Pulmonary embolism (PE), a critical condition characterized by the blockage of pulmonary arteries, demands swift and accurate diagnosis for effective intervention. In the landscape of diagnostic modalities, Computed Tomography Pulmonary Angiography (CTPA) has emerged as the Gold Standard For Pe Diagnosis. This article delves into the significance of CTPA, drawing upon a retrospective study that evaluated the role of unenhanced Multidetector Computed Tomography (MDCT) in comparison to the established gold standard.
This study, conducted at Chi-Mei Medical Center between 2010 and 2013, focused on patients admitted to the emergency department with suspected PE. Ethical approval was secured, with informed consent waived due to the study’s retrospective nature. The research specifically targeted acute central PE, a form associated with severe hemodynamic instability and high mortality, emphasizing the urgency for precise diagnostic tools. Central PE was defined as thrombus presence in the main, left, or right pulmonary artery, excluding chronic cases characterized by specific radiological markers like calcified thrombus and pulmonary artery alterations. Patients lacking CTPA or MDCT scans, or those with incomplete data for Wells score calculation, were excluded to maintain data integrity.
The diagnostic protocol at the institution included a non-enhanced CT scan followed by CTPA and a venous phase contrast-enhanced CT when PE was suspected. The study group comprised patients confirmed with acute, central PE via CTPA who also underwent non-enhanced MDCT. A control group, confirmed to be PE-negative by CTPA, was randomly selected from the same period. Patient records were initially identified using the ICD-9 code for pulmonary embolism (415.1) and subsequently reviewed by radiologists on a PACS workstation to confirm acute, central PE diagnosis based on CTPA findings.
Alt text: CTPA scan revealing a pulmonary embolism in a major pulmonary artery, highlighting the diagnostic capability of CTPA.
The imaging analysis was performed using a Toshiba Aquilion 64 Slice CT scanner, encompassing both unenhanced and enhanced scans. Image slice thickness ranged from 3 to 5 mm across examinations. Two experienced radiologists, blinded to patient history and clinical data, independently reviewed all MDCT images. Discrepancies were resolved through consensus, and unresolved cases were excluded to ensure diagnostic accuracy. The radiologists focused solely on non-contrast images to prevent bias from contrast-enhanced results. Three key radiological features on unenhanced MDCT were assessed against the Wells score: high-attenuation emboli in the pulmonary artery, main pulmonary artery dilatation exceeding 33.2 mm, and peripheral wedge-shaped consolidation. Patient inclusion required agreement on all features by both radiologists, underscoring the rigorous image interpretation process.
Alt text: Unenhanced MDCT image displaying potential indicators of pulmonary embolism, such as increased density in the pulmonary arteries, in comparison to the gold standard CTPA.
The Wells score, a clinical prediction rule, was calculated based on seven established variables [20]. These variables include clinical signs of deep vein thrombosis (DVT), absence of alternative diagnosis, heart rate exceeding 100 bpm, recent immobilization or surgery, prior DVT/PE, hemoptysis, and malignancy. Each variable is assigned a specific score, and the cumulative score determines the likelihood of PE. A score of ≤4 categorized PE as unlikely. Data for Wells score calculation were meticulously extracted from medical records, with cases excluded if any variable data was missing to maintain the integrity of the scoring process.
Statistical analysis employed CTPA as the definitive diagnostic benchmark – the gold standard for PE diagnosis. Categorical data were presented as numbers and percentages, and Fisher’s exact test was used to assess associations between Wells score components, unenhanced MDCT findings, and PE. Logistic regression analyses explored the relationship between CTPA-confirmed PE, Wells score, and the number of unenhanced MDCT findings, alongside individual MDCT features. Multivariate logistic regression, incorporating Wells score, MDCT findings count, patient age, and sex, was performed to identify significant independent predictors of PE diagnosis. The number of positive unenhanced MDCT findings was treated as a continuous variable in the regression model. Odds ratios (ORs) were derived from logistic regression. Receiver Operating Characteristic (ROC) curve analysis evaluated the diagnostic performance of unenhanced MDCT for PE detection. The area under the ROC curve (AUC) for unenhanced MDCT was compared to that of the Wells score using DeLong’s method [31]. Sensitivity, specificity, positive likelihood ratio (PLR), positive predictive value (PPV), negative likelihood ratio (NLR), and negative predictive value (NPV), along with their 95% confidence intervals (CIs), were calculated for each unenhanced MDCT finding in PE diagnosis. ROC curve analyses were conducted using MedCalc, and statistical analyses were performed using IBM SPSS software, with a p-value of <0.05 considered statistically significant.
In conclusion, this study underscores CTPA’s role as the gold standard for diagnosing pulmonary embolism. While unenhanced MDCT and clinical scoring systems like the Wells score can provide valuable insights, CTPA remains the most definitive and reliable method for confirming PE, especially in acute central cases requiring immediate and accurate diagnosis to improve patient outcomes.
