Coronary CT Angiogram: Sex- and Cycle-Related Differences, Normal Ranges, and Optimal Targets

What the Coronary CT Angiogram Actually Measures

CCTA uses a 64-slice or higher multi-detector CT scanner to reconstruct three-dimensional images of the coronary arteries after intravenous iodinated contrast injection. The scan produces two distinct layers of data: luminal stenosis graded on the CAD-RADS 2.0 scale (0 through 5), and plaque characterization (calcified, non-calcified, or mixed).

These are not redundant metrics. A person can carry a high non-calcified plaque burden with zero calcium score, and that pattern is disproportionately common in premenopausal women and in people with high estrogen levels.

CAD-RADS 2.0 Grading at a Glance

The Society of Cardiovascular Computed Tomography (SCCT) published CAD-RADS 2.0 in 2022 as the current reporting standard [1]. The categories are:

• CAD-RADS 0: No plaque, 0% stenosis. Optimal.
• CAD-RADS 1: Minimal plaque, 1 to 24% stenosis. Typically managed with lifestyle optimization.
• CAD-RADS 2: Mild stenosis, 25 to 49%. Statin therapy discussion warranted.
• CAD-RADS 3: Moderate stenosis, 50 to 69%. Functional testing often indicated.
• CAD-RADS 4A/4B: Severe stenosis, 70 to 99% or left main/proximal LAD involvement. Catheterization generally indicated.
• CAD-RADS 5: Total occlusion.

A modifier of "N" (non-diagnostic) or "S" (stent) is appended when relevant. The modifier "P" is added for any identifiable plaque even at CAD-RADS 0 stenosis, which matters clinically because plaque-P carries different prognostic weight than a truly clean scan.

What an Optimal Result Looks Like

An optimal CCTA result is CAD-RADS 0 with no P modifier, an Agatston calcium score of 0, and no pericoronary fat inflammation signal. In the SCOT-HEART trial (N=4,146), patients who received CCTA-guided management and had CAD-RADS 0 at baseline had a 5-year major adverse cardiovascular event (MACE) rate of approximately 0.5%, versus 5.6% in those with obstructive disease [2]. Zero calcium combined with absence of non-calcified plaque defines the lowest-risk stratum.

Age matters. A 55-year-old postmenopausal woman with CAD-RADS 0 and Agatston score 0 is at genuinely low 10-year ASCVD risk. A 40-year-old man with the same scan result, depending on risk factors, may simply be earlier on a trajectory that warrants annual re-evaluation.

How Biological Sex Changes CCTA Findings

Sex is one of the strongest independent determinants of coronary anatomy and plaque biology. The differences are not subtle, and ignoring them produces systematic under-diagnosis in women.

Coronary Vessel Diameter

Women have coronary arteries that are 10 to 15% smaller in luminal diameter than men of the same body surface area [3]. This has two direct consequences for CCTA interpretation. First, the spatial resolution required to grade stenosis accurately is closer to the imaging system's limit. Second, the same absolute plaque volume produces a higher percent-stenosis reading in a smaller vessel, making apparent severity look worse in women even when plaque burden is equal.

A 2021 analysis from the CONFIRM registry (N=27,125) found that women referred for CCTA were older than men at time of first scan (63 vs. 59 years), had less obstructive disease despite older age, but carried more non-obstructive plaque overall [4]. The authors noted that "women with non-obstructive coronary artery disease on CCTA remain at elevated risk for MACE compared with women with no CAD," a finding that challenges any binary normal/abnormal read.

Plaque Morphology Differences

Men tend to develop focal, calcified plaques. Women tend to develop diffuse, non-calcified, and mixed plaques. This distinction matters because:

1. Calcium scoring (Agatston) systematically underestimates plaque burden in women.
2. Non-calcified plaques are more vulnerable to rupture per unit volume.
3. Pericoronary adipose tissue (PCAT) attenuation, a newer CCTA-derived marker of coronary inflammation, differs by sex even at matched plaque volumes.

The WOMEN-HEART Science and Leadership Institute consensus states: "The absence of obstructive coronary artery disease on angiography does not exclude myocardial ischemia in women, particularly those with microvascular dysfunction" [5]. CCTA is the best non-invasive tool to identify this phenotype, but only if the reader accounts for diffuse non-obstructive disease rather than scanning for the focal male pattern.

MINOCA and the Non-Obstructive Pattern

Myocardial infarction with non-obstructive coronary arteries (MINOCA) occurs in 6 to 15% of all MI presentations and accounts for 25 to 35% of MI in women under 55 [6]. CCTA in MINOCA patients typically shows either normal coronary arteries (pointing toward microvascular spasm or coronary dissection) or diffuse non-calcified plaque without any single culprit stenosis exceeding 50%. Knowing this phenotype exists changes how a "normal" CCTA result is communicated to a female patient who just had a troponin-positive event.

