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

The goal of this observational study is to visualize the small vessels in normal and cancerous lymph nodes on the neck with a new ultrasound technique. The main questions it aims to answer are: * Is it possible to visualize the network of the smallest vessels in lymph nodes on the neck? * Is it possible to distinguish between healthy and cancerous lymph nodes using different parameters? The participants will have 1-2 lymph nodes ultrasound scanned with a standard ultrasound technique and the new technique.

Super-resolution ultrasound using erythrocytes (SURE) is a new ultrasound technique for visualizing the very small blood vessels in the body. The technique uses tracking of the blood's red blood cells (erythrocytes) to achieve a higher resolution of the blood vessels' shape, structure, and blood flow. The technique makes it possible to create images with much higher resolution than normal ultrasound, which means that even very small blood vessels can be imaged and measured. In many diseases, the small blood vessels change their function or structure. One of the major disease groups where SURE has significant potential is cancer. In cancerous nodes, the small blood vessels change: they become twisted, irregular, and function poorly. If changes in the small vessels can be detected at an early stage using SURE, it can lead to quicker diagnoses and better evaluations of the effectiveness of treatment. In this study, the investigators aim to demonstrate the practical feasibility of SURE imaging in human lymph nodes and investigate the clinical relevance of SURE imaging in the diagnosis of malignant lymph nodes by comparing lymph nodes from healthy participants with lymph nodes from participants with head and neck cancer metastases or lymphoma.