In 30 patients with genotype-confirmed hypertrophic cardiomyopathy, global PCCT-derived extracellular volume (ECV) closely matched cardiac MRI: 30.0 ± 4.8% vs 30.62 ± 4.2% (p = 0.59), with a small Bland–Altman bias of 0.6% and limits of agreement of −1.49% to 2.75%.
Agreement was also strong regionally, with segmental correlations of r = 0.89 at the base and r = 0.85 at both mid-ventricular and apical levels. Interobserver reproducibility was excellent for PCCT-derived ECV (ICC 0.982) and MRI-derived ECV (ICC 0.921).
A global PCCT ECV threshold of 33.4% identified patients with LGE ≥15% with 80% sensitivity and 76% specificity (AUC 0.77). PCCT ECV also correlated with functional and biomarker severity, including peak VO₂ (r = −0.76) and NT-proBNP (r = 0.59), supporting its potential as a combined coronary and myocardial tissue-characterization biomarker.
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Fig. 4. 47-year-old man with hypertrophic cardiomyopathy due to MYBPC3 mutation (hematocrit level, 0.46 %).
(A) Short-axis view of late iodine enhancement (iodine map) with photon-counting CT.
(B) Short-axis view of late gadolinium enhancement with cardiac MRI.
(C-D) Extracellular volume polar maps (17-segment model of the American Heart Association) derived from C. Photon-counting CT and D. Cardiac MRI. Eingefügter Text(20261024-07534…
Protocol
Detail | Value |
|---|
Scanner | NAEOTOM Alpha |
Scan area | Cardiac |
CCTA mode | High-pitch or sequential, prospectively ECG-triggered depending on heart rate and rhythm |
tube voltage [kV] | 90 |
IQ level | 56 |
reconstruction slice thickness [mm] | 0.4 |
reconstruction increment [mm] | 0.4 |
kernel | Bv56 |
iterative reconstruction | QIR 4 |
Late iodine enhancement mode | High-pitch spectral acquisition |
Late iodine enhancement timing | 5 min after reinjection |
Late iodine enhancement tube voltage [kV] | 120 |
Late iodine enhancement IQ level | 100 |
ECG gating / phase | ECG-triggered, fixed absolute RR interval 280 ms |
VMI | 40 keV |
LIE reconstruction slice thickness [mm] | 2 |
LIE reconstruction increment [mm] | 1 |
LIE kernel | Qr44 |
LIE iterative reconstruction | QIR 4 |
Spectral reconstruction | Iodine maps |
Contrast | Iobitridol 350 mg I/mL |
CCTA contrast volume | 50 mL |
LIE contrast volume | Additional 50 mL |
Injection rate | 4–5 mL/s |
Saline flush | 20 mL |
Post-processing | syngo.via VB40A; prototype Frontier Cardiac Functional Analyses for ECV |
Late-scan DLP [mGy·cm] | 106 ± 52 |
Late-scan effective dose [mSv] | 1.47 ± 0.6 |
Key Results
Parameter | Main finding |
|---|
Study population | 30 patients, 22 men; mean age ~59 years |
Global ECV | PCCT 30.0 ± 4.8% vs MRI 30.62 ± 4.2%, p = 0.59 |
PCCT–MRI agreement | Bias 0.6%, limits of agreement −1.49% to 2.75% |
Segmental correlation | Basal r = 0.89; mid-ventricular r = 0.85; apical r = 0.85 |
ECV threshold for LGE ≥15% | 33.4%; sensitivity 80%, specificity 76%, AUC 0.77 |
Clinical correlations | Peak VO₂ r = −0.76; NT-proBNP r = 0.59 |
Source:
Gkizas C, Longere B, Bechrouri S, Ridon H, Rodriguez Musso A, Haidar M, Croisille C, Montaigne D, De Groote P, Pontana F. Photon-counting CT myocardial extracellular volume: A non-invasive biomarker for fibrosis in patients with hypertrophic cardiomyopathy. Diagnostic and Interventional Imaging. 2026;107(1):17–24. doi:10.1016/j.diii.2025.09.001.
