Pulmonary Arterial Obstruction Index Research Articles

Optional therapeutic management of intermediate-risk pulmonary embolism patients

Background: Few studies have evaluated the thrombolytic treatment in patients with intermediate-high risk pulmonary embolism, making this study more valuable. Material and methods: It was a prospective, non-randomized, open-label, single-center study. Eligible patients at the age of 18 or older with an acute pulmonary embolism (PE) confirmed by CT pulmonary angiography with onset until 14 day and signs of right ventricular (RV) overload on echocardiography took part in the study. Pulmonary Arterial CT Obstruction Index Rate (PACTOIR) was used to define the localization and the expansion zone of thromboembolism. This study included 18 patients with intermediate risk and acute submassive pulmonary thromboembolism. In thrombolysis (TT) group (n=9) were used 50 mg of tissue-plasminogen activator (t-PA) administered in infusion as 0.4 mg/h for 2 hours. In the standard anticoagulation group, unfractioned heparin (UFH) was administered as a bolus of 70 units/kg or a maximum of 5000 units, followed by continuous infusion at an initial rate of 16 units/kg or a maximum of 1000 units/h. Results: The mean age for TT group was 69 vs 63 for the UFH group. PACTOIR was 100% in 3 patients in the half-dose rt-PA group and in 2 patients in the UFH group. RV/LV diameter ratio decreased from baseline to 48 h post-procedure (1.55 vs. 1.13; mean difference, -0.42; p < 0.0001). Mean pulmonary artery systolic pressure was 55 mm Hg in both groups (p < 0.05), with 53 [43–60] in TT group vs. 41.5 [37–45] mmHg in UFH group, P<0.05. Also, RV/ LV ratio and systolic PAP decreased significantly in both groups. Severe bleeding with a need in red blood cell transfusion was seen in 0.11% (1 patient) in the TT group vs 0 in UFH group. The hospitalization length of stay was significantly shorter in the TT group (3.8±1.8, p < 0.05). The rate of secondary endpoints was significantly higher in the UFH group with a high rate of pulmonary hypertension (0 vs. 19%, p=0.003). Conclusions: Half-dose thrombolytic therapy in patients diagnosed with submassive pulmonary embolism significantly reduced death and hemodynamic decompensation in the first 7 days compared to anticoagulant therapy only. With all that being said, it can be concluded that patients with high-intermediate risk PE could benefit from reduced-dose TT.

Correlation of qanadli obstruction index (QOI) and atrial size on CT pulmonary angiography (CTPA) in patients with pulmonary thromboembolism

BackgroundPulmonary thromboembolism (PTE) is a potentially fatal and life-threatening variation of venous thromboembolism (Faghihi Langroudi et al. in Radiol Res Pract 2:1–6, 2019). Computed Tomography Pulmonary Angiography (CTPA) has been proven to be an invaluable first-line diagnostic tool in the early identification of pulmonary thromboembolism (Aviram et al. J Thromb Haemost 9(2):293–299, 2011; Ghaye et al. in RadioGraphics. 26 1 23 39, 2006). Preliminary studies have suggested the correlation between atrial size and clot burden in the pulmonary arteries in patients with pulmonary thromboembolism (Faghihi Langroudi et al. in Radiol Res Pract 2:1–6, 2019; Aviram et al. J Thromb Haemost 9(2):293–299, 2011). Clot burden is calculated by applying the CTPA dependent score—Qanadli Obstruction Index (QOI)/Pulmonary Arterial Obstruction Index (PAOI) in the pulmonary arteries.ResultsThere was a significant negative correlation between left atrial/right atrial area, left atrial/right atrial short axis and left atrial/right atrial long axis with the PAOI, especially the left atrial/right atrial area ratio and left atrial/right atrial short axis ratio, which showed the most significant negative correlation. Additionally, an LA/RA area of ≤ 0.60 correlated with a PAOI of > 20 and an obstruction percentage of > 50%, which can serve as a predictor of right ventricular dysfunction.ConclusionsThese atrial dimensions can serve as additional early parameters that reflect changes in the cardiac morphology in response to the clot load within the pulmonary arteries, and can thus contribute towards a more comprehensive risk assessment in patients with acute pulmonary thrombo-embolism.

Association between pulmonary arterial obstruction index and right lateral ventricular wall thickness with in-hospital mortality in patients with acute pulmonary embolism.

