR imaging can be advantageously used to guide overlapping ablation if necessary as well as to define the endpoint of RF ablation after complete coverage of the target tissue is verified. Furthermore, monitoring of thermal effects is essential in order to prevent unintended thermal damage from critical structures surrounding the target region. Therefore, MR‐guided RF ablation offers the possibility for a safe and effective therapy option in the treatment of primary and secondary hepatic malignancies. The article summarizes the role of MR guidance for RF ablation of liver tumors. J. Magn. Reson. Imaging 2008;27:421–433. © 2008 Wiley‐Liss, Inc.
MR thermometry
Authors: Rieke Viola , Butts Pauly Kim 
Published: January 2008

AbstractMinimally invasive thermal therapy as local treatment of benign and malignant diseases has received increasing interest in recent years. Safety and efficacy of the treatment require accurate temperature measurement throughout the thermal procedure. Noninvasive temperature monitoring is feasible with magnetic resonance (MR) imaging based on temperature‐sensitive MR parameters such as the proton resonance frequency (PRF), the diffusion coefficient (D), T1 and T2 relaxation times, magnetization transfer, the proton density, as well as temperature‐sensitive contrast agents. In this article the principles of temperature measurements with these methods are reviewed and their usefulness for monitoring in vivo procedures is discussed. Whereas most measurements give a temperature change relative to a baseline condition, temperature‐sensitive contrast agents and spectroscopic imaging can provide absolute temperature measurements. The excellent linearity and temperature dependence of the PRF and its near independence of tissue type have made PRF‐based phase mapping methods the preferred choice for many in vivo applications. Accelerated MRI imaging techniques for real‐time monitoring with the PRF method are discussed. Special attention is paid to acquisition and reconstruction methods for reducing temperature measurement artifacts introduced by tissue motion, which is often unavoidable during in vivo applications. J. Magn. Reson. Imaging 2008;27:376–390. © 2008 Wiley‐Liss, Inc.
Targeted drug delivery under MRI guidance
Authors: Arepally Aravind 
Published: January 2008

AbstractThe main goal of local drug delivery is to increase the concentration of a specific therapeutic agent in a target tissue with minimal nontarget distribution. Compared to systemic therapy, local drug delivery provides a high level of therapeutic efficacy with minimal systemic effects. The current primary imaging modality for drug delivery has been x‐ray angiography, but it has major limitations including anatomical ambiguity and inability to visualize the targeted tissues. Due to these inherent problems, MR guidance has been explored as an alternative imaging modality for guiding and monitoring of drug therapy. Recently, interventional MR (XMR) systems have been implemented that have both dual x‐ray and MRI capabilities in a single suite and allow for real‐time interventional procedures to be performed in a clinical setting. In cases where drug delivery is required, this system provides a significant leap for catheter‐based therapies. Although clinical drug delivery procedures utilizing MR guidance are still in the early stages of development and application, recent technological advances should help further promote the adoption of such procedures. This review covers the emerging techniques of drug delivery using MR guidance. J. Magn. Reson. Imaging 2008;27:292–298. © 2008 Wiley‐Liss, Inc.
MR systems for MRI‐guided interventions
Authors: Hushek Stephen G. , Martin Alastair J. , Steckner Michael , Bosak Elyakim , Debbins Josef , Kucharzyk Walter 
Published: January 2008

AbstractThe field of MR imaging has grown from diagnosis via morphologic imaging to more sophisticated diagnosis via both physiologic and morphologic imaging and finally to the guidance and control of interventions. A wide variety of interventional procedures from open brain surgeries to noninvasive focused ultrasound ablations have been guided with MR and the differences between diagnostic and interventional MR imaging systems have motivated the creation of a new field within MR. This review discusses the various systems that research groups and vendors have designed to meet the requirements of interventional MR and suggest possible solutions to those requirements that have not yet been met. The common requirements created by MR imaging guidance of interventional procedures are reviewed and different imaging system designs will be independently considered. The motivation and history of the different designs are discussed and the ability of the designs to satisfy the requirements is analyzed. J. Magn. Reson. Imaging 2008;27:253–266. © 2008 Wiley‐Liss, Inc.
MR‐guided biopsy: A review of current techniques and applications
Authors: Weiss Clifford R. , Nour Sherif Gamal , Lewin Jonathan S. 
Published: January 2008

