Photon-Counting Computed Tomography for Tissue Characterization in Patients With a Left Ventricular Hypertrophic Phenotype.

BACKGROUND

Photon-counting computed tomography (PCCT) combines high spatial resolution with spectral imaging and can provide morphologic, functional, and tissue assessment in hypertrophic hearts.

OBJECTIVES

The authors investigated whether PCCT characterizes left ventricular hypertrophy (LVH) as accurately as cardiac magnetic resonance (CMR) overall and across hypertrophic phenotypes.

METHODS

Consecutive patients with LVH (n = 182; 72 with hypertrophic cardiomyopathy, 47 with amyloid transthyretin cardiomyopathy, and 63 with secondary LVH) underwent PCCT including late iodine enhancement (LIE) and PCCT-derived extracellular volume (ECV). Eighty-three patients (46%) also underwent CMR within ±12 months (median interval: -12 days). Agreement was assessed for morphofunctional indices, ECV, and LIE vs late gadolinium enhancement (LGE).

RESULTS

PCCT differentiated etiologies through distinctive tissue patterns. Transthyretin cardiac amyloidosis showed the highest left ventricular mass index (median: 104 g/m2), the greatest LIE extent (median: 17/17 segments), and the highest ECV (median: 47%). Hypertrophic cardiomyopathy showed patchy fibrosis (median 4 enhanced segments) with intermediate ECV (31%), whereas secondary LVH displayed minimal enhancement (median: 0 segments) and the lowest ECV (28%). In paired examinations, PCCT correlated closely with CMR for left ventricular mass index and left ventricular ejection fraction (r = 0.963 and r = 0.947; P < 0.001 for both) and for ECV (r = 0.868; P < 0.001). LIE extent strongly agreed with LGE extent (r = 0.998; P < 0.001); segment-wise LIE/LGE agreement was 99% to 100%, and PCCT detected CMR-LGE with excellent accuracy (AUC: 0.994; sensitivity 99%; specificity 100%). Global PCCT-derived ECV showed excellent inter-reader agreement (ICC: 0.98).

CONCLUSIONS

PCCT provides CMR-comparable assessment of ventricular geometry, function, and myocardial fibrosis/ECV while enabling coronary angiography, supporting its use when CMR is contraindicated, impractical, or nondiagnostic.