Computed Tomography Pulmonary Angiography Results Research Articles

The Value of CTPA for Diagnosing Acute Pulmonary Thromboembolism and the Ensuing Right Ventricular Dysfunction

The value of computed tomography pulmonary angiography (CTPA) for the diagnosis of right ventricular dysfunction (RVD) subsequent to acute pulmonary embolism (PE). The ultrasonic cardiography (UCG) was used to assess RVD, one of the diagnostic criteria of PE caused hemodynamic collapse. Seventy six patients with confirmed PE were divided into massive (52 cases) and non-massive PE group (24 cases). The diagnostic criteria assessed for the imminent RVD were: (1) the ratio of axial diameters of the right and left ventricular chambers (RVd/LVd) exceeding 1, or (2) the right ventricular end-diastolic diameter measuring >30 mm. The CTPA diagnosed RVD was positive in 36 and negative in 40 cases. The RVD assessed by UCG was positive in 31 and negative in 45 cases. In comparison to UCG, the CTPA results UCG exhibited 96.77 % sensitivity 96.77 % and 86.67 specificity. The evaluated values both of these techniques were found in good agreement by the kappa value (κ) of 0.81, P < 0.001. In 52 cases of massive PE, CTPA determined RVD was positive in 34, and negative in 18 cases. In comparison, UCG diagnosed RVD was positive in 31 and negative in 21 cases. The sensitivity and specificity of CTPA results compared to those of UCG were 91.18 and 85.71 %, respectively. The estimates obtained were in good agreement as indicated by 0.88 κ value and P < 0.001. Twenty four cases of non-massive PE were RVD negative when assessed by CTPA, UCG however showed two cases positive in this group. Compared to UCG, the specificity of CTPA in evaluating RVD was 100 %. In the massive PE group, the average estimate of RVd/LVd ratio was significantly higher than 1 as analyzed by the non-parametric Mann-Whitney test (P < 0.001). The CTPA and UCG results showed a good correlation in massive PE cases. However, in non-massive PE group, results from two techniques were not correlated. The CTPA can accurately and reliably diagnose the PE and ensuing by estimating changes in the anatomical parameters of right ventricle. Hence, it can allow prompt diagnosis and an appropriate treatment leading to an improved prognosis.

Predicting Pulmonary Embolus in Orthopedic Trauma Patients Using the Wells Score

The decision to perform computed tomography pulmonary angiography (CTPA) to rule out pulmonary embolism (PE) in orthopedic trauma patients is challenging. The Wells score is a commonly used clinical probability tool developed to determine the likelihood of PE and assist in determining the need for CTPA examination. This study evaluated the usefulness of the Wells score for predicting PE in patients admitted to the orthopedic trauma service. All patients who were admitted to the orthopedic trauma service at the authors' institution between 2001 and 2011 who underwent CTPA were identified. The Wells score was calculated retrospectively for each patient, and risk categories using the traditional and alternative interpretations of the Wells score were assigned. Pulmonary embolism was diagnosed in 27 (16%) of 169 patients who underwent CTPA. In total, 27 (0.39%) of 6854 patients admitted to the orthopedic trauma service were diagnosed with PE during initial hospitalization. Mean Wells score was 3.31 (95% confidence interval, ±.28) for the entire population, 3.32 for those without PE (95% confidence interval, ±.31), and 3.28 for those with PE (95% confidence interval, ±.72) (P=.91). Average times from admission to CTPA examination for those with and without PE were 6.18 and 5.7 days, respectively (P=.94). No significant correlation existed between the Wells score and CTPA results, indicating that the Wells score is limited in predicting PE risk in orthopedic trauma patients.

Evaluation of the Utility of the Wells Score in Predicting Pulmonary Embolism in Patients Admitted to a Spine Surgery Service