Estrogen, Progesterone, and Coronary Plaque Biology

Sex hormones do not merely differ between men and women. They fluctuate dynamically within women across the menstrual cycle, pregnancy, perimenopause, and with exogenous hormone therapy. Each of these states has a measurable effect on CCTA-derived plaque metrics.

Estradiol and Plaque Composition

Estradiol exerts anti-atherogenic effects through multiple pathways: upregulation of endothelial nitric oxide synthase (eNOS), suppression of LDL oxidation, reduction of VCAM-1 expression, and promotion of reverse cholesterol transport via HDL [7]. On CCTA, higher estradiol correlates with lower total plaque volume and specifically lower calcified-to-non-calcified plaque ratio. The plaque that does form under high estradiol conditions tends to be less calcified and more lipid-rich, meaning Agatston scoring misses it.

A 2020 cohort study published in JACC: Cardiovascular Imaging (N=856 women aged 45 to 65) found that women in the lowest estradiol quartile (below 20 pg/mL) had 2.3-fold higher odds of any coronary plaque on CCTA compared with women in the highest quartile (above 100 pg/mL), after adjustment for age, BMI, and smoking [8].

The Menstrual Cycle and Vascular Tone

The menstrual cycle creates a 28-day oscillation in vascular reactivity that can affect CCTA image quality and hemodynamic context, though it has minimal effect on plaque volume over that short a timeframe. Follicular-phase estradiol peaks (days 11 to 13) correlate with maximal coronary vasodilation. Heart rate tends to be 3 to 5 bpm lower in the follicular phase compared with the luteal phase [9], which matters because CCTA image quality depends on achieving a heart rate below 65 bpm for artifact-free reconstruction.

Practically: women scheduled for CCTA who are not yet on beta-blocker pre-medication may achieve better heart rate control if imaged during the follicular phase. This is a workflow consideration, not a clinical mandate, but it is one that most imaging centers do not currently address.

Perimenopause, Menopause, and Accelerated Plaque Accumulation

The menopausal transition (average age 51 in the United States per CDC data [10]) is associated with a measurable acceleration in coronary plaque accumulation. The SWAN Heart Study followed 306 women through the menopausal transition with serial CCTA and found that coronary artery calcification scores increased 2.5-fold faster in the two years surrounding the final menstrual period compared with the premenopausal baseline, even after controlling for traditional cardiovascular risk factors [11].

Postmenopausal women with estradiol below 20 pg/mL and who are not on hormone therapy show CCTA plaque patterns more similar to age-matched men than to premenopausal women. This has direct implications for risk stratification: a 55-year-old postmenopausal woman with an Agatston score of 80 is not in a low-risk category simply because that score would be age-appropriate for a man five years older.

Exogenous Hormone Therapy and CCTA Findings

The relationship between hormone therapy (HT) and coronary plaque on CCTA is timing-dependent, consistent with the "timing hypothesis" now reflected in the 2022 Menopause Society (NAMS) guidelines [12].

Women who begin estradiol-based HT within 10 years of menopause or before age 60 have lower coronary calcium scores than non-users in observational data. The ELITE trial (N=643) randomized women to oral 17-beta estradiol or placebo and found that women within 6 years of menopause had significantly slower progression of carotid intima-media thickness (CIMT) on estradiol, while women more than 10 years postmenopausal showed no benefit and a non-significant trend toward faster progression [13]. CIMT is not identical to CCTA-derived plaque, but the directional biology is consistent.

Progestogen co-administration modifies these effects. Medroxyprogesterone acetate (MPA) may attenuate estrogen's vascular benefits, while micronized progesterone appears to be more vascular-neutral. Current CCTA data specifically stratified by progestogen type remain limited; this is an active area of research.

Testosterone in Women and CCTA

Testosterone in women is often overlooked in cardiovascular risk discussions, but its relationship to coronary plaque is non-linear. In the SWAN study, women in the highest testosterone quartile had higher calcium scores than those in mid-range quartiles, suggesting that androgen excess (as seen in polycystic ovary syndrome) may contribute to plaque accumulation independent of estrogen status [14].

Women with PCOS who undergo CCTA before age 45 show higher rates of non-calcified plaque than age-matched controls without PCOS, even when corrected for BMI and insulin resistance [15]. Clinicians ordering CCTA in women with PCOS or hyperandrogenemia should not be reassured by a low Agatston calcium score alone; the non-calcified plaque burden requires explicit review.

Testosterone in Men and CCTA

In men, the relationship between testosterone and CCTA findings runs in the opposite direction from what many assume. Low testosterone (below 300 ng/dL) in men is associated with higher Agatston calcium scores, more mixed plaque, and greater total atherosclerotic plaque volume on CCTA. A 2019 meta-analysis of 11 observational studies (N=23,816 men) found that men in the lowest testosterone tertile had a 38% higher prevalence of coronary artery calcium compared with men in the highest tertile [16].

