This retrospective study explored the appearance of myocarditis lesions on arterial-phase cardiac spectral CT and examined how these findings related to late-enhancement (LE) CT and MRI-detected edema. Forty-seven patients with MRI-confirmed myocarditis who underwent cardiac spectral CT were retrospectively analyzed. Three lesion patterns were identified based on their arterial and LE attenuation features: HypoArt–NorLE, NorArt–HyperLE, and HypoArt–HyperLE.
Among 173 total lesions, the HypoArt–HyperLE pattern was the most frequent (42%). These lesions appeared significantly more hypodense and contained less iodine on arterial-phase images compared with normal myocardium, while showing higher density and iodine content on LE images. Notably, in patients with MRI evidence of myocardial edema, the HypoArt–HyperLE lesions were even more hypodense and exhibited a poor iodine concentration on arterial-phase CT.
In conclusion, most myocarditis lesions can be detected on both arterial and LE cardiac spectral CT acquisitions. Their appearance as epicardial hypodense areas on arterial-phase scans correlates with myocardial edema, suggesting that arterial-phase spectral CT can help to identify myocarditis during standard coronary evaluations and may represent a valid alternative to cardiac MRI.