PET-CT, or positron emission tomography-computed tomography, is a medical imaging technique that combines two different imaging technologies: positron emission tomography (PET) and computed tomography (CT). PET uses a radioactive tracer to produce detailed images of metabolic activity within the body, while CT provides detailed images of the body's anatomical structures. By combining these two techniques, PET-CT allows for the simultaneous imaging of both metabolic function and anatomical structure, making it a powerful tool for diagnosing and monitoring various conditions, such as cancer, cardiovascular disease, and neurological disorders. PET-CT is commonly used in oncology, cardiology, and neurology, among other medical specialties.