Repositioning the Bolus Tracking ROI to the Superior Vena Cava in CTPA Facilitates Contrast Volume Reduction

NCT07342374 | Completed

• 1 other identifier: NMRR-20-699-54086 (IIR)
• Study Type: interventional
• Target: 72
• Locations: 1 country
• Sites: 1

Brief Summary

This randomized controlled trial evaluates a protocol optimization for Computed Tomography Pulmonary Angiography (CTPA). The study investigates the impact of repositioning the bolus-tracking region-of-interest (ROI) from the standard pulmonary trunk (PT) to the superior vena cava (SVC). The goal is to compensate for the CT scanner's inherent transit delay time (TDT) to better align the scan with the peak arterial phase. By optimizing this timing, the study assesses whether contrast media volume can be safely reduced by 40% (from 50 ml to 30 ml) while maintaining diagnostic image quality and preventing venous contamination.

Conditions

Pulmonary Artery Embolism; Pulmonary Embolism (PE)

Keywords

Pulmonary Embolism; Computed Tomography Pulmonary Angiography; Contrast Media; Bolus Tracking; Superior Vena Cava; Image Quality; Low-volume Protocol

Outcome Measures

Primary Outcomes (1)

• Mean Difference in Hounsfield Unit (HU) Attenuation Between Pulmonary Artery and Pulmonary Vein

  This quantitative measurement assesses the degree of arterial opacification relative to venous contamination by calculating the difference in Hounsfield Units (HU). It is calculated by subtracting the mean HU value of the pulmonary vein from the mean HU value of the pulmonary artery at the same anatomical level. A larger positive difference indicates superior arterial enhancement with minimal venous contamination.

  At the time of post-procedural image analysis (approximately 48 hours after CTPA scan completion).

Secondary Outcomes (1)

• Qualitative Image Quality Score using a 5-point Likert Scale

  Within 1 month following the CTPA scan.

Study Arms (4)

Group A: PT-ROI, 50 ml (Control)

ACTIVE COMPARATOR

Standard CTPA protocol using the bolus tracking technique with the monitoring region of interest (ROI) placed at the pulmonary trunk (PT) and 50 ml of contrast media.

Diagnostic Test: Optimized CTPA Protocol

Group B: PT-ROI, 30 ml

EXPERIMENTAL

Modified CTPA protocol using the bolus tracking technique with the monitoring ROI at the pulmonary trunk (PT) and a reduced contrast volume of 30 ml.

Diagnostic Test: Optimized CTPA Protocol

Group C: SVC-ROI, 50 ml

EXPERIMENTAL

Modified CTPA protocol using the bolus tracking technique with the monitoring ROI repositioned upstream to the superior vena cava (SVC) and 50 ml of contrast media.

Diagnostic Test: Optimized CTPA Protocol

Group D: SVC-ROI, 30 ml

EXPERIMENTAL

Modified CTPA protocol using the bolus tracking technique with the monitoring ROI repositioned upstream to the superior vena cava (SVC) and a reduced contrast volume of 30 ml.

Diagnostic Test: Optimized CTPA Protocol

Interventions

Optimized CTPA Protocol DIAGNOSTIC_TEST

CTPA scans are performed on a 128-slice CT scanner using the bolus tracking technique. Non-ionic contrast medium (370 mgI/ml) is administered at a rate of 4 ml/s, followed by a 20 ml saline flush. The diagnostic scan is automatically triggered when enhancement in the monitoring region of interest (ROI) reaches a threshold of 100 HU, with a fixed transit delay time (TDT) of 5 seconds.

Group A: PT-ROI, 50 ml (Control); Group B: PT-ROI, 30 ml; Group C: SVC-ROI, 50 ml; Group D: SVC-ROI, 30 ml

Eligibility Criteria

• Age: 18 Years - 90 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• All patients scheduled for a Computed Tomography Pulmonary Angiography (CTPA) examination.
• Provision of written informed consent by the subject, guardian, or medical specialist.
• Patients with an upper extremity intravenous (IV) line using a 16-20 gauge cannula.
• Patients with a stable heart rate between 60 and 120 beats per minute (bpm).

You may not qualify if:

• Pregnancy, breastfeeding, or use of non-reliable methods of contraception.
• Patients with impaired renal function, including acute kidney injury or chronic kidney disease (CKD) with an eGFR less than 30 mL/min/1.73m².
• Patients with a lower extremity IV line, as this bypasses the Superior Vena Cava (SVC) and results in bolus tracking technique failure.
• Patients with a heart rate lower than 60 bpm or higher than 120 bpm.
• Patients with a cannula size of 22g or smaller, as it cannot accommodate the high flow rate (4 mL/s) required by the power injector.
• Patients with severe cardiac impairment or congenital heart disease.
• Patients with a Body Mass Index (BMI) exceeding 35 kg/m², as severe obesity causes beam hardening effects that degrade image quality.

Sponsors & Collaborators

• Hospital Queen Elizabeth, Malaysia: lead
• Universiti Sultan Zainal Abidin: collaborator

Study Sites (1)

Hospital Queen Elizabeth

Kota Kinabalu, Sabah, 88200, Malaysia

Location

MeSH Terms

Conditions

Pulmonary Embolism

Condition Hierarchy (Ancestors)

Lung Diseases; Respiratory Tract Diseases; Embolism; Embolism and Thrombosis; Vascular Diseases; Cardiovascular Diseases

Study Officials

• Kamarul Amin. bin Abdullah @ Abu Bakar., Assoc. Prof. Ts. Dr.

  Universiti Sultan Zainal Abidin (UniSZA)

  STUDY CHAIR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Masking Details: Three senior radiologists served as blinded outcomes assessors for this study. These assessors were blinded to all protocol details, including the anatomical location of the bolus-tracking region of interest (ROI) and the volume of contrast media administered for each participant. The CTPA images were anonymized and presented to the assessors in a randomized order to ensure objective qualitative evaluation of image quality using the 5-point Likert scale.
• Purpose: DIAGNOSTIC
• Intervention Model: PARALLEL
• Sponsor Type: OTHER GOV
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Diagnostic Radiographer

Model Details: This study uses a four-arm parallel assignment to compare two primary factors: the anatomical location of the bolus-tracking region of interest (ROI) and the volume of contrast media administered. Participants are randomized into one of four distinct protocol groups (Groups A, B, C, or D) to evaluate image quality and opacification differences across the various combinations of ROI placement (Pulmonary Trunk vs. Superior Vena Cava) and contrast volume (50 ml vs. 30 ml).

Study Record Dates

• First Submitted: January 8, 2026
• First Posted: January 15, 2026
• Study Start: February 1, 2023
• Primary Completion: December 16, 2024
• Study Completion: December 16, 2024
• Last Updated: January 15, 2026

Record last verified: 2026-01

Data Sharing

• IPD Sharing: Will not share

Locations

MY (1)