To retrospectively assess the correlation between pulmonary arterial obstruction index (PAOI) and right lateral ventricular wall thickness with in-hospital mortality in patients with acute pulmonary embolism. CT angiography (CTA) of 55 consecutive patients (30 males; 25 females; mean age ± SD, 59 ± 11years) with proven acute pulmonary embolism was investigated. PAOI was determined according to the Qanadli score on CTA. Right ventricular lateral wall thickness was also measured, and patients' in-hospital mortality was recorded. The correlation between PAOI and mortality, right ventricular lateral wall thickness and mortality, and PAOI and right ventricular lateral wall thickness was evaluated. PAOI was 23.6 and 10.4 in patients with and without in-hospital mortality, respectively (P < 0.001). Right ventricular lateral wall thickness was 8.7mm and 7.5mm in patients with and without in-hospital mortality, respectively (P < 0.001). PAOI more than 21.5 and right ventricular lateral wall thickness more than 8.75 were predictive of in-hospital mortality with a high accuracy. Also, PAOI and right ventricular lateral wall thickness had a significant correlation with each other (P < 0.001; r = 0.695). PAOI and right ventricular lateral wall thickness on CTA were highly predictive of in-hospital mortality in patients with pulmonary embolism. Right ventricular lateral wall thickness and PAOI had a significant correlation with each other as well.

The relationship between computed tomographic obstruction index and pulmonary vein cross-sectional area in acute pulmonary embolism.

To investigate whether the increased obstruction of the pulmonary arteries was associated with reduced pulmonary vein areas in acute pulmonary embolism (APE). We retrospectively analyzed a consecutive series of computed tomography pulmonary angiography studies of 107 patients with APE and 101 controls without APE between November 2010 and January 2019. The control and patient groups were compared with each other for differences between the mean cross-sectional areas of pulmonary veins. Further analysis was conducted by dividing the patient group into high-risk patients (≥ 20%) and low-risk patients (< 20%) according to the pulmonary arterial obstruction index. The mean cross-sectional area of the pulmonary veins in these two groups was compared. The mean cross-sectional areas of the 4 pulmonary veins at the ostium level (CSAPV) were significantly lower for the patient group (mean: 102.6 mm2) compared with the control group (111.8 mm2) (p < 0.001). CSAPV cutoff value for determining the diagnosis of APE that maximized the accuracy was 109.12 mm2 (AUC = 0.721; 95% CI 0.649-0.794); its sensitivity and specificity were 78.2% and 69.2%, respectively. CSAPV cutoff value for differentiating high-risk APE that maximized the accuracy was 102.6 mm2 (AUC = 0.634; 95% CI 0.525-0.743); its sensitivity and specificity were 61.9% and 53.8%, respectively. There is a negative correlation between the CSAPV and thrombotic material burden in the pulmonary arteries of patients with APE. Hence, the CSAPV can be used as a diagnostic tool in the evaluation of the presence and severity of pulmonary embolism.

Correlation of Hematologic Indices with CT-pulmonary Arterial Obstruction Index in Patients with Acute Pulmonary Emboli

Introduction: Acute Pulmonary thromboembolism (PTE) is an imperative medical condition with a considerable global impact. Inflammation is deemed to take a notable part in the pathophysiology of this potentially fatal disorder. The aim of the current study was to predict acute PTE severity in helical pulmonary CT-angiography using easily accessible hematological complete blood count (CBC) indices.Methods: After exclusion of inflammatory conditions that may affect CBC parameters, a total of 69 consecutive patients with definite diagnosis of acute PTE according to pulmonary helical CT –angiography were recruited. Laboratory tests, including CBC parameters were performed on admission in the emergency unit, before initiation of any therapy. Neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR) and RDW to platelet ratio (RPR) were calculated in each case of acute PTE. Ultimately, CT pulmonary arterial obstruction index (PAOI) was assessed subsequent to pulmonary helical CT-angiography for each patient.Results: We found that NLR is positively correlated with acute PTE severity according to CT pulmonary arterial obstruction index (PAOI) (P &lt; 0.01, r = 0.56); however, PLR, RDW and RPR did not appear to show such correlations (P &gt; 0.05).Conclusions: NLR could be an easily calculated and capable index to predict severity of acute PTE in pulmonary CT-angiography. Consequently, NLR might be used in precise risk stratification when suspicious for acute PTE and in accurately triage of patients who would benefit greatly from urgent diagnostic and therapeutic interventions.