AbstractBiopsy has become a cornerstone of modern medicine and most modern biopsies are performed percutaneously using image guidance, typically computed tomography or ultrasound. MR‐guided biopsy offers many advantages over these more traditional modalities, and the recent development of interventional MR imaging techniques has made MR‐guided percutaneous biopsies and aspirations a clinical reality. As the field of MR‐guided procedures continues to expand and to attract more attention from radiologists, it is important to understand the concepts, techniques, applications, advantages, and limitations of MR‐guided biopsy/percutaneous procedures. Radiologists should also recognize the need for their significant involvement in the technical aspects of MR‐guided procedures, since several user‐defined parameters can alter device visualization in the MR imaging environment and affect procedure safety. This article reviews the prerequisites, systems, and applications of MR‐guided biopsy. J. Magn. Reson. Imaging 2008;27:311–325. © 2008 Wiley‐Liss, Inc.
Bone marrow stromal cells protect oligodendrocytes from oxygen‐glucose deprivation injury
Authors: Zhang Jing , Li Yi , Zheng Xuguang , Gao Qi , Liu Zhongwu , Qu Runjiang , Borneman Jade , Elias Stanton B. , Chopp Michael 
Published: January 2008

AbstractOligodendrocyte (OLG) damage leads to demyelination, which is frequently observed in ischemic cerebrovascular diseases. In this study, we investigated the effect of bone marrow stromal cells (BMSCs) on OLGs subjected to oxygen‐glucose deprivation (OGD). N20.1 cells (mouse OLG cell line) were transferred into an anaerobic chamber for 3 hr in glucose‐free and serum‐free medium. After OGD incubation, OLG cultures were divided into the following groups: 1) OGD alone, 2) OLG cocultured with BMSCs, 3) treatment with the phosphoinostide 3‐kinase (PI3k) inhibitor LY294002, 4) LY294002‐treated OLGs with BMSC cocultured, and 5) anti‐p75 antibody‐treated OLGs. After an additional 3 hr of reoxygenation incubation, OLG viability and apoptosis were measured. The mRNA expression in the BMSCs and OLGs was analyzed using quantitative real‐time PCR (RT‐PCR). Serine/threonine‐specific protein kinase (Akt), phosphorylated Akt (p‐Akt), p75, and caspase 3 protein expressions in OLGs were measured by Western blot. Our results suggest that BMSCs produce growth factors, activate the Akt pathway, and increase the survival of OLGs. BMSCs also reduce p75 and caspase 3 expressions in the OGD‐OLGs, which leads to decreased OLG apoptosis. BMSCs participate in OLG protection that may occur with promoting growth factors/PI3K/Akt and inhibiting the p75/caspase pathways. Our study provides insight into white matter damage and the therapeutic benefits of BMSC‐based remyelinating therapy after stroke and demyelinating diseases. © 2008 Wiley‐Liss, Inc.
Maturational changes in laminin, fibronectin, collagen IV, and perlecan in germinal matrix, cortex, and white matter and effect of betamethasone
Authors: Xu Hongmin , Hu Furong , Sado Yoshikazu , Ninomiya Yoshifumi , Borza Dorin‐Bogdan , Ungvari Zoltan , LaGamma Edmund F. , Csiszar Anna , Nedergaard Maiken , Ballabh Praveen 
Published: January 2008

