Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: HUMANGGP:010955 (mda-7)
 464 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Refocused steady-state free precession (SSFP), or fast imaging with steady precession (FISP or TrueFISP), has recently proven valuable for cardiac imaging because of its high signal-to-noise ratio (SNR) and excellent blood-myocardium contrast. In this study, various implementations of multiecho SSFP or EPI-SSFP for imaging in the heart are presented. EPI-SSFP has higher scan-time efficiency than single-echo SSFP, as two or more phase-encode lines are acquired per repetition time (TR) at the cost of a modest increase in TR. To minimize TR, a noninterleaved phase-encode order in conjunction with a phased-array ghost elimination (PAGE) technique was employed, removing the need for echo time shifting (ETS). The multishot implementation of EPI-SSFP was used to decrease the breath-hold duration for cine acquisitions or to increase the temporal or spatial resolution for a fixed breath-hold duration. The greatest gain in efficiency was obtained with the use of a three-echo acquisition. Image quality for cardiac cine applications using multishot EPI-SSFP was comparable to that of single-echo SSFP in terms of blood-myocardium contrast and contrast-to-noise ratio (CNR). The PAGE method considerably reduced flow artifacts due to both the inherent ghost suppression and the concomitant reduction in phase-encode blip size. The increased TR of multishot EPI-SSFP led to a reduced specific absorption rate (SAR) for a fixed RF flip angle, and allowed the use of a larger flip angle without increasing the SAR above the FDA-approved limits.
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PMID:Multishot EPI-SSFP in the heart. 1194 26

The topic fast and ultrafast MR imaging commonly includes relatively slow gradient-echo techniques with spoiled transverse magnetization (FLASH, FFE-T1, SPGR), gradient-echo techniques with partially refocused transverse magnetization (FISP, FFE, GRASS), gradient-echo techniques with fully refocused transverse magnetization (trueFISP, balanced FFE, FIESTA), the multi-echo spin-echo techniques (RARE, TSE, FSE), a mixture of multi-echo spin-echo and gradient-echo techniques (GRASE, TGSE), and finally single-shot techniques (HASTE, SS-FSE, EPI). This article gives a description of the sequence structures of non-echo-planar fast imaging techniques and a list of potential clinical applications. Recent advances in faster imaging which are not sequence related, such as simultaneous acquisitions of spatial harmonics (SMASH) and sensitivity encoding (SENSE) for fast MRI, are mentioned as well as some novel techniques such as QUEST and BURST. Due to the recent success with gradient-echo techniques with fully refocused transverse magnetization (trueFISP, balanced FFE, FIESTA), this "faster" gradient-echo technique is discussed in more detail followed by multi-echo spin-echo techniques that present the counterpart to the multi-echo gradient-echo (EPI) technique, which is not discussed in this paper. Three major areas appear to be the domain for EPI: diffusion; perfusion; and blood oxygenation level dependent imaging (BOLD, fMRI). For all other applications there is ample room for utilizing other fast and ultrafast imaging techniques, due to some intrinsic problems with EPI.
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PMID:Fast and ultrafast non-echo-planar MR imaging techniques. 1243 64