摘要:

AbstractA series of solenoidal NMR probes were built to measureT1andT2relaxation timesin vivoin the mouse, over the frequency range of 5 to 60 MHz, using inversionrecovery and spin‐echo pulse sequences. KHT tumors growing in the legs of C3H mice were studied and compared with normal mouse legs. The tumor relaxation times were studied at 10 MHz during the course of tumor growth and as a function of frequency when the course of tumor growth and as a function of frequency when the tumor had a mass of approximately 0.9 g. Mouse legs with tumors have higherT1andT2values than those without tumors over the frequency range of 5 to 60 MHz. Significant changes in both relaxation times were detected before a palpable mass could be detected.T1contrast between normal and tumor‐bearing legs decreased with increasing frequency, whileT2contrast remained nearly constant. A comparison betweenin vivoandin vitromeasurements was done using four different types of sample preparation: live mouse, dead mouse, excised whole mouse leg, and tissue sample. These studies showed small but significant differences between the relaxation times measuredin vivoand those measuredin vi

ISSN:0740-3194    

DOI:10.1002/mrm.1910020102

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe proton nuclear magnetic relaxation rate, 1/T1, is reported as a function ofd5‐glycerol concentration for aqueous manganese(II) ion solutions over a range of magnetic field strengths corresponding to proton Larmor frequencies between 0.01 and 38 MHz. The data are analyzed in terms of the Solomon, Bloembergen, and Morgan equations which are found to be sufficient to account for the relaxation data over the field and concentration ranges studied. These data provide a useful reference for the viscosity dependence of manganese(II)‐ion‐induced magnetic relaxation in aqueous systems and a useful comparison with macromolecule bound manganese(II)‐ion‐induced relaxation where the theory is less s

ISSN:0740-3194    

DOI:10.1002/mrm.1910020103

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe slotted cylinder, and inductive structure with low self‐inductance, low electric field, has been studied as a probe for NMR imaging applications. A theoretical calculation allows us to map the magnetic field and to evaluate electrical parameters of the structure. Several implementations, including new designs, have been experimentally tested over a wide range of frequencies (4–40 MHz), and compared to a classical coil probe. This study demonstrates the efficiency of the slotted cylinder for NMR imaging. It is optimized for large conductive samples when imaging at high frequencies (for human head, above 20 M

ISSN:0740-3194    

DOI:10.1002/mrm.1910020104

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

年代:1985

数据来源: WILEY

摘要:

AbstractA novel generalized processing system is described whereby, using time‐varying gradients, simultaneous data acquisition can be provided for all points in a volume. This is in sharp distinction to the sensitive‐point method where only the null region is imaged. It is shown that time‐varying gradients systems provide unique phase modulation functions which, when appropriately decoded, enable every point in the volume to be simultaneously imaged from a single FID signal. Methods are shown using the technique to provide simultaneously acquired, localized NMR spectra. Alternative gradient signals are considered including both periodic and aperiodic wave

ISSN:0740-3194    

DOI:10.1002/mrm.1910020105

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

年代:1985

数据来源: WILEY

摘要:

AbstractSeven patients (five male and two female, age range from 50 to 88) with angiographic proven abdominal aortic aneurysms were evaluated with magnetic resonance (MR) imaging (1.5‐kG system) of the abdomen. Images were obtained in transverse, coronal, and saggital planes with three radiofrequency pulse sequences [saturation recovery (SR), inversion recovery (IR), and spin echo (SE)]. All of the aneurysms were identified as to site and relative size with MR images. The lumen in which there was rapidly flowing blood was always dark (low intensity), whereas the aneurysmal area which contained presumed clot or slow flowing blood was brighter (high intensity) on SR images. Although the size, location, and relationship to other blood vessels was best demonstrated on aortography, MR images provided similar information in all cases. MR imagescorrectly demonstrated thrombus in six cases. In conclusion, MR imaging provides a clear delineation of the anatomy of abdominal aortic aneurysms. In addition, it can provide information concerning tissue type, i. e., it distinguished clot from moving blood. It may be possible in the future to further characterize atherosclerotic and other pathological changes in vessel architecture by using various pulse sequences and timing parameters to providein vivohistological typin

ISSN:0740-3194    

DOI:10.1002/mrm.1910020106

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

年代:1985

数据来源: WILEY

摘要:

AbstractLimitations in resolution and sensitivity of13C NMR spectroscopy have reduced the information obtainable from intact biological systems. With the aim of increasing the information fromin vivo13C NMR two multipulse NMR techniques, the DEPT pulse sequence and the gated spin‐echo sequence, were used to obtain edited13C NMR spectra from different13C‐labeled mammalian tissues. This allowed the separation of the13C NMR signals from the tissues into subspectra containing either CH, CH2, or CH3signals, thereby increasing the information obtainable from these spectra. Comparing the two techniques, the DEPT sequence gives more accurate editing than the gated spin‐echo sequence but suffers from the difficulty of determining1H pulse anglesin

ISSN:0740-3194    

DOI:10.1002/mrm.1910020107

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

年代:1985

数据来源: WILEY

摘要:

AbstractA perfusion technique applicable to metabolic studies by NMR is described in detail. The utility and versatility of the approach are demonstrated by following gluconeogenesis from [2‐13C]pyruvate in the perfused, isolated mouse liver, and lipogenesis from [2‐13C]acetate in perfusedAcanthamoeba castellaniicells embedded in agarose filame

ISSN:0740-3194    

DOI:10.1002/mrm.1910020108

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

年代:1985

数据来源: WILEY

摘要:

AbstractWith the NMR lineshape‐relaxation correlation technique the relaxation times and the relative magnitudes of the proton spin ‐groups characterized by these respective relaxation times are obtained. In most tissues the spin‐lattice relaxation in the rotating frame is nonexponential. The magnetization evolution can be represented as the sum of three exponential decays characterized by threeT1prelaxation times. The shortT1pcomponent, corresponding to the rigid network protons, gives the most interesting information on the tissue. Results at 38 MHz are given for muscle, spleen, lung, and tumor EMT6 fibrosarcoma grown in the dorsal subcutaneous tissue of BALB/c mice. The absence of the magnetization component with shortT1pand shortT2in spleen tissue of tumorous mice demonstrates that the spleen is swollen to at least 5 times its original size so that the relative magnitude of the magnetization corresponding to collagen network is proportionally reduced. The NMR correlation technique is thus shown to be appropriate for such quantitative ana

ISSN:0740-3194    

DOI:10.1002/mrm.1910020109

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

年代:1985

数据来源: WILEY

摘要:

AbstractThis note considers the anomolous contrast in inversion recovery images produced by NMR scanners if a map |My′| is reconstructed, rather than a map ofMy

ISSN:0740-3194    

DOI:10.1002/mrm.1910020110

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

年代:1985

数据来源: WILEY

摘要:

AbstractA parametric spectral analysis based on linear prediction and singular value decomposition has been applied to the31P FID of a tumor implanted in a mouse. It is found that a number of complications that may arise inin vivoFFT NMR can be circumvented. The new method yields all parameters of the spectral components, i. e., the frequency, amplitude, damping constant, and phase.

ISSN:0740-3194    

DOI:10.1002/mrm.1910020111

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

年代:1985

数据来源: WILEY