Scans at a glance
The table covers the scans prevention-minded people ask about most. The last column gives the optimal plan first and the guideline minimum in parentheses; "guideline" means a major body such as the USPSTF (US Preventive Services Task Force) recommends it for that group. Radiation doses are typical adult values from RadiologyInfo.org, the patient site of the American College of Radiology (ACR) and the Radiological Society of North America.
| Scan | What it finds | Radiation (mSv) | Typical cost | Optimal plan (guideline minimum) |
|---|---|---|---|---|
| Coronary artery calcium (CAC) | Calcified plaque in heart arteries | 1.7 | Self-pay; one chain lists $349 | Men about 40, women about 45; five years earlier with high inherited risk (40+ and 45+ when a statin decision is uncertain) |
| Coronary CT angiography | Soft and hard plaque, narrowing | 8.7 | Insured for symptoms | Chest pain; optional with a zero calcium score and high inherited risk (symptoms only) |
| Carotid ultrasound | Narrowing of neck arteries | 0 | Insured when indicated | Do not screen (USPSTF recommends against) |
| Echocardiogram, ECG | Heart structure, valves, rhythm | 0 | Insured when indicated | Symptoms, murmurs, known disease; not screening |
| Aortic aneurysm ultrasound | Bulging abdominal aorta | 0 | Covered as prevention | Once at 65–75 if you, man or woman, ever smoked or a parent or sibling had one (men who ever smoked) |
| Mammogram, 3D mammogram | Breast cancer | 0.28–0.34 | Covered as prevention | Yearly from 40 (every 2 years, 40–74) |
| Breast MRI | Breast cancer in high-risk women | 0 | Varies | Yearly with high risk or dense breasts (ACR) |
| Low-dose lung CT | Lung cancer | 1.5 | Covered if eligible | Yearly at 50–80 with 20 pack-years, however long ago you quit (only if you quit within 15 years) |
| CT colonography | Colon polyps and cancer | 0.8–6 | Covered as prevention | An alternative if you decline colonoscopy, every 5 years |
| Prostate MRI | Significant prostate cancer | 0 | Insured after high PSA | After an abnormal PSA, before any biopsy |
| DEXA | Bone density; body composition | 0.001 | From $39 self-pay for body composition | Body composition from your 30s or 40s, every 1–2 years; bone density baseline in your 40s (women 65+) |
| Liver elastography | Liver scarring | 0 | Insured when indicated | FIB-4 of 1.3 or more, or fatty liver with risk factors |
| Brain MRI | Tumors, old strokes, aneurysms | 0 | Insured for symptoms | Symptoms; not screening |
| Thyroid ultrasound | Thyroid nodules | 0 | Insured when indicated | Do not screen (USPSTF recommends against) |
| Full-body MRI | Masses in many organs | 0 | $899–$3,999 self-pay | Not for average risk; standard for Li-Fraumeni syndrome |
| Whole-body CT | Many organs | About 14 | Self-pay | Avoid |
Heart and blood vessel scans
Heart disease kills more Americans than cancer, but only one heart scan has a clear screening role; see Heart and blood vessels.
Coronary artery calcium
A CAC scan is a quick, non-contrast CT that scores calcified plaque in the coronary arteries. Optimal: a first scan around 40 for men and 45 for women if you are not already on cholesterol-lowering treatment, and about five years earlier with a strong family history, familial hypercholesterolemia, high Lp(a), diabetes, or a long smoking history. Calcium is common earlier than many expect: among adults 30 to 45, 26% of White men and 10% of White women already had some Moderate. Guideline minimum: the 2026 ACC/AHA cholesterol guideline recommends it for men 40 and older and women 45 and older at borderline or intermediate risk when the score would change the statin decision.
A zero lowers near-term risk; any calcium means plaque is present. The dose is about 1.7 mSv, roughly six months of natural background, and because the scan includes part of the lungs, it can turn up a nodule that needs a follow-up scan. Scores, rescan intervals, and what to do with the result are in the heart chapter.
CT coronary angiography
Coronary CT angiography (CCTA) adds injected contrast to show soft plaque and narrowing, at about 8.7 mSv. Its evidence comes from people with chest pain: in the SCOT-HEART trial, adding CCTA for 4,146 such patients cut five-year coronary death or heart attack from 3.9% to 2.3%. Without symptoms, it is worth considering only when finding soft plaque would change treatment, such as a zero calcium score with a strong family history or high Lp(a); in one study of adults without symptoms, 16% of those with a zero score had plaque on CCTA Weak. Its risk is a cascade to stents that, in stable disease, did not prevent heart attacks or deaths. See CT angiography and plaque analysis.
