Here are the iMQC/DDF related abstracts that I found. Please email me if I missed one (especially yours!) corum@cmrr.umn.edu
Hopefully you, or a colleague has access to the login.
Curt
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1407.
Intermolecular Zero-Quantum Coherence Imaging in Structured Samples
Bernard Siow1, Li Sun1, Andrew M. Blamire1
1Newcastle University, Newcastle upon Tyne, UK
Intermolecular multiple quantum coherence imaging sequences have recently been shown to provide a fundamentally different contrast mechanism to conventional MRI. A numerical study of intermolecular zero-quantum coherence imaging has shown sensitivity to susceptibility gradients at selected distance scales. In this study, an iZQC sequence was implemented and iZQC signal verified. The sequence was used to investigate sensitivity to susceptibility gradients at selected distance scales in structured samples. Images show contrast in areas where susceptibility gradients are present. Furthermore, contrast was modulated by the distance scale selected. Further results suggest that contrast is modulated by specific resonant frequency difference at distance scale selected.
1454.
Fast Relaxation Induced by SPIO Compromises Contrast from Intermolecular Double–quantum Coherence in CRAZED–MRI
Elvira Mehlin1, Stefan Kirsch1, Peter Bachert1
1German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
The CRAZED sequence permits detection of signal generated by intermolecular double–quantum coherence (iDQC). When applied to 1H MRI, a novel type of contrast is obtained, in particular, a positive contrast when superparamagnetic iron oxide particles (SPIOs) are present. We demonstrate that the high T1–relaxivity of SPIOs can cause spurious signal in CRAZED MRI which cannot be attributed to iDQC.
1458.
Optimization of Parameters for the Distant Dipolar Field Signal Acquired in CRAZED-Multiecho Pulse Sequence
Chung Ki K. Wong1, Jianhui Zhong1
1University of Rochester, Rochester, New York, USA
The decrease of dipolar signal with refocusing pulses of finite duration in a CRAZED-multiecho acquisition was investigated previously. It was found that the rephasing of the dipolar signal during the refocusing pulses in the multiecho sequence depends substantially on the phase of the pulses. In this abstract, the total signal acquired from the multiecho sequence was optimized with the parameters of the sequence. The results show that the attenuation of the signal due to the finite duration of the refocusing pulses can be compensated with a longer τ2 and a proper choice of the phase of the pulses.
1562.
Time-Zero Signal Truncation in CRAZED Experiments Due to Rephasing Gradient Delays Leads to Incorrect Frequency-Domain Lineshapes
Stefan Kirsch1, William Edmund Hull1
1German Cancer Research Center (DKFZ), Heidelberg, Germany
In contrast to the decay of a conventional pulse-acquire FID, the time-domain signal from of a CRAZED-type pulse sequence for coherence order n > 1 increases from initially zero to a maximum, followed by an exponential decay. We show that the finite duration of the coherence rephasing gradient and any subsequent recovery delays lead to loss of the initial portion of the time-domain signal. This so-called “time-zero truncation artefact” results in an altered frequency-domain lineshape with incorrect integral and linewidth. Correct analysis requires time-domain fitting of right-shifted data.
1563.
In Vivo Human Whole Cerebellum MRS Under Severe Field Inhomogeneity with IDQC Method
Tianliang Gu1, 2, Zhong Chen1, Xiaoxu Liu1, Ling-chih Lin1, Jianhui Zhong1
1University of Rochester, Rochester, New York, USA
An intermolecular double quantum coherence (iDQC) 2D MRS pulse sequence was created and implemented on a 3T scanner for acquisition of human brain 1H spectra in regions susceptible to field inhomogeneity such as the cerebellum. High resolution 1D MRS could be obtained in a few minutes with iDQC over the whole cerebellum, whereas conventional single voxel 1D MRS was working successfully only when regions much smaller were covered. NAA/Cr and Cho/Cr measured with both methods in 5 healthy subjects agreed well with each other.
2361.
Enhanced BOLD Effect in the Mouse Brain with Fast CRAZED Imaging at High Magnetic Fields
Johannes Thomas Schneider, Cornelius Faber
A fast CRAZED sequence detecting the signal from intermolecular multiple-quantum coherences (iMQC) was implemented at 17.6 T to observe the BOLD effect in the mouse brain. Signal readout as echo train employing a four-step phase cycle for the refocusing pulses and an intensity-ordered k-space sampling allowed for acquisition of CRAZED images in 30 seconds. In the CRAZED images the BOLD effect was more pronounced than in RARE images but smaller than in gradient echo images. Combination of iMQC with T2*-effects may provide larger signal changes than conventional BOLD methods.
3063.
