TRADITIONAL POSTER - ismrm

Poster Sessions
Diffusion Modeling: General
Hall B Wednesday 13:30-15:30
1575. The Effects of Intracellular Organelles on the ADC of Water Molecules in Cells
Daniel C. Colvin 1 , Jerome Jourquin 2 , Junzhong Xu 1 , Mark D. Does 1 , Lourdes Estrada 2 , John C. Gore 1
1 Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States; 2 Cancer Biology, Vanderbilt
University, Nashville, TN, United States
Diffusion-weighted MRI methods are commonly used to characterize changes in tissue structure that accompany such pathologies as stroke and cancer.
However, the underlying biophysical mechanisms influencing the apparent diffusion coefficient (ADC) remain poorly understood. Temporal diffusion
spectroscopy techniques, which probe diffusion times two orders of magnitude shorter than conventional pulsed gradient methods, were implemented in a
study of packed human embryonic kidney cells treated with drugs that alter actin polymerization, microtubule formation, and Golgi structure. Results reveal
that these techniques may provide a more sensitive probe of changes in intracellular structure compared to conventional methods.
1576. The Influence of Holmium-166 Loaded Microspheres on ADC Measurements Using DWI
Gerrit Hendrik van de Maat 1 , Peter R. Seevinck 1 , Chris J.G Bakker 2
1 Image Sciences Institute, Utrecht, Netherlands; 2 Department of Radiology, University Medical Center, Utrecht, Netherlands
It was shown that the presence of HoMS attenuates the signal of diffusion weighted images leading to a ADC reduction of 0.1mm 2 /ms per mg/ml HoMS.
The reduction of the ADC is caused by the additional gradients induced by the microspheres resulting in a additional weighting factor for calculation of the
ADC which is not taken into account. The dependency of the ADC on concentration HoMS is an effect that should be considered when using DWI for
evaluating tumor viability after radioembolization. Since the local concentration can range up to 15mg/ml, a potential underestimation of the ADC of
1.5mm 2 /ms can occur which may lead to wrong diagnostic conclusions.
1577. Influence of Brain Ischemia on Biexponential Water Diffusion MRI Signal Decay
Renaud Nicolas 1 , Xavier Franceries 1 , Jeremie Pariente 1 , Nicolas Chauveau 1 , François Chollet 1 , Pierre
Celsis 1
1 UMR 825, INSERM; Imagerie cérébrale et handicaps neurologiques, F-31059 Toulouse, France, Metropolitan
Biexponential analysis of DWI isotropic contrast in a case of acute stroke is here presented. Main finding were an F(slow) rise that has the same anatomic
localization that has DWI positive signal but physiologic T.
1578. Three-Dimensional Models of Tissue Microstructure for Simulating High-Precision Diffusion MRI
Data
Eleftheria Panagiotaki 1 , Matt G. Hall 1 , Bernard Siow 1,2 , Mark F. Lythgoe 2 , Daniel C. Alexander 1
1 Centre for Medical Image Computing, Dept. of Computer Science, University College London, London, United Kingdom; 2 Centre
for Advanced Biomedical Imaging, University College London, London, United Kingdom
This work outlines a method to construct detailed three-dimensional geometric models of tissue microstructure using confocal laser scanning microscopy
(CLSM) images. We use these models to simulate the diffusion MRI signal from the tissue by running random-walk simulations within the resulting mesh.
The precise simulated data from our method provide a mechanism for evaluating the quality of simple parametric models and the parameter estimates they
provide.
1579. Effect of Gradient Pulse Duration on Diffusion-Weighted Imaging Estimation of the Diffusional
Kurtosis for the Kärger Model
Jens H. Jensen 1 , Joseph A. Helpern 1
1 Radiology, New York University School of Medicine, New York, NY, United States
The apparent diffusional kurtosis for the Kärger model is calculated as a function of the gradient pulse duration. It is found that the error relative to the true
value is at most a few percent for the parameter range of interest for brain. This result helps to justify the use of larger gradient pulse durations for diffusionweighted
imaging estimation of the diffusional kurtosis.
1580. Measuring Microstructural Features Related to Neuronal Activation Using Diffusion MRI and Three-
Compartment Diffusion Models: A Feasibility Study
Irina Kezele 1 , Daniel C. Alexander 2 , Philip Batchelor 3 , Jean-François Mangin 1 , Denis Le Bihan 1 , Cyril
Poupon 1
1 NeuroSpin, CEA, Gif-sur-Yvette, France; 2 University College , London, United Kingdom; 3 King's College , London, United
Kingdom
We propose an analytic three-compartment diffusion model to explain the diffusion signal coming from tissues that are assumed to comprehend the
intracellular and extracellular “free” water pools and a “membrane-bound” water pool, as hypothesized in a recent paper by Le Bihan (Phys. Med. Biol.
2007). Using this model we deliver an optimized imaging protocol to measure the relevant model parameters. Simulation experiments demonstrate the
accuracy of estimating all the model parameters. In particular, the accurate estimation of membrane-water compartment size promotes the potential to detect
the changes of this size that has been suggested to be related to neuronal activation.