SUper-Resolution Ultrasound Imaging of Erythrocytes (SURE) in Normal and Malignant Lymph Nodes

This study is testing a new ultrasound imaging technique called SURE (super-resolution ultrasound imaging of red blood cells) to see if it can detect abnormal blood flow patterns in lymph nodes that may signal cancer, potentially offering a non-invasive way to identify malignant lymph nodes. **You may be eligible if...** - You are between 18 and 70 years old - You can lie still for about 1 minute - If healthy: you have a normal-looking lymph node in the neck available for imaging - If you have cancer: you have a lymph node that is suspected or confirmed to be malignant **You may NOT be eligible if...** - You cannot hold still during the ultrasound - You do not have an accessible lymph node suitable for imaging - You do not meet the health criteria for your group (healthy or cancer) Talk to your doctor to see if this trial is right for you.