Routine evaluation of M0 ratios and T1 values from driven-equilibrium NMR spectra

Homer, John; Roberts, J. K.

doi:10.1016/0022-2364(90)90233-y

Cited by 6 publications

(10 citation statements)

References 8 publications

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“…It is not possible to perform a full-joint assessment of GAG distribution using single slice 2D-methods. It has been reported that interleaved multislice acquisitions cannot be used because magnetization transfer effects will introduce errors into the 2D-T 1 measurement (22)(23)(24)(25)(26). Furthermore, in single-slice 2D imaging, difficulties associated with obtaining the same section in subsequent imaging sessions make interpretation of follow-up scans unclear.…”

Section: Discussionmentioning

confidence: 99%

Rapid 3D‐T₁ mapping of cartilage with variable flip angle and parallel imaging at 3.0T

Wang¹,

Schweitzer²,

Padua³

et al. 2007

Magnetic Resonance Imaging

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Purpose: To rapidly acquire T 1 -weighted images using a three-dimensional fast low angle shot (3D FLASH) sequence in combination with generalized autocalibrating partially parallel acquisitions (GRAPPA) and variable flip angle (VFA) method at 3.0T. Materials and Methods:3D T 1 maps of model systems (gadolinium [Gd] and agarose phantoms), bovine cartilage, and human subjects were constructed on a 3.0T clinical whole-body MR scanner. The T 1 values of model systems measured using the 2D inversion-recovery fast-spin-echo (IR-FSE) sequence were considered as a reference method to validate the rapid 3D method for comparison. Results:The root mean square coefficient of variation percentage (RMS-CV%) of the median T 1 of agarose phantom across different acquisition methods was ϳ6.2%. The RMS-CV% of the median T 1 of bovine cartilage across different acquisition methods was ϳ4.1%. The RMS-CV% of median T 1 of the cartilages among the subjects was between ϳ7.3% to 11.1%. In our study, rapid 3D-T 1 mapping with VFA and parallel imaging with different acceleration factors (AFs) (AF ϭ 1, 2, 3, and 4) seems to have no obvious influence on the T 1 mapping (before and after contrast agent administration). Conclusion:The preliminary results demonstrate that it is possible to quantify 3D-T 1 mapping of the whole knee joint (with 0.7 mm 3 isotropic resolution) under approximately five minutes with excellent in vivo reproducibility at 3.0T.

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Section: Discussionmentioning

confidence: 99%

Rapid 3D‐T₁ mapping of cartilage with variable flip angle and parallel imaging at 3.0T

Wang¹,

Schweitzer²,

Padua³

et al. 2007

Magnetic Resonance Imaging

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“…In the case of SPGR, Wang et al (14) showed that T 1 calculated from two ideally chosen angles has the same precision as T 1 determined from 10 uniformly spaced angles. Although they optimized the pair of flip angles in their experiment, they did not optimize the 10 angles.…”

Section: Simulation Methodsmentioning

confidence: 99%

“…Previous authors (12,13), and most notably Wang et al (14), have investigated the parameters that influence the variable nutation SGPR T 1 estimate precision. In their approach they begin with a set of standard flip angles (SA) ϭ {10,20,30…80,90,100°} and examine the effect of altering TR for a given T 1 .…”

Section: Basic Despot1 Theorymentioning

confidence: 99%

“…Differentiating Eq. [14] shows that (T 1 NR ϩ T 2 NR) is maximized when:For most clinical anatomical imaging applications (T 1 ϭ 100 -3000 ms, T 2 ϭ 30 -600 ms, TR ϭ 5 ms), evaluation of Eq.[15] shows T 1 and T 2 precision is generally maximized when 75% of the exam time is devoted to collecting T 1 data. …”

mentioning

confidence: 99%

“…The variable nutation angle method originally introduced in 1974 (10) and investigated by a number of authors (11)(12)(13)(14) calculates T 1 with an accuracy similar to that achieved by the IR and SR techniques, but with a significant decrease in acquisition time. The sequence involves establishing a spoiled steady state followed by the collection of spoiled gradient echo (SPGR) images over a range of flip angles.…”

mentioning

confidence: 99%

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Rapid combined T₁ and T₂ mapping using gradient recalled acquisition in the steady state