Carotid ultrasound
Ultrasound of the neck arteries is sold at health fairs and in "vascular screening" packages. The USPSTF recommends against it for adults without symptoms (grade D, 2021) Negative, and here the optimal choice is the same. In the general population it produces many false positives, and the operations that follow carry real risk: within 30 days, 1.4% to 3.5% of people who have carotid surgery have a stroke or die. A calcium score is the better way to look for plaque. Symptoms of a mini-stroke, such as sudden one-sided weakness, numbness, or loss of vision, are a different matter and need emergency care.
Echocardiogram and ECG
An electrocardiogram (ECG) records the heart's electrical activity. The USPSTF recommends against screening ECGs, resting or exercise, in adults at low cardiovascular risk, and finds the evidence insufficient for those at intermediate or high risk (2018). An abnormal tracing in a healthy person usually leads to more tests, not better outcomes. Smartwatch ECGs help check palpitations (wearables).
An echocardiogram is an ultrasound of the heart's chambers, valves, and pumping. It is the right test for a new murmur, breathlessness, swelling, or a family history of inherited heart muscle disease, but it is diagnostic, not screening.
Abdominal aortic aneurysm ultrasound
An abdominal aortic aneurysm (AAA) is a bulge in the body's main artery that can rupture without warning. A one-time ultrasound finds it reliably, with no radiation Strong. The optimal plan follows the Society for Vascular Surgery (SVS), which screens women as well as men who have smoked, and relatives of people with an aneurysm.
| Group, ages 65–75 | Optimal (SVS 2018) | Guideline minimum (USPSTF 2019) |
|---|---|---|
| Men who have ever smoked (100 or more cigarettes) | Screen once | Screen once (grade B) |
| Women who have ever smoked | Screen once | Evidence insufficient (I) |
| A parent, sibling, or child with an aneurysm | Screen once (also after 75 if healthy) | Men: selectively (C); women: insufficient (I) |
| Never smoked, no family history | Not needed | Men: selectively (C); women: do not screen (D) |
Sources: USPSTF, SVS. The SVS also suggests a scan for smokers over 75 in good health who were never screened.
Cancer screening scans
These scans are covered in detail, with the optimal plan and the guidelines for each, in the cancer chapter. This section adds what you need to know about the scans themselves.
Mammography and breast MRI
Optimal: a breast cancer risk assessment by 25 and a mammogram every year from 40, as the ACR recommends; guideline minimum: the USPSTF recommends one every 2 years from 40 to 74. A screening mammogram delivers about 0.28 mSv, and a 3D mammogram (tomosynthesis) about 0.34, roughly five to six weeks of natural background. Both 2D and 3D (tomosynthesis) are effective, and since September 2024 every US report must say whether your breasts are dense, which matters because dense tissue hides cancers.
Breast MRI uses contrast dye and no radiation. The ACR recommends it yearly for women at high risk, starting at 25 to 30, and for women with dense breasts; the USPSTF finds the evidence insufficient for dense breasts. A full-body MRI is not a substitute. See Breast cancer.
Low-dose lung CT
Lung screening CT uses about 1.5 mSv, a quarter of a standard chest CT, and is done yearly from 50 to 80 with a 20 pack-year smoking history Strong. Optimal: follow the American Cancer Society, which screens former smokers however long ago they quit; guideline minimum: the USPSTF stops once you have been quit for 15 years. Positive results are common and mostly false alarms: in the National Lung Screening Trial, 24.2% of people had a positive scan over three rounds, and 96.4% of those positives were not cancer. Choose a center with a formal lung screening program, whose standardized reports say whether to wait, rescan sooner, or investigate (Lung cancer).
Colonoscopy and CT colonography
Colonoscopy is not imaging in the radiology sense (it is a camera on a flexible tube), but it is the reference test for the colon because it can remove polyps on the spot; the optimal plan in the cancer chapter starts it at 40, every 5 years if normal. CT colonography ("virtual colonoscopy") uses low-dose CT after the same bowel prep, at 0.8 to 5.3 mSv for screening protocols. It is a guideline option every 5 years, but a positive result means a colonoscopy anyway, and findings outside the colon need workup in 1.3% to 11.4% of exams, so it is a second choice.
Prostate MRI
A prostate MRI, read on a 1-to-5 scale (PI-RADS), is the optimal step after an abnormal PSA and before any biopsy. Using MRI to decide who needs a biopsy halved the diagnosis of harmless cancers in a Swedish trial of 17,980 men, without missing significant ones Strong. It is a follow-up test, not a first screen, and far more detailed than the pelvic portion of a full-body MRI. See Prostate cancer.
