Chad Hunter and Ran Klein

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Date: 
Thursday, April 18, 2013
Time: 
3:30 - 5:00 pm - April 18, 2013
Location: 
Room RPB 205B (boardroom), Health Canada, 775 Brookfield Road

1. “Patient body motion affects myocardial blood flow quantification with rubidium-82 PET imaging”
Chad Hunter – Carleton University

Abstract: Patient motion >0.7 cm occurs in >24% of rubidium-82 (Rb-82) dynamic PET scans, and is known to cause attenuation correction (AC) artifacts, but the effects on myocardial blood flow (MBF) quantification are less clear.  This study aimed to quantify inaccuracies in MBF, induced by patient body motion. Simulations were performed using patient-derived activity distribution and time-activity curves (TAC) of Rb-82 PET, and a digital NCAT phantom.  A simulation without motion was used as a reference standard.  Translational motion in three dimensions (±1 and ±2 cm) was simulated (n=12), consisting of an instantaneous shift in the body location at a shift-time (30, 60, 120, 240 s). Noise-free images were reconstructed using filtered back-projection.  Dynamic images were reconstructed with and without AC artifacts.  Blood flow quantification was performed using the 1-tissue-compartment model, including blood spillover and partial-volume corrections as implemented in the FlowQuant (UOHI) software program. Errors were greatest for shifts at 120s, CTAC misalignment artifacts alone accounted for 5 to 13% error in MBF measurements.  CTAC artifacts occurring after the shift-time resulted in 30% greater MBF error compared to those before the shift point.  Dynamic body motion alone with regional partial-volume recovery correction (RC) resulted in MBF errors as high as 230%, indicating that inconsistency in the dynamic TAC data is the dominant source of MBF inaccuracy.  Regional partial-volume recovery correction (RC) resulted in 80% increase in variability and 20% increase in the maximum MBF error compared to a global-average RC, indicating that regional partial-volume correction methods are also sensitive to body motion. Patient body motion of 1 to 2 cm can result in >200% error in MBF due to inconsistent myocardial TAC data, suggesting that post-reconstruction image-based motion correction may correct for the majority of body motion-induced bias in MBF measurements.

2.  "Myocardial blood flow quantification - 82Rb PET is the just the beginning"
Ran Klein – University of Ottawa Heart Institute

Abstract: Our work on quantification of myocardial blood flow using rubidium-82 (82Rb) positron emission tomography (PET) is poised to provide precise clinical information for effective patient management, while substantially reducing the cost of these exams, and radiation exposure. The lessons we learnt and the technology we developed is now being translated to new imaging modalities and applications. This talk will introduce our cutting edge 82Rb PET technology and will highlight ongoing research which exploits this technology.