Diagnostic Value of Photon-Counting CT in Pericardial Metastases: A Single-Center Retrospective Study

Pericardial metastases are common in advanced cancers but often remain undetected due to subtle symptoms. Photon-counting CT (PCT) offers improved spatial resolution and contrast-to-noise ratio (CNR) compared with conventional CT (CCT), potentially enhancing diagnostic performance. In this retrospective single-center study, patients diagnosed with pericardial metastases by transthoracic echocardiography (TTE) between April and September 2025, who underwent both unenhanced and contrast-enhanced chest CT were included. After Propensity Score Matching (PSM), two groups were established: the PCT group (n = 11; reconstructions at 0.4 and 1 mm) and the CCT group (n = 22). Diagnostic sensitivity, image quality, and radiation dose were assessed, with TTE as the reference standard. PCT-0.4 mm demonstrated the highest overall sensitivity (91.5%) and small-lesion sensitivity (88.9%), followed by PCT-1 mm (87.2% and 83.3%) and CCT-1 mm (86.1% and 78.6%). Although not statistically significant, PCT showed consistently better lesion detection. The PCT-0.4 mm group showed higher standardized CNR versus CCT-1 mm (Tukey-Kramer p = 0.021) but not versus PCT-1 mm (p = 0.641); overall one-way ANOVA p = 0.020, whereas SNR did not differ among groups (ANOVA p = 0.18). Radiation exposure was significantly lower with PCT than CCT (ED: 11.7 ± 3.9 vs. 20.6 ± 6.6 mSv; p < 0.001). Compared with the 1-mm CCT reconstruction, the 0.4-mm PCT showed a trend toward improved detection of both overall and small pericardial metastases, enhanced image quality, and reduced radiation dose, highlighting its potential clinical value in managing pericardial metastases.