Full-body MRI
Whole-body MRI from companies such as Prenuvo, Ezra, and SimonMed costs about $900 to $4,000 in 2026 and uses no radiation. Systematic reviews find that about 95% of people have at least one abnormal finding, 30% need further tests, and 1.1–1.6% have a cancer confirmed. There are no randomized trials and no evidence that it helps average-risk people live longer, and the ACR advises against it for people without symptoms Weak. It is standard care for Li-Fraumeni syndrome and a few other inherited conditions. See the full-body MRI deep dive.
Other scans people ask about
DEXA
DEXA (dual-energy X-ray absorptiometry) uses a tiny dose, about 0.001 mSv or three hours of background, and comes in two kinds that are easy to confuse.
| Type | What it measures | Optimal plan | Guideline minimum |
|---|---|---|---|
| Whole-body DEXA | Lean mass, fat mass, visceral fat | A baseline in your 30s or 40s, then every 1–2 years, or every 6–12 months during major weight loss or on a GLP-1 drug (expert) | None |
| Hip and spine DEXA | Bone density as a T-score, used to diagnose osteoporosis | A baseline in your 40s for women and men, early in menopause for women (expert); then by result (how often to repeat) | Women 65 and older, and younger postmenopausal women at increased risk (USPSTF 2025); men at 70 (BHOF) |
Body composition is the reason to scan often. Peter Attia describes DEXA as a scan you would do once, maybe twice a year, and it is the practical way to check that weight loss is fat rather than muscle: lean tissue made up anywhere from about 15% to 60% of the weight lost in trials of GLP-1 drugs. No trial shows that scanning itself improves health Weak; its value is in steering training and diet.
Bone density changes slowly, so repeat it by result: every 3 to 5 years if normal before 65, every 2 years from 65 (less often if normal), and yearly with a T-score of −2.0 to −2.5 (how often to repeat). A whole-body scan's bone number cannot diagnose osteoporosis, which needs separate hip and spine readings, and before 50 a low result is judged against people your age (the Z-score), not young adults.
Medicare covers bone density testing once every 24 months for eligible people. Body-composition scans are self-pay, from $39 at one national chain (2026). See Bone density testing.
Brain MRI
Brain MRI is a diagnostic test for symptoms such as new headaches, seizures, or neurological changes, not a screening test. In 2,000 Dutch adults with an average age of 63, a research brain MRI found silent strokes in 7.2%, aneurysms in 1.8%, and benign tumors in 1.6%, mostly meningiomas. Most of these will never cause trouble, but each raises a question about what to do next. Brain-volume reports sold as MRI add-ons (Prenuvo lists one at $799) have no screening role. See Brain health.
Thyroid ultrasound
The USPSTF recommends against screening for thyroid cancer in adults without symptoms (grade D, 2017) Negative, and this is one place where doing less is optimal. When South Korea promoted thyroid ultrasound, diagnoses of thyroid cancer soared while deaths did not change, and many people had thyroid surgery for cancers that would likely never have harmed them. A neck lump, hoarseness, or trouble swallowing is a reason for an ultrasound; a wellness package is not.
Liver elastography
Elastography uses ultrasound or MRI to measure liver stiffness, which rises with scarring (fibrosis). It is the usual next step when a FIB-4 score of 1.3 or more or other blood tests suggest that fatty liver disease may be causing damage, and it uses no radiation Moderate. When to get one is covered in Metabolic health.
Whole-body CT
Whole-body CT screening is still sold in some places, and it remains a bad idea Negative. The FDA "knows of no scientific evidence demonstrating that whole-body scanning of individuals without symptoms provides more benefit than harm," and prohibits manufacturers from promoting CT systems for it. A CT of the chest, abdomen, and pelvis delivers about 14 mSv (6.1 for the chest plus 7.7 for the abdomen and pelvis), about four and a half years of natural background, and yearly repeats multiply it. A whole-body PET/CT is higher still, at about 22.7 mSv. If you want a whole-body scan, an MRI at least carries no radiation.
Radiation basics
Radiation dose from imaging is measured in millisieverts (mSv), a unit that estimates overall cancer risk across the body. Everyone absorbs about 3 mSv a year from natural sources such as radon, cosmic rays, and the ground. MRI and ultrasound use no ionizing radiation.
| Exam | Effective dose (mSv) | Natural background equivalent |
|---|---|---|
| Bone density (DEXA) | 0.001 | 3 hours |
| Dental x-ray | 0.005 | 1 day |
| Chest x-ray | 0.1 | 10 days |
| Screening mammogram | 0.28 | 34 days |
| 3D mammogram | 0.34 | 42 days |
| Low-dose lung CT | 1.5 | 6 months |
| CT brain | 1.6 | 7 months |
| Coronary calcium CT | 1.7 | 6 months |
| CT colonography | 6 | 2 years |
| CT chest | 6.1 | 2 years |
| CT abdomen and pelvis | 7.7 | 2.6 years |
| Coronary CT angiography | 8.7 | 3 years |
| Whole-body PET/CT | 22.7 | 7.6 years |
Source: RadiologyInfo.org. Doses vary with body size and equipment.
