Hyperpolarized 129-Xenon MRI in Fibrosing Interstitial Lung Disease

Inclusion Criteria: * Informed signed consent * Age 18-90 * Pre-menopausal women must be confirmed non-pregnant by an onsite test. * Patients diagnosed with IPF or fibrotic ILD who fulfills PPF criteria, and are prescribed antifibrotic treatment. * Cognitively able to understand and participate in the study Exclusion Criteria: * Contraindications for MRI: * Pacemaker, neurostimulator or cochlear implant * Metal foreign bodies such as fragments and irremovable piercings * Unsafe medical implants (safety of heart valves, hips and the like must be confirmed) * Intrathoracic clips or coils * Cardiac pacemakers * Claustrophobia * Largest circumference including arms \> 160 cm * Contraindications to gadolinium contrast * eGFR \< 30 mL/min/1.73m2 * Previous adverse reactions to gadolinium * Overlapping emphysemic disease where the emphysema-component outweighs the fibrosis * Unable to perform breath-hold of minimum 20 seconds. * Allergy to Xenon * Breast feeding * Evidence of ongoing respiratory infections at time of MR examinations