Fig. 1

Unenhanced coronal and axial CT scan of the thorax showing a hyperdense linear tubular structure (white arrows) measuring approximately 6.2 cm in length within the right brachiocephalic vein extending to the superior vena cava (SVC), which at first glance was concerning for a retained catheter fragment. However, the discontinuous and interrupted appearance of this hyperdense structure, with a visible lumen suggested a calcified fibrin sheath instead