The risk is small per scan but real across a population. A 2025 analysis estimated that the 93 million CT scans done in the US in 2023 will cause about 103,000 future cancers, and that if current practice continues, CT could account for about 5% of new cancer diagnoses each year. The risk per scan is higher for children and young adults. A needed scan's benefit usually outweighs that risk; the concern is unnecessary, duplicated, and unproven screening scans.
The optimal schedule is a small dose. Using the doses above, a woman who has a 3D mammogram every year from 40 to 80, three calcium scans, and a yearly DEXA receives about 19 mSv over 40 years, under half a millisievert a year against about 3 from nature. A yearly lung CT adds 1.5 mSv a year, which is why it is reserved for heavy smokers.
Practical rules:
- Ask whether ultrasound or MRI could answer the same question.
- Keep track of recent CT scans and tell new doctors about them, so they are not repeated.
- Low-dose protocols exist for lung screening, calcium scoring, and CT colonography; make sure you are getting them.
Incidental findings
An incidental finding, or "incidentaloma," is an abnormality found by a scan done for another reason. They are common: in a review of 20 systematic reviews, incidental findings appeared on more than a third of cardiac MRIs, chest CTs, and CT colonographies. How often they are cancer depends heavily on the organ, from under 5% for the brain and adrenal glands to about a quarter for the kidney and thyroid.
The ACR publishes management guidance for common incidental findings in the kidney, adrenal glands, liver, pancreas, thyroid, and blood vessels, so that a small, typical-looking finding gets the right amount of follow-up and no more. Ask whether your radiologist followed it. A step-by-step guide to handling a finding is in the cancer chapter.
Two facts keep findings in perspective: one unchanged on an older scan is usually benign, and every follow-up test has its own costs and risks, so "just to be safe" is not always safe.
Choosing an imaging center
Accreditation and expertise
- Accreditation. The ACR accredits facilities in CT, MRI, ultrasound, nuclear medicine and PET, mammography, and breast ultrasound, and you can search for accredited sites. The Intersocietal Accreditation Commission is another recognized accreditor. Every US mammography facility must be certified under federal law; the FDA keeps a facility search.
- Subspecialty radiologists. For a breast, prostate, or full-body MRI, ask whether a radiologist trained in that area will read it.
- Low-dose CT. Ask about dose-reduction protocols, especially for lung screening and calcium scoring.
- Results. Ask how and when you will get results, and who will call if something needs action.
Your images and reports
You have a right to your health records, including imaging, in paper or electronic form. Ask for both the report and the images (DICOM files, usually through a portal) and keep them: a prior scan is often the quickest way to show that a finding is old and stable, which can spare you a biopsy.
AI in radiology
Of the 1,614 AI-enabled devices on the FDA's list as of September 2026, 1,230 are in radiology. The strongest evidence is in mammography: in the Swedish MASAI trial of 105,934 women, AI-supported reading found 29% more cancers and cut reading workload by 44%, with higher sensitivity and no increase in interval cancers Strong. Whether that lowers deaths is still being studied. FDA clearance means a tool performed as claimed for a specific task, not that it improves outcomes, and AI findings on consumer scans can add to the incidental-finding problem.
Cost and insurance
Preventive scans with a USPSTF A or B grade are free under most private plans, with no copay or deductible, when done in network: mammograms, lung CT for eligible people, CT colonography and colonoscopy for colorectal screening, AAA ultrasound for eligible men, and bone density scans for eligible women (HealthCare.gov). The Supreme Court upheld that requirement in June 2025. Scans on the optimal schedule that go beyond the USPSTF, such as lung CT for people who quit long ago or AAA ultrasound for women, may not be covered, and diagnostic scans, including follow-up of a screening finding, may be billed differently, so ask your insurer in advance.
Self-pay scans include calcium scores, body-composition DEXA, and full-body MRI. Prices for the same scan vary widely between hospitals and independent centers, so ask for a written cash price before you book. The IRS counts an electronic body scan as a deductible medical expense, which generally means you can pay with a health savings account or flexible spending account; see the IRS rules for HSAs and confirm with your plan administrator.
Budget for follow-up. The price of a self-pay scan is rarely the total cost. Incidental findings lead to more imaging and specialist visits, sometimes billed to you. See Building your care team for help ordering and interpreting scans.