Pulmonary Artery EmbolismNCT07342374
Repositioning the Bolus Tracking ROI to the Superior Vena Cava in CTPA Facilitates Contrast Volume Reduction
A study testing Optimized CTPA Protocol in people with Pulmonary Artery Embolism and Pulmonary Embolism (PE), run by Hospital Queen Elizabeth, Malaysia at 1 site in Malaysia.
Trial 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). Read more about this study
- Who is it for?
- Ages 18 to 90 years
- Conditions the study is for
- Pulmonary Artery Embolism, Pulmonary Embolism (PE)
- What is being tested?
- Optimized CTPA Protocol
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 72 participants
- Where
- 1 siteMalaysia
- Study dates
- 1 Feb 2023to 16 Dec 2024
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 90 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- 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).
Who cannot join
- 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.
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Optimising Bolus Tracking Technique by Repositioning the Region of Interest (ROI) at the Superior Vena Cava and Reducing Contrast Media Volume in Computed Tomography Pulmonary Angiography (CTPA)
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.
Read the detailed description
Background and Rationale: Computed Tomography Pulmonary Angiography (CTPA) is the gold standard for diagnosing pulmonary embolism (PE). However, standard bolus tracking (BT) protocols that place the monitoring region-of-interest (ROI) on the main pulmonary trunk (PT) often face challenges due to the system's inherent Transit Delay Time (TDT). This delay, typically 5 seconds, can cause the diagnostic scan window to overlap with the venous phase, leading to suboptimal arterial opacification and venous contamination. This study proposes repositioning the monitoring ROI upstream to the superior vena cava (SVC) to utilize the TDT as transit time for the bolus, thereby aligning the scan window with the peak arterial phase.
Study Objectives: The primary objective is to evaluate the effect of SVC ROI repositioning on diagnostic image quality while investigating the feasibility of reducing contrast media (CM) volume by 40% (from 50 ml to 30 ml).
Methodology: This is a single-center, prospective, randomized controlled trial involving 72 adult patients. Participants are randomized into four protocol groups:
Group A (Control): ROI at PT, 50 ml contrast media. Group B: ROI at PT, 30 ml contrast media. Group C: ROI at SVC, 50 ml contrast media. Group D: ROI at SVC, 30 ml contrast media.
Protocol Details:
- Contrast Administration: Non-ionic contrast medium (370 mgI/ml) is injected at a rate of 4 ml/s, followed by a 20 ml saline flush.
- Bolus Tracking: An elliptical ROI is placed either on the PT (above the carina) or SVC depending on the group assignment.
- Triggering: The diagnostic scan is automatically initiated when enhancement reaches a threshold of 100 HU. The TDT is set to a fixed 5 seconds.
- Assessment: Diagnostic quality is assessed quantitatively by calculating arterial-venous enhancement differences (HU) and qualitatively via a 5-point Likert scale by three blinded radiologists.
- Conditions
- Pulmonary Artery Embolism, Pulmonary Embolism (PE)
- Being tested
- Optimized CTPA Protocol
- Keywords
- Pulmonary Embolism, Computed Tomography Pulmonary Angiography, Contrast Media, Bolus Tracking, Superior Vena Cava, Image Quality, Low-volume Protocol
- Medical subject headings
- Pulmonary Embolism
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Optimized CTPA ProtocolDiagnostic 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.
| Study group | Role | What they receive |
|---|---|---|
| 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. Receives: 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. Receives: 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. Receives: 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. Receives: Diagnostic Test: Optimized CTPA Protocol |
What is being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: 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
Qualitative assessment of CTPA images performed by three blinded senior radiologists using a 5-point Likert scale (1 = Unacceptable, 2 = Sub-optimal, 3 = Acceptable, 4 = Good, 5 = Excellent). The score evaluates overall arterial enhancement, presence of artifacts, and diagnostic adequacy.
Measured: Within 1 month following the CTPA scan.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted15 Jan 2026
- Study start1 Feb 2023
- Primary completion16 Dec 2024
- Study completion16 Dec 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Pulmonary Artery EmbolismStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Diagnosis
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- 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).
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 72 participants (actual)
Sponsor and investigators
- Lead sponsor
- Hospital Queen Elizabeth, Malaysia
- Sponsor type
- Other government
- Collaborators
- Universiti Sultan Zainal Abidin
- Responsible party
- Principal investigator, MOHD ARI-NADZAHARI BIN ABD RAHMAN, Hospital Queen Elizabeth, Malaysia
- Investigators
- Kamarul Amin. bin Abdullah @ Abu Bakar., Assoc. Prof. Ts. Dr., Study chair, Universiti Sultan Zainal Abidin (UniSZA)
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07342374
- Sponsor's protocol ID
- NMRR-20-699-54086 (IIR)
- Status last verified
- Jan 2026
- First submitted
- 8 Jan 2026
- Last updated
- 15 Jan 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Individual participant data will be kept strictly confidential in accordance with the hospital's privacy policies and the informed consent agreement. To protect participant privacy, only aggregated results and statistical data will be reported in publications.
