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When to Order Imaging
Fishtown Medicine•8 min read
4.96 (124)

When to Order Imaging

Ashvin Vijayakumar MD

Medically Reviewed

Ashvin Vijayakumar MD•Updated May 29, 2026
On This Page
  • The one test I run before ordering any scan
  • Why "more data" can hurt you
  • How I match the scan to the question
  • When imaging is high-leverage
  • When imaging is low-leverage (or harmful)
  • How we make the order actually happen
  • Guidance from the clinic
  • Actionable Steps
  • Key Takeaways
  • Common Questions
  • When should I get a scan?
  • What is the difference between a CT and an MRI?
  • Should I get a full-body MRI for screening?
  • Is a calcium score enough for cardiovascular risk?
  • Why not just scan everything to be safe?
  • How long does it take to get an imaging report back?
  • Will my insurance cover the scan?
  • How do I know if I really need a repeat scan?
  • Deep Questions
  • How does Cleerly AI change cardiovascular imaging?
  • What is the incidentaloma rate and why does it matter so much?
  • How do you sequence labs and imaging?
  • When is liquid biopsy preferable to imaging?
  • How do you handle a small finding on a scan, like a 4 mm cyst?
  • Why is repeat imaging often the wrong instinct?
  • How do you think about radiation dose across scans?
  • How do you decide between hospital and independent imaging centers in Philadelphia?
  • Why do you often pair imaging with advanced lipid and biomarker panels?
  • How does your imaging philosophy change in younger patients?
  • What is the role of AI-assisted imaging reads?
  • Why is the "would this change the plan" test so central to your approach?
  • Scientific References

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TL;DR · 30-second take

We order imaging when the answer would change the plan. The right scan in the right patient can reshape a trajectory; the wrong one finds incidental things that drive anxiety and follow-up tests without changing the outcome. Our framework: name the clinical question first, run risk stratification and labs, then pick the scan that answers it directly. Coronary CT angiography is high-leverage for cardiovascular risk in the right patient; asymptomatic full-body MRI usually is not.

When to Order Imaging: How We Decide What's Worth Scanning

TL;DR: Imaging is one of medicine's strongest tools and one of its biggest sources of unnecessary anxiety. The deciding question is not "what could a scan find?" but "what would I do with the answer?" If a scan would change the plan, it earns its place. If it would not, we skip it, no matter how impressive the technology. Whole-body MRI in healthy adults finds an incidental abnormality in 30 to 60 percent of cases and a true early cancer in about 1 to 2 percent, so we use it selectively. The most useful imaging is matched precisely to a real clinical question. The most harmful is the asymptomatic full-body scan that sets off a year of follow-up for findings that meant nothing.
The modern imaging world is genuinely incredible. We can see soft plaque in the coronary arteries before it ruptures, characterize tissue without touching the patient, and catch early cancers before any symptom shows up. Used well, imaging is one of the most powerful prevention tools in medicine. Used poorly, it sends people into a year of biopsies for findings that mean nothing. The line between those outcomes is not the technology. It is the question we are trying to answer when we order the scan.

The one test I run before ordering any scan

The question I ask before every imaging order is simple: would the answer change the plan? If a positive result would lead to a treatment change, a tighter-cadence follow-up, or a meaningful update to your prevention strategy, the scan earns its place. If the answer would lead to the same next step either way, the scan is not adding value and is probably adding cost, time, and the risk of an incidental finding. That single question filters out most of the over-imaging I see in patient charts. People come in with five scans from different practices and no plan that actually changed because of them. The job of imaging is to move the plan, not to fill the chart.

Why "more data" can hurt you

The instinct is that more information is always better. With imaging, that is sometimes the opposite of the truth. The high sensitivity that lets a modern scanner catch a 5 mm early cancer also catches a 5 mm benign cyst, a stable nodule that has been there for twenty years, a quirk in your liver that means nothing. In whole-body MRI cohorts, 30 to 60 percent of healthy adults have at least one finding that prompts the radiologist to recommend follow-up imaging. The true cancer detection rate in screening is usually 1 to 2 percent. The cost of that gap is not just dollars. It is months of repeat scans, possible biopsies, and the steady anxiety of knowing a scan flagged "something" while you wait to find out what. For an average-risk person, that trade-off rarely pays off. This is the incidentaloma problem, and it is the single best reason to scan deliberately rather than broadly.
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How I match the scan to the question

