It is important to note that 3
He MRI is unique among pulmonary imaging methods because of its high spatial and temporal resolution of respiratory disease morphology (ADC) and
function (ventilation volumetry) and its safe use across a wide variety of vulnerable pediatric, respiratory compromised and elderly patients (25
) to explore mechanisms of disease pathophysiology. Hence, a number of important respiratory diseases have been evaluated in some depth and breadth across different research sites including COPD, asthma, cystic fibrosis and RILI. As with other functional imaging methods that are yet in the “imaging physics” and “image processing” domain, there remain significant challenges to translating 3
He MRI to clinical research and clinical care. The unique ability to measure disease morphological and functional consequences and explore mechanisms of disease pathophysiology does not necessarily directly translate to improved care unless alternative therapies exist that can benefit from the information provided by HP He MRI. However, for the specific cases of asthma and COPD, there is an increasing recognition that different phenotypes exist (40,102–103
) and that these patient groups may have differential response to therapy. Moreover as therapies become more diverse and patient-specific, imaging with HP He MRI will likely be one of the only ways to verify response and efficacy for an individual patient or group of patients. Nonetheless, HP He MRI techniques need to become more quantitative, sensitive and accessible to justify its current cost and complexity.
As with many functional imaging methods, there remain significant challenges to translating these methods to the clinic. It is also equally important to point out that currently respiratory diseases still have significant unmet treatment needs in terms of pharmaceutical and minimally invasive interventions; and these disorders stand alone among the leading causes of death and disease. As the world becomes more industrialized and polluted, respiratory illnesses will continue to increase in prevalence, morbidity and overall mortality. We believe this is largely the case because up until recently, lung imaging methods have been mainly restricted to x-ray based methods and the lung is particularly radiation sensitive which diminishes the numbers and types of imaging sessions that are practical. While pulmonary function testing is quite reliable and inexpensive there are many diseases that can not be easily diagnosed by this type of functional lung testing. Imaging is often not used in the diagnosis of COPD, CF, asthma or RILI in part because unlike many organ systems where early or sensitive diagnosis has lead to earlier and efficacious treatments, there is no such virtuous cycle in place for most respiratory diseases. As shown in , these current and emerging imaging methods for respiratory disease each have significant strengths and challenges. It is in this context or clinical reality that we continue to vigorously support the research and development of 3He MRI methods even in light of the increased costs, decreased availability and access that are predicted for the near future.
Strengths and Challenges of HRCT and HP 3He MRI for Pulmonary Functional Imaging