Attenuation-based estimation of myocardial extracellular volume from ECG-ungated whole-body CT examinations as an early biomarker of chemotherapy-induced cardiotoxicity: preliminary findings

Purpose: To evaluate whether myocardial extracellular volume (ECV) could be estimated from whole-body CT examinations without electrocardiographic gating in cancer patients before and after the chemotherapy, with the goal to detect early-stage myocardial alterations heralding chemotherapy-induced cardiotoxicity. Material and methods: Consecutive patients receiving chemotherapy with a high (High-risk group) or low (Low-risk group) risk of cardiotoxicity were retrospectively enrolled. Patients underwent a whole-body CT examination for cancer staging before (CT-I) and after the first chemotherapy cycle (CT-II). Precontrast, arterial phase, and late post-contrast CT-I and CT-II images were analysed using in-house software. Myocardial Attenuation-based estimation of ECV (ABE-ECV) maps were generated from the combined analysis of regions of interest in precontrast images and a pixel-wise analysis of late post-contrast images, whereas the increase of myocardial and blood densities in arterial phase from basal values were compared to calculate arterial myocardial λ (arterial increase of myocardial density/increase of blood density). Results: The population included 89 patients (mean age 63 ± 14 years): 58 High-Risk and 31 Low-Risk. High-risk patients showed a significant increase of ABE-ECV of the interventricular septum, from 32% (31-35%) to 37% (35-39%) (p = 0.0002) and lateral wall, from 30% (27-31) to 32% (29-34) (p = 0.028). In contrast, Low-risk patients showed no significant variation of septal (p = 0.16) and LV lateral wall ABE-ECV (p = 0.93). Arterial myocardial λ at CT-II was reduced compared to CT-I in 31% of High-risk patients vs 10% of Low-risk patients (p = 0.036). Conclusion: This preliminary study demonstrated that ECV can be estimated in ECG-ungated whole-body CT examinations for cancer staging in patients undergoing chemotherapy. Potentially cardiotoxic chemotherapy can be associated with alterations of ABE-ECV and arterial myocardial λ.