Enhanced Contrast in CEST MRI Via Intermolecular Double Quantum Coherences
Shengchun Zhang1, Huijun Sun1, Zhong Chen1, Congbo Cai1, Jianhui Zhong2
1Xiamen University, Xiamen, People's Republic of China; 2University of Rochester, Rochester, New York, USA
A CEST imaging technique based on intermolecular double quantum coherence (iDQC) is proposed. Quantitative analysis and experiments in glucose agarose-gel phantoms demonstrate that, in CEST MRI, iDQC signal is more sensitive to RF saturation than the conventional SQC signal, and thus needs RF saturation pulses of lower power to achieve similar CEST image contrast. Consequently, the method can reduce the potential RF burning in clinic applications, and is expected to facilitate the study of the CEST effect in the system with exchangeable protons of low concentrations.
3125.
High-Resolution MR Spectroscopy in Inhomogeneous and Unstable Fields Via Intermolecular Zero-Quantum Coherences
Xi Chen1, Meijin Lin1, Tao Lin1, Zhong Chen1, Jianhui Zhong2
1Xiamen University, Xiamen, People's Republic of China; 2University of Rochester, Xiamen, New York, USA
A new iZQC pulse sequence with stroboscopic acquisition is designed to achieve high-resolution magnetic resonance spectroscopy in inhomogeneous and unstable fields. Primary results suggest potential applications for suppressions of motion-caused t1 noises and inhomogeneous broadenings in in vivo studies.
3186.
High Resolution NMR Spectra in Inhomogeneous Fields Via Intermolecular Multiple Quantum Coherences Without Coherence Selection Gradients
Zhong Chen1, Congbo Cai1, Yanqin Lin1, Shuhui Cai1, Jianhui Zhong2
1Xiamen University, Xiamen, People's Republic of China; 2University of Rochester, Rochester, New York, USA
Coherence selection gradient has been thought to be essential for high resolution NMR spectra in inhomogeneous field based on intermolecular multiple quantum coherences (iMQC). However, our experimental results show that it can be omitted if correct phase cycling is applied. This means that the measured line-width of high resolution spectral peaks is not determined by the dipolar correlation distance caused by coherence selection gradient, but only affected by the effects of diffusion and T2 relaxation. This result prompts us to reconsider the iMQC high resolution mechanism.
3188.
An Effective Fast Acquisition Scheme to Achieve High-Resolution MRS with J-Coupling Scaling Via Intermolecular Multiple-Quantum Coherences
Xi Chen1, Meijin Lin1, Jincan Chen1, Tao Lin1, Zhong Chen1
1Xiamen University, Xiamen, People's Republic of China
A series of intermolecular double-quantum filtered (iDQF) sequence with efficient solvent suppression and different scaling factors of J-coupling constants, named iDQF-HOMOGENIZED II (abbreviated as iDH2), are designed to achieve fast acquisition of high-resolution spectra in inhomogeneous fields. Experiments on swine brain tissues were performed to test the feasibility of the new method. The results suggest potential applications for in vivo spectroscopy.
3189.
A Flexible IMQC Method for Accurate Determination of J-Coupling Constants in Inhomogeneous Fields
Yanqin Lin1, Shuhui Cai1, Yuqing Huang1, Zhong Chen1, Jianhui Zhong2
1Xiamen University, Xiamen, People's Republic of China; 2University of Rochester, Rochester, New York, USA
An improved pulse sequence was developed to scale apparent J coupling constants by a scaling factor ranging theoretically from zero (completely decoupled) to infinity under inhomogeneous fields via intermolecular multiple-quantum coherences. Scaling up the apparent J coupling constants allows more accurate measurement of small J coupling constants, and a completely decoupled homonuclear spectrum can be of considerable help for improving signal separation and thus peak assignment in MRS. The resulting spectrum retains conventional high-resolution NMR spectral information.
3351.
Apparent Diffusion Behaviors Modulated by Distant Dipolar Field in Solution NMR
Shuhui Cai1, Guiping Shen1, Congbo Cai1, Zhong Chen1
1Xiamen University, Xiamen, People's Republic of China
A modified CRAZED sequence was designed to observe and characterize apparent diffusion behaviors of signals from intermolecular double-quantum coherences during the mixing period. It is found that their apparent diffusion behaviors are different from conventional single-quantum coherences, and different orientation of diffusion weighting gradients relative to coherence selection gradients results in different apparent diffusion behaviors. This indicates
that the apparent diffusion behavior is influenced by the distant dipolar field.
3647.
Enhancement of MT, CEST and NOE Contrast Via Intermolecular Multiple Quantum Coherences
Wen Ling1, Uzi Eliav1, Xu Yang2, Gil Navon1, Alexej Jerschow2
1Tel Aviv University, Israel; 2New York University, New York, New York, USA
We demonstrate that using intermolecular multiple-quantum coherences can enhance contrast in MTC/CEST/NOE experiments in proportion to (Mz/Mo)p, where Mz is the the saturated level of the z-component of the magnetization, Mo its value in equilibrium and l is the coherence order used. These methods are demonstrated on a series of glycosaminoglycan (GAG) samples, and also for a piece of bovine articular cartilage.
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