TRADITIONAL POSTER - ismrm

Poster Sessions
2964. T2* Mapping at 7 T
Kai Zhong 1 , Ralf Deichmann 2 , Weiqiang Dou 1 , Oliver Speck 1
1 Biomedical Magnetic Resonance, Otto-von-Guericke University, Magdeburg, Saxon-Anhalt, Germany; 2 Brain Imaging Center,
University Frankfurt, Frankfurt, Germany
Previous studies at 7 T have related T2* maps to the iron deposition in brain tissue. However, the field inhomogeneity and susceptibility distortion at 7 T are
significantly higher compared to lower field. This potentially distorts the true T2* values and could lead to false estimation of the tissue iron content. In this
study, T2* correction based on the susceptibility gradients was applied to 7 T and can improve the resulting T2* maps. This method therefore should help to
improve the accurate determination of T2* at 7 T for clinical studies. On the other hand, stronger dephasing is encountered, so thinner slices should be
chosen than at lower fields to avoid systematic errors.
2965. R2* Reference Phantoms for Longitudinal Research Studies
Matthew T. Latourette 1 , James E. Siebert 1
1 Radiology, Michigan State University, East Lansing, MI, United States
In longitudinal research studies that employ R2*/T2* quantitation, reference phantoms can serve to improve the sensitivity and reproducibility of R2*
measurements through detection and correction of bias and reduction of the variance of pooled study data. Stable phantoms comprised of agarose and
carageenan gel doped with SPIO, NiCl 2 , and methylisothiazolinone were developed, enabling reliable R2* measurements that are adequately insensitive to
temperature variations near room temperature. The phantoms’ R2* dependence on B 0 was evaluated at field strengths of 0.35T, 0.7T, 1.5T, 3.0T. Chemical
stability has been evaluated since phantom construction in April 2009.
2966. Transverse Relaxation of Water in Ferritin Gel: Relative Contributions of Iron and Gel
Nobuhiro Takaya 1 , Hidehiro Watanabe 1 , Fumiyuki Mitsumori 1
1 National Institute for Environmental Studies, Tsukuba, Ibaraki, Japan
Transverse relaxation of tissue water in human brain was explained with a linear combination of contributions from ferritin iron and the macromolecular
mass fraction defined as 1-water fraction. This work examined whether the same scheme is applicable to relaxation of a model system composed of ferritin
and agarose gel. The result of multiple regression analysis on the system showed that transverse relaxation in the system was described in the same manner
as in human brain. B 0 dependence of R 2 demonstrated that the relaxation mechanism due to iron in gel samples is identical to that reported for a ferritin
solution.
2967. Water-Specific Quantitative MRI Relaxometry of the Brain Using Spatial-Spectral Water Excitation:
Preliminary Experience
Stephan William Anderson 1 , Jorge A. Soto 1 , Osamu Sakai 1 , Hernan Jara 1
1 Radiology, Boston University Medical Center, Boston, MA, United States
The purpose of this work was to test a pulse sequence for spatial- and spectral-selective qMRI relaxometry in vivo for deriving qMRI parameters in brain
imaging. The brain of a volunteer was imaged using both non-chemically selective mixed-TSE sequence as well as the SSE-mixed-TSE pulse sequence to
derive parametric maps of PD, T1, T2 (including secular-T2), and ADC of the brain. T2 was found to be consistently longer for the SSE-mixed-TSE pulse
sequence. Spectrally selective qMRI may offer insight into both normal structures as well as pathology without the confounding effects of lipids.
2968. Simultaneous T1 and T2 Mappings Using Partially Spoiled Steady State Free Precession (PSSFP)
Paulo Loureiro de Sousa 1,2 , Alexandre Vignaud 3 , Laurie Cabrol 1,2 , Pierre G. Carlier 1,2
1 Institut de Myologie, Laboratoire de RMN, Paris, France; 2 CEA, I2BM, Paris, France; 3 Siemens Healthcare, Saint Denis, France
A fast 3D T2 mapping technique based on two partially Spoiled Steady State Free Precession (pSSFP) acquisitions has recently been presented. For most
human soft tissues, accurate T2 measurements can only be obtained for high flip angle (FA) leading to SAR issues especially at high field. In this work we
proposed an analytical expression derived from pSSFP theory which allowed us to introduce a more flexible T2 mapping technique. By doubling data
collection, T1 map can also be extracted. The method has been validated on a phantom comparing pSSFP results with standard T1 and T2 measurements.
2969. Single-Shot Proton Density, T 1 and T 2 Quantification with Radial IR TrueFISP: Effect of
Magnetization Transfer and Long RF Pulses
Philipp Ehses 1,2 , Vikas Gulani 3 , Stephen Yutzy 3 , Nicole Seiberlich 3 , Peter Michael Jakob 1,2 , Mark A.
Griswold 3
1 Dept. of Experimental Physics 5, Universität Würzburg, Würzburg, Germany; 2 Research Center Magnetic Resonance Bavaria
(MRB), , Würzburg, Germany; 3 Department of Radiology, Case Western Reserve University and University Hospitals of Cleveland,
Cleveland, OH, United States
The IR TrueFISP sequence has been shown to be a promising approach for the simultaneous quantification of proton density, T 1 and T 2 maps. For accurate
quantification, segmentation is usually necessary, leading to an increase in scan time. In this work, a full set of parameter maps was obtained in a single-shot
by combining the IR TrueFISP sequence with a golden-ratio based radial trajectory and using extensive view-sharing. The effects of both magnetization
transfer and the violated instantaneous RF assumption on parameter quantification were further analyzed by prolonging the RF pulses and TR (thereby
reducing RF power and thus MT).
2970. T1 and T2 Quantification for Short T2 Tissues: Challenges and Solutions
Michael Carl 1 , Jiang Du 2 , Jing-Tzyh Alan Chiang 2 , Eric Han 1 , Christine Chung 2
1 GE Healthcare, Waukesha, WI, United States; 2 University of California, San Diego
The relaxation properties T1 and T2 of MRI images are important parameters in assessment of pathology. Many musculoskeletal (MSK) tissues (cortical
bone, tendon, ligaments, etc) have very short transverse relaxation times. UTE imaging of MSK tissues can pose unique challenges for the quantification of
the longitudinal or transverse relaxation. We describe these challenges and offer simple solutions to help overcome them.