Prof. Kai Ruppert & Faraz Amzajerdian - CMIC/WEISS Joint Seminar Series

Speaker: Prof. Kai Ruppert - FMIG (Functional and Metabolic Imaging Group), UPenn

Title: Assessing Pulmonary Physiology with 0-D and 1-D Hyperpolarized Xenon-129 MRI

Abstract: 
Measuring hyperpolarized xenon-129 (HXe) transfer from the alveolar gas phase to the lung tissue, the so-called dissolved-phase compartment, can provide important insights into pulmonary function. The dissolved-phase imaging techniques currently in use can be divided into two general types: (1) spatially-resolved measurements of the macroscopic xenon distribution within the lung parenchyma as dictated by the structure and physiology of the lung; and (2) high-speed spectroscopic or 1-D measurements with millisecond temporal resolution that capture the xenon gas uptake by the lung tissue and transport by the pulmonary circulation as a function of time. This talk will focus on the latter, in particular how microscopic
changes in the alveolar septal wall far below the spatial resolution of existing diagnostic imaging modalities are accessible to this technique in the form of altered xenon dissolved-phase signal dynamics.

Bio:
Dr. Ruppert received his Master's degree from the Technical University of Braunschweig, Germany, in 1994. He subsequently entered graduate school at the University of Virginia, USA, where he was awarded his PhD degree in Biophysics in 1999. He stayed at the University of Virginia for another 1.5 years as a postdoc and became involved in the budding hyperpolarized noble gas MRI program at that institution. For the past 25+ years he has been working to develop MRI pulse sequences, and for 20+ years his work has been particularly focused on pulse sequences in the field of hyperpolarized media MRI with emphasis on the lung. In recent years, Dr. Ruppert has studied the feasibility of using metrics of pulmonary xenon gas exchange for assessing lung function with hyperpolarized xenon-129 MRI.

Speaker: Faraz Amzajerdian - FMIG (Functional and Metabolic Imaging Group), UPenn

Title: Imaging Ventilation and Gas Exchange Dynamics with Xenon MRI

Abstract: 
Traditional hyperpolarized xenon-129 (HXe) approaches have typically involved long breath-holds at end-inspiration or end-expiration, producing static snapshots which may not fully characterize lung behavior and may be insensitive to the heterogeneous replacement of air with xenon. Therefore to fully quantify the dynamics of ventilation and gas exchange, information from all phases of the breathing cycle is needed. While acquiring this information in a single breath is challenging due to signal limitations, imaging over the course of several breaths instead replenishes available signal and better represents natural breathing. In this talk, we will present a novel approach for continuously imaging gas- and dissolved-phase xenon in free-breathing subjects and retrospectively gating the acquired signals into distinct respiratory phases for analysis. 

Bio:
Mr. Amzajerdian is a graduate student in the department of bioengineering at the University of Pennsylvania. He has been developing and implementing MRI pulse sequences for hyperpolarized xenon-129 with a focus on imaging and assessing late-stage lung disease patients and lung transplant recipients. His work primarily involves quantifying gas exchange and capturing the dynamics of xenon uptake for single-breath, multi-breath, and free-breathing regimes. 

Chair: Geoff Parker