Calcium Fracture Detection by Optical Coherence Tomography Versus Intravascular Ultrasound Following Intravascular...

Calcium fracture is a metric used to assess lesion preparation success. We have shown previously that optical coherence tomography (OCT) misses approximately half of these fractures. Intravascular ultrasound (IVUS) is the most commonly used intravascular imaging modality. The sensitivity of IVUS for detecting calcium fractures after intravascular lithotripsy (IVL) is unknown.

This study sought to assess the frequency and characteristics of calcium fracture observed on IVUS in comparison to OCT and gold standard micro-computed tomography (micro-CT) using heavily calcified coronary artery cadaveric vessels.

In an ex vivo study of 5 cadaveric hearts (15 coronary lesions), OCT, IVUS, and micro-CT were obtained before and after IVL coronary artery treatment. Fracture detection rates and appearance patterns were compared across modalities. Receiver operating characteristic analyses evaluated OCT-measured fracture width thresholds for IVUS detectability.

Compared with micro-CT, OCT and IVUS significantly underestimated fracture occurrence, but OCT demonstrated higher detection sensitivity than IVUS (P < 0.05 by McNemar's test). Narrow linear nondisplaced fractures identified on OCT were frequently undetectable on IVUS or appeared as subtle hyperechoic shadows. Fracture width was strongly associated with IVUS detectability; fracture width >115 μm on OCT were identified by IVUS with excellent diagnostic performance (area under the curve: 0.99 [95% CI: 0.98-1.00], sensitivity 100%, specificity 92%).

OCT and IVUS underestimate the occurrence of IVL-induced calcium fractures compared with micro-CT, with IVUS demonstrating lower sensitivity than OCT. IVUS detectability is strongly dependent on fracture width. Absence of visible fracture on either OCT or IVUS does not exclude calcium modification.