Every imaging modality is a different lens. Picking the wrong one is like using a microscope to look at the moon.
ModalityBest atWhen we reach for it
UltrasoundSoft tissue and motion in real timeEchocardiogram for the pump and valves, abdominal for gallbladder or liver, vascular for carotid plaque or DVT. No radiation, low cost, often the first move.
CTBone, lung air, acute bleeding, coronary arteriesCoronary calcium scoring and coronary CT angiography for cardiovascular risk; low-dose CT for lung cancer in smokers; CT for acute chest, abdominal, or head pain.
MRISoft-tissue characterization without radiationBrain and spine, joints, prostate, cardiac muscle. Slower and pricier, with a higher rate of incidentals if used broadly.
Nuclear / PET-CTFunctional and metabolic imagingStaging and tracking known cancer; not for screening healthy adults (radiation dose is significant).
Liquid biopsy + geneticsA complementary first answerGalleri and targeted genetic panels can shift whether imaging is even the next move.
The sequence usually goes: clinical question first, simplest answer-getting tool next, deeper scan only if those did not settle it.

When imaging is high-leverage

A short list of the places imaging is most worth ordering in our practice:
  • Coronary CT angiography (CCTA) with plaque analysis in patients with elevated ApoB, Lp(a), strong family history, or atypical chest pain. Unlike a calcium score, a CCTA sees the soft plaque most likely to rupture and trigger a heart attack. Finding it in your 40s is a gift; it changes the medication and lifestyle plan immediately. The 2021 chest pain guidelines now favor CCTA over stress testing in many low-to-intermediate-risk new chest pain workups.
  • Coronary artery calcium (CAC) score in age 40 to 75 patients at borderline cardiovascular risk where the question is "do we start a statin?" A zero CAC can defer; a high CAC can earn one. The data here is strong.
  • Echocardiogram for shortness of breath, murmurs, suspected heart failure, or valve issues. Cheap, fast, no radiation.
  • Targeted MRI for a specific neurological sign, a confirmed disc herniation deciding surgery, or a cardiac question after an abnormal echo.
  • Standard cancer screenings with decades of outcomes data: colonoscopy, mammography, low-dose CT for lung cancer in smokers, Pap. Boring, well-validated, and the highest-yield imaging most people will ever do.
  • Whole-body MRI or boutique scans for patients with a Li-Fraumeni or other strong cancer-predisposition syndrome, BRCA, prior cancer history, or persistent unexplained symptoms a standard workup has missed.

When imaging is low-leverage (or harmful)

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The places imaging often does more harm than good:
  • Asymptomatic full-body MRI in an average-risk person. High incidental finding rate, long follow-up tail, modest evidence for outcome benefit at average risk. For the average 40-year-old without specific genetic risk, this scan is mostly bought for peace of mind and often delivers the opposite.
  • Routine thyroid ultrasound without a palpable nodule, family history of thyroid cancer, or specific clinical indication. Finds many small benign nodules that drive years of surveillance.
  • PET-CT for screening healthy adults. High radiation dose (around 25 mSv), high false-positive rate. PET-CT is for staging known cancer and tracking treatment, not for asymptomatic screening.
  • MRI for non-specific chronic back pain in the first month without red-flag signs. Most degenerative findings on lumbar MRI show up in asymptomatic adults too, and the scan rarely changes the conservative-care plan.
  • Repeat imaging on an existing benign finding without a new clinical question. Once a stable nodule or cyst has been characterized, repeat scans should be governed by guideline cadence, not by anxiety.

How we make the order actually happen

Once we have decided a scan is worth ordering, the goal is to make the rest feel like one move, not five.
  • The order goes from your chart directly to a facility that fits your insurance, location, or cash-pay preference. We coordinate with Medmo for many imaging orders, especially MRI, CT, and ultrasound; Medmo helps you schedule at a nearby facility and shows you cash-pay pricing where it fits.
  • For complex cases, we work with Penn, Jefferson, Temple, and select Mainline facilities so the radiology subspecialty actually matches your question. For routine MRI and CT, independent imaging centers in Center City, Northern Liberties, and the suburbs are often faster and cheaper.
  • Prior authorizations for MRI, CCTA, and similar are handled by our team. You should not have to chase your own insurer.
  • When the report lands, you get a plain-English summary, not a copy-pasted radiology read. Incidental findings get sorted into "actually matters," "watch with guideline cadence," and "ignore."
See Managing Labs and Imaging with Ease for the full logistics view.

