Comparison of computed tomography in relation to ventilation perfusion scan in the diagnosis of pulmonary embolism

Introduction: Pulmonary embolism is still a challenge in diagnosis due to its variable and non-specific symptoms. Computed tomography and ventilation/perfusion scanning are the modalities most commonly used in the diagnosis of pulmonary embolism, and both modalities have their advantages and disadvantages. One of the most important factors in the assessment and localization of pulmonary embolism is the diagnostic accuracy of these modalities, which serves to model different diagnostic strategies in the diagnosis of pulmonary embolism. Material and methods: The research was conducted as a review of professional literature available in scientific research databases. A selection of 20 professional papers was made, based on which an analysis was conducted and a database was formed. Criteria for inclusion in the research were scientific research papers that report on the sensitivity and specificity of diagnostic modalities of CT and V/P scanning as well as the results of diagnostic tests based on which the comparison of data from two modalities determined a diagnostically more accurate modality. Results: Sensitivity of 91.89% and specificity of 98.86% and diagnostic accuracy of 94.83% were determined in the case of computed tomography. Sensitivity of 90.58% and specificity of 98.

Computed tomography is still the number one method of choice in clinics around the world, but what can be noticed is that the comparison of computed tomography and ventilation/ perfusion scanning in the diagnosis of pulmonary embolism, which is also the subject of this paper, is the subject of more scientific papers and discussions.

Material and methods
The study is designed as a review of the pri-

Results
We conducted a bias free assessment for diagnostic test accuracy studies using a revised diagnostic accuracy study quality assessment tool-2. Signal questions are included to help assess the risk of bias (4). The risk of bias is assessed as "low", "high" or "unclear".
Data from 10 relevant studies according to the table below were used to analyze the sensitivity and specificity of computed tomography in the diagnosis of pulmonary embolism. The table lists the names of the studies and the reliability estimates for each of the studies where sensitivity and specificity were tested (with a 95% C.I.): 12  Udruženje inžinjera medicinske radiologije u FBiH Radiološke tehnologije -Časopis iz oblasti radiološke tehnologije, Volumen 13, Decembar/Prosinac 2022. godine

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For each of these studies, we obtained data on truly positive and negative patients, and false positive and negative patients, which allows us to further analyze the sensitivity and specificity of computed tomography and calculate the necessary parameters (table below).  14 Sensitivity represents the likelihood that a person will be classified by the model as ill if she really is. If the sensitivity were 100%, the model would be correctly classified by all patients, which would mean that the model in terms of sensitivity is set ideally. In our case, the sensitivity is 91.89%, which means that computed tomography in the diagnosis of pulmonary embolism per 100 people we know to have 91.89 (≈92) will make the correct diagnosis.
Specificity is the probability that a model will not classify a person as ill if he or she is not really ill.
If the specificity were 100% it would mean that the model 'recognized' all those who were not sick and classified them correctly. In our case, the specificity is 96.86%, which would mean that in 96.89% (≈97) cases, computed tomography in the diagnosis of pulmonary embolism declares healthy patients healthy, which is a very good result in the diagnosis.
Since the specificity is higher than the sensitivity, it can be concluded that this model is better in the diagnosis of pulmonary embolism in recognizing and classifying those who are not ill.
Data from 10 other relevant studies according to the table below was used to analyze the sensitivity and specificity of ventilation / perfusion scanning in the diagnosis of pulmonary embolism. The table lists the names of the studies and the reliability estimates for each of the studies where sensitivity and specificity were tested (with a 95% C.I.). For each of the studies, we obtained data on truly positive and negative persons, and false positive and negative persons, which allows us to further analyze the sensitivity and specificity of venous perfusion scanning and calculate the necessary parameters (table below).  The sensitivity in ventilation / perfusion scanning in the diagnosis of pulmonary embolism is 90.58%, which is again a very high sensitivity, although slightly lower than in computed tomography. This would mean that a ventilatory / perfusion scan in the diagnosis of pulmonary embolism per 100 people we know to have 90.58 (≈91) will correctly diagnose.
The specificity of ventilation / perfusion scanning in the diagnosis of pulmonary embolism is 98.33%, which is the highest measure of diagnostic accuracy in this study. Again, specificity is greater than sensitivity, which means that even in ventilation / perfusion scanning in the diagnosis of pulmonary embolism, the model is more likely to recognize and correctly classify healthy people than sick ones. The accuracy of the diagnostic procedure gives us the answer to the question of how well this test distinguishes two conditions or traits (in our case, sick people from healthy people). For the calculation, we use truly positive and negative patients in relation to the total sample.
In our study, we calculated the accuracy for both diagnostic procedures. The calculated accuracy in computed tomography in the diagnosis of pulmonary embolism is 94.83%, while the accuracy in ventilation / perfusion scanning is 96.43%.
From the above we can conclude that the use of ventilation / perfusion scanning in the diagnosis of pulmonary embolism is more accurate than computed tomography with an accuracy greater than 1.6% in favor of ventilation / perfusion scanning. Since this difference is very small (1.6%), we can conclude that both diagnostic modalities have a high level of accuracy in the diagnosis of pulmonary embolism.
We found that both diagnostic procedures had a high level of accuracy. Also, for both models we can conclude that they will better recognize and correctly classify healthy people than sick ones (higher specificity in relation to sensitivity), with this percentage being higher in ventilation / perfusion scanning in the diagnosis of pulmonary embolism (98.33% in relation to at 96.86%). According to the obtained results, computed tomography is a slightly more precise procedure in the diagnosis of pulmonary embolism in sick people (91.89% of them will make the correct diagnosis, while the percentage of ventilation / perfusion scan is 90.58%).

Disscusion
The review paper included 20 professional articles, 10 professional articles in the field of radiodiag- In this paper, a sensitivity of 83% was determined in relation to the specificity of 96% in the case of computed tomography, while in the case of ventilatory perfusion scanning a sensitivity of 85% was determined in relation to the specificity of 93% (6). The difference in diagnostic inferiority of these two modalities in most cases is not large deviations, which was found in the work of Anderson et al.
In 2007 in a study of 1400 patients, but most pulmonary embolism was diagnosed using computed tomography (7). As the two most common diagnostic methods in the diagnosis of pulmonary embolism, CT angiography of the lungs and V / P lung scanning are the subject of many scientific papers, patients, sensitivity and specificity were found to be 85% and 93% in the case of ventilatory perfusion lung scan, while computed tomography of the lungs was found to be 85% sensitive and 90% specific.
The results of this study indicate that ventilatory perfusion scanning is slightly superior to computed tomography with an established accuracy of 88% compared to 86% in the diagnosis of pulmonary embolism (9). According to the obtained results of the research, as well as the observed researches of other authors, ventilation / perfusion scanning in the diagnosis of pulmonary embolism has a slightly Print: ISSN 2232-8726 Online: ISSN 2637-3297 Udruženje inžinjera medicinske radiologije u FBiH Radiološke tehnologije -Časopis iz oblasti radiološke tehnologije, Volumen 13, Decembar/Prosinac 2022. godine 19 higher percentage of accuracy compared to the use of computed tomography. But as the difference between the diagnostic modalities in both this study and the above is very small, we can say with certainty that both modalities have high diagnostic accuracy.

Conclusion
Ventilation/perfusion lung scanning will better identify healthy individuals while on the other hand we can conclude that computed tomography is more accurate in diagnosing embolism in sick individuals.
We can conclude that both diagnostic procedures have a high level of accuracy.