3He pO2 mapping is limited by delayed‐ventilation and diffusion in chronic obstructive pulmonary disease. Issue 3 (9th May 2013)

• Record Type: Journal Article
• Authors: Marshall, Helen; Parra‐Robles, Juan; Deppe, Martin H.; Lipson, David A.; Lawson, Rod; Wild, Jim M.
• Is Part Of: Magnetic resonance in medicine. Volume 71:Issue 3(2014:Mar.)
• Page Start: 1172
• Page End: 1178
• Publication Date: 2013-05-09
• Subjects: Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.24779
• Languages: English
• ISSNs: 0740-3194

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="mrm24779-sec-0001" sec-type="section"> <title>Purpose</title> <p>Lung pO<sub>2</sub> mapping with <sup>3</sup>He MRI assumes that the sources of signal decay with time during a breath‐hold are radiofrequency depolarization and oxygen‐dependent <italic>T</italic><sub>1</sub> relaxation, but the method is sensitive to other sources of spatio‐temporal signal change such as diffusion. The purpose of this work was to assess the use of <sup>3</sup>He pO<sub>2</sub> mapping in patients with chronic obstructive pulmonary disease.</p> </sec> <sec id="mrm24779-sec-0002" sec-type="section"> <title>Methods</title> <p>Ten patients with moderate to severe chronic obstructive pulmonary disease were scanned with a 3D single breath‐hold pO<sub>2</sub> mapping sequence.</p> </sec> <sec id="mrm24779-sec-0003" sec-type="section"> <title>Results</title> <p>Images showed signal increasing over time in some lung regions due to delayed ventilation during breath‐hold. Regions of physically unrealistic negative pO<sub>2</sub> values were seen in all patients, and regional mean pO<sub>2</sub> values of −0.3 bar were measured in the two patients most affected by delayed ventilation (where mean time to signal onset was 3–4 s).</p> </sec> <sec id="mrm24779-sec-0004" sec-type="section"> <title>Conclusions</title> <p>Movement of gas within the lungs during breath‐hold causes regional changes in signal over time that are not related to oxygen concentration, leading to erroneous pO<sub>2</sub> measurements using the linear oxygen‐dependent signal decay model. These spatio‐temporal sources of signal change cannot be reliably separated at present, making pO<sub>2</sub> mapping using this methodology unreliable in chronic obstructive pulmonary disease patients with significant bullous emphysema or delayed ventilation. <bold>Magn Reson Med 71:1172–1178, 2014. © 2013 Wiley Periodicals, Inc.</bold></p> </sec> </abstract>