AbstractGerminal matrix is selectively vulnerable to hemorrhage in premature infants, and use of prenatal betamethasone is associated with a lower occurrence of germinal matrix hemorrhage. Because the major components of extracellular matrix of the cerebral vasculature—laminin, fibronectin, collagen IV, and perlecan—provide structural stability to blood vessels, we examined whether the expression of these molecules was decreased in the germinal matrix and affected by betamethasone. In both human fetuses and premature infants, fibronectin was significantly lower in the germinal matrix than in the cortical mantle or white matter anlagen. Conversely, laminin α1 gene expression was greater in the human germinal matrix compared with the cortical mantle or white matter. Expression of α1‐ and α2(IV) collagen chains increased with advancing gestational age. Low‐dose prenatal betamethasone treatment enhanced fibronectin level by 1.5–2‐fold whereas a high dose reduced fibronectin expression by 2‐fold in rabbit pups. Because fibronectin provides structural stability to the blood vessels, its reduced expression in the germinal matrix may contribute to the fragility of germinal matrix vasculature and the propensity to hemorrhage in premature neonates. © 2008 Wiley‐Liss, Inc.
Expression of polyalanine stretches induces mitochondrial dysfunction
Authors: Toriumi Kazuya , Oma Yoko , Kino Yoshihiro , Futai Eugene , Sasagawa Noboru , Ishiura Shoichi 
Published: January 2008

AbstractIn recent years, several novel types of disorders have been characterized, including what have been termed polyalanine diseases, in which patients have expanded triplet repeats in specific genes, resulting in the translation of aberrantly elongated polyalanine stretches. In this study, we showed that yellow fluorescent protein (YFP)‐fused elongated polyalanine stretches localized exclusively to the cytoplasm and formed aggregates. Additionally, the polyalanine stretches themselves were toxic. We sought to identify proteins that bound directly to the polyalanine stretches, as factors that might be involved in triggering cell death. Many mitochondrial proteins were identified as polyalanine‐binding proteins. We showed that one of the identified proteins, succinate dehydrogenase subunit A, was decreased in the mitochondria of cells expressing polyalanine stretches; as a result, succinate oxidative activity was decreased. Furthermore, the polyalanine stretches also associated directly with mitochondria. This suggests that polya‐lanine stretches might directly induce cell death. Additionally, the mitochondrial membrane potential was reduced in cells expressing polyalanine stretches. We propose a novel mechanism by which polyalanine stretches may cause cytotoxicity through mitochondrial dysfunction. This may be a common mechanism underlying the pathogenesis of all polyalanine diseases. © 2008 Wiley‐Liss, Inc.
Ciliary neurotrophic factor and interleukin‐6 differentially activate microglia
Authors: Krady J. Kyle , Lin Hsiao‐Wen , Liberto Christina M. , Basu Anirban , Kremlev Sergey G. , Levison Steven W. 
Published: January 2008

AbstractStudies have shown that cytokines released following CNS injury can affect the supportive or cytotoxic functions of microglia. Interleukin‐6 (IL‐6)‐family cytokines are among the injury factors released. To understand how microglia respond to IL‐6 family cytokines, we examined the effects of ciliary neurotrophic factor (CNTF) and IL‐6 on primary cultures of rat microglia. To assess the functional state of the cells, we assayed the expression of tumor necrosis factor‐α (TNFα), interleukin‐1β (IL‐1β), and cyclooxygenase 2 (COX‐2) following stimulation. We show that CNTF reduces COX‐2 levels, whereas IL‐6 increases the expression of IL‐1β, TNFα, and Cox‐2. We also examined trophic factor expression and found that CNTF enhances glial cell‐line derived neurotrophic factor (GDNF) mRNA and protein secretion, whereas IL‐6 has no effect. Correspondingly, conditioned media from CNTF‐stimulated microglia promote motor neuron survival threefold beyond controls, whereas IL‐6‐stimulated microglia decrease neuronal survival twofold. To understand better the signaling mechanisms responsible for the opposite responses of these IL‐6‐family cytokines, we examined STAT‐3 and ERK phosphorylation in CNTF‐ and IL‐6‐stimulated microglia. IL‐6 markedly increases STAT‐3 and ERK phosphorylation after 20 min of treatment, whereas these signal transducers are weakly stimulated by CNTF across a range of doses. We conclude that CNTF modifies microglial activation to support neuronal survival and that IL‐6 enhances their capacity to do harm, as a result of different modes of intracellular signaling. © 2008 Wiley‐Liss, Inc.