This is a proof-of-concept study with exploratory objective to assess whether superficial tissue oxygenation patterns measured by Snapshot NIRS, in conjunction with the Provocative Elevation Maneuver of the Lower Extremity (PEMLE) and/or the Plantar Palmar Index (PPI), are associated with the severity of peripheral arterial disease (PAD) as determined by standard of care assessments and can be used to assess tissue oxygenation after revascularization, where applicable.

Inclusion Criteria:

• Subjects between the ages of 21 and 99 years inclusive at the time of screening referred to the investigative site for further evaluation of known/suspected PAD.
• Subject has at least 1 intact forefoot.
• Can achieve leg positions as specified in the protocol to complete the study.
• Willing and able to provide written consent and adhere to protocol requirements

Exclusion Criteria:

• The subject is unwilling or unable to comply with the protocol (including but not limited to ability to tolerate leg lift) or scheduled appointments.
• The subject has had higher than trans metatarsal amputation on both limbs.
• Subjects who are pregnant, nursing or plan to become pregnant.
• For any reason as deemed appropriate by the Principal Investigator to be unsuitable for the study.

Subjects will be identified and enrolled through the PI's routine clinic population. Subjects who are identified for study participation will be screened for all eligibility requirements. Those meeting eligibility criteria for the study will have the study explained to them by the Principal investigator and have the opportunity to ask questions. An Informed Consent Form (ICF) will be signed prior to subjects undergoing any study procedures. Subjects will be encouraged to ask the study staff questions about the study.