Contrast Circulation Time to Assess Right Ventricular Dysfunction in Pulmonary Embolism: A Retrospective Pilot Study

Abstract

ObjectiveTo optimize enhancement of pulmonary arteries and facilitate diagnosis of pulmonary embolism (PE), modern computed tomography angiography (CTA) contains a contrast bolus tracking system. We explored the diagnostic accuracy of the time-intensity curves given by this automated system to identify right ventricular dysfunction (RVD) in acute PE.Methods114 CTAs with a diagnosis of PE were reviewed. RVD was defined as right-to-left ventricular diameter ratio of 1 or greater. Four parameters on time-intensity curves were identified. Parameters between CTAs with and those without RVD were compared with the Wilcoxon rank-sum test. The ability of the four parameters to discriminate patients with RVD was explored by compiling the area under the operating curves (AUC).ResultsThe time needed by the contrast media to reach the pulmonary artery [8 seconds (IQR: 7–9) versus 7 seconds (IQR: 6–8), p<0.01], the time needed to reach 40 Hounsfield units (HU) [11 seconds (IQR: 8.5–14) versus 9.5 seconds (IQR: 8–10.5), p<0.01], and the contrast intensity reached after 10 seconds [19 HU (IQR: 4–67) versus 53 HU (IQR: 32–80), p<0.05] were all statistically different between CTA with and CTA without RVD. Those three parameters changed gradually across severity categories of RVD (p<0.05 for trend). Their AUC to identify RVD ranged from 0.63 to 0.66. The slope of contrast intensity over time was not informative: [31 HU/s (IQR: 20–57) in CTA with, compared to 36 HU/s (IQR: 22.5–53) in CTA without RVD, p = 0.60].ConclusionSeveral parameters of the time-intensity curve obtained by the bolus tracking system are associated with RVD assessed on CTA images. Of those, the time needed to reach a predefined threshold seems to be the easiest to obtain in any CTA without additional processing time or contrast injection. However, the performance of those parameters is globally low.

The Prognostic Significance of Pulmonary CT Angiography in Predicting the Outcomes of Acute Pulmonary Thromboembolism

“…For example, in a study by Lin et al (15) on 71 patients with acute PE, both bolus curve upslope time > 6 seconds and 50% downslope time > 6 seconds predicted PE mortality. In line with our findings, John et al (26) concluded that variables which were related to the time-intensity curve were not accurate enough for identifying right ventricular dysfunction in 114 patients with PE. One possible explanation for this inconsistency is that the right ventricular dysfunction is more likely to occur in patients with central PE, in whom the main pulmonary vasculature becomes acutely obstructed (15).…”

Characterization of lung-to-finger circulation time in sleep study assessment: the Multi-Ethnic Study of Atherosclerosis

“…The Ct was first introduced as a clinical test to assess heart failure (HF) nearly a century ago (Blumgart and Weiss 1927, 1928, Blumgart 1931. While rarely being used in the current era, its core concept that the Ct is mainly influenced by cardiac output and central blood volume is still utilized in modern medicine particularly with advanced imaging techniques (Puskas and Schuierer 1996, Muller et al 2000, Shors et al 2003, Bae 2010, John et al 2016. Similar to intravenous dyes that have been used as indicators for Ct measurement in the past, O 2 can be used as an indicator allowing for Ct measurement in the presence of dynamic O 2 change (Wexler et al 1946, Kasravi et al 1998.…”