Study Design: A retrospective medical chart review of 4179 patients admitted to the spine surgery service. Objective: To evaluate the utility of the Wells score in predicting pulmonary embolism (PE) in patients admitted to a spine surgery service. Summary of Background Data: The decision to perform computed tomography pulmonary angiography (CTPA) to diagnose PE in patients who have undergone spine surgery requires consideration of multiple factors: false-positive CTPA results may lead to unnecessary anticoagulation treatment, and computed tomography scans are costly and expose patients to ionizing radiation. The Wells score was developed to assign risk categories to patients with suspected PE and thereby indicate the need for CTPA. However, the utility of the Wells score in predicting the likelihood of PE, specifically in spine surgery patients, has not been described to date. We identified all patients who were admitted to the spine surgery service at our institution from January 1, 2001 to December 31, 2011 and underwent CTPA. Each patient's CTPA result was classified as positive or negative for PE, and the reason for ordering the CTPA was recorded. The Wells score was calculated retrospectively for each patient, and risk categories were assigned by using the traditional and alternative interpretations of the Wells score. The reason for the CTPA, the Wells score, and Wells risk category were compared for patients who were classified as being positive or negative for PE. Results: Sixty-six of the 4179 patients who were admitted to the spine surgery service underwent CTPA for suspected PE. Nineteen of the 66 patients (28.8%) were diagnosed with acute PE, and the overall PE rate was 0.45% (19 of 4179 patients). The mean Wells score for patients diagnosed with PE was 5.3, whereas the mean score for the remaining patients was 4.9 (P = 0.793). Neither the traditional nor the alternative interpretation of the Wells score was predictive of PE (P = 0.394 and P = 0.178, respectively). Our study examined the utility of the Wells score in predicting PE in spine surgery patients. Conclusion: The results of the CTPA did not show a significant correlation with the Wells score or the reason for the test. Our findings indicate the need to develop a predictive scoring system that assesses the risk of PE and assists in the decision-making process for ordering CTPA in spine surgery patients.

Implementation of a clinical prediction tool for pulmonary embolism diagnosis in a tertiary teaching hospital reduces the number of computed tomography pulmonary angiograms performed

To evaluate the effect of implementing the Wells score clinical prediction tool (CPT) on rationalising the use of computed tomography pulmonary angiography (CTPA) for diagnosing pulmonary embolism (PE). Within a tertiary teaching hospital, a retrospective study was conducted applying Wells score to all CTPA ordered in the first quarter of 2007. Subsequently, an algorithm including Wells score and d-dimer assay was developed to assist clinicians in rationalising their ordering of CTPA. A prospective study was performed from February to August 2009 to assess the impact of this algorithm. CTPA results, d-dimer levels, referral sources and dates were recorded. The number of CTPA performed over a 7-month period following implementation of the algorithm was compared with the same period during the previous year. PE prevalence within each risk category was compared with the published literature. Three hundred and thirty-three patients were investigated with CTPA in the prospective study period. Two hundred and sixty-eight patients (80.4% of cases) had complete data. The prevalence of PE in the present study was 13.8% with 57 (21.2%) patients stratified to low risk, 169 (63.0%) to intermediate risk and 42 (15.6%) to high risk. Subgroup prevalence was 8.8%, 11.8% and 23.8% respectively. Compared with the same period in 2008, 121 (26.6%) less CTPA were performed. Institutional implementation of a clinical prediction tool into the decision-making process is feasible and significantly reduces the number of CTPA being performed, with substantial cost savings and patient benefits.

Correlation between the clinical pretest probability score and the lung ventilation and perfusion scan probability.

Purpose:Aim of the study was to determine the accuracy of the clinical pretest probability (PTP) score and its association with lung ventilation and perfusion (VQ) scan.Materials and Methods:A retrospective analysis of 510 patients who had a lung VQ scan between 2008 and 2010 were included in the study. Out of 510 studies, the number of normal, low, and high probability VQ scans were 155 (30%), 289 (57%), and 55 (11%), respectively.Results:A total of 103 patients underwent computed tomography pulmonary angiography (CTPA) scan in which 21 (20%) had a positive scan, 81 (79%) had a negative scan and one (1%) had an equivocal result. The rate of PE in the normal, low-probability, and high-probability scan categories were: 2 (9.5%), 10 (47.5%), and 9 (43%) respectively. A very low correlation (Pearson correlation coefficient r = 0.20) between the clinical PTP score and lung VQ scan. The area under the curve (AUC) of the clinical PTP score was 52% when compared with the CTPA results. However, the accuracy of lung VQ scan was better (AUC = 74%) when compared with CTPA scan.Conclusion:The clinical PTP score is unreliable on its own; however, it may still aid in the interpretation of lung VQ scan. The accuracy of the lung VQ scan was better in the assessment of underlying pulmonary embolism (PE).