Longitudinal Study of Xenon-129 MRI Imaging Effects of Cannabis Smoking

Inclusion Criteria: * Patient understands study procedures and is willing to participate in the study as indicated by the patient's signature * Provision of written, informed consent prior to any study specific procedures * Males and females aged 18-85 * Current or former cannabis smoker (medicinal or recreational) with or without concurrent tobacco smoking history * Participant is able to perform reproducible pulmonary function testing (i.e. the 3 best acceptable spirograms have Forced Expiratory Volume in 1 second (FEV1) values that do not vary more than 150 millilitres) * Participant is able to perform a breathhold for 16s * FEV1 \> 25% predicted * Forced Vital Capacity (FVC) \> 25% predicted and \>0.5 litres Exclusion Criteria: * Participant is, in the opinion of the investigator, mentally or legally incapacitated, preventing informed consent from being obtained, or cannot read or understand written material * Participant is medically unstable in the opinion of the Principal Investigator * Participant has a daytime room air oxygen saturation \<90% while lying supine * Participant is unable to perform spirometry or plethysmography maneuvers * Patient is pregnant at time of enrolment * In the opinion of the investigator, patient suffers from any physical, psychological or other condition(s) that might prevent performance of the MRI, such as severe claustrophobia * Patient has implanted mechanically, electrically or magnetically activated device or any metal in their body, which cannot be removed, including but not limited to pacemakers, neurostimulators, biostimulators, implanted insulin pumps, aneurysm clips, bioprosthesis, artificial limb, metallic fragment or foreign body, shunt, surgical staples (including clips or metallic sutures and/or ear implants) - at the discretion of the MRI Technologist.