Standardized Uptake Value – 3D and Quantitative Imaging Laboratory

SUV (Standardized Uptake Value) serves a crucial function in the identification, measurement, and evaluation of tumors within the body. This metric quantifies the absorption of a radiotracer by tissues, which assists with the identification of cancerous or suspicious areas exhibiting heightened metabolic activity. In oncology, SUV is extensively applied for purposes such as cancer detection, staging, and characterization, as well as for planning treatments, tracking treatment progress, and detecting potential tumor reappearance.

To generate an SUV measurement for a patient, a PET scan utilizes a radiotracer such as FDG (Fluorodeoxyglucose) to identify areas with elevated metabolic activity; particularly in cancer cells which are known for their increased energy and sugar consumption. To precisely locate these active regions, FDG is injected into the patient’s bloodstream and the PET scan is performed after waiting an hour or so for absorption. Functioning like a glucose mimic, the radiotracer is attracted to sites with heightened metabolic activity. The PET images depict these active zones as darker areas, providing medical professionals with valuable insights into the tumor’s location, size, and activity.

Certain organs, like the brain and liver, exhibit elevated metabolic activity, resulting in darker appearances on PET scans compared to the surrounding tissues. These organs serve as reference points when searching for tumors, which similarly appear dark due to their heightened metabolic activity.

Figure A: Base-line CT of the patient.

Figure B: Radiotracer-enhanced PET scan of the patient. Dark areas indicate regions of increased metabolic activity.

Figure C: A fusion of the CT and PET scan provides a more detailed view of the anatomical locations with elevated metabolic activity. The PET overlay of this fused scan shows high metabolic activity as bright areas.

A specific region of interest (ROI) is defined on the scan, typically focusing on areas of interest like suspected tumors. Advanced computer algorithms then analyze data within this ROI, tracking radiotracer distribution and concentration. This process results in a calculated SUV representing radiotracer uptake, reflecting metabolic activity in the specified area. The SUV, expressed as a number, provides a standardized quantitative representation of radiotracer concentration, accounting for factors like injected dose and patient’s body weight, allowing for comparability across patients.

By providing a standardized quantitative measure of tracer uptake, SUV allows healthcare professionals to make informed decisions about treatment strategies and patient care. This approach not only enhances the accuracy of treatment assessments but also contributes to the growing field of personalized medicine, where treatment plans are tailored to individual patient needs. Calculating SUV is a common part of our TRAC program, where it is included in longitudinal analysis. https://3dqlab.stanford.edu/longitudinal-analysis/

Figure D: Rotational MIP with the suspected tumor circled in red.

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