• Magnitude of lung water density measured with MRI at Hospital Admission [ Time Frame: Baseline (hospital admission) ]
  Lung water density (0-100%) is the fraction of lung tissue that contains water
• Difference in lung water density measured with MRI at hospital admission and hospital discharge [ Time Frame: 7 days ]
  Absolute change in lung water density from baseline (hospital admission) to hospital discharge. Lung water density will be 0%-100% at each time point.
• Number and timing of clinical events and their statistical association with Outcome 1 (Magnitude of lung water density measured with MRI at Hospital Admission) [ Time Frame: Up to 5 years ]
  Clinical events include cardiovascular hospitalization, cardiovascular emergency department visits or death
• Number and timing of clinical events and their statistical association with Outcome 2 (Difference in lung water density measured with MRI at hospital admission and hospital discharge) [ Time Frame: Up to 5 years ]
  Clinical events include cardiovascular hospitalization, cardiovascular emergency

Heart failure is a condition where the heart is unable to pump enough blood to meet the body's needs and Acute Heart Failure is a sudden worsening of this condition. It is associated with many symptoms but most commonly includes shortness of breath due to pulmonary edema (or increased "lung water").

A physical exam and chest x-ray are commonly used to diagnose AHF and estimate the amount of increased lung water in patients with AHF. This study will use images from MRI (Magnetic Resonance Imaging) scans to obtain a more accurate measurement of the increased lung water in AHF patients. Lung water will be measured via MRI at hospital admission and discharge to find out the change in lung water over the course of hospitalization and treatment. The investigators will collect NT-proBNP and perform a chest x-ray upon hospital admission and again upon discharge, if not already done as part of usual care. The investigators will follow medical records for one year after hospitalization to see if the accurate lung water measurements obtained in hospital can predict long term outcomes. This is a single-centre project and a total of 300 patients will be recruited to participate.

• Acute Heart Failure
• Pulmonary Edema With Heart Failure

Inclusion Criteria:

• 18 years of age or older and willing/able to provide informed consent
• patients being treated for acute heart failure (including those patients with both reduced and preserved ejection fraction)
• patients receiving medical therapy for pulmonary edema by current standard of care (including oral or IV diuretics)
• patients identified within 48 hours of initiation of medical therapy for pulmonary edema, defined as the time of first diuretic (IV or PO) or escalation of existing diuretic therapy administered within the ED or hospital

Exclusion Criteria:

• contraindication to MRI
• patient too critically ill/unstable as per the clinical care team for transport to MRI scanner within the required scanning window
• moderate to severe dementia