Guidance from the clinic

Dr. Ash
"More data is not always better data. The most useful imaging is the imaging that changes the plan. The most harmful is the asymptomatic full-body scan that finds a thing, sets off a year of follow-up, and ends right where you started, except more anxious. Before we scan, we agree on the question. After we scan, we agree on what the answer means. Without those two conversations, even great imaging is just a story without a point."

Actionable Steps

Before you ask for a scan.
  1. Name the question. What specifically do you want to know? "Is there plaque in my coronary arteries?" is a real question. "I want to make sure nothing is wrong" is not.
  2. Ask what changes. If the result comes back positive, what is the plan? If negative, what is the plan? If those answers are the same, the scan is probably not the move.
  3. Match the modality. Soft-tissue questions usually want MRI or ultrasound. Bone, lung, and acute questions usually want CT. Cardiovascular risk wants CCTA or CAC.
  4. Start simple if you can. ApoB, Lp(a), and a thorough family history often tell us where to scan and where not to.
  5. Plan the result conversation in advance. Decide who will read the report, who will translate it, and what follow-up cadence you are committing to before the scan.

Key Takeaways

  • The deciding question for any scan is whether the answer would change the plan. If not, do not order it.
  • Modern imaging is sensitive enough to find incidental things in 30 to 60 percent of healthy adults; selective imaging beats broad imaging at every scale.
  • Pick the modality to match the question: ultrasound and echo for soft tissue and motion, CT for bone and acute findings, MRI for soft-tissue characterization, CCTA with plaque analysis for cardiovascular risk.
  • Standard cancer screenings (colonoscopy, mammography, low-dose CT in smokers, Pap) are still the highest-yield imaging most people will ever do.
  • Logistics matter as much as the order. Coordination, prior authorizations, and result translation are what make imaging actually useful.

Scientific References

  1. Gulati, M., et al. (2021). 2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain. Journal of the American College of Cardiology, 78(22), e187-e285.
  2. Greenland, P., et al. (2018). Coronary Calcium Score and Cardiovascular Risk. Journal of the American College of Cardiology, 72(4), 434-447.
  3. Williams, M. C., et al. (2020). Coronary Atherosclerosis Imaging by Coronary CT Angiography for the Prevention of Cardiovascular Events. Circulation: Cardiovascular Imaging, 13(8), e009829.
  4. Berland, L. L., et al. (2010). Managing Incidental Findings on Abdominal CT: White Paper of the ACR Incidental Findings Committee. Journal of the American College of Radiology, 7(10), 754-773.
  5. Hricak, H., et al. (2021). Medical imaging and nuclear medicine: a Lancet Oncology Commission. The Lancet Oncology, 22(4), e136-e172.
  6. Schrag, D., et al. (2023). Blood-based tests for multicancer early detection (PATHFINDER): a prospective cohort study. The Lancet, 402(10409), 1251-1260.
Medical Disclaimer: This resource provides clinical context for educational purposes. In the world of Precision Medicine, there is no "one size fits all." The right imaging plan must be matched to your unique risk factors, history, and goals. Consult Dr. Ash or your own physician before making decisions, especially if you have chronic health conditions, a strong family history, or persistent unexplained symptoms.
Ashvin Vijayakumar MD (Dr. Ash)