The Association between the Pulmonary Arterial Obstruction Index and Atrial Size in Patients with Acute Pulmonary Embolism.

Purpose Pulmonary embolism (PE) is a common and potentially fatal form of venous thromboembolism. The aim of this study is to investigate the association between the pulmonary arterial obstruction index and atrial size in patients with acute pulmonary embolism. Basic Procedure The study consisted of 86 patients with clinical symptoms of PE. Out of 86 individuals, 50 patients were diagnosed with PE and considered as the patient group. The others were considered as the control group. All patients were scanned by a multidetector CT scanner. Using the radiology workstation, an expert radiologist calculated the left atrium (LA) and right atrium (RA) areas from planimetric measurements obtained from free-hand delineation of the atrial boarders using an electronic pen. Quantitative volumetric measurements of LA and RA were obtained from original axial images. Main Findings There were 25 males and 25 females with PE, who had a mean age of 58 years. There was not a significant difference in the positive history of diabetes mellitus, hypertension, asthma, chronic obstructive pulmonary diseases, ischemic heart disease, and smoking between patients and control group. There was a significant negative correlation between almost all LA measurements and the PAOI. RA area and volume had the highest area under the curves for recognizing larger clot burden. Principal Conclusions A higher clot load is associated with a smaller LA size and increased RA/LA ratios, measured with CTPA. Atrial measurements are correlated with POAI, and they could be used as sensitive parameters in predicting heart failure in patients with PE.

D-Dimer Predicts Disease Severity but Not Long-Term Prognosis in Acute Pulmonary Embolism.

D-dimer might be correlated with prognosis in pulmonary embolism (PE). The predictive value of plasma D-dimer for disease severity and survival was investigated in the lowest and highest D-dimer quartile among 200 patients with PE. Patients with high D-dimers were significantly more often hypotensive (P = .001), tachycardic (P = .016), or hypoxemic (P = .001). Pulmonary arterial obstruction index (PAOI) values were significantly higher in the high D-dimer quartile (P < .001). Elevated troponin I (TNI) levels (P < .001), simplified PE severity indices ≥1 (P < .001), right-to-left ventricular (RV/LV) diameter ratios ≥1 (P < .001), and thrombolysis (P = .001) were more frequent in the high D-dimer quartile. D-dimer was associated with RV/LV ratios ≥1 (P = .021), elevated PAOI (P < .001) or TNI levels (P < .001), hypotension (P < .001), tachycardia (P = .003), and hypoxemia (P < .001), but not with long-term all-cause mortality. D-dimer predicts disease severity but not long-term prognosis in acute PE, possibly due to a more aggressive treatment strategy in severely affected patients.

Can Pulmonary Arterial CT Obstruction Index Rate Predict Right Ventricular Dilatation in Pulmonary Thromboembolism?

Can Pulmonary Arterial CT Obstruction Index Rate Predict Right Ventricular Dilatation in Pulmonary Thromboembolism?

Quantification of Pulmonary Thromboembolism in CT Angiography Reports and Predicting Right Ventricular Dysfunction and Patient Mortality

