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)
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 发起方
- 入组人数
- 72
- 试验地点
- 1
- 主要终点
- Mean Difference in Hounsfield Unit (HU) Attenuation Between Pulmonary Artery and Pulmonary Vein
研究概览
简要总结
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.
详细描述
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:
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Diagnostic
- 盲法
- Single (Outcomes Assessor)
盲法说明
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.
入排标准
- 年龄范围
- 18 Years 至 90 Years（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •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).
排除标准
- •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.
结局指标
主要结局
Mean Difference in Hounsfield Unit (HU) Attenuation Between Pulmonary Artery and Pulmonary Vein
时间窗: 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.
次要结局
- Qualitative Image Quality Score using a 5-point Likert Scale(Within 1 month following the CTPA scan.)
研究者
MOHD ARI-NADZAHARI BIN ABD RAHMAN
Diagnostic Radiographer
Hospital Queen Elizabeth, Malaysia