TRADITIONAL POSTER - ismrm

Poster Sessions
that no single exchange time value dominates the time evolution of the XTC signal. It is demonstrated that the XTC90 experiment (employing 90° flips
instead of 180°) should generate results similar to CSSR experiments.
2557. Lung Inflation State Dominates Over Intrapulmonary PO 2 Regarding T 2 * of 3 He in Human Lungs
Martin H. Deppe 1 , Salma Ajraoui 1 , Helen Marshall 1 , Jim M. Wild 1
1 Academic Radiology, University of Sheffield, Sheffield, Yorkshire, United Kingdom
This work investigates the influence of O 2 on the T 2 * of hyperpolarized 3He in human lungs. To separate the effect of O 2 from the known lung inflation
dependence, T 2 * maps were obtained at expiration and full inspiration, both at baseline breathing air and after 4 min of pure O 2 . It is found that the effect of
lung inflation dominates over any potential O 2 effect, which is proposed to be due to a combination of motional narrowing and the fact that 3 He is distributed
over the whole alveolus, while 1 H spins are confined to the interfaces, where susceptibility gradients are strongest.
2558. Motion-Corrected PO 2 Mapping in Human Lungs Using Hyperpolarized Xe-129 MRI
G. Wilson Miller 1 , John P. Mugler III 1 , Talissa A. Altes 1 , Isabel Dregely 2 , Iulian Ruset 3 , Steve Ketel 3 , Jeff
Ketel 3 , William F. Hersman 2,3 , Kai Ruppert 1
1 Radiology, University of Virginia, Charlottesville, VA, United States; 2 Physics, University of New Hampshire, Durham, NH; 3 Xemed
LLC, Durham, NH
Lung pO2 mapping using hyperpolarized Xe-129 was performed in 6 healthy volunteers and 4 disease patients. An image registration algorithm was used to
correct for subject motion during the breath hold acquisition.
2559. An Integrated Small-Animal Ventilator and Recycling System for Small-Animal Hyperpolarized Gas
MRI
John C. Nouls 1 , Manuel Fanarjian 2 , Bastiaan Driehuys 1,3
1 Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, United States; 2 Biomedical Engineering, Duke
University, Durham, NC, United States; 3 Radiology, Duke University Medical Center
We present a constant-volume small-animal ventilator that offers precise control of gas delivery, permits high-resolution hyperpolarized gas imaging, and
captures the exhaled mixture containing 3He or 129Xe for recycling. The captured gas is compressed by a piston and stored in a cylinder to be sent for repurification.
The same ventilator can ventilate different small animals, simply by changing flow constrictors. The ventilator is inexpensive to duplicate and
only uses off-the shelf components. By recapturing exhaled gas, it alleviates some of the costs associated with HP gas imaging.
2560. Hyperpolarized Noble Gas MR Imaging SNR Comparison Between 73.5 MT and 3 T in Rat Lung
William Dominguez-Viqueira 1,2 , Matthew S. Fox, 1,3 , Giles E. Santyr 2,4
1 Imaging Laboratories, Robarts Research Institute, London, Ontario, Canada; 2 Department of Medical Biophysics, University of
Western Ontario, London, Ontario, Canada; 3 Department of Physics and Astronomy, University of Western Ontario, London, Ontario,
Canada; 4 Department of Medical Imaging, University of Western Ontario, London, Ontario, Canada
The maximum SNR in Hyperpolarized Noble Gas (HNG) MR imaging of rodent lung is expected to be at high fields (>3T). However, SNR improvements
of up to 300% have been demonstrated in rat lung at 73.5mT using Litz-wire coils. In this work the SNR for HNG MRI of rat lung was investigated
theoretically and in vivo, using multi-turn Litz-wire coils at 73.5mT and compared to images obtained at 3T using 129 Xe and 3 He. The use of Litz-wire coils
significantly reduces the advantage (from factor ten to a factor of two) of using high fields for HNG imaging of rat lungs.
2561. Quantitative Assessment of Alveolar Recruitment with Hyperpolarized Gas MRI
Kiarash Emami 1 , Masaru Ishii 2 , Stephen J. Kadlecek 1 , Jianliang Zhu 3 , Stephen Pickup 1 , Yi Xin 1 , Puttisarn
Mongkolwisetwara 1 , Harrilla Profka 1 , Rahim R. Rizi 1
1 Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States; 2 Department of Otolaryngology, Johns
Hopkins University, Baltimore, MD, United States; 3 Department of Surgery, University of Pennsylvania, Philadelphia, PA, United
States
This study evaluates the preliminary use of HP gas diffusion MRI to assess alveolar recruitment dynamics in a healthy rat model. After a period of
ventilation at zero positive end-expiratory pressure (PEEP), recruitment was studied at elevated PEEP and constant tidal volume. After recruitment, it was
found that regional ADC values initially diminished and consistently recovered with the removal of elevated PEEP. It is therefore proposed that before
recruitment, accumulated alveolar collapse causes the over-extension of active alveoli (high ADC); after recruitment, the fixed tidal volume is shared by the
greater number of recruited alveoli (corresponding to decreased ADC).
2562. Alveolar Gas Diffusion MRI as a Function of Pulmonary Pressure
Kiarash Emami 1 , Stephen J. Kadlecek 1 , Yi Xin 1 , Puttisarn Mongkolwisetwara 1 , Harrilla Profka 1 , Stephen
Pickup 1 , Jianliang Zhu 2 , Masaru Ishii 3 , Rahim R. Rizi 1
1 Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States; 2 Department of Surgery, University of
Pennsylvania, Philadelphia, PA, United States; 3 Department of Otolaryngology, Johns Hopkins University, Baltimore, MD, United
States
In this work, we evaluate the use of HP gas ADC measurements to assess the positive end-expiratory pressure (PEEP) dependence of alveolar recruitment in
a healthy rat model. By maintaining a constant tidal volume, ADC can be decoupled from volume dependence and thus considered a measurement of
average alveolar size. In general, it was found that higher ADC values correspond with large PEEP. Additionally, at any given PEEP, the end-inhale ADC
value is larger than the end-exhale ADC value, supporting the theory that in low-recruitment conditions (large numbers of collapsed alveoli), active alveoli
are over-inflated (yielding high ADC).