Evaluation of MRI Measures of Lung Water With Posture Changes in Healthy Volunteers and in Patients With Cardiac Failure

Inclusion Criteria: * Heart Failure Patients: * Established diagnosis of mild to moderate heart failure of any aetiology with symptoms defined as corresponding to the New York Heart Association (NYHA) class I, II or III * Able in the opinion of the patient and investigator to be supine for 1 hour and to experience passive leg raising (PLR) whilst in the MRI scanner * Male or female over 18 years of age at the time of signing the informed consent * Negative urine or serum pregnancy test * Capable of giving written informed consent * Registered with a UK general practitioner. * Participants must read (in English) at a level sufficient to adequately complete study related questionnaires * Able to understand and comply with protocol requirements, instructions and protocol-stated restrictions * Healthy Volunteers: * Healthy as determined by a responsible physician * Male or female over 18 years of age at the time of signing the informed consent * Capable of giving written informed consent * Negative urine or serum pregnancy test * Registered with a UK general practitioner * Participants must read (in English) at a level sufficient to adequately complete study related questionnaires * Able to understand and comply with protocol requirements, instructions and protocol-stated restrictions Exclusion Criteria: * Heart Failure Patients * History of primary pulmonary disease requiring current medication or other therapy. * Orthopnoea of sufficient severity to preclude supine scanning. * Hip or leg pathology of sufficient severity to prevent extension of both legs to 45 degrees. * Unstable heart failure, defined as change in NYHA status, change in heart failure therapy regimen or hospitalization for acute decompensation of heart failure within preceding 6 weeks. * Unstable angina within the past 3 months * Current smoker, defined as having smoked in the preceding 1 year * Uncontrolled hypertension (resting systolic BP \> 160 mmHg or resting diastolic BP \> 100mmHg) * Resting hypoxia (SaO2 \<93%). * Contraindication to MRI scanning * Pregnant females * Positive drugs of abuse or alcohol screen. * Unwillingness or inability to follow the procedures outlined in the protocol. * Healthy Volunteers * History of primary pulmonary disease requiring current medication or other therapy * Current smoker, defined as having smoked in the preceding 1 year * Hip or leg pathology of sufficient severity to prevent extension of both legs to 45 degrees * Contraindication to MRI scanning * Pregnant females * Positive drugs of abuse or alcohol screen * Unwillingness or inability to follow the procedures outlined in the protocol