Patent ductus arteriosus is a common congenital cardiovascular lesion. Echocardiography is the first-line imaging method in children, but exact delineation of ductal morphology and its relation to adjacent vessels may be challenging in selected patients. Cross-sectional imaging can therefore be helpful when additional anatomical detail is needed for diagnosis or procedural planning. Photon-counting CT offers improved spatial resolution and reduced electronic noise compared with conventional detector technology, making it attractive for the assessment of small vascular structures. ^{Reference Schneider and Moore1–Reference Rajendran and McCollough5}

A 10-year-old girl was referred after a cardiac murmur was detected during routine examination. She had no cyanosis, respiratory distress, or previous cardiac intervention. Contrast-enhanced chest CT was performed on a photon-counting detector system to clarify the anatomy. The study demonstrated a tubular communication between the descending thoracic aorta, just distal to the origin of the left subclavian artery, and the proximal left pulmonary artery, consistent with patent ductus arteriosus. Axial images depicted the aortopulmonary communication, whereas multiplanar reconstructions defined the ductal course. The minimal luminal diameter was approximately 3.6 mm, and the ductal length was approximately 8.6 mm (Figure 1). Three-dimensional volume-rendered images further illustrated the relation of the ductus to the aortic arch, descending thoracic aorta, and proximal left pulmonary artery (Figure 2). These findings provided detailed anatomical information relevant to potential transcatheter or surgical planning. ^{Reference Goo and Park6,Reference Porstmann, Wierny and Warnke7}

Figure 1.

( a ) Axial contrast-enhanced CT image demonstrates abnormal communication between the descending thoracic aorta and the proximal left pulmonary artery. ( b , c ) Multiplanar reconstructed images show the ductal course and permit measurement of the minimal luminal diameter (approximately 3.6 mm) and ductal length (approximately 8.6 mm).

Figure 1. Long description

The axial contrast-enhanced CT image displays an abnormal connection between the descending thoracic aorta and the proximal left pulmonary artery. Multiplanar reconstructed images illustrate the ductal course, allowing for the measurement of the minimal luminal diameter, which is approximately 3.6 millimeters, and the ductal length, which is approximately 8.6 millimeters. The images provide detailed visualization of the vascular structures and their spatial relationships.

Figure 2.

Three-dimensional volume-rendered CT image demonstrates the spatial relationship among the aortic arch, descending thoracic aorta, proximal left pulmonary artery, and patent ductus arteriosus.

Figure 2. Long description

The image is a three-dimensional volume-rendered CT scan illustrating the anatomical relationship between the aortic arch, descending thoracic aorta, proximal left pulmonary artery, and patent ductus arteriosus. The patent ductus arteriosus is a tubular communication between the descending thoracic aorta, just distal to the origin of the left subclavian artery, and the proximal left pulmonary artery. The image highlights the spatial arrangement and connections of these vascular structures, providing a clear view of their relative positions and interactions.

Echocardiography remains the primary tool for diagnosis, haemodynamic assessment, and follow-up in children with patent ductus arteriosus. ^{Reference Lai, Geva and Shirali2} However, CT may be valuable when acoustic windows are limited or when a comprehensive three-dimensional depiction of the duct and adjacent vascular structures is needed. ^{Reference Goo4,Reference Goo and Park6} In this case, photon-counting CT allowed direct measurement of ductal diameter and length on high-resolution multiplanar images and clearly demonstrated the spatial relationships that are difficult to appreciate on a single projection. The potential relevance of photon-counting CT in congenital cardiovascular imaging lies in its technical advantages. By directly converting incoming photons into electrical signals and sorting them by energy, this detector design can improve spatial resolution and reduce electronic noise compared with conventional CT systems. ^{Reference Willemink, Persson and Pourmorteza3,Reference Rajendran and McCollough5,Reference Symons, Cork and Sahbaee9} Early cardiovascular experience suggests that these properties may improve delineation of fine vascular anatomy while maintaining diagnostic image quality. ^{Reference Symons, Cork and Sahbaee9,Reference Goo10} For selected children who require precise anatomical mapping beyond echocardiography, photon-counting CT may therefore serve as a useful complementary tool. Radiation exposure and the need for iodinated contrast remain important considerations, so its use should be individualised and justified clinically. ^{Reference Frush and Donnelly8,Reference Goo10}