Study at a glance
From the registry record, last updated by the sponsor on 15 Jan 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Optimising Bolus Tracking Technique by Repositioning the Region of Interest (ROI) at the Superior Vena Cava and Reducing Contrast Media Volume in Computed Tomography Pulmonary Angiography (CTPA)
- ClinicalTrials.gov ID
- NCT07342374
- Acronym / sponsor ID
- NMRR-20-699-54086 (IIR)
- 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
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 72 participants (actual)
- Lead sponsor
- Hospital Queen Elizabeth, MalaysiaOther government
- Collaborators
- Universiti Sultan Zainal Abidin
- Study start
- 1 Feb 2023 (actual)
- Primary completion
- 16 Dec 2024 (actual)
- Study completion
- 16 Dec 2024 (actual)
- First posted
- 15 Jan 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed description
Background and Rationale: Computed Tomography Pulmonary Angiography (CTPA) is the gold standard for diagnosing pulmonary embolism (PE). However, standard bolus tracking (BT) protocols that place the monitoring region-of-interest (ROI) on the main pulmonary trunk (PT) often face challenges due to the system's inherent Transit Delay Time (TDT). This delay, typically 5 seconds, can cause the diagnostic scan window to overlap with the venous phase, leading to suboptimal arterial opacification and venous contamination. This study proposes repositioning the monitoring ROI upstream to the superior vena cava (SVC) to utilize the TDT as transit time for the bolus, thereby aligning the scan window with the peak arterial phase.
Study Objectives: The primary objective is to evaluate the effect of SVC ROI repositioning on diagnostic image quality while investigating the feasibility of reducing contrast media (CM) volume by 40% (from 50 ml to 30 ml).
Methodology: This is a single-center, prospective, randomized controlled trial involving 72 adult patients. Participants are randomized into four protocol groups:
Group A (Control): ROI at PT, 50 ml contrast media. Group B: ROI at PT, 30 ml contrast media. Group C: ROI at SVC, 50 ml contrast media. Group D: ROI at SVC, 30 ml contrast media.
Protocol Details:
- Contrast Administration: Non-ionic contrast medium (370 mgI/ml) is injected at a rate of 4 ml/s, followed by a 20 ml saline flush.
- Bolus Tracking: An elliptical ROI is placed either on the PT (above the carina) or SVC depending on the group assignment.
- Triggering: The diagnostic scan is automatically initiated when enhancement reaches a threshold of 100 HU. The TDT is set to a fixed 5 seconds.
- Assessment: Diagnostic quality is assessed quantitatively by calculating arterial-venous enhancement differences (HU) and qualitatively via a 5-point Likert scale by three blinded radiologists.
Study design
- Primary purpose
- Diagnosis
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 4
- Model description
- 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).
| Arm | Type | Receives |
|---|---|---|
| Group A: PT-ROI, 50 ml (Control) | Active comparator | Diagnostic Test: Optimized CTPA ProtocolStandard 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. |
| Group B: PT-ROI, 30 ml | Experimental | Diagnostic Test: Optimized CTPA ProtocolModified CTPA protocol using the bolus tracking technique with the monitoring ROI at the pulmonary trunk (PT) and a reduced contrast volume of 30 ml. |
| Group C: SVC-ROI, 50 ml | Experimental | Diagnostic Test: Optimized CTPA ProtocolModified 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. |
| Group D: SVC-ROI, 30 ml | Experimental | Diagnostic Test: Optimized CTPA ProtocolModified 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. |
Who may qualify
- Ages
- 18 to 90 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- 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).
Key exclusion criteria (7 listed)
- 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.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Optimized CTPA ProtocolCTPA 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. | Diagnostic test | 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 |
Primary outcome
Mean Difference in Hounsfield Unit (HU) Attenuation Between Pulmonary Artery and Pulmonary Vein
Time frame: At the time of post-procedural image analysis (approximately 48 hours after CTPA scan completion).
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.
1 secondary outcome
Qualitative Image Quality Score using a 5-point Likert Scale
Time frame: Within 1 month following the CTPA scan.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 15 Jan 2026.
- Individual participant dataSharing planned: No. Individual participant data will be kept strictly confidential in accordance with the hospital's privacy policies and the informed consent agreement. To protect participant privacy, only aggregated results and statistical data will be reported in publications.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Kamarul Amin. bin Abdullah @ Abu Bakar., Assoc. Prof. Ts. Dr. study chair
Universiti Sultan Zainal Abidin (UniSZA)
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Optimized CTPA Protocol in people with Pulmonary Artery Embolism and Pulmonary Embolism (PE), run by Hospital Queen Elizabeth, Malaysia at 1 site in Malaysia.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 15 Jan 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Malaysia. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Mean Difference in Hounsfield Unit (HU) Attenuation Between Pulmonary Artery and Pulmonary Vein (time frame: At the time of post-procedural image analysis (approximately 48 hours after CTPA scan completion).). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 15 Jan 2026.