Fishtown Medicine | Diagnostics

2418 E York St, Philadelphia, PA 19125·(267) 360-7927·hello@fishtownmedicine.com·HSA/FSA Eligible

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Frequently Asked Questions

Common Questions

You should get a scan when the answer would change your treatment, follow-up plan, or prevention strategy. If the next step would be the same whether the scan is positive or negative, the scan usually is not adding value.
CT uses X-ray and is fast and excellent for bone, lung, acute bleeding, and coronary arteries. MRI uses magnetic fields and is excellent for soft tissue, brain, spine, joints, and cardiac muscle. CT involves radiation; MRI does not. Speed, cost, and what you are looking for all factor in.
For most average-risk adults, no. Whole-body MRI in healthy people finds an incidental abnormality in 30 to 60 percent of cases and a true early cancer in about 1 to 2 percent. The scan is most useful for patients with specific genetic risk, a strong family history, prior cancer, or unexplained symptoms a standard workup has not solved.
A calcium score is a useful starting point, but it only sees old, hardened plaque. Most heart attacks happen in soft plaque that has not calcified yet. For higher-risk patients, coronary CT angiography (CCTA) with plaque analysis sees both calcified and soft plaque and is a more complete picture.
Scanning everything is not safer. Incidental findings drive follow-up scans, biopsies, and anxiety, with real costs and no outcome benefit at population level. Selective, question-driven imaging gives better answers with less harm.
Most CT and MRI reports return within 24 to 72 hours. Echocardiogram and ultrasound reports often return the same day or next business day. Specialty scans like Cleerly plaque analysis or Galleri liquid biopsy take 1 to 4 weeks.
Insurance usually covers imaging with a clear clinical indication, like documented symptoms or abnormal labs. Calcium scores are often self-pay (around 100 dollars). Coronary CTA and MRI usually need prior authorization, which our team handles. Boutique full-body scans like Prenuvo are usually self-pay.
You need a repeat scan when guidelines call for it or a new clinical question changes the picture. Repeat scans for the same benign finding on an anxious cadence almost never change the plan. We follow published surveillance guidelines and avoid repeat imaging that adds anxiety without information.

Deep-Dive Questions

Cleerly AI turns a subjective radiologist read into a quantitative, reproducible measurement of plaque burden, type, and distribution. Instead of "moderate plaque," you get an exact volume by plaque category. That precision lets us track regression on therapy and decide whether to escalate medication or lifestyle changes.
The incidentaloma rate on whole-body MRI is 30 to 60 percent in healthy adults; nearly all of those findings are benign. It matters because each one triggers follow-up imaging, biopsies, or surveillance that has real time, dollar, and psychological costs. At population scale, the cumulative harm from those workups is the strongest argument for selective imaging.
We sequence labs first, then imaging only when labs and clinical context warrant it. ApoB, Lp(a), fasting insulin, hsCRP, and a careful history usually tell us where to look. An elevated ApoB plus family history pushes us toward CCTA; a clean panel often makes a deep scan unnecessary.
Liquid biopsy (Galleri and similar) is often preferable to whole-body imaging when the question is "is there a hidden cancer signal?" without a specific organ in mind. It has a lower incidentaloma burden and can detect signals from cancers MRI struggles with (gastric, colorectal, head and neck). It is often paired with targeted imaging rather than replaced by it.
We handle small findings by following published surveillance guidelines, not anxiety. For most small benign-appearing cysts under 2 cm, the right move is no immediate action with a guideline-directed repeat in 6 to 12 months. Cysts with concerning features get referred to the appropriate specialist for further characterization.
Most "abnormal" findings are stable and benign. Repeating a scan without a new clinical question usually confirms what we already knew and adds to anxiety. We watch findings on the cadence the guidelines support, not on the cadence the worry suggests.
We treat radiation dose as a cost to weigh against the answer. Low-dose CT for lung cancer screening in a smoker is well worth a small dose. A PET-CT (around 25 mSv) for screening a healthy adult is not. Modern CT protocols have lowered doses significantly, and ultrasound and MRI have none. We pick the lowest-dose modality that answers the question.
We choose based on the complexity of the question, the radiologist subspecialty needed, and your insurance and cost preferences. Penn, Jefferson, and Temple are best for complex cases and subspecialty reads. Independent centers in Center City, the suburbs, and Northern Liberties are often faster and lower cost for routine MRI, CT, and ultrasound.
Imaging shows the current state. Labs show the ongoing risk drivers. Pairing them answers a different question: not just "is there plaque?" but "is your trajectory still building it?" An ApoB that has crept up over five years tells a very different story than a stable one, even when the scan looks the same.
In younger patients with lower baseline cardiovascular risk and more years ahead, we are more selective with radiation-using imaging and lean toward MRI, ultrasound, or careful watchful waiting on benign findings. The lifetime cost of an incidental finding workup is larger when more years are ahead of you.
AI adds quantitative measurement and consistency to expert radiology. Cleerly for coronary plaque, AI-assisted lung nodule tracking, and AI-flagged mammography reads are credible examples. AI does not replace the radiologist; it makes the read reproducible across time and centers.
Because imaging is not a substitute for clinical thinking. If the plan is the same either way, we are scanning to feel better, not to make a better decision. The discipline of stopping at the test protects you from both unnecessary scans and the anxiety those scans seed.

Still have a question?

He answers personally. Usually within a few hours.

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