Diagnostic Value of Photon-Counting CT in Subsegmental Pulmonary Embolism

NCT07575503 | Recruiting

• 1 other identifier: 2025-1248
• Study Type: observational
• Target: 696
• Locations: 1 country
• Sites: 1

Brief Summary

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.

Conditions

Subsegmental Pulmonary Embolism; Photon-Counting Computed Tomography

Outcome Measures

Primary Outcomes (1)

• Detection rate of subsegmental pulmonary embolism (SSPE) using photon-counting CT versus dual-energy CT

  The proportion of patients with suspected acute pulmonary embolism in whom SSPE is detected on photon-counting CT compared with dual-energy CT. All scans will be independently assessed by two blinded radiologists to determine diagnostic yield.

  perioperative period

Secondary Outcomes (3)

• Objective image quality scores for SSPE diagnosis

  perioperative period

• Subjective image quality scores for SSPE diagnosis

  perioperative period

• Incidence of Venous Thromboembolism (VTE)

  3 months

Study Arms (2)

Group 1Title: Conventional CT group

Description: Patients with suspected pulmonary embolism who undergo dual-source or energy-integrating detector CT pulmonary angiography (EID-CTPA).

Group 2 Title: Photon-counting CT group

Description: Patients with suspected pulmonary embolism who undergo photon-counting computed tomography (PCCT) for diagnosis.

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

Adults (≥18 years) presenting with clinical symptoms and signs suggestive of acute pulmonary embolism will be enrolled. Eligible patients are those with a simplified revised Geneva score ≥3 and abnormal findings on electrocardiogram, echocardiography, or pulse oximetry, which support the suspicion of pulmonary embolism. Patients will be prospectively recruited from the emergency department and inpatient wards of the Second Affiliated Hospital, Zhejiang University School of Medicine. The study population is representative of patients with suspected acute pulmonary embolism who require CT pulmonary angiography for diagnostic confirmation.

You may qualify if:

• Age ≥ 18 years
• Clinical manifestations supporting the diagnosis of acute pulmonary embolism, including:
• Acute onset or progressive dyspnea Unexplained hypoxemia Chest pain Hemoptysis Syncope or presyncope Combined with abnormal findings on electrocardiogram, echocardiography, or pulse oximetry
• Revised simplified Geneva score ≥ 3
• Written informed consent obtained from the patient or the patient's legally authorized representative

You may not qualify if:

• Patients requiring prophylactic or therapeutic doses of anticoagulant medication for reasons other than venous thromboembolism (VTE).
• Life expectancy less than three months.
• Patients unable to undergo CT scanning due to severe condition or hemodynamic instability.
• History of allergy to contrast media, renal insufficiency (creatinine clearance \< 30 mL/min), or ongoing long-term dialysis.
• Pregnancy.
• Refusal to provide informed consent or inability to complete follow-up for any reason.

Sponsors & Collaborators

• Second Affiliated Hospital, School of Medicine, Zhejiang University: lead

Study Sites (1)

The Second Affiliated Hospital of Zhejiang University School of Medicine

Hangzhou, Zhejiang, 310009, China

RECRUITING

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: November 17, 2025
• First Posted: May 8, 2026
• Study Start: January 1, 2026
• Primary Completion (Estimated): September 1, 2026
• Study Completion (Estimated): January 1, 2027
• Last Updated: May 8, 2026

Record last verified: 2025-09

Locations

CN (1)