Evaluation of Diagnostic Quality and Accuracy of Pulmonary CT Angiography Using Spectral CT with Iomeprol in Pulmonary Embolism Patients

The primary objective of this randomized clinical trial is to qualitatively and quantitatively compare three protocols for the administration of iodinated contrast in **pulmonary CT angiography**. This is achieved by measuring attenuation at pulmonary arteries, assessing the quality of perfusion maps, and evaluating the diagnostic accuracy for **pulmonary embolism**. The study involves three different protocols with varying volumes of iodinated contrast: 20 mL of contrast medium diluted with 20 mL of saline, 30 mL, and 40 mL of iodinated contrast. The clinical relevance of this objective lies in optimizing contrast administration to enhance diagnostic quality and accuracy, which is crucial for the effective diagnosis and management of pulmonary embolism.

Secondary objectives include comparing the incidence of contrast-induced nephropathy among the three protocols. This is important for assessing the safety profile of each protocol, as contrast-induced nephropathy is a significant concern in patients undergoing contrast-enhanced imaging procedures.

The clinical trial involves participants diagnosed with **pulmonary embolism**. The study population includes both male and female subjects, with an age range spanning from 18 to 64 years. Participants are generally in a stable health condition, as the trial does not focus on a vulnerable population. The total number of participants is not specified, as the sponsor has not provided this information. Selection criteria include patients who have been referred for a pulmonary CT angiography to rule out pulmonary thromboembolism. Lifestyle factors such as diet, physical activity, or habits are not specified in the available data. The trial does not include any vulnerable populations, ensuring a focus on individuals who are likely to tolerate the procedures involved in the study.

The clinical trial is designed as a **randomized**, double-blind, controlled study to evaluate the diagnostic quality and accuracy of pulmonary CT angiography using spectral CT with three different iodinated contrast administration protocols. The trial aims to compare the attenuation in pulmonary arteries, the quality of perfusion maps, and the diagnostic accuracy for **pulmonary embolism** using contrast volumes of 20 mL, 30 mL, and 40 mL. The investigational medicinal product, Iomeron 400 mgI/ml solution for injection, containing the active substance **iomeprol**, is administered via intravenous bolus. The trial is categorized as a low-intervention study, as it involves the use of authorized diagnostic products in accordance with their marketing authorization and poses minimal additional risk to participants.

The trial is expected to commence recruitment on August 1, 2024, and conclude by March 31, 2025. Participants will be involved in the study for a maximum treatment period of one day, with the primary endpoints focusing on the attenuation achieved in pulmonary arteries, detection of pulmonary thromboembolism, and lung perfusion based on iodine density. The study visits include an initial screening visit to confirm eligibility, followed by the administration of the contrast medium during the CT angiography procedure. There are no specified follow-up visits, as the study's primary assessments are conducted during the imaging session. The end-of-study visit coincides with the completion of the CT angiography and data collection.

Participants are eligible if they are referred for a pulmonary CT angiography to rule out pulmonary thromboembolism. There are no principal exclusion criteria specified. Early termination from the study may occur if a participant withdraws consent or if any unforeseen adverse events arise that compromise participant safety. The trial's methodology ensures that the investigational procedures align with standard clinical practices, thereby maintaining the integrity and safety of the study.

The clinical trial involves the use of **Iomeron 400 mgI/ml solution for injection**, an experimental medication containing the active substance **iomeprol**. This pharmaceutical form is a solution for injection, specifically designed for **intravenous bolus use**. The trial evaluates three different administration protocols of iodinated contrast in pulmonary CT angiography, with volumes of 20 mL, 30 mL, and 40 mL. The maximum daily and total dose of iomeprol is set at 40 mg/l, with a treatment period limited to one day. The solution is manufactured by Bracco Imaging S.p.A. and is not a pediatric formulation.

In this study, no non-experimental treatments such as standard-of-care therapy, placebo, or comparator treatments are utilized. The focus is solely on the administration of the experimental medication, Iomeron, to assess its diagnostic quality and accuracy in pulmonary CT angiography. Participant compliance with the dosing schedule is monitored to ensure adherence to the protocol, and the trial aims to measure attenuation at pulmonary arteries, quality of perfusion maps, and diagnostic accuracy for pulmonary thromboembolism.

Efficacy in this clinical trial will be assessed by evaluating the diagnostic quality and accuracy of pulmonary CT angiography using spectral CT with three different iodinated contrast administration protocols. The primary endpoints for efficacy assessment include the **attenuation** achieved in the pulmonary arteries at both conventional and low-energy monoenergetic images, the detection of pulmonary thromboembolism, and lung perfusion based on iodine density. These parameters will be measured to qualitatively and quantitatively compare the three protocols, which involve administering 20 mL, 30 mL, and 40 mL of iodinated contrast medium.