Diagnostic Value of Photon-Counting CT in Subsegmental Pulmonary Embolism

Pulmonary embolism (PE) is a serious and potentially life-threatening condition caused by blood clots in the lungs. A particular type, subsegmental pulmonary embolism (SSPE), involves very small branches of the pulmonary arteries. Although these clots occur in smaller vessels, their risk of recurrence and complications may be similar to larger clots. Conventional CT pulmonary angiography (CTPA) is the standard imaging test for suspected PE, but image quality can sometimes be limited by motion artifacts, poor contrast filling, or body habitus, making the detection of SSPE challenging. Photon-counting computed tomography (PCCT) is a new CT technology that provides higher image resolution, lower radiation dose, and improved visualization of small blood vessels. Early studies suggest PCCT may reduce motion artifacts and increase the accuracy of detecting SSPE compared with conventional CT. This prospective cohort study will compare PCCT with dual-source CT in patients with suspected acute PE. The study aims to determine whether PCCT improves the detection rate and image quality for SSPE, and whether it can provide more reliable diagnostic information to guide clinical care.

NCT Number	NCT07575503
Lead Sponsor	Second Affiliated Hospital, School of Medicine, Zhejiang University
Conditions	Subsegmental Pulmonary Embolism, Photon-Counting Computed Tomography
Enrollment	696 participants
Start Date	2026-01-01
Primary Completion	2026-09 (estimated)
Study Completion	2027-01 (estimated)
Updated on ClinicalTrials.gov	2026-05-08