Deoni

Rutt

Peters

2003

Magnetic Resonance in Med

659

815

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A novel, fully 3D, high-resolution T 1 and T 2 relaxation time mapping method is presented. The method is based on steadystate imaging with T 1 and T 2 information derived from either spoiling or fully refocusing the transverse magnetization following each excitation pulse. T 1 is extracted from a pair of spoiled gradient recalled echo (SPGR) images acquired at optimized flip angles. This T 1 information is combined with two refocused steady-state free precession (SSFP) images to determine T 2 . T 1 and T 2 accuracy was evaluated against inversion recovery (IR) and spin-echo (SE) results, respectively. Error within the T 1 and T 2 maps, determined from both phantom and in vivo measurements, is approximately 7% for T 1 between 300 and 2000 ms and 7% for T 2 between 30 and 150 ms. The efficiency of the method, defined as the signal-to-noise ratio (SNR) of the final map per voxel volume per square root scan time, was evaluated against alternative mapping methods. With an efficiency of three times that of multipoint IR and three times that of multiecho SE, our combined approach represents the most efficient of those examined. Acquisition time for a whole brain T 1 map (25 ؋ 25 ؋ 10 cm) is less than 8 min with 1 mm 3 isotropic voxels. An additional 7 min is required for an identically sized T 2 map and postprocessing time is less than 1 min on a 1 GHz PIII PC. A fast and accurate method of determining the longitudinal, T 1 , and transverse, T 2 , relaxation constants on a voxelby-voxel basis has long been a goal of MRI scientists. Rigorous characterization of T 1 and T 2 may allow for greater tissue discrimination, segmentation, and classification, thereby improving disease detection and monitoring, as well as enhancing the images used for image-guided surgical procedures. Absolute determination of T 1 and T 2 is clinically useful in areas such as in-flow perfusion studies (1) and dynamic contrast agent studies (2), as well as in the diagnosis of epilepsy (3) and in determining the severity of Parkinson's disease (4). Therefore, a method that permits simultaneous T 1 and T 2 determination in a rapid manner would be useful in a wide range of imaging applications.In order to be clinically useful for neuroimaging applications, T 1 and T 2 maps should be of high resolution, with a voxel volume less than 1 mm 3 , and have low noise. Imaging time should be less than 30 min for a large volume (25 ϫ 25 ϫ 10 cm) with minimal postprocessing time. Ideally, postprocessing would be performed at the scanner console.Despite the long acquisition times, the principal methods for T 1 and T 2 mapping remain inversion-recovery (IR) and saturation-recovery (SR) for T 1 , and spin echo (SE) and multiple or fast spin echo (mSE, FSE) for T 2 . Although alternative methods (5-9) have been developed to rapidly and accurately determine T 1 or T 2 , the low signal-to-noise ratio (SNR), lengthy reconstruction time, or special hardware requirements associated with these newer methods reduce their appeal.The variable nutation angle method original...

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Measurement of R1 dynamics using sliding window‐DESPOT

Schulz

Korn

Woenne

et al. 2009

Magnetic Resonance Imaging

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Routine evaluation of M0 ratios and T1 values from driven-equilibrium NMR spectra

Cited by 6 publications

References 8 publications

Rapid 3D‐T₁ mapping of cartilage with variable flip angle and parallel imaging at 3.0T

Rapid 3D‐T₁ mapping of cartilage with variable flip angle and parallel imaging at 3.0T

Rapid combined T₁ and T₂ mapping using gradient recalled acquisition in the steady state

Measurement of R1 dynamics using sliding window‐DESPOT

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Routine evaluation of M0 ratios and T1 values from driven-equilibrium NMR spectra

Cited by 6 publications

References 8 publications

Rapid 3D‐T1 mapping of cartilage with variable flip angle and parallel imaging at 3.0T

Rapid 3D‐T1 mapping of cartilage with variable flip angle and parallel imaging at 3.0T

Rapid combined T1 and T2 mapping using gradient recalled acquisition in the steady state

Measurement of R1 dynamics using sliding window‐DESPOT

Contact Info

Product

Resources

About

Rapid 3D‐T₁ mapping of cartilage with variable flip angle and parallel imaging at 3.0T

Rapid 3D‐T₁ mapping of cartilage with variable flip angle and parallel imaging at 3.0T

Rapid combined T₁ and T₂ mapping using gradient recalled acquisition in the steady state