A pictorial description of steady-states in rapid magnetic resonance imaging

Scheffler, Klaus

doi:10.1002/(sici)1099-0534(1999)11:5<291::aid-cmr2>3.0.co;2-j

Cited by 146 publications

(238 citation statements)

References 20 publications

Supporting

Mentioning

236

Contrasting

Order By: Relevance

“…In the following, we will refer to the representation [11] as "configuration model," the m (n) ν as "configuration vectors," and the upper index n as "configuration order. "…”

Section: Configuration Modelmentioning

confidence: 99%

“…[11] into Eq. [9] and making use of the phase cycling condition [5], we arrive at a recursion relation for m [12] where the matrix B (n,m) is defined as B (n,m) ij := y n B ij δ m,n−j [13] with y := e iφ .…”

Section: Configuration Modelmentioning

confidence: 99%

“…Instead of the abstract index counting presented in Ref. 10, a graph theoretical formulation will be used this time, so that the connection with the familiar phase graph formalism (3,11) should become more transparent.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Analytical solution to the transient phase of steady‐state free precession sequences

Ganter

2009

Magnetic Resonance in Med

View full text Add to dashboard Cite

The transient phase of short-TR steady-state free precession (SSFP) sequences exhibits an often striking complexity and is not only important for nonequilibrium applications (e.g., rapid T 1 -measurements), but can also cause severe artifacts in conventional imaging. In both cases, balanced SSFP sequences are practically (with regard to preparation efficiency) and conceptually (concerning the theoretical understanding of the decay) easier to handle their unbalanced counterparts, for which currently no theory is available. Based on a decomposition of coherence pathways into irreducible subpaths, an exact mathematical solution to the transient phase of unbalanced SSFP sequences is presented in this article, which also includes the known results for balanced SSFP and the steady state of arbitrary SSFP sequences as special cases. As an application, it is shown that the familiar Look-Locker expression for the accelerated magnetization recovery in RFspoiled sequences is only valid for T 2 → 0. In addition to oscillatory perturbations, systematic deviations from the monoexponential decay are observed for T 2 > 0 as a consequence of memory effects. Magn Reson Med 62:149-164, 2009.

show abstract

“…In the following, we will refer to the representation [11] as "configuration model," the m (n) ν as "configuration vectors," and the upper index n as "configuration order. "…”

Section: Configuration Modelmentioning

confidence: 99%

Section: Configuration Modelmentioning

confidence: 99%

See 1 more Smart Citation

Analytical solution to the transient phase of steady‐state free precession sequences

Ganter

2009

Magnetic Resonance in Med

View full text Add to dashboard Cite

show abstract

“…The ability of the VIPR-SFFP sequence to achieve short TRs is highly advantageous. Short TRs can broaden the passband and thereby reduce signal dropout or banding artifacts, which are commonly seen in SSFP images in regions of magnetic susceptibility (12). Short TRs also make the separation of fat and water signal using the LC-SSFP method more robust (5).…”

mentioning

confidence: 99%

Evaluation of the articular cartilage of the knee joint with vastly undersampled isotropic projection reconstruction steady‐state free precession imaging

Kijowski

Block

et al. 2006

Magnetic Resonance Imaging

View full text Add to dashboard Cite

Purpose:To determine the feasibility of the vastly undersampled isotropic projection reconstruction steady-state free precession (VIPR-SSFP) sequence for evaluating the articular cartilage of the knee joint. Materials and Methods:A magnetic resonance (MR) examination of the knee was performed on 33 subjects using a GE 1.5T scanner and a phased-array extremity coil. VIPR-SSFP, proton density-weighted fast spin-echo (PD-FSE), fat-suppressed T2-weighted fast spin-echo (T2-FSE), and three-dimensional fat-suppressed spoiled gradient recall-echo (SPGR) sequences were performed on three asymptomatic volunteers and 10 patients with osteoarthritis of the knee joint. Signalto-noise efficiency, and contrast-to-noise ratio (CNR) measurements were calculated for all sequences and compared with the use of paired t-tests. The VIPR-SSFP sequence was then performed on 20 consecutive patients who were undergoing a routine MR examination of the knee. Results:The cartilage signal-to-noise efficiency of the VIPR-SSFP sequence was not significantly different from that of the PD-FSE and SPGR sequences. The cartilage signal-to-noise efficiency of the VIPR-SSFP sequence was significantly higher (P Ͻ 0.05) than that of the T2-FSE sequence. The VIPR-SSFP sequence produced images with significantly higher (P Ͻ 0.05) CNR between cartilage and synovial fluid than the PD-FSE and SPGR sequences, and significantly higher (P Ͻ 0.05) CNR between cartilage and subchondral bone than the T2-FSE sequence. The VIPR-SSFP sequence allowed excellent visualization of the articular cartilage of the knee joint in all subjects. All articular cartilage defects identified on the PD-FSE, T2-FSE, and SPGR images were well visualized on the VIPR-SSFP images.Conclusion: VIPR-SSFP images had high cartilage signalto-noise efficiency and high CNR between cartilage and adjacent synovial fluid and subchondral bone; therefore, the sequence is well suited for evaluating the articular cartilage of the knee joint.

show abstract

“…When we formulate the model for bSSFP sequences, we will be concerned with repetition time, the time between successive excitation pulses. Repetition time always effects signal generation, but for spoiled pulses, it can be excluded from calculations of the complex phase of the signal, whereas for bSSFP, phase (and magnitude) are very sensitive to repetition times (Zur et al, 1988;Scheffler, 1999).…”

Section: Dixon Methodsmentioning

confidence: 99%

Magnetic resonance tissue quantification using optimal bSSFP pulse-sequence design

et al. 2007

View full text Add to dashboard Cite

Abstract. We propose a merit function for the expected contrast to noise ratio in tissue quantifications, and formulate a nonlinear, nonconvex semidefinite optimization problem to select locally-optimal balanced steady-state free precession (bSSFP) pulse-sequence design variables. The method could be applied to other pulse sequence types, arbitrary numbers of tissues, and numbers of images. To solve the problem we use a mixture of a grid search to get good starting points, and a sequential, semidefinite, trust-region method, where the subproblems contain only linear and semidefinite constraints. We give the results of numerical experiments for the case of three tissues and three, four or six images, in which we observe a better increase in contrast to noise than would be obtained by averaging the results of repeated experiments. As an illustration, we show how the pulse sequences designed numerically could be applied to the problem of quantifying intraluminal lipid deposits in the carotid artery.

show abstract

A pictorial description of steady-states in rapid magnetic resonance imaging

Cited by 146 publications

References 20 publications

Analytical solution to the transient phase of steady‐state free precession sequences

Analytical solution to the transient phase of steady‐state free precession sequences

Evaluation of the articular cartilage of the knee joint with vastly undersampled isotropic projection reconstruction steady‐state free precession imaging

Magnetic resonance tissue quantification using optimal bSSFP pulse-sequence design

Contact Info

Product

Resources

About