Noble gas MRI research feasible, well-tolerated by patients

Pulmonary imaging research involving the use hyperpolarized noble gas MRI is feasible at smaller centers without significant human resources, according to a study published in the November issue of Academic Radiology.

Using inhaled helium-3 (3He) and xenon-129 (129Xe) to evaluate chronic obstructive pulmonary disease (COPD), cystic fibrosis, asthma or radiation-induced lung injury is also very tolerable and safe for patients, according to authors Miranda Kirby, PhD, and Grace Parraga, PhD, of Robarts Research Institute in London, Canada.

“The hyperpolarized noble gas MRI community's highly collaborative efforts and motivation to further the development and application of this tool has resulted in a moment-of-opportunity to translate the method clinically to provide an improved understanding of pulmonary disease,” wrote the authors.

Kirby and Parraga described their start-up experience with noble gas MRI, in which they evaluated pulmonary function in 330 different subjects from Feb. 1, 2006, through Nov. 1, 2012. Over a third of the subjects were COPD patients, while 17 percent were asymptomatic ex-smokers. Asthma, cystic fibrosis and lung cancer patients with comorbid radiation-induced lung injury made up 9, 4 and 8 percent of the subjects, respectively, with the rest being healthy volunteers.

A total of 312 subjects were successfully screened with image acquisition that was deemed acceptable, reported the authors. Most subjects attended a single visit with multiple scans, though 21 percent attended multiple visits. Three patients were scanned more than 10 times.

Patient size, claustrophobia, MRI-incompatible implants and a failure to breathe in and hold the 3He were listed as reasons for unsuccessful imaging.

A number of patients experienced adverse effects related to the scan, but they were all mild and only resulted in one subject withdrawing from the study. Ninety-five subjects had a temporary decrease in arterial oxygen saturation below 88 percent, and 11 subjects reported other non-serious events such as headache, lightheadedness or cough.

The authors noted that their successful hyperpolarized noble gas MRI research depended on several factors, including:

  • A partnership of private and public funding that provided core facilities and infrastructure support;
  • Collaboration between radiology, imaging physics, pulmonary medicine and other stakholders;
  • A highly receptive and educated patient population; and
  • The assistance of graduate students, postdoctoral fellow and medical residents.

“The method is fast and well tolerated by even the most severely compromised respiratory patients, providing excellent proof of concept for high patient throughput—all of which bodes well for the translation of the method to clinical use,” wrote Kirby and Parraga.