: Recently, attempts have been made to quantify the clot burden on the basis of CT angiographic findings. The development of clot burden index [pulmonary arterial obstruction index (PAOI)] may have important prognostic and therapeutic implications and may provide a reproducible standard for measuring response to thrombolytic therapy. The presence of right ventricular dysfunction (RVD) is a marker for adverse clinical outcome in patients with acute pulmonary embolism (PE). The ratio of the right ventricle to left ventricle short axis diameters (RV/LV) has been proposed as an accurate sign for the presence of RVD. Other studies suggested that the quantification of a clot at pulmonary computed tomography (CT) angiography is an important predictor of right heart failure and patients' outcome in the setting of PE. In this study, we assess the measurement of PAOI and RV/LV ratio in pulmonary CT angiography and discuss the significant correlations between them. Patients and Methods: The study population comprised 42 patients (19 women, 23 men; mean age, 52 + 18 years) with the definite diagnosis of PE based on their pulmonary CT angiography. The CT angiographies of patients were reviewed, and PAOI and RV/LV ratio were measured. PAOI was calculated from the size of embolus and the location of thrombus on CT images in accordance with another study by Qanadli et al. The index was defined as the product of N x D, where N was the value of the proximal clot site, equal to the number of segmental bronchial branches, and D was the degree of obstruction, defined as 1 for partial obstruction and 2 for total obstruction. Furthermore, the scans were evaluated by measuring the minor axes of the right and left ventricles of the heart in the transverse plane at their widest points between the inner surface of the free wall and interventricular septum. By using logistic regression, PAOIs were compared with RV/LV ratio. Correlation between PAOI and RV/LV ratio was evaluated by Spearman correlation test, and receiver operating characteristic (ROC) curve was used to determine an optimal cut-off value for PAOI. : Results: In our study group, mean PAOI was 24.3 + 19.2%. Nine cases (21.4%) had a PAOI of more than 40%. The mean RV/LV ratio was 1.03 + 0.25; eighteen patients (43%) had an RV/LV ratio of more than 1; twenty-four patients (57%) had an RV/LV ratio of less than 1. There was a statistically significant correlation between PAOI and RV/LV ratio (P = 0.007; r = 0.4). The mean PAOI of patients with RV/LV ratio of >1 was significantly higher than that of patients with RV/LV ratio of ? 1 (32.6% vs. 18.1%; P = 0.02). However, based on ROC analysis, an ideal cut-off value for PAOI could not be defined. Also, there was no significant difference in PAOIs between different age (P > 0.05) and sex (P > 0.05) groups. Conclusion: Our findings were in agreement with those of Wu et al. and suggested that the quantification of a clot at CT pulmonary angiography is an important predictor of right heart failure and determines patients' outcome in the setting of PE. There was a significant correlation between PAOI and RV/LV ratio in PE. However, there was no ideal PAOI cut-off value for the diagnosis of right ventricular dysfunction (RV/LV ratio > 1). Further studies with a larger study population may be necessary to generalize our findings and to suggest a sensitive and specific cut-off point for ventricular dysfunction in patients with PE. The prognostic role of RV/LV ratio and obstruction index on spiral CT may also warrant further investigation in patients with PE.

Can platelet indices predict obstruction level of pulmonary vascular bed in patients with acute pulmonary embolism?

Computed tomography pulmonary arterial obstruction index ratio (CTPAOIR) is related with the severity of pulmonary embolism (PE). Platelet indices including mean platelet volume (MPV), platelet distribution width (PDW) are reported to be increased in acute PE. In this study, we aimed to evaluate the relationship between CTPAOIR and platelet indices and the utility of these parameters in the determination of PE severity. We retrospectively analysed the demographic data, clinical probability scores, laboratory data and echocardiographic findings of 63 acute PE patients who were diagnosed by pulmonary arterial computed tomography angiography. The hospital records of 38 (60.3%) male and 25 (39.7%) female patients with acute PE and 29 (58%) male and 21 (42%) female healthy control were evaluated (P = 0.803). The mean value of MPV, PDW levels, platelet counts and red cell distribution width levels were higher in PE groups than in control subjects (P < 0.05). Massive PE was present in 33.3% of PE patients. There were statistically significant differences in terms of hospital length of stay (HLS), mean value of MPV, CTPAOIR and systolic pulmonary arterial pressure (sPAP) in addition to systolic arterial pressure between massive and submassive PE patients (P < 0.05 for all). CTPAOIR was positively correlated with HLS, clinical probability scores, D-Dimer level, MPV, PDW levels and sPAP. Platelet indices, MPV and PDW, can be used for the determination of disease severity, and lead to therapeutic strategies for PE patients.

Can we use CT pulmonary angiography as an alternative to echocardiography in determining right ventricular dysfunction and its severity in patients with acute pulmonary thromboembolism?

Our aim was to investigate the role of computed tomography pulmonary angiography (CTPA) in the diagnosis of right ventricular dysfunction (RVD) and massive pulmonary thromboembolism (PTE). We retrospectively involved a total of 61 patients. In CTPAs, pulmonary arterial obstruction index (PAOI), right ventricular/left ventricular diameter ratio (RV/LV), and superior vena cava (SVC) diameters were calculated, followed by echocardiography (ECHO), and clinical results were evaluated based on the reports available. CTPA findings that included PAOI, RV/LV ratio, and SVC diameter were, respectively, 54.9 ± 22.7 %, 1.58 ± 0.51, and 20.3 ± 0.2 mm in patients with RVD on ECHO, whereas corresponding values were, respectively, 37.8 ± 24.2 %, 1.32 ± 0.47, and 18.4 ± 3.3 mm in those without RVD (respectively, p = 0.006, p = 0.038, and p = 0.026). PAOI was 63.3 ± 22.0 % in patients among whom massive PTE was detected and 43.1 ± 23.9 % in the group without massive PTE (p = 0.01). As for mortality; given an RV/LV ratio >1.0, this ratio had 100 % sensitivity and 35.6 % specificity, whereas given a PAOI of ≥50 %, sensitivity and specificity were 83.3 % and 57.8 %, respectively. We concluded that in the patients with PTE, PAOI ≥50 % and RV/LV >1.0 in CTPA could be helpful to demonstrate RVD.