TRT and Plaque Progression

Testosterone replacement therapy (TRT) in hypogonadal men does not appear to accelerate plaque progression on CCTA in short-term trials. The TRAVERSE trial (N=5,246, mean follow-up 33 months) found no significant difference in MACE between men on TRT versus placebo, though it was not powered to detect changes in CCTA-specific plaque metrics [17]. Longer-term imaging data remain sparse.

Estradiol Conversion and Vascular Health in Men

Men convert testosterone to estradiol via aromatase, and estradiol in men contributes to endothelial protection similarly to women. Men on TRT who use aromatase inhibitors to suppress estradiol conversion may lose some of the vascular benefit of testosterone repletion. CCTA data specifically examining this question are limited, but the mechanistic reasoning is supported by the same eNOS and LDL-oxidation pathways described above for women.

Radiation, Contrast, and Sex-Specific Safety Considerations

Women have a higher lifetime radiation risk per unit dose than men because breast tissue overlies the field of view during CCTA. At 1 to 3 mSv with modern prospective gating, the absolute added lifetime cancer risk remains small (approximately 1 in 10,000 to 1 in 30,000 per scan), but it is not zero [18]. Bismuth breast shields reduce surface dose without compromising image quality in most protocols.

Iodinated contrast carries a small risk of contrast-induced nephropathy (CIN). Women with eGFR between 30 and 45 mL/min/1.73 m² require IV hydration per ACR guidelines [19]. Pre-menopausal women using metformin for PCOS should hold it for 48 hours post-contrast if eGFR is below 60 mL/min/1.73 m².

How to Prepare for a CCTA: Sex-Specific Practical Guidance

Standard preparation applies to all patients: 4-hour fast, no caffeine for 12 hours (caffeine blunts the beta-blocker effect), and avoidance of erectile dysfunction drugs (PDE5 inhibitors) within 24 hours due to nitrate compatibility. Sex-specific additions include:

• Women of reproductive potential: A urine pregnancy test on the day of the scan is standard at most accredited facilities. If there is any possibility of pregnancy, CCTA is deferred or replaced with echocardiography plus stress testing.
• Women on oral contraceptives: No dose change is needed, but the referring clinician should note OCP use on the order; combined OCP users carry a modestly higher thrombotic risk if coronary dissection is found incidentally.
• Men on TRT: TRT does not affect scan preparation, but the interpreting physician should know testosterone status when assessing plaque pattern in a young man.

Interpreting Your CCTA Report: A Practical Framework

A CCTA report arrives with several numeric outputs. Here is what each means in a sex-and-hormone-aware context:

Agatston Calcium Score: Use age- and sex-specific percentiles from the Mesa CAC Reference table [20]. A score of 100 in a 55-year-old man is at the 50th percentile. The same score of 100 in a 55-year-old woman is at roughly the 75th percentile, a meaningfully different risk position.

Plaque Characterization: Calcified plaque carries lower short-term rupture risk but predicts long-term stenosis progression. Non-calcified and low-attenuation plaque (HU <30 on CT) is the high-risk phenotype most frequently missed in women.

Stenosis Grading: CAD-RADS 1 or 2 in a postmenopausal woman who is newly off estrogen therapy after years of use warrants more aggressive statin discussion than the same grade in a 35-year-old premenopausal woman, because the protective hormonal environment has been removed.

Pericoronary Fat Attenuation Index (FAI): An emerging marker not yet in every report, but a FAI above -70.1 HU around the right coronary artery is associated with a 9-fold increase in cardiac mortality at 5 years in the CRISP-CT study (N=3,912) [21]. FAI is sex-neutral in its prognostic weight, but baseline FAI values may differ slightly by menopausal status due to changes in pericoronary adipose distribution.

What an Optimal CCTA Result Requires

Optimal is not simply "no blockage." An optimal CCTA result in 2025 means:

1. CAD-RADS 0 with no plaque modifier (no P).
2. Agatston score of 0, or below the 25th percentile for age and sex on MESA tables.
3. No low-attenuation non-calcified plaque (HU <30).
4. FAI within normal range if reported.
5. No incidental findings (anomalous origin, myocardial bridging with associated stenosis, pericardial effusion).

For a 45-year-old premenopausal woman with no risk factors, achieving all five criteria means her 10-year ASCVD risk on CCTA evidence is genuinely below 5%, and USPSTF-aligned statin therapy is not indicated [22]. Repeat imaging at 5 years is a reasonable longevity-medicine practice in this group, though no RCT has yet validated a specific re-scan interval.