Reproducibility of CT Signs of Right Ventricular Dysfunction in Acute Pulmonary Embolism

Abstract

Contrast medium-enhanced pulmonary CT angiography (CTA) is increasingly used as the first-line imaging test in suspected PE and is available 24 hours a day at most institutions [10][11][12][13][14]. Pulmonary CTA not only allows direct visualization of emboli but provides information regarding the status of the right heart [15,16]. In several studies, the ratio of the RV to left ventricle (LV) diameters on pulmonary CTA has been proposed as a sign for RV dysfunction [17][18][19]. Other signs have been described, including bowing of the interventricular septum and reflux of contrast medium into the inferior vena cava (IVC) [20,21]. However, a variety of different methods for the quantitative assessment of RV dysfunction on pulmonary CTA have been proposed [17][18][19][20][21][22][23][24] and the literature shows variable results for the prognostic power of pulmonary CTA signs of RV dysfunction to predict adverse outcomes. This variability may in part be explained by the somewhat subjective nature of diagnosing RV dysfunction on pulmonary CTA because formal criteria for es- AJR 2010; 194:1500-1506 0361-803X/10/1946-1500 © American Roentgen Ray Society A cute pulmonary embolism (PE) is a common disease with a 3-month mortality rate of up to 17.4% [1][2][3][4]. Even if PE is properly treated with anticoagulation, the mortality rate in hemodynamically stable patients varies from 8.1% to 15.1% [4,5]. Death is usually caused by acute right heart failure [4][5][6][7][8][9]. Acute PE increases the pressure of the pulmonary arterial system and right ventricle (RV) resulting in RV dysfunction, which may progress to right heart failure and circulatory collapse [5,6]. Patients with RV dysfunction have a higher mortality rate than those without, even if they are initially hemodynamically stable [6,7]. Thus, the presence of RV dysfunction is a marker for adverse clinical outcome in patients with acute PE [6][7][8]. Echocardiography is the most common first-line examination to diagnose the signs of RV dysfunction [6][7][8][9]. However, this test has limited off-hour availability at many institutions, and occasionally the RV may be difficult to image with the trans thoracic approach. OBJECTIVE. The purpose of our study was to determine the interobserver reproducibility of CT findings of right ventricular (RV) dysfunction in pulmonary embolism (PE). Reproducibility of CT C a r d io p u lm o n a r y I m ag i ng • O r ig i n a l R e s e a rc hMATERIALS AND METHODS. Two experienced observers independently and retrospectively evaluated pulmonary CT angiography (CTA) studies of 50 patients with acute PE for the following signs: bowing of the interventricular septum, inferior vena cava (IVC) contrast medium reflux, RV diameter (RVD)/left ventricular diameter (LVD) ratio on axial sections and four-chamber (4-CH) views, and RV volume (RVV)/left ventricular volume (LVV) ratio. Analysis used kappa statistics, Spearman's rank correlation, and Bland-Altman statistics.RESULTS. The two observers had fair to moderate agreement (κ = 0.32-0.44)...

Usefulness of Combined Assessment With Computed Tomographic Signs of Right Ventricular Dysfunction and Cardiac Troponin T for Risk Stratification of Acute Pulmonary Embolism

“…However, this study was focused on the incremental value of combined assessment rather than comparisons between CT signs. Moreover, 2 previous studies reported that the volumetric assessment of ventricles showed higher interobserver agreement 4 and seemed to be superior for the identification of high-risk patients with adverse clinical outcomes. 5 …”

The role of computed tomography in the diagnosis of acute and chronic pulmonary embolism

“…Non-ECG-gated volumetric analysis seems to be slightly superior to identify high-risk patients with adverse clinical outcome compared to RV/LV diameter ratio measurements (71,74). Furthermore, axial and four-chamber view measurements of RV/LV diameter ratio have shown considerable interobserver variability, while volumetric measurements have shown better reproducibility (71). In another study of 60 patients, a RV/LV volumetric ratio >1.28 measured in non-ECG-gated CTPA showed 89% sensitivity, 75% specificity, 42% PPV and 97% NPV to predict adverse clinical outcome (74).…”

“…A RV/LV diameter ratio cutoff value of >1.0 is commonly considered to represent RV dysfunction and has been shown to predict short-term adverse outcome and mortality (10,71,72). Axial and four-chamber view measurements of RV/LV diameter ratio >1.0 are comparable for predicting 30-day mortality (10,73).…”

“…It has been suggested that volumetric measurements, obtained with or without ECG-gating may be more useful as a marker for RV dysfunction in patients with acute PE (69,71). In a study with 260 PE patients, a RV/LV volume ratio >1.2 resulted in a six-fold increased risk for 30-day mortality, while 97.8% survived with a ratio <1.2 (71).…”

“…In a study with 260 PE patients, a RV/LV volume ratio >1.2 resulted in a six-fold increased risk for 30-day mortality, while 97.8% survived with a ratio <1.2 (71). Non-ECG-gated volumetric analysis seems to be slightly superior to identify high-risk patients with adverse clinical outcome compared to RV/LV diameter ratio measurements (71,74). Furthermore, axial and four-chamber view measurements of RV/LV diameter ratio have shown considerable interobserver variability, while volumetric measurements have shown better reproducibility (71).…”