Automated volumetric analysis of four cardiac chambers in pulmonary embolism

Identification of patients with acute pulmonary embolism (PE) who might be at risk of circulatory collapse by using a fast, automated system is highly desired. It was our objective to investigate whether automated cardiac volumetric analysis following computerised tomographic pulmonary angiography (CTPA) is useful to identify increased clot load and adverse prognosis in patients with acute PE. We retrospectively analysed a consecutive series of non-gated CTPA studies of 124 patients with acute PE and 43 controls. Right and left ventricular diameters (RV/LV) were measured on four-chamber view, while each cardiac chamber underwent automatic volumetric measurements. Findings were correlated to the pulmonary arterial obstruction index (PAOI). Outcome was expressed by admission to an intensive care unit (ICU) or mortality within 30 days. There was a significant positive correlation between the PAOI and the volumes of the right side cavities (r=0.25 for the atrium and r=0.49 for the ventricle), and between the right-to-left atrial and ventricular volume ratios (r=0.49 and r=0.57, respectively). Results for the combined outcome of mortality or ICU admission that fell in the upper tertile of the right atrial and right ventricular volumes yielded hazard ratios of 3.9 and 3.3, respectively, compared to those in the lower tertile. RV/LV diameter ratio did not correlate with outcome. In conclusion, adverse outcome and significant pulmonary clot load in patients with acute PE are associated with a volume shift towards right heart cavities, which correlates to prognosis better than the CT-measured RV/LV diameter ratio, suggesting the advantage of using fast fully automatic volumetric analysis to identify patients at risk.

The association between the embolic load and atrial size in acute pulmonary embolism

Early identification by computed tomography pulmonary angiography (CTPA) of patients with acute pulmonary embolism (PE) who have signs associated with a high embolic burden would be highly desirable. To investigate whether an increased obstruction of the pulmonary vasculature is associated with reduced left atrial (LA) and increased right atrial (RA) areas. We retrospectively analyzed a consecutive series of CTPA studies of 137 patients with acute PE and 38 controls without PE between October 2004 and March 2006. Left and right atrial areas and longitudinal and short axis diameters were measured and correlated with the pulmonary arterial obstruction index (PAOI) divided into tertiles (obstruction of < 12.5%, 12.5%-42.5% and ≥ 42.5%). There was a significant negative age- and gender-adjusted correlation between the PAOI and LA measurements, particularly the LA area (r = -0.259) and the LA short axis diameter (r = -0.331). All RA measurements had positive correlations (RA area, r = 0.279; RA short axis diameter, r = 0.313). The LA/RA area ratio correlated negatively with the PAOI (r = -0.447). All above-mentioned correlations had P < 0.002. All the LA measurements were the largest in the controls and gradually decreased with higher PAOIs. A receiver operating characteristic curve analysis demonstrated that the RV/LV diameter, LA/RA area and LA/RA short axis diameter ratios had comparable discriminative ability for higher PAOI tertiles. The higher the clot load in the pulmonary arteries, the smaller the LA area and the larger the RA area. Atrial area measurements by CTPA may serve as a real-time parameter in assessing the severity of PE upon diagnosis.

