Abstract | INTRODUCTION: Computed tomography pulmonary angiogram ( CTPA) is widely considered the gold standard for diagnosis of pulmonary embolism (PE) with previous studies demonstrating high sensitivity and specificity. Despite this, nondiagnostic and indeterminate CTPA rates of 5%-26% remain a concern. As part of a continuing quality assurance program, a new weight-adjusted contrast dose and increased administration rate CTPA protocol was studied with an aim to improve diagnostic accuracy of PE evaluation. METHODS: A total of 2,398 CTPA examinations were reviewed to assess pulmonary arterial enhancement and PE yield in this retrospective study. Between 1 August 2014 and 1 August 2015, 1,133 patients received a fixed-volume (60 mL) contrast dose technique at 4 mL/s (protocol A). A new protocol was then implemented as part of a continuing quality assurance program. Between 15 September 2015 and 15 September 2016, 1,265 patients received a weight-adjusted contrast dose (1 mL/kg) and increased administration rate (5 mL/s) CTPA technique (protocol B). Studies were classed into categories based on quality of study; diagnostic: HU > 211, nondiagnostic: HU < 211 and PE yield; positive, negative, and indeterminate. These variables were compared with cross-sectional surface area to assess the relationship between patient habitus, CTPA diagnostic quality, and PE yield. RESULTS: A weight-adjusted contrast dose and increased administration rate CTPA protocol (protocol B) resulted in a significant increase in mean PA enhancement (P < .0001), 55.23% decrease in nondiagnostic studies and 43.04% decrease in indeterminate studies. Protocol B demonstrated increased positive and negative CTPA rates with decreased indeterminate rates from 12.38% to 7.04%. Comparison with cross-sectional area demonstrated significant increase in proportion of diagnostic studies and reduction in nondiagnostic and indeterminate CTPAs using protocol B in obese patients. CONCLUSIONS: A weight-adjusted contrast dose and increased administration rate CTPA protocol can significantly increase PA enhancement, especially in obese patients, resulting in greater high-quality and fewer nondiagnostic and indeterminate CTPA examinations. A CTPA protocol with a higher rate of conclusive examinations can provide greater confidence in PE evaluation for reporting radiologists and accurate clinical decision-making pathways for referring physicians.
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Authors | Prasanna J Ratnakanthan, Helen Kavnoudias, Eldho Paul, Warren J Clements |
Journal | Journal of medical imaging and radiation sciences
(J Med Imaging Radiat Sci)
Vol. 51
Issue 3
Pg. 451-461
(09 2020)
ISSN: 1876-7982 [Electronic] United States |
PMID | 32620525
(Publication Type: Journal Article)
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Copyright | Copyright © 2020. Published by Elsevier Inc. |
Chemical References |
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Topics |
- Adult
- Aged
- Body Weight
- Clinical Protocols
- Computed Tomography Angiography
(methods)
- Contrast Media
(administration & dosage)
- Female
- Humans
- Male
- Middle Aged
- Obesity
(complications)
- Pulmonary Embolism
(complications, diagnostic imaging)
- Radiographic Image Enhancement
- Retrospective Studies
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