Automated volumetric analysis of four cardiac chambers in pulmonary embolism

Left atrium volume and ventricular volume ratio algorithm as indication of pulmonary hypertension etiology

BACKGROUND

Pressure overload of the right heart (pulmonary hypertension [PH]) can be an acute or a chronic process with various pathophysiologic changes affecting the dimensions of the heart chambers. The automatic four-chamber volumetric analysis tool is now available to measure the volume of the cardiac chambers in patients undergoing a computed tomography pulmonary angiogram (CTPA).

PURPOSE

To characterize the volumetric changes that occurred in response to increased systolic pulmonary arterial pressures (sPAP) in acute events, such as acute pulmonary embolism (APE), compared with other etiologies.

MATERIAL AND METHODS

Consecutive patients who underwent CTPA and echocardiography within 24 h between 2011 and 2015 were included. Differences in cardiac chamber volumes were investigated in correlation to the patients' sPAP.

RESULTS

The final cohort of 961 patients included 221 (23%) patients diagnosed with APE. The right (RV) to left (LV) ventricular volume ratio (VVR) was higher, while the left atrial (LA) volume index was smaller (P < 0.001) in the patients with APE. A decision tree for the prediction of APE showed that an RV to left VVR >2.8 was characteristic of APE, whereas an LA volume index >37.5 mL/m² was more compatible with PH due to other etiologies (P < 0.001).

CONCLUSION

The combination of VVR and LA volume index may help in differentiating between APE and chronic PH. CTPA-based volumetric information may be used to help clarify the underlying etiology of the dyspnea.

Optimized definition of right ventricular dysfunction on computed tomography for risk stratification of pulmonary embolism

OBJECTIVES

There is an ongoing discussion on the optimal right to left (RV/LV) diameter ratio threshold and the best definition of RV dysfunction on computed tomography pulmonary angiography (CTPA) for risk assessment of pulmonary embolism (PE).

METHODS

On routine diagnostic CTPA, volumetric and diameter measurements (axial and reconstructed views) of the ventricles and reflux of contrast medium into the inferior vena cava (IVC) and hepatic veins were assessed in consecutive PE patients enrolled in a prospective single-center registry. In-hospital adverse outcome was defined as PE-related death, cardiopulmonary resuscitation, mechanical ventilation or catecholamine administration.

RESULTS

Of 609 patients (median age, 69 [IQR, 56-77] years; 47 % male) included in the analysis, 68 patients (11.2 %) had an adverse outcome and 35 (5.7 %) died. While neither a RV/LV volume ratio ≥1.0 nor RV/LV diameter ratios ≥1.0 were able to predict an adverse outcome, higher thresholds increased specificity. Further, neither volumetric measurements nor reconstruction of images provided superior prognostic information compared to RV/LV ratios measured in axial planes. The combination of an axial RV/LV diameter ratio ≥1.5 with substantial reflux of contrast medium was present in 134 patients (22 %) and associated with the best prognostic performance to predict an adverse outcome in unselected (OR 3.7 [95 % CI, 2.0-6.6]) and normotensive (OR 2.8 [95 % CI, 1.1-6.7]) patients.

CONCLUSION

A new definition of RV dysfunction (axial RV/LV diameter ratio ≥1.5 and substantial reflux of contrast medium to the IVC and hepatic veins) allows an optimized CTPA-based prediction of PE-related adverse outcome.

Biatrial Volumetric Assessment by Non-ECG-Gated CT Pulmonary Angiography Correlated with Transthoracic Echocardiography in Patients with Normal Diastology

Atrial size is a predictor of cardiovascular mortality. Non-ECG-gated computed tomography pulmonary angiography (CTPA) is a common test for cardiopulmonary evaluation but normative values for biatrial volumes are lacking. We derived normal CT biatrial volumes using manual and semiautomated segmentation with contemporaneous transthoracic echocardiography (TTE) to confirm normal diastology. Thirty-five consecutive cases in sinus rhythm with no history of cardio-vascular, renal, or pulmonary disease and normal diastolic function were selected. Planimetric CTPA measurements were compared to TTE volumes measured using area length method. TTE and CTPA derived normal LAVi and RAVi were 27 + 5 and 20 + 6 mL/m², and 30 + 8 and 29 + 9 mL/m², respectively. Bland-Altman analysis revealed an underestimation of biatrial volumes by TTE. TTE-CT mean biases for LAV and RAV were -5.7 + 12.0 mL and -16.2 + 14.8 mL, respectively. The CT intraclass correlation coefficients (ICC 95% CI) for LA and RA volumes were 0.99 (0.96-1.00) and 0.96 (0.76-0.99), respectively. There was excellent correlation (p &lt; 0.001) between the semiautomated and manual measurements for LA (r 0.99, 95% CI 0.98-0.99) and RA (r 0.99, 95% CI 0.99-1.00). Atrial volumetric assessment on CTPA is easy and reproducible and can provide additional metric in cardiopulmonary assessment.

