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An audit of the adequacy of contrast enhancement in CTPAs in a South African tertiary academic hospital setting
Poster Title: An audit of the adequacy of contrast enhancement in CTPAs in a South African tertiary academic hospital setting
Submitted on 30 Oct 2020
Author(s): Dr D.J. Basson, Dr H. Moodley
Affiliations: Department of Diagnostic Radiology, Charlotte Maxeke Johannesburg Academic Hospital; University of the Witwatersrand , Johannesburg, South Africa
This poster was presented at BIR Annual Congress 2020
Poster Views: 866
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Poster Information
Background: The primary imaging modality in diagnosing pulmonary embolism (PE), a common and life-threatening disease, is computed tomography pulmonary angiography (CTPA). Accurate diagnosis is imperative. Suboptimal contrast enhancement is the second most common cause of indeterminate CTPAs.
Objectives: Audit the adequacy of contrast enhancement of CTPAs at Charlotte Maxeke Johannesburg Academic Hospital (CMJAH), South Africa, using the Royal College of Radiologists guidelines (≤ 11% of studies with < 210 Hounsfield units). To determine if suboptimal enhancement is affected by size and site of IV cannula, flow rate, volume of contrast, contrast leakage and day shift versus after hours.
Method: Contrast enhancement was measured in all eligible CTPAs in a retrospective (December 2019) and prospective audit (January – March 2020). The protocol variables were collected prospectively from questionnaires completed by radiographers performing the studies.
Results: A total of 62 (retrospectively) and 130 patients (prospectively) were included with suboptimal contrast enhancement rates of 19% (n=12) and 21% (n=27) respectively. The majority of CTPAs were performed during the day 56% (n=73) with a 20G cannula 58% (n=76) in the forearm 34% (n=44) injecting 100ml contrast 41% (n=54) at 3ml/s 63% (n=82). The median flow rate (3ml/s) and contrast volume (80ml) were identical in both optimal and suboptimal groups, while the rest of the variables were not significantly different.
Conclusion: The rate of suboptimally enhanced CTPAs is too high, whilst the protocol variables did not have a significant influence on the rate of suboptimal enhancement. Further study is required to optimise the current scanning protocol.

Summary: Contrast enhancement in CTPA's were audited according to the Royal College of Radiology guidelines, in a South African academic hospital. We also examined whether flow rate, IV cannula site and size, contrast volume, time of day and presence of contrast leakage had an influence on the rate of suboptimal contrast enhancement. The rate of suboptimal contrast enhancement were too high, whilst the protocol variables did not significantly influence the rate of suboptimal enhancement.References: 1. Meaney T., Raudkivi U., McIntyre W. Detection of low-contrast lesions in computed body tomography: An experimental study of simulated lesions. Radiology. 1980;134(1):149-154.
2. Muller M., Beattie A. Adequate Contrast Enhancement of CT pulmonary angiograms [Internet]. 2013 [cited 9 September 2020] Available from:
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