摘要:

AbstractThe ability to map spectroscopic components forin vivoapplication is a highly desirable goal. Thusfar it has been unavailable because of the low SNR inherent in the measurement of each voxel. In this paper we deal with this low SNR in two ways. First, estimation theory, using a priori data, is used to estimate the amplitudes in each voxel. Second, the resultant estimates are presented in an image format so that they are readily correlated with anatomical and physiological patterns. A computer simulation is presented of a case where the SNR is‐10 dB. At this level, conventional Fourier transform spectroscopy provides meaningless results. Using estimation theory and an imaging format, a simulated lesion is readily seen. © 1986 Academic Press, I

ISSN:0740-3194    

DOI:10.1002/mrm.1910030112

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

年代:1986

数据来源: WILEY

摘要:

AbstractA quadrature multiplexed pulse sequence to double the data information in a given acquisition time is proposed for NMR tomography. This technique takes advantage of the Hermitian property of the Fourier transform operation in NMR imaging. The proposed technique uses two rf pulses with 90° phase difference simultaneously applied for the excitation of the spins in two different slices. The method results in truly simulaneous data acquisition coming from two different anatomical slices which can be separated into the real and imaginary parts of the image domain. This technique, therefore, also allows us either to reduce the experiment time by half or double the number of slices in the same examination time, depending on the applied imaging scheme. As a preliminary study, simultancous dual‐slice imaging of a human head using a conventional single‐slice imaging scheme was performed. © 1986 Academic Press

ISSN:0740-3194    

DOI:10.1002/mrm.1910030113

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

年代:1986

数据来源: WILEY

摘要:

AbstractThere exists some uncertainty about the hazards which the quenching of a superconducting magnet would present to a subject undergoing an NMR examination. To investigate this problem, a 1.6‐T whole‐body magnet was quenched with an anesthetized pig lying in the bore. This paper reports our finding which, in the circumstances of this experiment, suggest that the risks are small. © 1986 Academic Press,

ISSN:0740-3194    

DOI:10.1002/mrm.1910030114

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

年代:1986

数据来源: WILEY

ISSN:0740-3194    

DOI:10.1002/mrm.1910030115

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

年代:1986

数据来源: WILEY

ISSN:0740-3194    

DOI:10.1002/mrm.1910030116

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

年代:1986

数据来源: WILEY

摘要:

AbstractWe investigatedin vitroNMR properties of bleomycin‐induced alveolitis and pulmonary fibrosis in 18 Lewis rats (6 controls). When alveolitis or fibrosis had developed, animal lungs were excised and examined histologically and gravimetrically and theirT1andT2were determined by a NMR spectrometre at 10.7 MHz and 37°C. Clinical diagnosis was confirmed histologically in each case. The NMR signal intensities were siginificantly elevaed in both disease states (P<0.001). BothT1andT2values of alveolitic lungs were about the same as in controls, but were significantly decreased in fibrotic lungs (P<0.01). Changes inT1andT2correlated well (P<0.001) with changes in water content of discased lungs. © 1986 Academic Press,

ISSN:0740-3194    

DOI:10.1002/mrm.1910030117

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

年代:1986

数据来源: WILEY

摘要:

AbstractModulus reconstruction of inversion‐recovery images causes a pixel value to be assigned the absolute magnitude of the signal amplitude. Consequently, contrast between tissues is reduced if they have amplitudes of opposite sign. When contrast is reduced between adjacent tissues, dark line artifacts are created at the tissue boundaries. The artifacts may enable tissues to be spatially distinguished even if there is no contrast between them. However, the artifacts may lead to misinterpretation of the image since they may be difficult to distinguish from real anatomical structures. © 1986 Academic Press, I

ISSN:0740-3194    

DOI:10.1002/mrm.1910030118

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

年代:1986

数据来源: WILEY

摘要:

AbstractIn equations describing multiple spin‐echo pulse sequences, theT1dependence is often approximated by a saturation‐recovery expression, which is valid only when the repetition timeTRis much greater than the time required for the echoes. A slight modification of this approximation greatly increases its accuracy for smallTRvalues. © 1986 Academic Press,

ISSN:0740-3194    

DOI:10.1002/mrm.1910030119

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

年代:1986

数据来源: WILEY

摘要:

AbstractA novel resonator for receiving31P NMR signals at 1.5 T, which because of its topology has been named a “sectorial resonator,” exhibits good radio frequency coupling to the adult human liver. Minimal contamination from nonliver tissue (i. e., muscle) was achieved by the use of depth selective pulses and also because the geometry results in cancellation of signals arising from tissues that are close to the two openings of the structure. © 1986 Academic Press,

ISSN:0740-3194    

DOI:10.1002/mrm.1910030120

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

年代:1986

数据来源: WILEY

摘要:

AbstractAn NMR imaging technique sensitive to slow flow (∼ 1 mm/s) using a conventional imaging gradient strength (0.025 mT/cm) is described. Two projections with different spatial magnetic periodicity (determined by the SSFP pulse interval), and thus with different flow sensitivities, are subtracted to give signal from flows in a velocity window. © 1986 Academic Press, I

ISSN:0740-3194    

DOI:10.1002/mrm.1910030121

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

年代:1986

数据来源: WILEY