Medical imaging is a powerful tool used to detect cancer and other diseases. It involves taking pictures of the inside of the body to detect tumors, changes, and the severity of the disease. Magnetic resonance imaging (MRI) is one of the most commonly used diagnostic imaging techniques for cancer detection, staging, monitoring response to treatment, counseling for biopsy, and guidance on minimally invasive therapy. Ultrasound is another popular diagnostic imaging method used to diagnose tumors in the thyroid, breast, prostate, liver, pancreas, ovary, uterus, and kidney.
Positron emission imaging is used to measure the effectiveness of chemotherapy by evaluating delivery and specific approaches to maximize the concentration of the drug in tumors relative to normal tissues. Laparoscopy is also useful if you feel pain in the pelvic region or if an imaging test has detected a tumor or other abnormality. Diffusion-weighted images (DWI) are based on the altered diffusion of water molecules in tumor tissues and a lower apparent diffusion constant (ADC), which produces a high signal in DWI images. PET molecules are being developed to image processes that influence cancer progression and response to treatment, such as proliferation, transport, blood flow, angiogenesis, apoptosis and hypoxia.
Switch to higher field intensities with 3T MRI systems has been favored by parallel imaging, which can reduce the effect of T1 lengthening, reduce susceptibility artifacts and avoid specific absorption rate (SAR) values that are too high. Cameras have a large inactive area on the edge of the detector that prevents the camera from taking images of breast tissue adjacent to the chest wall. Typical radionuclides used in nuclear medicine imaging are 131I (half-life 8 days), 123I (half-life 13.3 h), 111 inches (half-life 67.3 h), 99mTc (half-life 6.02 h), 201 Tl (half-life 73 h) and 67Ga (half-life 78 h). For preclinical PET imaging of solid tumors, a chimeric monoclonal antibody labeled with 74As has been used.
Imaging of axillary lymph nodes with dextran-coated ultra-small particle iron oxide (USPIO) contrast agents are based on the accumulation of iron oxide nanoparticles in macrophages. Early detection of cancer through image-based screening tests is probably the factor that most contributes to reducing mortality from certain types of cancer. For more information on how specific cancers are diagnosed, see the PDQ summaries on cancer treatment in adults and children. These summaries include detailed information and images of diagnostic tests and procedures for each specific type of cancer.