Left atrial size measured on CT pulmonary angiography: another parameter of pulmonary embolism severity? A systematic review

We systematically review the potential role of left atrial (LA) size, evaluated at computed tomography angiography (CTA) in patients with acute pulmonary embolism (PE), as a new parameter of PE severity. A literature search based on PubMed (MEDLINE), Scopus, Cochrane library and Google Scholar databases was performed to locate previous published investigations reporting data on the severity of acute PE based on the evaluation of LA size (either volume, diameter or area). Six studies, corresponding to a total of 990 patients, published between 2012 and 2019 were included into the analysis. The severity of acute PE, in terms of hemodynamic impairment, increases with the reduction of the LA volume and a significant negative correlation was observed between the pulmonary artery obstruction index (PAOI) and the LA area. Similarly, the longest left-to-right as well as the anteroposterior diameters of the LA had a significant positive correlation with the PAOI index for both the measurement. The LA volume significantly decreased with the increasing of the PAOI index. Moreover, a lower LA volume was observed in those subjects with a saddle PE appearing as the best single parameter able to discriminate between patients having or not a saddle acute PE. Intriguingly, PE patients died within 30 days from the acute event had a significant small LA volume compared to survivors. Data obtained from the current medical literature seem to suggest that the evaluation of LA size evaluation could be a new parameter of PE severity. Further and larger prospective studies are needed to confirm preliminary findings.

CTPA pulmonary artery distensibility in assessment of severity of acute pulmonary embolism and right ventricular function

To investigate the characteristics of pulmonary artery distensibility (PAD) in patients with acute pulmonary embolism (APE) and to assess the correlation of PAD with APE severity and right ventricular function. A total of 33 patients who underwent retrospective electrocardiogram (ECG)-gated computed tomography pulmonary angiography (CTPA) with a definite diagnosis of APE were included in the study. According to APE severity, the patients were divided into severe (SPE) and non-severe (NSPE) groups. Data from a control group without APE matching the basic demographics of the APE patients were collected. Pulmonary artery distensibility (PAD) and right ventricular function parameters were compared among the 3 groups, their relationships were investigated, and receiver operating characteristic (ROC) curves were used to determine the sensitivity and specificity of the above parameters for the diagnosis of APE severity. The PAD values of the control, NSPE, and SPE groups were (7.877 ± 2.637) × 10-3 mm/Hg, (6.050 ± 2.011) × 10-3 mm/Hg, (4.321 ± 1.717) × 10-3 mm/Hg, respectively (P < .01). There were statistically significant differences in right ventricular function parameters among the 3 groups (P < .05). The correlation analysis between PAD and right ventricular function parameters showed a weak negative correlation (r = -0.281--0.392). The area under the ROC curve of PAD was 0.743, the critical value was 4.200, and the sensitivity and specificity were 62.5% and 94.1%, respectively. The PAD obtained by retrospective ECG-gated CTPA could accurately evaluate APE severity and right ventricular function. As the severity of APE increases, PAD decreases, which is helpful to identify patients at high risk of APE.

High Prevalence of Right Ventricular/Left Ventricular Ratio ≥1 Among Patients Undergoing Computed Tomography Pulmonary Angiography

AIM

Increased ratio between the right and left ventricular (RV/LV) diameters ≥1 is considered an important imaging marker for risk stratification among patients diagnosed with acute pulmonary embolism (PE). Our goal was to assess the prevalence of RV/LV≥1 among consecutive patients undergoing computed tomography pulmonary angiography, and to compare the prevalence of RV/LV≥1 between patients with and without PE.

METHODS

Retrospective analysis of consecutive patients who underwent computed tomography pulmonary angiography due to clinical suspicion of PE between January 1, 2014 and December 31, 2014. The axial RV/LV diameters were measured. The prevalence of RV/LV ≥1 was compared between patients with and without PE and among PE patients, between those with central versus peripheral PE.

