ELECTRONIC POSTER - ismrm

using both methods but the difference between the ASL label and control signal (ΔM) was decreased compared to medical air and
increased during CO 2 inhalation. ASL was able to detect changes in CBF with equal precision to PCA CBF measurements.
15:00 4087. Human Retinal Blood Flow MRI Using Pseudo-Continuous Arterial Spin Labeling
and Balanced Steady State Free Precession
Sung-Hong Park 1 , Yi Zhang 1 , Jinqi Li 1 , Qi Peng 1 , Jiongjiong Wang 2 , Timothy Q. Duong 1
1 Research Imaging Institute, Ophthalmology/Radiology, University of Texas Health Science Center at San
Antonio, San Antonio, TX, United States; 2 Radiology and Neurology, University of Pennsylvania, Philadelphia,
PA, United States
Mapping human retinal blood flow has not been easy with EPI-based arterial spin labeling (ASL) techniques because of significant
susceptibility effects around eyes. In this study, we propose to use a combination of pseudo-continuous ASL and balanced steady state
free precession (bSSFP) readout for mapping blood flow in the human retina. The results showed reproducible human retinal blood
flow, free of motion artifacts, image distortion, signal drop out and bSSFP banding artifacts.
Dynamic Contrast Enhancement MRI
Hall B Monday 14:00-16:00 Computer 62
14:00 4088. Design and Testing of a Phantom for Calibration of MRI Systems Used in DCE-
MRI Clinical Trials
Michael H. Buonocore 1 , David H. Gultekin 2 , Michael A. Jacobs 3 , Steffen Sammet 4 ,
Natarajan Raghunand 5 , Joshua Levy 6 , Michael V. Knopp 4
1 Radiology, UC Davis Imaging Research Center, Sacramento, CA, United States; 2 Memorial Sloan-Kettering
Cancer Center, New York, NY, United States; 3 Radiology, Johns Hopkins University, Baltimore, MD, United
States; 4 Radiology, Ohio State University, Columbus, OH, United States; 5 Radiology, University of Arizona,
Tucson, AZ, United States; 6 The Phantom Laboratory, Inc., Salem, NY, United States
This study presents a new DCE-MRI phantom designed for calibration of MRI systems to be used in multi-site clinical trials.
Preliminary results at four clinical sites show the ability of the phantom to reveal critical similarities but also expected and unexpected
differences in the images and derived DCE-MRI parameters.
14:30 4089. Monte Carlo Simulation to Study the Robustness of Empirical DCE-MRI Kinetic
Parameters to Gaussian Noise
Ka-Loh Li 1 , Alan Jackson 1 , Gerard Thompson 1 , Xiaoping Zhu 1
1 Imaging Science and Biomedical Engineering, The University of Manchester, Manchester, United Kingdom
Using empirical descriptors to assess T1-weighted DCE-MRI data is easy to perform. However, the effects of MRI noise on the
reliability of empirical kinetic parameters have not been systematically investigated. This study investigated the robustness of several
empirical parameters to Gaussian noise under various pharmacokinetic and noisy conditions using Monte Carlo simulation. We found
that area under the enhancement curves was most robust to Gaussian noise. Signal enhancement ratio is mostly sensitive to noise and
pharmacokinetic conditions. The study improved our understanding of the noise effect on empirical kinetic parameters, leading to
better interpretation of these parametric images.
15:00 4090. Optimal Period of Linearity Using Patlak Analysis in Brain Tumors
Rajan Jain 1 , Hassan Bagher-Ebadian 2,3 , Jayant Narang 1 , Siamak Pourabdollah Nejad-
Davarani 2 , Sona Sakesna 1 , Lonni Schultz 4 , Mohammad H. Asgari 2 , James R. Ewing 2,3
1 Radiology, Henry Ford Hospital, Detroit, MI, United States; 2 Neurology, Henry Ford Hospital, Detroit, MI,
United States; 3 Physics, Oakland University, Rochester, MI, United States; 4 Biostatistics and Research
Epidemiology, Henry Ford Hospital, Detroit, MI, United States
In Patlak analysis, contrast agent transport is assumed to be unidirectional (from plasma space into extracellular extravascular space).
Although this model has the advantage of simplicity, it is important to note that it will give inaccurate results when this assumption is
incorrect as in leaky brain tumors. Using longer acquisition fit-times will probably yield overestimates of fV and underestimates of
Ktrans in the leaky regions as these will fall into the non-linear part of the Patlak plot. Hence, understanding of the optimal fit-times as
well as proper modeling used for Patlak analysis is important for measuring the physiologic parameters accurately.
15:30 4091. The Patlak Plot in MRI Pharmacokinetic Analysis
Charles S. Springer, Jr. 1 , William D. Rooney 1 , Xin Li 1
1 Advanced Imaging Research Center, Oregon Health & Science University, Portland, OR, United States
An honored method for pharmacokinetic interpretation is the Patlak Plot – the popular linearization technique introduced over 25
years ago for graphical tracer data analyses. In (Dynamic-Contrast-Enhanced) DCE-MRI, the injected contrast reagent (CR) plays the
tracer role. However, there are crucial differences between the molecular mechanisms underlying the detection of tracers and CRs.
This contribution discusses how these differences impact the use of the Patlak Plot for the analysis of DCE-MRI data.