TRADITIONAL POSTER - ismrm

Poster Sessions
2648. A Novel Whole Body Diffusion Weighted Imaging Technique with Continuously Moving Table:
Preliminary Results
Yeji Han 1 , Sandra Huff 1 , Juergen Hennig 1 , Ute Ludwig 1
1 Medical Physics, Dept. of Diagnostic Radiology, University Hospital Freiburg, Freiburg, Germany
Superior disease contrast and no need for extra administration of exogenous contrast medium contribute to the advantages of diffusion-weighted imaging
(DWI) over other modalities for patient screening and treatment monitoring. However, the clinical impact of whole-body DWI (wbDWI) remains limited
due to the technical difficulties of multistation approach. In this study, we have developed a continuously moving table (CMT) wbDWI method based on a
STIR-EPI sequence as an alternative to currently used multistation wbDWI sequence. The preliminary results successfully demonstrate that CMT wbDWI
can be a promising technique to overcome the problems of multistation wbDWI approach.
2649. Characterization of Multicompartmental Renal Diffusion Using a Stretched Exponential Model
Claudia Lenz 1 , Gregor Sommer 2 , Klaus Scheffler 1 , Leopold Winter 2 , Markus Klarhöfer 1
1 Radiological Physics, University of Basel Hospital, Basel, Switzerland; 2 Department of Radiology, University of Basel Hospital,
Basel, Switzerland
In biologic tissues, microscopic motion of water not only includes molecular diffusion, but also microcirculation of blood in the capillary network. The
intraxovel incoherent motion model has been introduced to describe these combined diffusion and microcirculation effects in diffusion weighted imaging.
Analysis of the multicompartmental water diffusion is mostly performed by applying a biexponential fit function to the diffusion curve and evaluating the
diffusion and perfusion components separately. However, this technique often suffers from high standard fit errors, especially for the perfusion fraction f. In
2003, Bennett et al. proposed a stretched exponential model to account for the multiexponential behavior of diffusion curves in the brain. In this work, we
extended the stretched exponential model to the abdomen and present fit results from the kidneys of healthy subjects.
2650. Interference of Inversion Recovery with Diffusion Weighted Imaging: Negative Apparent Diffusion
Coefficients!
Thomas Gaass 1 , Bram Stieltjes, Frederik Laun 1
1 Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany
The aim of this work was to evaluate whether diffusion weighted imaging (DWI) and inversion recovery (IR) may be applied without interference. DWI of
the liver shows that the apparent diffusion coefficient (ADC) measured in a single voxel is clearly dependent on the inversion time and ADCs vary between -
0.007 s/mm² and 0.009 s/mm² in a 100 ms TI interval. The counterintuitive negative diffusion is observed in the liver and in regions with incomplete fat
saturation. This can be explained by the here proposed two compartment model. Thus, DWI and IR can generally not be applied without interference.
2651. Diffusion-Weighted Imaging of the Kidney: Beyond Mono- And Bi-Exponential Models
Anna Caroli 1 , Luca Antiga 1 , Giuseppe Petralia 2 , Massimo Bellomi 2 , Andrea Remuzzi 1,3 , Paul Summers 2
1 Bioengineering Department, Mario Negri Institute for Pharmacological Research, Bergamo, Italy; 2 Division of Radiology, European
Institute of Oncology, Milan, Italy; 3 University of Bergamo, Bergamo, Italy
Mono-exponential models do not accurately predict diffusion-weighted signal decay in the kidney, while bi-exponential models are unable to differentiate
contributions. We propose a “piece-wise” exponential model, separately fitting low and high b-values with two exponentials, expressive of fast and slow
transport components. Ten healthy volunteers underwent DWI both pre- and post-lunch, and acquisitions were repeated within one of the two sessions. The
model was stable, and accurately fit signal attenuation. Diffusion parameters showed high repeatability, but significant differences between pre- and postmeal
acquisitions. These results point out the need for more complete interpretations of DWI signal in describing the complex transport in the kidney.
2652. Impact of Low and High B-Value MR Diffusion in HIV/HCV-Coinfected, HIV-Monoinfected and
Uninfected Subjects
Susan Moyher Noworolski 1,2 , Phyllis Tien 3,4 , Michelle Nystrom 1 , Suchandrima Banerjee 5 , Aliya Qayyum 1
1 Radiology and Biomedical Imaging, University of California, San Francisco, CA, United States; 2 The Graduate Group in
Bioengineering, University of California, San Francisco and Berkeley, CA, United States; 3 Medicine, University of California, San
Francisco, CA, United States; 4 Medicine, Veteran Affairs Medical Center, San Francisco, CA, United States; 5 MR Applied Science
Lab, GE Healthcare, Menlo Park, CA, United States
The impact of a perfusion regime, low b-value ADC, and a tissue regime, high b-value ADC were evaluated in comparison to a conventional ADC in three
groups of subjects: HIV/HCV (hepatitis C) coinfection, HIV-monoinfection, and without infection. Liver ADC was measured using b values of 0 and 150
(ADC low ), 150 and 600 (ADC high ) and 0 and 600 (ADC conv ) in one breathhold sequence. ADC low and ADC high provided unique information. HIV tended to
have the highest ADC levels and was significantly higher than HIV/HCV for ADC low and ADC conv . HIV status may thus be an important consideration in
interpretation of liver ADC.
2653. SSFP Diffusion Prepared SSFSE
Weiying Dai 1 , Philip M. Robson 1 , David C. Alsop 1
1 Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States
SSFP diffusion weighted imaging in the body can have improved image quality relative to echoplanar imaging. Its stronger diffusion attenuation of longer
T2 fluid may also be a particular benefit in cancer screening studies, but the slow acquisition speed is a major limitation. Here we propose performing a
diffusion weighted SSFP sequence as a preparation for a faster SSFSE sequence. The theoretical signal is described and pulse parameters are optimized. The
resulting sequence is then applied to in-vivo diffusion weighted imaging of volunteers. Excellent suppression of fluid and blood signal is demonstrated.