RESULTS

The final cohort included 862 patients. A total of 142 (16.5%) had PE. RV/LV ≥1 was found in 553 (64.1%) of all patients, of them in 453 (63%) patients without PE and in 100 (70.4%) patients with PE (P=0.117). On multivariate analysis, PE was not significantly associated with RV/LV ≥1 (odds ratio [OR]: 1.4; 95% confidence interval [CI]: 0.9-2.1; P=0.102). There was no significant difference in the prevalence of RV/LV ≥1 among patients with central versus peripheral PE distribution (79.5% vs. 67%, P=0.101). Older age (OR: 1.03; 95% CI: 1.02-1.04; P<0.001) and male gender (OR: 1.51; 95% CI: 1.11-2.03; P=0.008), among all patients, were significantly associated with RV/LV diameter ≥1.

CONCLUSION

As RV/LV ≥1 is highly prevalent (64.1%), without a significant difference between those with and without PE, an RV/LV ≥1 might not represent the cardiac response to the acute PE event, but rather the patient's baseline condition.

Higher Mortality in Case of Small Left Atrium on Nongated Computed Tomography Pulmonary Angiography Is Associated With the Presence of Malignancy

PURPOSE

The purpose of this study was to evaluate the association between small left atria (LA) according to computed tomography pulmonary angiography (CTPA) and mortality among individuals without pulmonary embolism, and to examine which volumes begin to portend adverse outcomes.

MATERIALS AND METHODS

Left atrial volume indices (LAVIs) of 752 consecutive patients who underwent CTPA, in which pulmonary embolism were ruled out, were measured retrospectively using an automatic 4-chamber volumetric analysis software. Groups of 5 percentiles within the lower quartile were investigated, and the interquartile range (25th to 75th percentiles) was regarded as the control group.

RESULTS

Patients within the lower 25th LAVI percentiles (<33 mL/m2; n=188) were younger and had less cardiovascular morbidities, while malignancies were less common in the control group (LAVI: 33 to 54 mL/m2; n=376). Percentiles 5th to 25th did not demonstrate an independent association with mortality. After adjustment for baseline characteristics, the risk for 30-day and 1-year mortality was 5.6 (95% confidence interval: 2.1-14.8, P=0.001) and 6.1 (95% confidence interval: 2.4-15.1, P<0.001) times higher, respectively, among the lowest five LAVI percentiles (<24 mL/m2) compared with the control group. Among patients with small LA who died within 1 year, 83% had a diagnosis of malignancy. Albeit, only a minority (3%) of patients with malignancies had small LA.

CONCLUSIONS

Individuals undergoing CTPA whose LAVI is within the lowest five percentiles have a markedly increased risk for short-term and long-term mortality. The risk can probably be attributed to an underlying malignancy. The feasibility of 4-chamber volumetric analysis while avoiding a time-consuming process due to the automatic properties enables the introduction of this feature to clinical practice.

Predictive Value of Computed Tomography in Acute Pulmonary Embolism: Systematic Review and Meta-analysis

BACKGROUND

Many computed tomography (CT) parameters have been proposed as potential predictors of outcome in acute pulmonary embolism. We sought to summarize available evidence on the predictive value of CT severity parameters for short-term clinical outcome in pulmonary embolism.

METHODS

We searched PubMed and EMBASE through February 2014 for studies that reported on the association between CT parameters of acute pulmonary embolism severity and short-term (≤6 months) clinical outcome. Risk estimates for quantitative parameters of right ventricular (RV) dysfunction (abnormally increased RV/left ventricular [LV] diameter ratio on transverse sections and 4-chamber views), qualitative parameters of RV dysfunction (abnormal septal morphology and contrast reflux), thrombus load, and central thrombus location were derived using random effect regression analysis. Meta-regression analysis was performed to quantify and explain study heterogeneity.

RESULTS

A total of 49 studies with 13,162 patients with acute pulmonary embolism (median age of 61 years, 55.1% were women) who underwent diagnostic CT imaging were included in the analysis. An abnormally increased RV/LV diameter ratio measured on transverse sections was associated with an approximately 2.5-fold risk for all-cause mortality (pooled odds ratio [OR], 2.5; 95% confidence interval [CI], 1.8-3.5) and adverse outcome (OR, 2.3; 95% CI, 1.6-3.4) and a 5-fold risk for pulmonary embolism-related mortality (OR, 5.0; 95% CI, 2.7-9.2). Thrombus load (OR, 1.6, 95% CI, 0.7-3.9; P = .2896) and central location (OR, 1.7; 95% CI, 0.7-4.2; P = .2609) were not predictive for all-cause mortality, although both were associated with adverse clinical outcome.

