Commentary on “The influence of lung airways branching structure and diffusion time on measurements and models of short-range 3He gas MR diffusion”

Direct comparison of 129Xe diffusion measurements with quantitative histology in human lungs

“…During the 5-ms diffusion time in our experiments, a gas atom would most likely encounter one or more tissue walls that restrict motion without drifting outside of one alveolar duct. Although discussion on the importance of diffusion time and modeling has been debated extensively in the literature (48,49), experiments with 3 He have demonstrated that the diffusion time has a relatively small effect on the measured ADC compared with differences seen as a result of airspace enlargement (50). In the future we will explore multiple b-value diffusion experiments with xenon.…”

Mapping of regional lung microstructural parameters using hyperpolarized 129Xe dissolved‐phase MRI in healthy volunteers and patients with chronic obstructive pulmonary disease

“…Certain lung microstructural parameters can also be obtained using gas diffusion MRI and models of acinar microstructure . Although there is significant evidence for the validity of these models from comparison to histology, there are some limitations that might affect their accuracy …”

Advanced pulmonary MRI to quantify alveolar and acinar duct abnormalities: Current status and future clinical applications

“…In patient studies, MRI L m values were also shown to agree with stereological measurements . Excellent correspondence between MRI‐based L m estimates and the histology mean linear intercept estimates was confirmed . Although there has not been a direct comparison of 129 Xe morphology measurements to histology, recently there have been comparisons of 129 Xe and 3 He‐derived measures, including 129 Xe ADC and histology‐based L m .…”

“…MRI has been used to investigate emphysematous changes in current and exsmokers with COPD and to monitor potential lung regrowth in rodents and lung cancer patients . The relationship of in vivo MRI estimates and histological measurements in excised tissues were also determined . These previous results have generated a strong foundation for the optimization and strategic clinical research application of MRI in patients, to directly measure treatment efficacy, and help accelerate the development of novel therapies including cell‐based and whole‐organ replacement therapy.…”

“…Currently, a cylinder morphometry model is the most widely used, and is histologically validated in patients and histology/micro‐CT‐validated in animal models . Although the cylinder model has a complete mathematical framework for both 3 He and 129 Xe clinical/preclinical lung morphometry, most morphometry studies were conducted with 3 He gas.…”