Cardiac CT: fast slices of anatomy
Cardiac CT spins an X-ray source around the chest and reconstructs thin cross-sectional slices, frozen in a heartbeat. With a dye injection, a CT coronary angiogram can trace the coronary arteries without ever entering them — a non-invasive road map. Its great strength is ruling out disease: in someone with low-to-moderate risk and chest pain, a clean CT angiogram very reliably says the arteries are open. It uses radiation and iodine dye, so it is chosen with care, not by default.
The calcium score: counting hardened plaque
A special quick CT needs no dye at all: the coronary calcium score. Old atherosclerotic plaque tends to harden with calcium, and calcium lights up brightly on CT. The scan counts how much calcium sits in the coronary walls and gives a single number. More calcium means more long-standing atherosclerosis and a higher future risk — it sharpens a cardiovascular risk score when the decision to start prevention is borderline.
Coronary calcium score (Agatston) — interpreting the number Score Meaning Future-risk signal 0 no detectable calcium very low 1-99 mild calcified plaque mildly increased 100-399 moderate plaque moderately increased >= 400 extensive plaque high Worked use (a 55-year-old, borderline risk): 10-year risk by calculator alone = 9% (borderline) calcium score comes back = 0 -> risk reclassified DOWNWARD; statin can often wait same calculator risk, calcium score = 300 -> risk reclassified UPWARD; prevention favored A score of 0 does NOT erase symptoms today — it speaks to long-term risk, not an acute chest-pain emergency.
Cardiac MRI: the tissue gold standard
Cardiac MRI uses strong magnets and radio waves — no ionizing radiation — to image the heart muscle with unmatched detail. It gives the most accurate chamber volumes and ejection fraction, but its true superpower is tissue characterization. With a gadolinium contrast agent, MRI can light up scar tissue from an old infarct, the patchy inflammation of myocarditis, or the distinctive signal of cardiac amyloidosis. When the question is “what is the muscle itself made of?”, MRI usually answers best.