Inversion Recovery Snapshot FLASH MR Imaging

Haase, Axel; Matthaei, D.; Bartkowski, R; Dühmke, Eckhart; Leibfritz, Dieter

doi:10.1097/00004728-198911000-00016

Cited by 143 publications

(61 citation statements)

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“…Most T 1 quantification techniques are based on measuring the longitudinal magnetization at different time intervals TI after an inversion or saturation pulse (1)(2)(3)(4)(5). The magnitude of the longitudinal magnetization as a function of TI is then fitted to a monoexponential recovery function [M 0 (1 Ϫ e TI/T1 ) for saturation, and M 0 (1 Ϫ 2e TI/T1 ) for inversion recovery] to give T 1 and proton density M 0 values.…”

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confidence: 99%

“…Conventionally, one data set with a given TI is acquired after each inversion pulse and the experiment is repeated after a sufficient long recovery period (Ͼ 5T 1 ) with different TIs (single-point method (1)). As an alternative to this time-consuming technique, inversion recovery snapshot fast low-angle shot (FLASH) can be used (5). Here, the magnitude of the longitudinal magnetization is acquired continuously during its recovery using a FLASH sequence with low excitation flip angles of 5°to 10°.…”

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T₁ quantification with inversion recovery TrueFISP

Scheffler

Hennig

2001

Magnetic Resonance in Med

177

186

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A snapshot FLASH sequence can be used to acquire the time course of longitudinal magnetization during its recovery after a single inversion pulse. However, excitation pulses disturb the exponential recovery of longitudinal magnetization and may produce systematic errors in T 1 estimations. In this context the possibility of using the TrueFISP sequence to detect the recovery of longitudinal magnetization for quantitative T 1 measurements was examined. Experiments were performed on different Gd-doped water phantoms and on humans. Most T 1 quantification techniques are based on measuring the longitudinal magnetization at different time intervals TI after an inversion or saturation pulse (1-5). The magnitude of the longitudinal magnetization as a function of TI is then fitted to a monoexponential recovery function [M 0 (1 Ϫ e TI/T1 ) for saturation, and M 0 (1 Ϫ 2e TI/T1 ) for inversion recovery] to give T 1 and proton density M 0 values. Conventionally, one data set with a given TI is acquired after each inversion pulse and the experiment is repeated after a sufficient long recovery period (Ͼ 5T 1 ) with different TIs (single-point method (1)). As an alternative to this time-consuming technique, inversion recovery snapshot fast low-angle shot (FLASH) can be used (5). Here, the magnitude of the longitudinal magnetization is acquired continuously during its recovery using a FLASH sequence with low excitation flip angles of 5°to 10°. An intrinsic drawback of this method is the influence of the excitation pulses on the recovery of longitudinal magnetization even for small flip angles.Inversion recovery-prepared true Fast Imaging with Steady Precession (TrueFISP) was first proposed by Deimling and Heid (6) to modify the mainly T 2 -weighted image contrast of TrueFISP. In this work, we examined the possibility of replacing the intrinsically T 1 -weighted FLASH readout module by a TrueFISP readout module to continuously acquire the recovery of longitudinal magnetization. Quantitative T 1 measurements on phantoms and humans based on FLASH and TrueFISP were compared to the gold standard of separately acquired TI measurements. THEORYThe FISP sequence as proposed by Oppelt et al. (7) (now called TrueFISP (Siemens) or fully refocused SSFP (8)) consists of consecutive ␣ excitation pulses with alternating polarity. The gradient areas between these Ϯ␣ pulses are zero for all three gradient axes. Figure 1 shows one repetition cycle of TrueFISP, starting at the center of the ϩ␣ pulse and ending at the center of the Ϫ␣ pulse. At the beginning of one TR cycle the steady-state magnetization is aligned in the z direction and is then flipped into transverse magnetization by the ϩ␣/2 pulse. The echo is Fourier encoded by a symmetric readout gradient GR consisting of a dephasing period, a readout period, and a final rephasing step to refocus transverse magnetization. This pure transverse magnetization is finally flipped back to the z axis by the Ϫ␣/2 pulse. Except for T 2 and T* 2 effects, no transverse magnetization is lost between ␣ pu...

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confidence: 99%

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confidence: 99%

T₁ quantification with inversion recovery TrueFISP

Scheffler

Hennig

2001

Magnetic Resonance in Med

177

186

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“…The IRSFL T 1 mapping sequence as described by Haase et al (6) was implemented on two 1.5T whole body MR scanners (Magnetom VISION and Magnetom Symphony; Siemens, Germany). The pulse sequence consists of a preceding nonselective fast passage adiabatic inversion pulse (duration ϭ 10.24 msec) that is followed by a series of T 1 -weighted snapshot FLASH (SFL) images.…”

Section: Irsfl Sequencementioning

confidence: 99%

“…In previously published work, as a first step toward quantification of tumor microcirculation, the so-called PI value given by (6) was calculated (14 -16) from the obtained concentration-time curves. Thereby, taking the density of tissue into account, PI represents the maximum slope of the concentration-time curve of tissue normalized by the maximum of the arterial input function (AIF), c a max (Fig.…”

Section: Evaluation Of Perfusion Parametersmentioning

confidence: 99%

“…A recently described (4,5) direct approach to quantify concentration-time curves free of these sources of error uses fast dynamic T 1 mapping with inversion-recovery (IR) snapshot fast low-angle shot (SFL) (referred to as IRSFL sequence in the following) sequences as originally described by Haase et al (6). The quantification of concentration-time curves is, thereby, based on the widely used assumption of a linear relationship between changes in longitudinal relaxation rate, R 1 ϭ 1/T 1 , and CA concentration, which has recently been demonstrated (4).…”

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Dynamic T₁ mapping predicts outcome of chemoradiation therapy in primary rectal carcinoma: Sequence implementation and data analysis

Kremser

Trieb

Rudisch

et al. 2007

Magnetic Resonance Imaging

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Purpose:To describe details about the implementation of a dynamic T 1 -mapping technique and a simple data analysis strategy that can be used to predict therapy outcome in primary rectal carcinoma and to investigate the physiologic meaning of the obtained parameter. Materials and Methods:Contrast-enhanced dynamic T 1 mapping was achieved with a snapshot fast low-angle shot (FLASH) T 1 mapping sequence implemented on a 1.5T MR scanner. This method was applied to 58 patients with primary rectal cancer before onset of chemoradiation therapy. A simple data analysis strategy based on the calculation of the maximum slope of the tissue concentration-time curve divided by the maximum of the arterial input function (AIF) was used as a measure of tumor microcirculation (PI values). Results:The snapshot FLASH (SFL) T 1 -mapping technique is accurate and sensitive enough to detect inhomogeneous uptake kinetics within tumor tissue. Classifying the patients into two groups according to therapy response showed lower mean PI values for responders as compared to nonresponders. PI was found to combine information about permeability surface area product (PS) and blood volume. Conclusions:The described method based on dynamic T 1 mapping has the potential to be a clinical tool for predicting therapy outcome of preoperative chemoradiation in patients with primary rectal carcinoma.

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