CONCLUSIONS

Across all end points, the RV/LV diameter ratio on transverse CT sections has the strongest predictive value and most robust evidence base for adverse clinical outcomes in patients with acute pulmonary embolism.

Pulmonary Hypertension: A Nomogram Based on CT Pulmonary Angiographic Data for Prediction in Patients without Pulmonary Embolism

PURPOSE

To use cardiovascular data from computerized tomographic (CT) pulmonary angiography for facilitating the identification of pulmonary hypertension (PH) in patients without acute pulmonary embolism.

MATERIALS AND METHODS

The institutional human research committee approved this retrospective study; informed consent was waived. Patients without pulmonary embolism who underwent CT pulmonary angiography and echocardiography within 24 hours of each other between December 2008 and October 2012 were retrospectively identified. The diameters of the pulmonary artery, aorta, and right and left ventricles and the severity of reflux of contrast material were assessed. The volumes of each cardiac compartment were calculated. Doppler echocardiography served as a reference standard for PH. A prediction model for PH was built by using backward logistic regression and was presented on a nomogram. The prediction model was evaluated with 10-fold cross-validation, and a test group of patients was studied between November 2012 and June 2014.

RESULTS

The final study group included 182 patients, of whom 98 (54%) were given a diagnosis of PH on the basis echocardiographic results. Age of 67 years or older (odds ratio [OR] = 4.46), reflux grade of 3 or higher (OR = 2.63), right atrial volume of greater than or equal to 106 cm(3) (OR = 3.59), pulmonary artery diameter greater than or equal to 28 mm (OR = 2.52) and pulmonary artery diameter to aorta diameter ratio of greater than or equal to 0.86 (OR = 2.17) were independently associated with PH. The logistic model showed good discrimination ability (area under the curve = 0.844, discrimination slope = 0.359). Tenfold cross-validation showed 85.7% sensitivity, 60.7% specificity, 71.3% positive predictive value, and 76.1% negative predictive value for identification of PH, while the test group showed similar results (84.1%, 60.5%, 71.2%, and 76.7%, respectively).

CONCLUSION

Cardiovascular data derived from CT pulmonary angiography are associated with PH, and a nomogram can be created that may facilitate identification of PH after exclusion of acute pulmonary embolism.

Performance of Automated Software in the Assessment of Segmental Left Ventricular Function in Cardiac CT: Comparison with Cardiac Magnetic Resonance

OBJECTIVE

To evaluate the accuracy, reliability and time saving potential of a novel cardiac CT (CCT)-based, automated software for the assessment of segmental left ventricular function compared to visual and manual quantitative assessment of CCT and cardiac magnetic resonance (CMR).

METHODS

Forty-seven patients with suspected or known coronary artery disease (CAD) were enrolled in the study. Wall thickening was calculated. Segmental LV wall motion was automatically calculated and shown as a colour-coded polar map. Processing time for each method was recorded.

RESULTS

Mean wall thickness in both systolic and diastolic phases on polar map, CCT, and CMR was 9.2 ± 0.1 mm and 14.9 ± 0.2 mm, 8.9 ± 0.1 mm and 14.5 ± 0.1 mm, 8.3 ± 0.1 mm and 13.6 ± 0.1 mm, respectively. Mean wall thickening was 68.4 ± 1.5 %, 64.8 ± 1.4 % and 67.1 ± 1.4 %, respectively. Agreement for the assessment of LV wall motion between CCT, CMR and polar maps was good. Bland-Altman plots and ICC indicated good agreement between CCT, CMR and automated polar maps of the diastolic and systolic segmental wall thickness and thickening. The processing time using polar map was significantly decreased compared with CCT and CMR.

CONCLUSION

Automated evaluation of segmental LV function with polar maps provides similar measurements to manual CCT and CMR evaluation, albeit with substantially reduced analysis time.

KEY POINTS

• Cardiac computed tomography (CCT) can accurately assess segmental left ventricular wall function. • A novel automated software permits accurate and fast evaluation of wall function. • The software may improve the clinical implementation of segmental functional analysis.

