The objective of the study is to define the analytical repeatability of quantifying flow-mediated dilation of the brachial artery using brachial artery ultrasound imaging using upper arm cuff occlusion.

Inclusion Criteria:

1. Men and women, ≥18 years old
2. Eastern Cooperative Oncology Group/Zubrod score performance status of 0, 1, or 2, determined within 7 days prior to FMD testing on Study Day 1 (Visit 1)
3. Written informed consent understood and signed; understanding of study procedures and ability to comply with them for the length of the study

Exclusion Criteria:

1. Body mass index (BMI) >50 kg/m2
2. Mid-upper arm circumference of arm selected for FMD testing <17 cm or >42 cm
3. Sinus arrhythmia (RR intervals vary by >50%), atrial fibrillation, atrial flutter, multifocal atrial tachycardia, frequent (>1 per 10-sec strip) premature atrial or ventricular contractions (isolated, non-isolated, or alternating), documented by 12-lead ECG with rhythm strip at the time of subject screening.
4. Clinical signs and/or symptoms of active viral or bacterial infections
5. Resting tremor or inability to remain still for the duration of the testing period
6. Systolic blood pressure (SBP) at rest of >170 mmHg or diastolic blood pressure (DBP) at rest of ≥110 mmHg.
7. Diabetic subjects - Type I or II
8. Previous intolerable adverse reaction(s) to vascular testing using an upper extremity occlusive pneumatic cuff