Downstream Effects of Airway Mucus Plugs on 129Xenon MRI in Severe Asthma

Inclusion Criteria: * Adequate completion of informed consent process with written documentation * Patients 18 - 65 years old * Physician diagnosis of asthma for \> 1 year * Able to perform reproducible spirometry according to ATS criteria based on clinical PFTs within previous 30 days of enrollment * All racial/ethnic backgrounds may participate * Blood eosinophil count \> 300 cells/μL * Smoking history \<10 pack years * No smoking history (including vapes, cigar, or marijuana use) in the last 3 months * About to initiate asthma therapy with either dupilumab, tezepelumab, or benralizumab as part of their standard of care Exclusion Criteria: * Respiratory tract infection within the 4 weeks prior to Visit 1 * Body mass index (BMI) \> 30 at Visit 1 * One-time doses such as intra-articular injections require a 4-week washout prior to Visit 1 * Asthma-related ER visit within the previous 4 weeks of Visit 1 or at any time while on the study * Significant concomitant medical illness, including (but not limited to) heart disease, cancer, uncontrolled diabetes, other chronic lung diseases (determined by the Investigator.) * Resting O2 saturation \<90% with maximum supplemental O2 delivered by nasal cannula * Positive urine pregnancy test at Visit 1 or at any time while on the study * Participation in an intervention study (including bronchoscopy) or use of investigative drugs within the past 30 days or plans to enroll in such a trial during the study * Unable or unlikely to complete study assessments in the opinion of the Investigator * Study intervention poses undue risk to patient in the opinion of the Investigator * Conditions that will prohibit MRI scanning determined by the MRI safety screening.