Prognostic role of embolic burden assessed at computed tomography angiography in patients with acute pulmonary embolism: systematic review and meta-analysis

BACKGROUND

In patients with acute pulmonary embolism (PE), risk stratification is indicated for tailoring of both diagnostic strategies and acute treatment. Whether embolic burden assessed at computed tomography (CT) angiography has a role in risk stratification in these patients is debated.

OBJECTIVE

To systematically review and perform a meta-analysis to evaluate the role of CT-assessed burden associated with embolic obstruction and embolic localization in the prognostic stratification of patients with acute PE.

METHODS

We performed a systematic search in EMBASE and MEDLINE up until 30 June 2013. Studies reporting on the 30-day outcome of patients with confirmed PE and CT-assessed embolic burden were included. The study outcome was death.

RESULTS

Thirty studies reporting on the prognostic value of CT-assessed embolic burden met the inclusion criteria for this systematic review; of these, 19 were included in the meta-analysis. Five studies (2215 patients) were included in the analysis of localization: an association between embolus localization in the central arteries and 30-day mortality was found after heterogeneity was resolved (odds ratio [OR] 2.24, 95% confidence interval [CI] 1.29-3.89, I(2)  = 0%). No correlation was observed between obstruction index (according to the Qanadli scoring system) and 30-day mortality after heterogeneity was reduced (16 studies, 3884 patients, OR 1.22, 95% CI 0.99-1.51, I(2)  = 27%).

CONCLUSION

Localization of emboli assessed at CT angiography can be used for risk stratification in patients with acute PE. Moreover, no correlation was observed between obstruction index and prognosis.

Computed tomography-assessed right ventricular dysfunction and risk stratification of patients with acute non-massive pulmonary embolism: systematic review and meta-analysis

BACKGROUND

The ability of computed tomography (CT)-assessed right ventricular dysfunction (RVD) to identify normotensive patients with acute pulmonary embolism (PE) at high risk of mortality or adverse outcome lacks clarity.

METHODS AND RESULTS

We performed a systematic review and a meta-analysis of studies in normotensive patients with acute PE to assess the prognostic value of CT-assessed RVD for death and a predefined composite outcome of PE-related complications. We conducted unrestricted searches of MEDLINE and EMBASE from 1980 to March 2013, and used the terms 'computed tomography', 'pulmonary embolism', and 'prognos*'. We used a random-effects model to pool study results, funnel-plot inspection to evaluate for publication bias, and I(2) testing to assess for heterogeneity. The analysis included data from 10 studies (2288 patients). Overall, 99 of 1268 patients with RVD assessed by CT died (7.8%; 95% confidence interval [CI] 6.3-9.3) as compared with 52 of 1020 without RVD (5.1%; 95% CI 3.7-6.4). CT-assessed RVD had significant associations with mortality (odds ratio [OR] 1.8; 95% CI 1.3-2.6), with death resulting from PE (OR 7.4; 95% CI 1.4-39.5), and with PE-related complications (OR 2.4; 95% CI 1.2-4.7). Pooled likelihood ratios (LRs) were not extreme (negative LR 0.71; 95% CI 0.57-0.89; and positive LR 1.27; 95% CI 1.12-1.43).

CONCLUSIONS

Although RVD assessed by CT showed an association with an increased risk of mortality in patients with hemodynamically stable PE, it resulted in only small increases in the ability to classify risk.

Evaluation factors of pulmonary embolism severity and prognosis

Management of pulmonary embolism (PE) is still unclear. We summarized 16 kinds of evaluation factors of PE severity and prognosis, and we analyzed the single and joint value for short-term and long-term prognosis. Among them, biomarkers such as brain natriuretic peptide or N-terminal probrain natriuretic peptide, troponin, and heart-type fatty acid-binding protein are the best indicators of PE severity and short-term prognosis. They might replace imaging detections in evaluating PE severity. But the positive predictive value of all the biomarkers is low, and we need to improve each value through joint detection. The PE severity index and simplified PE severity index are more suitable for evaluating the overall risk and long-term prognosis. They could be used as complements of indicators of the PE severity, especially in identifying low-risk group. Integrated risk stratification and strategies of management should be established based on the 2 aspects mentioned previously.

Medical emergencies: pulmonary embolism and acute severe asthma

In this, the second of two articles covering specific medical emergencies, we discuss the definitions, epidemiology, pathophysiology, acute and chronic management of pulmonary embolus and acute severe asthma.