Which scan answers which question

Scans are not interchangeable. Each one is built to answer a particular kind of question, and choosing the right one is most of the value. Here is what each does.

Ultrasound uses sound waves, no radiation, and is excellent for soft tissues and organs in real time: the thyroid, the abdomen, the pelvis, the testes, and for taking a closer look at a lump you can feel. It is safe and often the first step.

CT uses X-rays to build detailed cross-sections, and it is good at the chest, the abdomen and bone, and at the heart through the calcium score and the coronary angiogram. It carries a radiation dose, which is why it is matched to the question rather than used to browse.

MRI uses magnets, not radiation, and gives the most detail in soft tissue: the brain and spine, joints, the prostate, the liver, and the whole body in one pass. It takes longer and is more involved, so it is chosen where its detail adds something.

X-ray is the low-dose workhorse for bones and chests, and DEXA is a low-dose scan for bone density and body composition.

More detail is not always better. A whole-body MRI run for reassurance can raise more questions than a targeted ultrasound of the thing you are worried about. The doctor step before any scan is there to match the scan to your question.

Ready to start? Choose the check that fits your question and tell us a little about yourself. A doctor reviews it, arranges what you need, and explains what it means. Most of it is done online, with the clinic there if you would rather be seen.