Calcium Score, CCTA, Whole-Body MRI: What to Order and When

I had a 44-year-old this week who came in with a list: whole-body MRI, coronary calcium score, DEXA. Her 10-year risk by pooled cohort equations is 3.1%, but her apoB is 118 and her Lp(a) is 168 nanomoles per liter. What do I actually order?

That Lp(a) is the number that matters most for sequencing. Lp(a) — lipoprotein(a), a genetically elevated atherogenic particle that pooled cohort equations don't capture — at 168 puts her at meaningfully higher cardiovascular risk than her calculator suggests. That's your reason to image.

So start with coronary calcium scoring?

Yes, with one caveat. Coronary calcium scoring detects calcified plaque only. In a 44-year-old, atherosclerosis is often still soft, non-calcified plaque — which calcium scoring misses entirely. A zero calcium score in her does not mean clean arteries. That's guideline-acknowledged, not speculative.

So if her calcium score comes back zero, I'm not done?

Correct. With her Lp(a) and apoB, a zero calcium score should prompt CCTA — CT coronary angiography — which images the vessel wall directly and can detect non-calcified plaque. That's where the image beats the score: it tells you what's actually there in this patient, not what a cohort like her tends to do.

How strong is that evidence — that CCTA changes outcomes?

The SCOT-HEART trial showed CCTA-guided care reduced fatal and non-fatal myocardial infarction at five years compared with standard care. That's clinical endpoint data. It's the strongest evidence for any advanced coronary imaging study in prevention.

What about the whole-body MRI she's asking for?

That's where I'd slow down. Whole-body MRI finds incidentalomas — unexpected findings — in roughly 15 to 40 percent of asymptomatic people depending on the protocol. Most are benign. But each one generates a downstream cascade of further imaging, biopsies, anxiety. There are no randomized trial data showing mortality benefit in general screening populations.

So it's marketed without evidence?

Marketed without outcome evidence, yes. The imaging itself is technically excellent. The question is whether finding more incidentalomas helps her live longer or just generates more procedures. We genuinely don't know yet, and I'd tell her that directly.

She already has a DEXA from a body-composition studio. Is that clinically useful?

DEXA gives you bone density and body composition. The bone density is guideline-supported for fracture risk stratification — FRAX uses it. The visceral fat estimate from body-composition DEXA has mechanistic interest but no guideline-recommended threshold to act on yet.

And CPET — cardiopulmonary exercise testing — where does that fit?

VO2 max, measured directly by CPET, is one of the strongest predictors of all-cause mortality in the observational literature. It also gives you a baseline to train from. What it doesn't give you is a scan — it's functional, not anatomical. In someone whose coronary imaging is clear, it's the next most useful study.

So for my patient: calcium score, then CCTA if the score is zero or if she has significant plaque, hold the whole-body MRI pending a real conversation about cascades, accept the DEXA bone data, add CPET if the coronary picture is reassuring?

That's the sequence. And the principle underneath it: an image demonstrates what's present in this patient; a risk score estimates what a cohort like her does. When they disagree, the image guides the decision — but only if you're prepared to act on what it finds.

What's the one thing to hold onto?

Don't order a scan unless the result can change a decision. If you wouldn't start statin therapy on a positive CCTA in a low-calculated-risk patient, don't scan her. The test is only useful when you're prepared to own every answer it might give.