Investigation of relationship between the D-dimer and ischemia-modified albumin levels with the radiological imaging-based pulmonary embolism severity score in acute pulmonary embolism

To investigate possible relationship between the D-dimer and ischemia-modified albumin (IMA) levels and radiological imaging-based severity scores in pulmonary embolism (PE) based on two different radiological characteristics; the pulmonary arterial obstruction index (PAOI) and the right ventricle/left ventricle (RV/LV) ratio. In this prospective cohort study, forty-seven patients presenting to the emergency department and definitively diagnosed with PE using spiral computerized tomography (CT) were initially enrolled in the study. Levels of IMA and D-dimer were assessed colorimetrical and immuno-turbidimetric methods, respectively. The PAOI and RV/LV ratios were calculated from CT images. The levels of biochemical parameters between the groups were compared with use of Mann-Whitney U and Kruskal-Wallis tests and relationship between the radiological scores were assessed using the Spearman correlation test. Analysis of the calculated PAOI and RV/LV ratio revealed a significant correlation between them (r=0.36, p=0.023). D-dimer levels differed considerably among the mild (=40%), moderate (40%-60%) and severe (60%) groups constituted on the basis of PAOI (p=0.039). This difference stemmed from those in D-dimer levels in the mild group, PAOI =40 % and the severe group, PAOI 60% (p=0.02; Z= -2.328). In addition, D-dimer levels and PAOI revealed a positive correlation, but no similar correlation was determined between D-dimer levels and RV/LV. There were no significant correlations between IMA and D-dimer levels, PAOI and RV/LV ratios. In the biochemical determination of severity of PE based on radiological characteristics, D-dimer may be a more relevant marker than IMA, which has been proposed as a new marker.

Suspected and incidental pulmonary embolism on multidetector-row CT: Analysis of technical and morphological factors influencing the diagnosis in a cross-sectional cancer centre patient cohort

To assess technical and computed tomography (CT) predictors of true-positive (TP) and false-negative (FN) radiological diagnoses in a retrospective patient cohort with pulmonary embolism (PE) in the setting of a cancer centre. Two thousand, four hundred and twelve consecutive chest multidetector-row CT images from 1869 patients were reviewed for presence of PE. CT protocols and TP and FN radiological reports were determined and the clinical files reviewed for suspicion of PE. The severity of PE was assessed by an arterial obstruction index. Ancillary pulmonary findings were scored qualitatively and on a lobar basis. Statistical tests included analysis of variance and univariate and multivariate logistic regressions. Ninety-one out of a total of 111 PE-positive images were included. Thirty-five patients had clinically suspected PE; 56 were not suspected of having PE. Forty-eight patients had TP diagnoses; 43 (39 of whom were not suspected of having PE) had FN radiological diagnoses. FN diagnoses were most frequent in oesophageal (17/19; 89.5%) and standard chest CT (19/35; 54.3%). Pulmonary CT angiography was associated with TP diagnosis (p<0.0001), whereas oesophageal CT was associated with FN diagnosis (p=0.001). Artefacts and arterial attenuation did not influence PE detection (p=0.017 and 0.066 for artefacts and arterial attenuation, respectively). However, the arterial obstruction index strongly predicted PE diagnosis (p=0.001). This was confirmed on multivariate analysis (p=0.041, 0.027 and 0.020 for pulmonary CT angiography, oesophageal protocols and arterial obstruction index, respectively). When stratified for clinically unsuspected cases, the arterial obstruction index remained the only predictor of PE diagnosis (p=0.009). Predictors of PE diagnosis were PE severity and technical factors; the latter were linked to clinical suspicion of PE. Arterial enhancement appears unlikely to contribute to missed diagnoses, if judged adequate for diagnosis of PE, and ancillary chest findings are unlikely to improve embolus detection.

CT pulmonary angiography: quantification of pulmonary embolus as a predictor of patient outcome--initial experience.

To determine whether quantification of pulmonary embolus (PE) with computed tomographic (CT) pulmonary angiography by using a standardized index is a predictor of patient outcome. Multi-detector row CT was performed in 59 hospitalized patients (mean age, 61 years; age range, 22-89 years). PE was identified retrospectively by two radiologists who were blinded to patient outcome. A pulmonary arterial obstruction index was derived for each set of images on the basis of embolus size and location. By using logistic regression, PE indexes were compared with patient outcome-survival or death-to determine if there was a correlation between PE volume and survival. The PE index is a significant predictor of patient outcome (P =.002). One of 53 patients (1.9%) with an index of less than 60% died. Cause of death was end-stage malignancy. Five of six patients (83%) with an index of 60% and higher died. All five deaths were related to the presence of PE. The one survivor with a PE index higher than 60% received thrombolytic therapy. By using a cutoff of 60%, the PE index was used to identify 52 of 53 (98%) patients who survived and five of six (83%) patients who died. Preliminary evidence suggests that quantification of clot with CT pulmonary angiography is an important predictor of patient death in the setting of PE.