摘要:

AbstractThein vivocontour plot is a superior representation of the data from stimulus experiments. Its performance is illustrated by four examples, viz., necrosis of a superfused rat heart, anoxia on perfused mouse liver, ischemiae on Langendorff heart in the presence and absence of a Ca antagonist, and the internal stimulus of the cardiac cycle. Thein vivocontour plot visualizes line intensities (metabolite concentrations), line positions (pH), and linewidths, as well as the time derivatives of these parameters in any available number of Spectra. © 1987 Academic Press, Inc

ISSN:0740-3194    

DOI:10.1002/mrm.1910040602

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractBecause of their longT2relaxation time (400 ms), larvae of the tapewormTaenia crassicepscan be distinctly imaged in the mouse peritoneal cavity by NMR. An echo time of 400 ms sharply contrasted the parasites against the surrounding abdominal organs. A rapid, quantitative assay for parasite load can be obtained by recording the amplitude of a spin echo with no applied gradients at an echo time of 400–1000 ms. TheT2of the vesicular fluid of the human parasiteTaenia soliumwas also long (600 ms), indicating that the same approach (long TE and long TR) can be used to image this parasite for diagnosis of human cysticercosis by NMR imaging. © 1987 Academic Press, I

ISSN:0740-3194    

DOI:10.1002/mrm.1910040603

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe chemical‐shift effect often degrades slice selectivity thereby degrading the contrast and spatial resolutions in a high‐field NMR imaging. We propose a new pulse sequence which can compensate for this chemical‐shift effect during slice selection. This technique provides correct slice definition as well as clear separation between water and lipid protons in high‐field proton NMR imaging. Particular applications of this technique are 2D imaging with a thin‐slice selection and chunk 3D imaging, where correction of the chemical‐shift effect in slice selection is important. Another interesting application of the technique is chemical‐shift‐selective (CHESS) imaging. This technique does not require spectral‐selective rf pulses and it takes advantage of the chemical‐shift effect during slice selection. The latter is found to be useful for humanin vivochemical‐shift imaging in high‐field NMR. In this paper, the theoretical derivation of the proposed gradient reversal technique, its applications, and related experimental results are presented. ©

ISSN:0740-3194    

DOI:10.1002/mrm.1910040604

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractAn attempt to resolve the complicated proton NMR signal of a heterogeneous material is presented. Lung tissue is used to illustrate the approach to this problem, which is based on resolving the total proton magnetization into components according to their relaxation times. This procedure is utilized at both low and high magnetic fields. These results are then correlated and analyzed for the effect of exchange between spin groups. For example, the total proton NMR signal of lung tissue is shown to arise from three interacting proton groups: protons on solid macromolecules, bound water protons, and bulk water protons. The dynamics of water is modeled to satisfy the dispersivity and the values of the relaxation parameters obtained considering the effect of exchange. It is proposed that this approach is generally applicable. © 1987 Academic Press, Inc

ISSN:0740-3194    

DOI:10.1002/mrm.1910040605

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractProton NMR spectroscopy was used to study the relationship between proton relaxation times and other resonances in the proton spectra, such as lipids, creatine, and choline/ carnitine in subacute (8‐day‐old) myocardial infarctions. Eight mongrel dogs received operative ligation of the left anterior descending coronary artery (four were permanently occluded, four were occluded for 1 h and reperfused) and were sacrificed 8 days later so that tissue samples could be prepared for NMR spectroscopy. The results of this study indicate that (for the core of infarcted tissue) the lipids do not contribute directly to the increased bulk relaxation times associated with myocardial infarction and that the lipid peaks (2.3, 1.2, 0.8 ppm) and creatine peak (3.0 ppm) are more specific to the kind of infarct than to the relaxation times. Therefore, analysis of the proton spectrum of myocardial tissue may Serve as a method for tissue characterization. © 1987 Academic Press,

ISSN:0740-3194    

DOI:10.1002/mrm.1910040606

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractWhole cells are made up of molecules in different environments to which NMR spectroscopy is sensitive. In particular, malignant and transformed cells contain lipids not only in bilayers but in isotropically tumbling domains which give rise to high‐resolution spectra. We have recently developed a technique for simultaneously analyzing broadline and high‐resolution signals (M. Bloom, K. T. Holmes, C. E. Mountford, and P. G. Williams,J. Magn. Reson., in press) and we report here its application to a range of rat, mouse, and human cell lines. Some selected features of the NMR spectra were compared with the chemical analysis of the whole‐cell lipid. We found that in general the proportion of protons in the narrow methylene resonance at 1.3 ppm increased with the neutral lipid content of the cells. This peak was chosen because itsT2relaxation behavior correlates with metastatic potential in a rat model system. This new technique could be applied to other high‐resolution components both in healthy and in diseased states. © 1987 Academic Pr

ISSN:0740-3194    

DOI:10.1002/mrm.1910040607

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractAn experimental protocol for the quantitation of lactate is demonstrated forin vivo1H NMR surface coil spectroscopy. Thein vivolactate concentration can be calculated by comparing thein vivoandin vitroratios of lactate and N‐acetylaspartate (NAA) NMR signals. With this protocol, approximately 25% of lactate present in the hypoxic or ischemic rat brain is observed by NMR. © 1987 Academic press I

ISSN:0740-3194    

DOI:10.1002/mrm.1910040608

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractA series of iron(III) ethylenebis(2‐hydroxypheny1)glycine [Fe(EHPG)]‐ derivatives have been examined for their role as paramagnetic hepatobiliary contrast agents for magnetic resonance (MR) imaging. The 5‐substituted complexes, Fe(5‐Me‐EHPG)−, Fe(5‐Cl‐EHPG)−, and Fe(5‐Br‐EHPG)−, have been compared to the parent compound in rat bio‐distribution and MR imaging studies; correlativein vitroparameters for the complexes, including octanol‐buffer partition coefficients and albumin binding affinity, have also been obtained. The three new derivatives exhibited higher degrees of lipophilicity and albumin binding affinity and varying degrees of improvement in liver‐to‐blood and bile‐to‐liver concentration ratios measured at 30 min postinjection. The 5‐C1 complex had the best overall performance in terms of these tissue ratios as well as in terms of total biliary excretion. Sequential MR images of rats after administration of the complexes revealed subtle pharmacokinetic differences among the derivatives and, in general, correlated well with and complemented the biodistribution results. This study points to the sensitivity of hepatocellular uptake and excretion to simple chemical modifications and, moreover, demonstrates the importance of screening multiple derivatives to select optimal hepatobiliary MR imagi

ISSN:0740-3194    

DOI:10.1002/mrm.1910040609

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractA long solenoid is capable of producing, at least theoretically, a B, field that is relatively more homogeneous than other known structures. This paper describes the design of a UHF probe incorporating a one‐turn solenoid associated with a pair of parallel‐plate transmission line feeders and presents a practical example used in a 360‐MHz spectrometer for micro‐imaging experiments. Numerical evaluation of the solenoid inductance using King's method for direct calculation of elliptic integrals is also included. © 1987 Academic pr

ISSN:0740-3194    

DOI:10.1002/mrm.1910040610

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractMumps virus‐infected and normal newborn hamster brains were imaged with magnetic resonance (MR) within 24 h after birth and serially scanned. Hydrocephalus developed explosively on Day 6 postinfection and progressed until death occurred soon after Day 10. This study demonstrates the utility of MR in the investigation of experimental viral encephalitis in very small laboratory animals. © 1987 Academic press I

ISSN:0740-3194    

DOI:10.1002/mrm.1910040611

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY