On a bone scan, white dots appear surrounding the dark patches, which indicate an increasing deposition of radioactive material. In other words, the white patches surround the black areas, which, depending on their location, suggest a variety of medical conditions, including cancer and arthritis. According to MedlinePlus, an abnormal bone scan reveals hot and/or cold areas in relation to the surrounding bone.
According to MedlinePlus, a bone scan includes injecting a very small amount of radioactive material into a vein. The substance travels through the blood to the bones, emitting radiation that is caught by the scanner’s camera.
According to the Johns Hopkins Medicine Health Library, hot spots are places with a high concentration of radioactive material, and cool spots are areas with a low concentration of radioactive material. Hot spots may suggest the existence of arthritis, malignant bone tumours, metastatic bone cancer, bone infections, bone damage that is not seen on standard X-rays, and other bone diseases. In reality, bone scans are typically used to detect the spread of metastatic cancer.
WebMD adds that cold areas may indicate a lack of blood supply to the bone or certain types of cancer. According to the website, hot patches may indicate conditions such as arthritis, a tumour, a fracture, or an infection.